for Journals by Title or ISSN
for Articles by Keywords

Publisher: Oxford University Press   (Total: 369 journals)

 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  

        1 2 | Last   [Sort by number of followers]   [Restore default list]

Showing 1 - 200 of 369 Journals sorted alphabetically
Acta Biochimica et Biophysica Sinica     Hybrid Journal   (Followers: 6, SJR: 0.881, h-index: 38)
Adaptation     Hybrid Journal   (Followers: 8, SJR: 0.111, h-index: 4)
Aesthetic Surgery J.     Hybrid Journal   (Followers: 6, SJR: 1.538, h-index: 35)
African Affairs     Hybrid Journal   (Followers: 57, SJR: 1.512, h-index: 46)
Age and Ageing     Hybrid Journal   (Followers: 79, SJR: 1.611, h-index: 107)
Alcohol and Alcoholism     Hybrid Journal   (Followers: 14, SJR: 0.935, h-index: 80)
American Entomologist     Full-text available via subscription   (Followers: 5)
American Historical Review     Hybrid Journal   (Followers: 120, SJR: 0.652, h-index: 43)
American J. of Agricultural Economics     Hybrid Journal   (Followers: 41, SJR: 1.441, h-index: 77)
American J. of Epidemiology     Hybrid Journal   (Followers: 146, SJR: 3.047, h-index: 201)
American J. of Hypertension     Hybrid Journal   (Followers: 19, SJR: 1.397, h-index: 111)
American J. of Jurisprudence     Hybrid Journal   (Followers: 15)
American journal of legal history     Full-text available via subscription   (Followers: 4, SJR: 0.151, h-index: 7)
American Law and Economics Review     Hybrid Journal   (Followers: 26, SJR: 0.824, h-index: 23)
American Literary History     Hybrid Journal   (Followers: 12, SJR: 0.185, h-index: 22)
Analysis     Hybrid Journal   (Followers: 23)
Annals of Botany     Hybrid Journal   (Followers: 33, SJR: 1.912, h-index: 124)
Annals of Occupational Hygiene     Hybrid Journal   (Followers: 24, SJR: 0.837, h-index: 57)
Annals of Oncology     Hybrid Journal   (Followers: 48, SJR: 4.362, h-index: 173)
Annals of the Entomological Society of America     Full-text available via subscription   (Followers: 9, SJR: 0.642, h-index: 53)
Annals of Work Exposures and Health     Hybrid Journal  
AoB Plants     Open Access   (Followers: 4, SJR: 0.78, h-index: 10)
Applied Economic Perspectives and Policy     Hybrid Journal   (Followers: 18, SJR: 0.884, h-index: 31)
Applied Linguistics     Hybrid Journal   (Followers: 51, SJR: 1.749, h-index: 63)
Applied Mathematics Research eXpress     Hybrid Journal   (Followers: 1, SJR: 0.779, h-index: 11)
Arbitration Intl.     Full-text available via subscription   (Followers: 19)
Arbitration Law Reports and Review     Hybrid Journal   (Followers: 12)
Archives of Clinical Neuropsychology     Hybrid Journal   (Followers: 25, SJR: 0.96, h-index: 71)
Aristotelian Society Supplementary Volume     Hybrid Journal   (Followers: 2, SJR: 0.102, h-index: 20)
Arthropod Management Tests     Hybrid Journal   (Followers: 2)
Astronomy & Geophysics     Hybrid Journal   (Followers: 46, SJR: 0.144, h-index: 15)
Behavioral Ecology     Hybrid Journal   (Followers: 47, SJR: 1.698, h-index: 92)
Bioinformatics     Hybrid Journal   (Followers: 222, SJR: 4.643, h-index: 271)
Biology Methods and Protocols     Hybrid Journal  
Biology of Reproduction     Full-text available via subscription   (Followers: 10, SJR: 1.646, h-index: 149)
Biometrika     Hybrid Journal   (Followers: 18, SJR: 2.801, h-index: 90)
BioScience     Hybrid Journal   (Followers: 28, SJR: 2.374, h-index: 154)
Bioscience Horizons : The National Undergraduate Research J.     Open Access   (Followers: 1, SJR: 0.213, h-index: 9)
Biostatistics     Hybrid Journal   (Followers: 15, SJR: 1.955, h-index: 55)
BJA : British J. of Anaesthesia     Hybrid Journal   (Followers: 132, SJR: 2.314, h-index: 133)
BJA Education     Hybrid Journal   (Followers: 65, SJR: 0.272, h-index: 20)
Brain     Hybrid Journal   (Followers: 61, SJR: 6.097, h-index: 264)
Briefings in Bioinformatics     Hybrid Journal   (Followers: 43, SJR: 4.086, h-index: 73)
Briefings in Functional Genomics     Hybrid Journal   (Followers: 4, SJR: 1.771, h-index: 50)
British J. for the Philosophy of Science     Hybrid Journal   (Followers: 32, SJR: 1.267, h-index: 38)
British J. of Aesthetics     Hybrid Journal   (Followers: 24, SJR: 0.217, h-index: 18)
British J. of Criminology     Hybrid Journal   (Followers: 489, SJR: 1.373, h-index: 62)
British J. of Social Work     Hybrid Journal   (Followers: 77, SJR: 0.771, h-index: 53)
British Medical Bulletin     Hybrid Journal   (Followers: 7, SJR: 1.391, h-index: 84)
British Yearbook of Intl. Law     Hybrid Journal   (Followers: 26)
Bulletin of the London Mathematical Society     Hybrid Journal   (Followers: 3, SJR: 1.474, h-index: 31)
Cambridge J. of Economics     Hybrid Journal   (Followers: 55, SJR: 0.957, h-index: 59)
Cambridge J. of Regions, Economy and Society     Hybrid Journal   (Followers: 9, SJR: 1.067, h-index: 22)
Cambridge Quarterly     Hybrid Journal   (Followers: 10, SJR: 0.1, h-index: 7)
Capital Markets Law J.     Hybrid Journal  
Carcinogenesis     Hybrid Journal   (Followers: 2, SJR: 2.439, h-index: 167)
Cardiovascular Research     Hybrid Journal   (Followers: 11, SJR: 2.897, h-index: 175)
Cerebral Cortex     Hybrid Journal   (Followers: 37, SJR: 4.827, h-index: 192)
CESifo Economic Studies     Hybrid Journal   (Followers: 15, SJR: 0.501, h-index: 19)
Chemical Senses     Hybrid Journal   (Followers: 1, SJR: 1.436, h-index: 76)
Children and Schools     Hybrid Journal   (Followers: 5, SJR: 0.211, h-index: 18)
Chinese J. of Comparative Law     Hybrid Journal   (Followers: 3)
Chinese J. of Intl. Law     Hybrid Journal   (Followers: 19, SJR: 0.737, h-index: 11)
Chinese J. of Intl. Politics     Hybrid Journal   (Followers: 8, SJR: 1.238, h-index: 15)
Christian Bioethics: Non-Ecumenical Studies in Medical Morality     Hybrid Journal   (Followers: 11, SJR: 0.191, h-index: 8)
Classical Receptions J.     Hybrid Journal   (Followers: 17, SJR: 0.1, h-index: 3)
Clinical Infectious Diseases     Hybrid Journal   (Followers: 58, SJR: 4.742, h-index: 261)
Clinical Kidney J.     Open Access   (Followers: 4, SJR: 0.338, h-index: 19)
Community Development J.     Hybrid Journal   (Followers: 23, SJR: 0.47, h-index: 28)
Computer J.     Hybrid Journal   (Followers: 8, SJR: 0.371, h-index: 47)
Conservation Physiology     Open Access   (Followers: 1)
Contemporary Women's Writing     Hybrid Journal   (Followers: 11, SJR: 0.111, h-index: 3)
Contributions to Political Economy     Hybrid Journal   (Followers: 6, SJR: 0.313, h-index: 10)
Critical Values     Full-text available via subscription  
Current Legal Problems     Hybrid Journal   (Followers: 25)
Current Zoology     Full-text available via subscription   (SJR: 0.999, h-index: 20)
Database : The J. of Biological Databases and Curation     Open Access   (Followers: 11, SJR: 1.068, h-index: 24)
Digital Scholarship in the Humanities     Hybrid Journal   (Followers: 12)
Diplomatic History     Hybrid Journal   (Followers: 18, SJR: 0.296, h-index: 22)
DNA Research     Open Access   (Followers: 4, SJR: 2.42, h-index: 77)
Dynamics and Statistics of the Climate System     Open Access   (Followers: 2)
Early Music     Hybrid Journal   (Followers: 13, SJR: 0.124, h-index: 11)
Economic Policy     Hybrid Journal   (Followers: 47, SJR: 2.052, h-index: 52)
ELT J.     Hybrid Journal   (Followers: 25, SJR: 1.26, h-index: 23)
English Historical Review     Hybrid Journal   (Followers: 45, SJR: 0.311, h-index: 10)
English: J. of the English Association     Hybrid Journal   (Followers: 12, SJR: 0.144, h-index: 3)
Environmental Entomology     Full-text available via subscription   (Followers: 11, SJR: 0.791, h-index: 66)
Environmental Epigenetics     Open Access   (Followers: 1)
Environmental History     Hybrid Journal   (Followers: 25, SJR: 0.197, h-index: 25)
EP-Europace     Hybrid Journal   (Followers: 1, SJR: 2.201, h-index: 71)
Epidemiologic Reviews     Hybrid Journal   (Followers: 9, SJR: 3.917, h-index: 81)
ESHRE Monographs     Hybrid Journal  
Essays in Criticism     Hybrid Journal   (Followers: 15, SJR: 0.1, h-index: 6)
European Heart J.     Hybrid Journal   (Followers: 46, SJR: 6.997, h-index: 227)
European Heart J. - Cardiovascular Imaging     Hybrid Journal   (Followers: 9, SJR: 2.044, h-index: 58)
European Heart J. - Cardiovascular Pharmacotherapy     Full-text available via subscription   (Followers: 1)
European Heart J. - Quality of Care and Clinical Outcomes     Hybrid Journal  
European Heart J. Supplements     Hybrid Journal   (Followers: 8, SJR: 0.152, h-index: 31)
European J. of Cardio-Thoracic Surgery     Hybrid Journal   (Followers: 7, SJR: 1.568, h-index: 104)
European J. of Intl. Law     Hybrid Journal   (Followers: 141, SJR: 0.722, h-index: 38)
European J. of Orthodontics     Hybrid Journal   (Followers: 4, SJR: 1.09, h-index: 60)
European J. of Public Health     Hybrid Journal   (Followers: 22, SJR: 1.284, h-index: 64)
European Review of Agricultural Economics     Hybrid Journal   (Followers: 12, SJR: 1.549, h-index: 42)
European Review of Economic History     Hybrid Journal   (Followers: 25, SJR: 0.628, h-index: 24)
European Sociological Review     Hybrid Journal   (Followers: 37, SJR: 2.061, h-index: 53)
Evolution, Medicine, and Public Health     Open Access   (Followers: 11)
Family Practice     Hybrid Journal   (Followers: 13, SJR: 1.048, h-index: 77)
Fems Microbiology Ecology     Hybrid Journal   (Followers: 8, SJR: 1.687, h-index: 115)
Fems Microbiology Letters     Hybrid Journal   (Followers: 19, SJR: 1.126, h-index: 118)
Fems Microbiology Reviews     Hybrid Journal   (Followers: 24, SJR: 7.587, h-index: 150)
Fems Yeast Research     Hybrid Journal   (Followers: 13, SJR: 1.213, h-index: 66)
Foreign Policy Analysis     Hybrid Journal   (Followers: 21, SJR: 0.859, h-index: 10)
Forestry: An Intl. J. of Forest Research     Hybrid Journal   (Followers: 17, SJR: 0.903, h-index: 44)
Forum for Modern Language Studies     Hybrid Journal   (Followers: 6, SJR: 0.108, h-index: 6)
French History     Hybrid Journal   (Followers: 29, SJR: 0.123, h-index: 10)
French Studies     Hybrid Journal   (Followers: 19, SJR: 0.119, h-index: 7)
French Studies Bulletin     Hybrid Journal   (Followers: 10, SJR: 0.102, h-index: 3)
Gastroenterology Report     Open Access   (Followers: 2)
Genome Biology and Evolution     Open Access   (Followers: 10, SJR: 3.22, h-index: 39)
Geophysical J. Intl.     Hybrid Journal   (Followers: 31, SJR: 1.839, h-index: 119)
German History     Hybrid Journal   (Followers: 24, SJR: 0.437, h-index: 13)
GigaScience     Open Access   (Followers: 3)
Global Summitry     Hybrid Journal  
Glycobiology     Hybrid Journal   (Followers: 14, SJR: 1.692, h-index: 101)
Health and Social Work     Hybrid Journal   (Followers: 46, SJR: 0.505, h-index: 40)
Health Education Research     Hybrid Journal   (Followers: 12, SJR: 0.814, h-index: 80)
Health Policy and Planning     Hybrid Journal   (Followers: 21, SJR: 1.628, h-index: 66)
Health Promotion Intl.     Hybrid Journal   (Followers: 19, SJR: 0.664, h-index: 60)
History Workshop J.     Hybrid Journal   (Followers: 25, SJR: 0.313, h-index: 20)
Holocaust and Genocide Studies     Hybrid Journal   (Followers: 22, SJR: 0.115, h-index: 13)
Human Molecular Genetics     Hybrid Journal   (Followers: 10, SJR: 4.288, h-index: 233)
Human Reproduction     Hybrid Journal   (Followers: 74, SJR: 2.271, h-index: 179)
Human Reproduction Update     Hybrid Journal   (Followers: 15, SJR: 4.678, h-index: 128)
Human Rights Law Review     Hybrid Journal   (Followers: 60, SJR: 0.7, h-index: 21)
ICES J. of Marine Science: J. du Conseil     Hybrid Journal   (Followers: 53, SJR: 1.233, h-index: 88)
ICSID Review     Hybrid Journal   (Followers: 8)
ILAR J.     Hybrid Journal   (Followers: 1, SJR: 1.099, h-index: 51)
IMA J. of Applied Mathematics     Hybrid Journal   (SJR: 0.329, h-index: 26)
IMA J. of Management Mathematics     Hybrid Journal   (Followers: 2, SJR: 0.351, h-index: 20)
IMA J. of Mathematical Control and Information     Hybrid Journal   (Followers: 2, SJR: 0.661, h-index: 28)
IMA J. of Numerical Analysis - advance access     Hybrid Journal   (SJR: 2.032, h-index: 44)
Industrial and Corporate Change     Hybrid Journal   (Followers: 8, SJR: 1.37, h-index: 81)
Industrial Law J.     Hybrid Journal   (Followers: 29, SJR: 0.184, h-index: 15)
Information and Inference     Free  
Integrative and Comparative Biology     Hybrid Journal   (Followers: 7, SJR: 1.911, h-index: 90)
Interacting with Computers     Hybrid Journal   (Followers: 10, SJR: 0.529, h-index: 59)
Interactive CardioVascular and Thoracic Surgery     Hybrid Journal   (Followers: 4, SJR: 0.743, h-index: 35)
Intl. Data Privacy Law     Hybrid Journal   (Followers: 27)
Intl. Health     Hybrid Journal   (Followers: 4, SJR: 0.835, h-index: 15)
Intl. Immunology     Hybrid Journal   (Followers: 4, SJR: 1.613, h-index: 111)
Intl. J. for Quality in Health Care     Hybrid Journal   (Followers: 32, SJR: 1.593, h-index: 69)
Intl. J. of Constitutional Law     Hybrid Journal   (Followers: 50, SJR: 0.613, h-index: 19)
Intl. J. of Epidemiology     Hybrid Journal   (Followers: 115, SJR: 4.381, h-index: 145)
Intl. J. of Law and Information Technology     Hybrid Journal   (Followers: 3, SJR: 0.247, h-index: 8)
Intl. J. of Law, Policy and the Family     Hybrid Journal   (Followers: 18, SJR: 0.307, h-index: 15)
Intl. J. of Lexicography     Hybrid Journal   (Followers: 8, SJR: 0.404, h-index: 18)
Intl. J. of Low-Carbon Technologies     Open Access   (Followers: 1, SJR: 0.457, h-index: 12)
Intl. J. of Neuropsychopharmacology     Open Access   (Followers: 4, SJR: 1.69, h-index: 79)
Intl. J. of Public Opinion Research     Hybrid Journal   (Followers: 8, SJR: 0.906, h-index: 33)
Intl. J. of Refugee Law     Hybrid Journal   (Followers: 34, SJR: 0.231, h-index: 21)
Intl. J. of Transitional Justice     Hybrid Journal   (Followers: 13, SJR: 0.833, h-index: 12)
Intl. Mathematics Research Notices     Hybrid Journal   (Followers: 1, SJR: 2.052, h-index: 42)
Intl. Mathematics Research Surveys - advance access     Hybrid Journal  
Intl. Political Sociology     Hybrid Journal   (Followers: 24, SJR: 1.339, h-index: 19)
Intl. Relations of the Asia-Pacific     Hybrid Journal   (Followers: 17, SJR: 0.539, h-index: 17)
Intl. Studies Perspectives     Hybrid Journal   (Followers: 7, SJR: 0.998, h-index: 28)
Intl. Studies Quarterly     Hybrid Journal   (Followers: 33, SJR: 2.184, h-index: 68)
Intl. Studies Review     Hybrid Journal   (Followers: 17, SJR: 0.783, h-index: 38)
ISLE: Interdisciplinary Studies in Literature and Environment     Hybrid Journal   (Followers: 1, SJR: 0.155, h-index: 4)
ITNOW     Hybrid Journal   (Followers: 2, SJR: 0.102, h-index: 4)
J. of African Economies     Hybrid Journal   (Followers: 15, SJR: 0.647, h-index: 30)
J. of American History     Hybrid Journal   (Followers: 38, SJR: 0.286, h-index: 34)
J. of Analytical Toxicology     Hybrid Journal   (Followers: 13, SJR: 1.038, h-index: 60)
J. of Antimicrobial Chemotherapy     Hybrid Journal   (Followers: 20, SJR: 2.157, h-index: 149)
J. of Antitrust Enforcement     Hybrid Journal   (Followers: 1)
J. of Applied Poultry Research     Hybrid Journal   (Followers: 3, SJR: 0.563, h-index: 43)
J. of Biochemistry     Hybrid Journal   (Followers: 43, SJR: 1.341, h-index: 96)
J. of Chromatographic Science     Hybrid Journal   (Followers: 18, SJR: 0.448, h-index: 42)
J. of Church and State     Hybrid Journal   (Followers: 11, SJR: 0.167, h-index: 11)
J. of Competition Law and Economics     Hybrid Journal   (Followers: 34, SJR: 0.442, h-index: 16)
J. of Complex Networks     Hybrid Journal   (Followers: 1, SJR: 1.165, h-index: 5)
J. of Conflict and Security Law     Hybrid Journal   (Followers: 11, SJR: 0.196, h-index: 15)
J. of Consumer Research     Full-text available via subscription   (Followers: 38, SJR: 4.896, h-index: 121)
J. of Crohn's and Colitis     Hybrid Journal   (Followers: 9, SJR: 1.543, h-index: 37)
J. of Cybersecurity     Hybrid Journal   (Followers: 2)
J. of Deaf Studies and Deaf Education     Hybrid Journal   (Followers: 8, SJR: 0.69, h-index: 36)
J. of Design History     Hybrid Journal   (Followers: 15, SJR: 0.166, h-index: 14)
J. of Economic Entomology     Full-text available via subscription   (Followers: 6, SJR: 0.894, h-index: 76)
J. of Economic Geography     Hybrid Journal   (Followers: 32, SJR: 2.909, h-index: 69)
J. of Environmental Law     Hybrid Journal   (Followers: 25, SJR: 0.457, h-index: 20)
J. of European Competition Law & Practice     Hybrid Journal   (Followers: 19)
J. of Experimental Botany     Hybrid Journal   (Followers: 13, SJR: 2.798, h-index: 163)
J. of Financial Econometrics     Hybrid Journal   (Followers: 21, SJR: 1.314, h-index: 27)
J. of Global Security Studies     Hybrid Journal   (Followers: 2)
J. of Heredity     Hybrid Journal   (Followers: 3, SJR: 1.024, h-index: 76)
J. of Hindu Studies     Hybrid Journal   (Followers: 7, SJR: 0.186, h-index: 3)
J. of Hip Preservation Surgery     Open Access  
J. of Human Rights Practice     Hybrid Journal   (Followers: 21, SJR: 0.399, h-index: 10)
J. of Infectious Diseases     Hybrid Journal   (Followers: 39, SJR: 4, h-index: 209)
J. of Insect Science     Open Access   (Followers: 9, SJR: 0.388, h-index: 31)

        1 2 | Last   [Sort by number of followers]   [Restore default list]

Journal Cover Cerebral Cortex
  [SJR: 4.827]   [H-I: 192]   [37 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1047-3211 - ISSN (Online) 1460-2199
   Published by Oxford University Press Homepage  [369 journals]
    • PubDate: 2017-03-06
  • Reduced Inhibition within Layer IV of Sert Knockout Rat Barrel Cortex is
           Associated with Faster Sensory Integration
    • Authors: Miceli S; Nadif Kasri N, Joosten J, et al.
      Abstract: AbstractNeural activity is essential for the maturation of sensory systems. In the rodent primary somatosensory cortex (S1), high extracellular serotonin (5-HT) levels during development impair neural transmission between the thalamus and cortical input layer IV (LIV). Rodent models of impaired 5-HT transporter (SERT) function show disruption in their topological organization of S1 and in the expression of activity-regulated genes essential for inhibitory cortical network formation. It remains unclear how such alterations affect the sensory information processing within cortical LIV. Using serotonin transporter knockout (Sert−/−) rats, we demonstrate that high extracellular serotonin levels are associated with impaired feedforward inhibition (FFI), fewer perisomatic inhibitory synapses, a depolarized GABA reversal potential and reduced expression of KCC2 transporters in juvenile animals. At the neural population level, reduced FFI increases the excitatory drive originating from LIV, facilitating evoked representations in the supragranular layers II/III. The behavioral consequence of these changes in network excitability is faster integration of the sensory information during whisker-based tactile navigation, as Sert−/− rats require fewer whisker contacts with tactile targets and perform object localization with faster reaction times. These results highlight the association of serotonergic homeostasis with formation and excitability of sensory cortical networks, and consequently with sensory perception.
      PubDate: 2017-02-08
  • Different Effects of Sleep Deprivation and Torpor on EEG Slow-Wave
           Characteristics in Djungarian Hamsters
    • Authors: Vyazovskiy VV; Palchykova SS, Achermann PP, et al.
      Abstract: AbstractIt has been shown previously in Djungarian hamsters that the initial electroencephalography (EEG) slow-wave activity (power in the 0.5–4.0 Hz band; SWA) in non-rapid eye movement (NREM) sleep following an episode of daily torpor is consistently enhanced, similar to the SWA increase after sleep deprivation (SD). However, it is unknown whether the network mechanisms underlying the SWA increase after torpor and SD are similar. EEG slow waves recorded in the neocortex during sleep reflect synchronized transitions between periods of activity and silence among large neuronal populations. We therefore set out to investigate characteristics of individual cortical EEG slow waves recorded during NREM sleep after 4 h SD and during sleep after emergence from an episode of daily torpor in adult male Djungarian hamsters. We found that during the first hour after both SD and torpor, the SWA increase was associated with an increase in slow-wave incidence and amplitude. However, the slopes of single slow waves during NREM sleep were steeper in the first hour after SD but not after torpor, and, in contrast to sleep after SD, the magnitude of change in slopes after torpor was unrelated to the changes in SWA. Furthermore, slow-wave slopes decreased progressively within the first 2 h after SD, while a progressive increase in slow-wave slopes was apparent during the first 2 h after torpor. The data suggest that prolonged waking and torpor have different effects on cortical network activity underlying slow-wave characteristics, while resulting in a similar homeostatic sleep response of SWA. We suggest that sleep plays an important role in network homeostasis after both waking and torpor, consistent with a recovery function for both states.
      PubDate: 2017-02-07
  • Positive and Negative Somatotopic BOLD Responses in Contralateral Versus
           Ipsilateral Penfield Homunculus
    • Authors: Tal Z; Geva R, Amedi A.
      Abstract: AbstractOne of the basic properties of sensory cortices is their topographical organization. Most imaging studies explored this organization using the positive blood oxygenation level-dependent (BOLD) signal. Here, we studied the topographical organization of both positive and negative BOLD in contralateral and ipsilateral primary somatosensory cortex (S1). Using phase-locking mapping methods, we verified the topographical organization of contralateral S1, and further showed that different body segments elicit pronounced negative BOLD responses in both hemispheres. In the contralateral hemisphere, we found a sharpening mechanism in which stimulation of a given body segment triggered a gradient of activation with a significant deactivation in more remote areas. In the ipsilateral cortex, deactivation was not only located in the homolog area of the stimulated parts but rather was widespread across many parts of S1. Additionally, analysis of resting-state functional magnetic resonance imaging signal showed a gradient of connectivity to the neighboring contralateral body parts as well as to the ipsilateral homologous area for each body part. Taken together, our results indicate a complex pattern of baseline and activity-dependent responses in the contralateral and ipsilateral sides. Both primary sensory areas were characterized by unique negative BOLD responses, suggesting that they are an important component in topographic organization of sensory cortices.
      PubDate: 2017-02-07
  • ADAM10-Initiated Release of Notch Intracellular Domain Regulates
           Microtubule Stability and Radial Migration of Cortical Neurons
    • Authors: Yang Z; Li P, Chen R, et al.
      Abstract: AbstractProper neuronal migration is orchestrated by combined membrane signal paradigms, whereas the role and mechanism of regulated intramembrane proteolysis (RIP) remain to be illustrated. We show here that the disintegrin and metalloprotease-domain containing protein 10 (ADAM10) regulates cortical neurons migration by initiating the RIP of Notch. We found that Notch intracellular domain (NICD) significantly rescued the migration defect of ADAM10-deficient neurons. Moreover, ADAM10 deficiency led to reduced neuronal motility and disrupted microtubule (MT) structure, which were associated with downregulated expression of acetylated tubulin and MT-associated proteins. Specifically, the NICD/RBPJ complex bound directly to the promoter, and regulated the neuronal expression level of doublecortin (DCX), a modulator of the MT cytoskeleton. Functionally, DCX overexpression largely restored neuron motility and reversed migration defect caused by ADAM10 knockout. Taken together, these findings demonstrate the direct requirement of ADAM10 in cortical radial migration and reveal the underlying mechanism by linking ADAM10-initiated RIP of Notch to the regulation of MT cytoskeleton through transcriptional control of Dcx expression.
      PubDate: 2017-02-03
  • Heparan Sulfates Support Pyramidal Cell Excitability, Synaptic Plasticity,
           and Context Discrimination
    • Authors: Minge D; Senkov O, Kaushik R, et al.
      Abstract: AbstractHeparan sulfate (HS) proteoglycans represent a major component of the extracellular matrix and are critical for brain development. However, their function in the mature brain remains to be characterized. Here, acute enzymatic digestion of HS side chains was used to uncover how HSs support hippocampal function in vitro and in vivo. We found that long-term potentiation (LTP) of synaptic transmission at CA3–CA1 Schaffer collateral synapses was impaired after removal of highly sulfated HSs with heparinase 1. This reduction was associated with decreased Ca2+ influx during LTP induction, which was the consequence of a reduced excitability of CA1 pyramidal neurons. At the subcellular level, heparinase treatment resulted in reorganization of the distal axon initial segment, as detected by a reduction in ankyrin G expression. In vivo, digestion of HSs impaired context discrimination in a fear conditioning paradigm and oscillatory network activity in the low theta band after fear conditioning. Thus, HSs maintain neuronal excitability and, as a consequence, support synaptic plasticity and learning.
      PubDate: 2017-01-24
  • In Vivo Evidence of Reduced Integrity of the Gray–White Matter Boundary
           in Autism Spectrum Disorder
    • Authors: Andrews D; Avino TA, Gudbrandsen M, et al.
      Abstract: AbstractAtypical cortical organization and reduced integrity of the gray–white matter boundary have been reported by postmortem studies in individuals with autism spectrum disorder (ASD). However, there are no in vivo studies that examine these particular features of cortical organization in ASD. Hence, we used structural magnetic resonance imaging to examine differences in tissue contrast between gray and white matter in 98 adults with ASD and 98 typically developing controls, to test the hypothesis that individuals with ASD have significantly reduced tissue contrast. More specifically, we examined contrast as a percentage between gray and white matter tissue signal intensities (GWPC) sampled at the gray–white matter boundary, and across different cortical layers. We found that individuals with ASD had significantly reduced GWPC in several clusters throughout the cortex (cluster, P < 0.05). As expected, these reductions were greatest when tissue intensities were sampled close to gray–white matter interface, which indicates a less distinct gray–white matter boundary in ASD. Our in vivo findings of reduced GWPC in ASD are therefore consistent with prior postmortem findings of a less well-defined gray–white matter boundary in ASD. Taken together, these results indicate that GWPC might be utilized as an in vivo proxy measure of atypical cortical microstructural organization in future studies.
      PubDate: 2017-01-05
  • Reduced Hippocampal Functional Connectivity During Episodic Memory
           Retrieval in Autism
    • Authors: Cooper RA; Richter FR, Bays PM, et al.
      Abstract: AbstractIncreasing recent research has sought to understand the recollection impairments experienced by individuals with autism spectrum disorder (ASD). Here, we tested whether these memory deficits reflect a reduction in the probability of retrieval success or in the precision of memory representations. We also used functional magnetic resonance imaging (fMRI) to study the neural mechanisms underlying memory encoding and retrieval in ASD, focusing particularly on the functional connectivity of core episodic memory networks. Adults with ASD and typical control participants completed a memory task that involved studying visual displays and subsequently using a continuous dial to recreate their appearance. The ASD group exhibited reduced retrieval success, but there was no evidence of a difference in retrieval precision. fMRI data revealed similar patterns of brain activity and functional connectivity during memory encoding in the 2 groups, though encoding-related lateral frontal activity predicted subsequent retrieval success only in the control group. During memory retrieval, the ASD group exhibited attenuated lateral frontal activity and substantially reduced hippocampal connectivity, particularly between hippocampus and regions of the fronto-parietal control network. These findings demonstrate notable differences in brain function during episodic memory retrieval in ASD and highlight the importance of functional connectivity to understanding recollection-related retrieval deficits in this population.
      PubDate: 2017-01-05
  • Compensatory Actions of Ldb Adaptor Proteins During Corticospinal Motor
           Neuron Differentiation
    • Authors: Leone DP; Panagiotakos G, Heavner WE, et al.
      Abstract: AbstractAlthough many genes that specify neocortical projection neuron subtypes have been identified, the downstream effectors that control differentiation of those subtypes remain largely unknown. Here, we demonstrate that the LIM domain-binding proteins Ldb1 and Ldb2 exhibit dynamic and inversely correlated expression patterns during cerebral cortical development. Ldb1-deficient brains display severe defects in proliferation and changes in regionalization, phenotypes resembling those of Lhx mutants. Ldb2-deficient brains, on the other hand, exhibit striking phenotypes affecting layer 5 pyramidal neurons: Immature neurons have an impaired capacity to segregate into mature callosal and subcerebral projection neurons. The analysis of Ldb2 single-mutant mice reveals a compensatory role of Ldb1 for Ldb2 during corticospinal motor neuron (CSMN) differentiation. Animals lacking both Ldb1 and Ldb2 uncover the requirement for Ldb2 during CSMN differentiation, manifested as incomplete CSMN differentiation, and ultimately leading to a failure of the corticospinal tract.
      PubDate: 2016-02-01
  • Hippocampus and Prefrontal Cortex Predict Distinct Timescales of
           Activation in the Human Ventral Tegmental Area
    • Authors: Murty VP; Ballard IC, Adcock R.
      Abstract: AbstractThe mesolimbic dopamine system contributes to a remarkable variety of behaviors at multiple timescales. Midbrain neurons have fast and slow signaling components, and specific afferent systems, such as the hippocampus (HPC) and prefrontal cortex (PFC), have been demonstrated to drive these components in anesthetized animals. Whether these interactions exist during behavior, however, is unknown. To address this question, we developed a novel analysis of human functional magnetic resonance imaging data that fits models of network excitation and inhibition on ventral tegmental area (VTA) activation. We show that specific afferent systems predict distinct temporal components of midbrain VTA signal. We found that PFC, but not HPC, positively predicted transient, event-evoked VTA activation. In contrast, HPC, but not PFC, positively predicted slow shifts in VTA baseline variability. Thus, unique functional contributions of afferent systems to VTA physiology are detectable at the network level in behaving humans. The findings support models of dopamine function in which dissociable neural circuits support different aspects of motivated behavior via active regulation of tonic and phasic signals.
      PubDate: 2016-01-29
  • Cc2d1a Loss of Function Disrupts Functional and Morphological Development
           in Forebrain Neurons Leading to Cognitive and Social Deficits
    • Authors: Oaks AW; Zamarbide M, Tambunan DE, et al.
      Abstract: AbstractLoss-of-function (LOF) mutations in CC2D1A cause a spectrum of neurodevelopmental disorders, including intellectual disability, autism spectrum disorder, and seizures, identifying a critical role for this gene in cognitive and social development. CC2D1A regulates intracellular signaling processes that are critical for neuronal function, but previous attempts to model the human LOF phenotypes have been prevented by perinatal lethality in Cc2d1a-deficient mice. To overcome this challenge, we generated a floxed Cc2d1a allele for conditional removal of Cc2d1a in the brain using Cre recombinase. While removal of Cc2d1a in neuronal progenitors using Cre expressed from the Nestin promoter still causes death at birth, conditional postnatal removal of Cc2d1a in the forebrain via calcium/calmodulin-dependent protein kinase II-alpha (CamKIIa) promoter-driven Cre generates animals that are viable and fertile with grossly normal anatomy. Analysis of neuronal morphology identified abnormal cortical dendrite organization and a reduction in dendritic spine density. These animals display deficits in neuronal plasticity and in spatial learning and memory that are accompanied by reduced sociability, hyperactivity, anxiety, and excessive grooming. Cc2d1a conditional knockout mice therefore recapitulate features of both cognitive and social impairment caused by human CC2D1A mutation, and represent a model that could provide much needed insights into the developmental mechanisms underlying nonsyndromic neurodevelopmental disorders.
      PubDate: 2016-01-29
  • Gradient COUP-TFI Expression Is Required for Functional Organization of
           the Hippocampal Septo-Temporal Longitudinal Axis
    • Authors: Flore G; Di Ruberto G, Parisot J, et al.
      Abstract: AbstractThe hippocampus (HP), a medial cortical structure, is subdivided into a distinct dorsal (septal) and ventral (temporal) portion, which is separated by an intermediate region lying on a longitudinal curvature. While the dorsal portion is more dedicated to spatial navigation and memory, the most ventral part processes emotional information. Genetic factors expressed in gradient during development seem to control the size and correct positioning of the HP along its longitudinal axis; however, their roles in regulating differential growth and in supporting its anatomical and functional dissociation remain unexplored. Here, we challenge the in vivo function of the nuclear receptor COUP-TFI (chicken ovalbumin upstream promoter transcription factor 1) in controlling the hippocampal, anatomical, and functional properties along its longitudinal axis. Loss of cortical COUP-TFI function results in a dysmorphic HP with altered shape, volume, and connectivity, particularly in its dorsal and intermediate regions. Notably, topographic inputs from the entorhinal cortex are strongly impaired in the dorsal portion of COUP-TFI mutants. These severe morphological changes are associated with selective spatial learning and memory impairment. These findings identify a novel transcriptional regulator required in the functional organization along the hippocampal septo-temporal axis supporting a genetic basis of the hippocampal volumetric growth with its final shape, circuit, and type of memory function.
      PubDate: 2016-01-26
  • NKCC1-Mediated GABAergic Signaling Promotes Postnatal Cell Death in
           Neocortical Cajal–Retzius Cells
    • Authors: Blanquie O; Liebmann L, Hübner CA, et al.
      Abstract: AbstractDuring early development, a substantial proportion of central neurons undergoes programmed cell death. This activity-dependent process is essential for the proper structural and functional development of the brain. To uncover cell type-specific differences in the regulation of neuronal survival versus apoptosis, we studied activity-regulated cell death in Cajal–Retzius neurons (CRNs) and the overall neuronal population in the developing mouse cerebral cortex. CRNs in the upper neocortical layer represent an early-born neuronal population, which is important for cortical development and largely disappears by apoptosis during neonatal stages. In contrast to the overall neuronal population, activity blockade with tetrodotoxin improved survival of CRNs in culture. Activation of GABAA receptors also blocked spontaneous activity and caused overall cell death including apoptosis of CRNs. Blockade of the Na–K–Cl transporter NKCC1 in vitro or its genetic deletion in vivo rescued CRNs from apoptosis. This effect was mediated by blockade of the p75NTR receptor signaling pathway. In summary, we discovered a novel developmental death pathway mediated by NKCC1, via GABAA receptor-mediated membrane depolarization and p75NTR signaling in CRNs. This pathway controls apoptosis of CRNs and may be critically involved in neurodevelopmental disorders such as autism and schizophrenia.
      PubDate: 2016-01-26
  • Cerebral Activation During Initial Motor Learning Forecasts Subsequent
           Sleep-Facilitated Memory Consolidation in Older Adults
    • Authors: King BR; Saucier P, Albouy G, et al.
      Abstract: AbstractOlder adults exhibit deficits in motor memory consolidation; however, little is known about the cerebral correlates of this impairment. We thus employed fMRI to investigate the neural substrates underlying motor sequence memory consolidation, and the modulatory influence of post-learning sleep, in healthy older adults. Participants were trained on a motor sequence and retested following an 8-h interval including wake or diurnal sleep as well as a 22-h interval including a night of sleep. Results demonstrated that a post-learning nap improved offline consolidation across same- and next-day retests. This enhanced consolidation was reflected by increased activity in the putamen and the medial temporal lobe, including the hippocampus, regions that have previously been implicated in sleep-dependent neural plasticity in young adults. Moreover, for the first time in older adults, the neural substrates subserving initial motor learning, including the putamen, cerebellum, and parietal cortex, were shown to forecast subsequent consolidation depending on whether a post-learning nap was afforded. Specifically, sufficient activation in a motor-related network appears to be necessary to trigger sleep-facilitated consolidation in older adults. Our findings not only demonstrate that post-learning sleep can enhance motor memory consolidation in older adults, but also provide the system-level neural correlates of this beneficial effect.
      PubDate: 2016-01-22
  • cAMP-Dependent Calcium Oscillations of Astrocytes: An Implication for
    • Authors: Ujita S; Sasaki T, Asada A, et al.
      Abstract: AbstractAstrocytes in various brain regions exhibit spontaneous intracellular calcium elevations both in vitro and in vivo; however, neither the temporal pattern underlying this activity nor its function has been fully evaluated. Here, we utilized a long-term optical imaging technique to analyze the calcium activity of more than 4000 astrocytes in acute hippocampal slices as well as in the neocortex and hippocampus of head-restrained mice. Although astrocytic calcium activity was largely sparse and irregular, we observed a subset of cells in which the fluctuating calcium oscillations repeated at a regular interval of ∼30 s. These intermittent oscillations i) depended on type 2 inositol 1,4,5-trisphosphate receptors; ii) consisted of a complex reverberatory interaction between the soma and processes of individual astrocytes; iii) did not synchronize with those of other astrocytes; iv) did not require neuronal firing; v) were modulated through cAMP-protein kinase A signaling; vi) were facilitated under pathological conditions, such as energy deprivation and epileptiform hyperexcitation; and vii) were associated with enhanced hypertrophy in astrocytic processes, an early hallmark of reactive gliosis, which is observed in ischemia and epilepsy. Therefore, calcium oscillations appear to be associated with a pathological state in astrocytes.
      PubDate: 2016-01-22
  • Regulation of Cognitive Processing by Hippocampal Cholinergic Tone
    • Authors: Al-Onaizi MA; Parfitt GM, Kolisnyk B, et al.
      Abstract: AbstractCholinergic dysfunction has been associated with cognitive abnormalities in a variety of neurodegenerative and neuropsychiatric diseases. Here we tested how information processing is regulated by cholinergic tone in genetically modified mice targeting the vesicular acetylcholine transporter (VAChT), a protein required for acetylcholine release. We measured long-term potentiation of Schaffer collateral-CA1 synapses in vivo and assessed information processing by using a mouse touchscreen version of paired associates learning task (PAL). Acquisition of information in the mouse PAL task correlated to levels of hippocampal VAChT, suggesting a critical role for cholinergic tone. Accordingly, synaptic plasticity in the hippocampus in vivo was disturbed, but not completely abolished, by decreased hippocampal cholinergic signaling. Disrupted forebrain cholinergic signaling also affected working memory, a result reproduced by selectively decreasing VAChT in the hippocampus. In contrast, spatial memory was relatively preserved, whereas reversal spatial memory was sensitive to decreased hippocampal cholinergic signaling. This work provides a refined roadmap of how synaptically secreted acetylcholine influences distinct behaviors and suggests that distinct forms of cognitive processing may be regulated in different ways by cholinergic activity.
      PubDate: 2016-01-22
  • Direct Recordings from Human Anterior Insula Reveal its Leading Role
           within the Error-Monitoring Network
    • Authors: Bastin J; Deman P, David O, et al.
      Abstract: AbstractThe ability to monitor our own errors is mediated by a network that includes dorsomedial prefrontal cortex (dmPFC) and anterior insula (AI). However, the dynamics of the underlying neurophysiological processes remain unclear. In particular, whether AI is on the receiving or driving end of the error-monitoring network is unresolved. Here, we recorded intracerebral electroencephalography signals simultaneously from AI and dmPFC in epileptic patients while they performed a stop-signal task. We found that errors selectively modulated broadband neural activity in human AI. Granger causality estimates revealed that errors were immediately followed by a feedforward influence from AI onto anterior cingulate cortex and, subsequently, onto presupplementary motor area. The reverse pattern of information flow was observed on correct responses. Our findings provide the first direct electrophysiological evidence indicating that the anterior insula rapidly detects and conveys error signals to dmPFC, while the latter might use this input to adapt behavior following inappropriate actions.
      PubDate: 2016-01-21
  • Whole Transcriptome Screening Reveals Myelination Deficits in Dysplastic
           Human Temporal Neocortex
    • Authors: Donkels C; Pfeifer D, Janz P, et al.
      Abstract: AbstractFocal cortical dysplasias (FCDs) are local malformations of the human neocortex with strong epileptogenic potential. To investigate the underlying pathomechanisms, we performed a whole human transcriptome screening to compare the gene expression pattern of dysplastic versus nondysplastic temporal neocortex. Tissue obtained from FCD IIIa cases (mean age 20.5 years) who had undergone surgical treatment, due to intractable epilepsy, was compared with nondysplastic specimens (mean age 19.9 years) by means of Affymetrix arrays covering 28 869 genes. We found 211 differentially expressed genes (DEX) among which mainly genes important for oligodendrocyte differentiation and myelination were downregulated in FCD IIIa. These findings were confirmed as functionally important by Database for Annotation, Visualization, and Integrated Discovery (DAVID) analysis. The reduced expression of myelin-associated transcripts was confirmed for FCD Ia, IIa, and IIIa by real-time RT–qPCR. In addition, we found that the density of myelin basic protein mRNA-expressing oligodendrocytes and of 2′,3′-cyclic nucleotide 3′-phosphodiesterase-positive myelin fibers was significantly reduced in dysplastic cortex. Moreover, high-resolution confocal imaging and 3D reconstruction revealed that the myelin fiber network was severely disorganized in dysplastic neocortex, indicating a disturbance of myelin sheath formation and maintenance in FCD.
      PubDate: 2016-01-21
  • Asc-1 Transporter Regulation of Synaptic Activity via the Tonic Release of
           d -Serine in the Forebrain
    • Authors: Sason H; Billard J, Smith G, et al.
      Abstract: Abstractd-Serine is a co-agonist of NMDA receptors (NMDARs) whose activity is potentially regulated by Asc-1 (SLC7A10), a transporter that displays high affinity for d-serine and glycine. Asc-1 operates as a facilitative transporter and as an antiporter, though the preferred direction of d-serine transport is uncertain. We developed a selective Asc-1 blocker, Lu AE00527, that blocks d-serine release mediated by all the transport modes of Asc-1 in primary cultures and neocortical slices. Furthermore, d-serine release is reduced in slices from Asc-1 knockout (KO) mice, indicating that d-serine efflux is the preferred direction of Asc-1. The selectivity of Lu AE00527 is assured by the lack of effect on slices from Asc-1-KO mice, and the lack of interaction with the co-agonist site of NMDARs. Moreover, in vivo injection of Lu AE00527 in P-glycoprotein-deficient mice recapitulates a hyperekplexia-like phenotype similar to that in Asc-1-KO mice. In slices, Lu AE00527 decreases the long-term potentiation at the Schaffer collateral-CA1 synapses, but does not affect the long-term depression. Lu AE00527 blocks NMDAR synaptic potentials when typical Asc-1 extracellular substrates are present, but it does not affect AMPAR transmission. Our data demonstrate that Asc-1 mediates tonic co-agonist release, which is required for optimal NMDAR activation and synaptic plasticity.
      PubDate: 2016-01-21
  • Common Neural Representations for Visually Guided Reorientation and
           Spatial Imagery
    • Authors: Vass LK; Epstein RA.
      Abstract: AbstractSpatial knowledge about an environment can be cued from memory by perception of a visual scene during active navigation or by imagination of the relationships between nonvisible landmarks, such as when providing directions. It is not known whether these different ways of accessing spatial knowledge elicit the same representations in the brain. To address this issue, we scanned participants with fMRI, while they performed a judgment of relative direction (JRD) task that required them to retrieve real-world spatial relationships in response to either pictorial or verbal cues. Multivoxel pattern analyses revealed several brain regions that exhibited representations that were independent of the cues to access spatial memory. Specifically, entorhinal cortex in the medial temporal lobe and the retrosplenial complex (RSC) in the medial parietal lobe coded for the heading assumed on a particular trial, whereas the parahippocampal place area (PPA) contained information about the starting location of the JRD. These results demonstrate the existence of spatial representations in RSC, ERC, and PPA that are common to visually guided navigation and spatial imagery.
      PubDate: 2016-01-12
  • Facial Expressions Evoke Differential Neural Coupling in Macaques
    • Authors: Liu N; Hadj-Bouziane F, Moran R, et al.
      Abstract: AbstractIn humans and monkeys, face perception activates a distributed cortical network that includes extrastriate, limbic, and prefrontal regions. Within face-responsive regions, emotional faces evoke stronger responses than neutral faces (“valence effect”). We used fMRI and Dynamic Causal Modeling (DCM) to test the hypothesis that emotional faces differentially alter the functional coupling among face-responsive regions. Three monkeys viewed conspecific faces with neutral, threatening, fearful, and appeasing expressions. Using Bayesian model selection, various models of neural interactions between the posterior (TEO) and anterior (TE) portions of inferior temporal (IT) cortex, the amygdala, the orbitofrontal (OFC), and ventrolateral prefrontal cortex (VLPFC) were tested. The valence effect was mediated by feedback connections from the amygdala to TE and TEO, and feedback connections from VLPFC to the amygdala and TE. Emotional faces were associated with differential effective connectivity: Fearful faces evoked stronger modulations in the connections from the amygdala to TE and TEO; threatening faces evoked weaker modulations in the connections from the amygdala and VLPFC to TE; and appeasing faces evoked weaker modulations in the connection from VLPFC to the amygdala. Our results suggest dynamic alterations in neural coupling during the perception of behaviorally relevant facial expressions that are vital for social communication.
      PubDate: 2016-01-12
  • Asymmetry and Structure of the Fronto-Parietal Networks Underlie
           Visuomotor Processing in Humans
    • Authors: Budisavljevic S; Dell'Acqua F, Zanatto D, et al.
      Abstract: AbstractResearch in both humans and monkeys has shown that even simple hand movements require cortical control beyond primary sensorimotor areas. An extensive functional neuroimaging literature demonstrates the key role that cortical fronto-parietal regions play for movements such as reaching and reach-to-grasp. However, no study so far has examined the specific white matter connections linking the fronto-parietal regions, namely the 3 parallel pathways of the superior longitudinal fasciculus (SLF). The aim of the current study was to explore how selective fronto-parietal connections are for different kinds of hand movement in 30 right-handed subjects by correlating diffusion imaging tractography and kinematic data. We showed that a common network, consisting of bilateral SLF II and SLF III, was involved in both reaching and reach-to-grasp movements. Larger SLF II and SLF III in the right hemisphere were associated with faster speed of visuomotor processing, while the left SLF II and SLF III played a role in the initial movement trajectory control. Furthermore, the right SLF II was involved in the closing grip phase necessary for efficient grasping of the object. We demonstrated for the first time that individual differences in asymmetry and structure of the fronto-parietal networks were associated with visuomotor processing in humans.
      PubDate: 2016-01-12
  • Intracortical Microstimulation Maps of Motor, Somatosensory, and Posterior
           Parietal Cortex in Tree Shrews ( Tupaia belangeri ) Reveal Complex
           Movement Representations
    • Authors: Baldwin ML; Cooke DF, Krubitzer L.
      Abstract: AbstractLong-train intracortical microstimulation (LT-ICMS) is a popular method for studying the organization of motor and posterior parietal cortex (PPC) in mammals. In primates, LT-ICMS evokes both multijoint and multiple-body-part movements in primary motor, premotor, and PPC. In rodents, LT-ICMS evokes complex movements of a single limb in motor cortex. Unfortunately, very little is known about motor/PPC organization in other mammals. Tree shrews are closely related to both primates and rodents and could provide insights into the evolution of complex movement domains in primates. The present study investigated the extent of cortex in which movements could be evoked with ICMS and the characteristics of movements elicited using both short train (ST) and LT-ICMS in tree shrews. We demonstrate that LT-ICMS and ST-ICMS maps are similar, with the movements elicited with ST-ICMS being truncated versions of those elicited with LT-ICMS. In addition, LT-ICMS-evoked complex movements within motor cortex similar to those in rodents. More complex movements involving multiple body parts such as the hand and mouth were also elicited in motor cortex and PPC, as in primates. Our results suggest that complex movement networks present in PPC and motor cortex were present in mammals prior to the emergence of primates.
      PubDate: 2016-01-11
  • Through Thick and Thin: a Need to Reconcile Contradictory Results on
           Trajectories in Human Cortical Development
    • Authors: Walhovd KB; Fjell AM, Giedd J, et al.
      Abstract: AbstractUnderstanding how brain development normally proceeds is a premise of understanding neurodevelopmental disorders. This has sparked a wealth of magnetic resonance imaging (MRI) studies. Unfortunately, they are in marked disagreement on how the cerebral cortex matures. While cortical thickness increases for the first 8–9 years of life have repeatedly been reported, others find continuous cortical thinning from early childhood, at least from age 3 or 4 years. We review these inconsistencies, and discuss possible reasons, including the use of different scanners, recording parameters and analysis tools, and possible effects of variables such as head motion. When tested on the same subsample, 2 popular thickness estimation methods (CIVET and FreeSurfer) both yielded a continuous thickness decrease from 3 years. Importantly, MRI-derived measures of cortical development are merely our best current approximations, hence the term “apparent cortical thickness” may be preferable. We recommend strategies for reaching consensus in the field, including multimodal neuroimaging to measure phenomena using different techniques, for example, the use of T1/T2 ratio, and data sharing to allow replication across analysis methods. As neurodevelopmental origins of early- and late-onset disease are increasingly recognized, resolving inconsistencies in brain maturation trajectories is important.
      PubDate: 2016-01-11
  • Ordering Information in Working Memory and Modulation of Gamma by Theta
           Oscillations in Humans
    • Authors: Rajji TK; Zomorrodi R, Barr MS, et al.
      Abstract: AbstractOrdering information is a critical process underlying several cognitive functions, especially working memory. Theta phase-gamma amplitude coupling is regarded as a neurophysiological representation of ordering information during working memory performance. However, direct evidence has been lacking in humans. Seventy healthy subjects performed the N-back task, a working memory task that tests ordering information at 3 different levels of difficulties and with 3 different types of trials. Using electroencephalography (EEG) during N-back performance, theta–gamma coupling was assessed during response trials. Multivariate general linear model (GLM) and discriminant analysis were used to assess coupling and theta and gamma power across the N-back conditions and the trial types. During the N-back trials that required ordering of information, N-back condition had independent effects on coupling and on theta and gamma power, with equal contributions among these 3 variables. Theta–gamma coupling contribution declined significantly on the trials that did not require ordering and was intermediate on trials that favored but not necessarily required ordering. Our findings demonstrate for the first time the role of theta–gamma coupling as a mechanism that supports ordering information. They also highlight the potential of using theta–gamma coupling as a neurophysiological marker of brain function in health or disease states.
      PubDate: 2016-01-11
  • Spatio-Temporal Patterning in Primary Motor Cortex at Movement Onset
    • Authors: Best MD; Suminski AJ, Takahashi K, et al.
      Abstract: AbstractVoluntary movement initiation involves the engagement of large populations of motor cortical neurons around movement onset. Despite knowledge of the temporal dynamics that lead to movement, the spatial structure of these dynamics across the cortical surface remains unknown. In data from 4 rhesus macaques, we show that the timing of attenuation of beta frequency local field potential oscillations, a correlate of locally activated cortex, forms a spatial gradient across primary motor cortex (MI). We show that these spatio-temporal dynamics are recapitulated in the engagement order of ensembles of MI neurons. We demonstrate that these patterns are unique to movement onset and suggest that movement initiation requires a precise spatio-temporal sequential activation of neurons in MI.
      PubDate: 2016-01-11
  • Intraneuronal Amyloid Beta Accumulation Disrupts Hippocampal
           CRTC1-Dependent Gene Expression and Cognitive Function in a Rat Model of
           Alzheimer Disease
    • Authors: Wilson EN; Abela AR, Do Carmo S, et al.
      Abstract: AbstractIn Alzheimer disease (AD), the accumulation of amyloid beta (Aβ) begins decades before cognitive symptoms and progresses from intraneuronal material to extracellular plaques. To date, however, the precise mechanism by which the early buildup of Aβ peptides leads to cognitive dysfunction remains unknown. Here, we investigate the impact of the early Aβ accumulation on temporal and frontal lobe dysfunction. We compared the performance of McGill-R-Thy1-APP transgenic AD rats with wild-type littermate controls on a visual discrimination task using a touchscreen operant platform. Subsequently, we conducted studies to establish the biochemical and molecular basis for the behavioral alterations. It was found that the presence of intraneuronal Aβ caused a severe associative learning deficit in the AD rats. This coincided with reduced nuclear translocation and genomic occupancy of the CREB co-activator, CRTC1, and decreased production of synaptic plasticity-associated transcripts Arc, c-fos, Egr1, and Bdnf. Thus, blockade of CRTC1-dependent gene expression in the early, preplaque phase of AD-like pathology provides a molecular basis for the cognitive deficits that figure so prominently in early AD.
      PubDate: 2016-01-11
  • Perceptual Learning Induces Persistent Attentional Capture by Nonsalient
    • Authors: Qu Z; Hillyard SA, Ding Y.
      Abstract: AbstractVisual attention can be attracted automatically by salient simple features, but whether and how nonsalient complex stimuli such as shapes may capture attention in humans remains unclear. Here, we present strong electrophysiological evidence that a nonsalient shape presented among similar shapes can provoke a robust and persistent capture of attention as a consequence of extensive training in visual search (VS) for that shape. Strikingly, this attentional capture that followed perceptual learning (PL) was evident even when the trained shape was task-irrelevant, was presented outside the focus of top-down spatial attention, and was undetected by the observer. Moreover, this attentional capture persisted for at least 3–5 months after training had been terminated. This involuntary capture of attention was indexed by electrophysiological recordings of the N2pc component of the event-related brain potential, which was localized to ventral extrastriate visual cortex, and was highly predictive of stimulus-specific improvement in VS ability following PL. These findings provide the first evidence that nonsalient shapes can capture visual attention automatically following PL and challenge the prominent view that detection of feature conjunctions requires top-down focal attention.
      PubDate: 2016-01-11
  • Spontaneous Fluctuations in Visual Cortical Responses Influence Population
           Coding Accuracy
    • Authors: Gutnisky DA; Beaman CB, Lew SE, et al.
      Abstract: AbstractInformation processing in the cerebral cortex depends not only on the nature of incoming stimuli, but also on the state of neuronal networks at the time of stimulation. That is, the same stimulus will be processed differently depending on the neuronal context in which it is received. A major factor that could influence neuronal context is the background, or ongoing neuronal activity before stimulation. In visual cortex, ongoing activity is known to play a critical role in the development of local circuits, yet whether it influences the coding of visual features in adult cortex is unclear. Here, we investigate whether and how the information encoded by individual neurons and populations in primary visual cortex (V1) depends on the ongoing activity before stimulus presentation. We report that when individual neurons are in a “low” prestimulus state, they have a higher capacity to discriminate stimulus features, such as orientation, despite their reduction in evoked responses. By measuring the distribution of prestimulus activity across a population of neurons, we found that network discrimination accuracy is improved in the low prestimulus state. Thus, the distribution of ongoing activity states across the network creates an “internal context” that dynamically filters incoming stimuli to modulate the accuracy of sensory coding. The modulation of stimulus coding by ongoing activity state is consistent with recurrent network models in which ongoing activity dynamically controls the balanced background excitation and inhibition to individual neurons.
      PubDate: 2016-01-07
  • Processing Narratives Concerning Protected Values: A Cross-Cultural
           Investigation of Neural Correlates
    • Authors: Kaplan JT; Gimbel SI, Dehghani M, et al.
      Abstract: AbstractNarratives are an important component of culture and play a central role in transmitting social values. Little is known, however, about how the brain of a listener/reader processes narratives. A receiver's response to narration is influenced by the narrator's framing and appeal to values. Narratives that appeal to “protected values,” including core personal, national, or religious values, may be particularly effective at influencing receivers. Protected values resist compromise and are tied with identity, affective value, moral decision-making, and other aspects of social cognition. Here, we investigated the neural mechanisms underlying reactions to protected values in narratives. During fMRI scanning, we presented 78 American, Chinese, and Iranian participants with real-life stories distilled from a corpus of over 20 million weblogs. Reading these stories engaged the posterior medial, medial prefrontal, and temporo-parietal cortices. When participants believed that the protagonist was appealing to a protected value, signal in these regions was increased compared with when no protected value was perceived, possibly reflecting the intensive and iterative search required to process this material. The effect strength also varied across groups, potentially reflecting cultural differences in the degree of concern for protected values.
      PubDate: 2016-01-07
  • Caspr Controls the Temporal Specification of Neural Progenitor Cells
           through Notch Signaling in the Developing Mouse Cerebral Cortex
    • Authors: Wu Z; Li D, Huang Y, et al.
      Abstract: AbstractThe generation of layer-specific neurons and astrocytes by radial glial cells during development of the cerebral cortex follows a precise temporal sequence, which is regulated by intrinsic and extrinsic factors. The molecular mechanisms controlling the timely generation of layer-specific neurons and astrocytes remain not fully understood. In this study, we show that the adhesion molecule contactin-associated protein (Caspr), which is involved in the maintenance of the polarized domains of myelinated axons, is essential for the timing of generation of neurons and astrocytes in the developing mouse cerebral cortex. Caspr is expressed by radial glial cells, which are neural progenitor cells that generate both neurons and astrocytes. Absence of Caspr in neural progenitor cells delays the production cortical neurons and induces precocious formation of cortical astrocytes, without affecting the numbers of progenitor cells. At the molecular level, Caspr cooperates with the intracellular domain of Notch to repress transcription of the Notch effector Hes1. Suppression of Notch signaling via a Hes1 shRNA rescues the abnormal neurogenesis and astrogenesis in Caspr-deficient mice. These findings establish Caspr as a novel key regulator that controls the temporal specification of cell fate in radial glial cells of the developing cerebral cortex through Notch signaling.
      PubDate: 2016-01-06
  • Impaired Valuation Leads to Increased Apathy Following Ventromedial
           Prefrontal Cortex Damage
    • Authors: Hogeveen J; Hauner KK, Chau A, et al.
      Abstract: AbstractApathy is defined by reduced goal-directed behavior, and is common in patients with damage to the ventromedial prefrontal cortex (vmPFC). Separately, in neuroeconomics research, the vmPFC has been shown to play a role in reward processing—namely, in “stimulus valuation,” or the computation of the subjective reward value of a stimulus. Here, we used a sample of patients with focal brain lesions (N = 93) and matched healthy controls (N = 21) to determine whether the association between vmPFC damage and increased apathy is driven by impaired valuation. An auction task was used to measure valuation, and apathy was assessed via caregiver ratings of patients' day-to-day behavior. Lesion-symptom mapping identified the locus of impaired valuation in the vmPFC, and patients with damage to this region demonstrated increased apathy relative to patients with damage to dorsomedial prefrontal cortex (dmPFC), patients with damage to other brain regions, and healthy controls. Critically, the association between vmPFC damage and apathy was mediated by impaired valuation, with no effect as a function of dmPFC damage. Our results implicate a valuation-based mechanism underlying the relationship between vmPFC integrity and apathy, bridging findings from both the clinical literature and neuroeconomics research.
      PubDate: 2016-01-06
  • Genetic Variation in S100B Modulates Neural Processing of Visual Scenes in
           Han Chinese
    • Authors: Kong X; Song Y, Zhen Z, et al.
      Abstract: AbstractSpatial navigation is a crucial ability for living. Previous animal studies have shown that the S100B gene is causally related to spatial navigation performance in mice. However, the genetic factors influencing human navigation and its neural substrates remain unclear. Here, we provided the first evidence that the S100B gene modulates neural processing of navigationally relevant scenes in humans. First, with a novel protocol, we demonstrated that the spatial pattern of S100B gene expression in postmortem brains was associated with brain activation pattern for spatial navigation in general, and for scene processing in particular. Further, in a large fMRI cohort of healthy adults of Han Chinese (N = 202), we found that S100B gene polymorphisms modulated scene selectivity in the retrosplenial cortex (RSC) and parahippocampal place area. Finally, the serum levels of S100B protein mediated the association between S100B gene polymorphism and scene selectivity in the RSC. Our study takes the first step toward understanding the neurogenetic mechanism of human spatial navigation and suggests a novel approach to discover candidate genes modulating cognitive functions.
      PubDate: 2016-01-05
  • Auditory to Visual Cross-Modal Adaptation for Emotion: Psychophysical and
           Neural Correlates
    • Authors: Wang X; Guo X, Chen L, et al.
      Abstract: AbstractAdaptation is fundamental in sensory processing and has been studied extensively within the same sensory modality. However, little is known about adaptation across sensory modalities, especially in the context of high-level processing, such as the perception of emotion. Previous studies have shown that prolonged exposure to a face exhibiting one emotion, such as happiness, leads to contrastive biases in the perception of subsequently presented faces toward the opposite emotion, such as sadness. Such work has shown the importance of adaptation in calibrating face perception based on prior visual exposure. In the present study, we showed for the first time that emotion-laden sounds, like laughter, adapt the visual perception of emotional faces, that is, subjects more frequently perceived faces as sad after listening to a happy sound. Furthermore, via electroencephalography recordings and event-related potential analysis, we showed that there was a neural correlate underlying the perceptual bias: There was an attenuated response occurring at ∼ 400 ms to happy test faces and a quickened response to sad test faces, after exposure to a happy sound. Our results provide the first direct evidence for a behavioral cross-modal adaptation effect on the perception of facial emotion, and its neural correlate.
      PubDate: 2016-01-05
  • Disrupted Cortical State Regulation in a Rat Model of Fragile X Syndrome
    • Authors: Berzhanskaya J; Phillips MA, Gorin A, et al.
      Abstract: AbstractChildren with Fragile X syndrome (FXS) have deficits of attention and arousal. To begin to identify the neural causes of these deficits, we examined juvenile rats lacking the Fragile X mental retardation protein (FMR-KO) for disruption of cortical activity related to attention and arousal. Specifically, we examined the switching of visual cortex between activated and inactivated states that normally occurs during movement and quiet rest, respectively. In both wild-type and FMR-KO rats, during the third and fourth postnatal weeks cortical activity during periods of movement was dominated by an activated state with prominent 18–52 Hz activity. However, during quiet rest, when activity in wild-type rats became dominated by the inactivated state (3–9 Hz activity), FMR-KO rat cortex abnormally remained activated, resulting in increased high-frequency and reduced low-frequency power during rest. Firing rate correlations revealed reduced synchronization in FMR-KO rats, particularly between fast-spiking interneurons, that developmentally precede cortical state defects. Together our data suggest that disrupted inhibitory connectivity impairs the ability of visual cortex to regulate exit from the activated state in a behaviorally appropriate manner, potentially contributing to disrupted attention and sensory processing observed in children with FXS by making it more difficult to decrease cortical drive by unattended stimuli.
      PubDate: 2016-01-05
  • Rap1 GTPases Are Master Regulators of Neural Cell Polarity in the
           Developing Neocortex
    • Authors: Shah B; Lutter D, Tsytsyura Y, et al.
      Abstract: AbstractDuring the development of the mammalian neocortex, the generation of neurons by neural progenitors and their migration to the final position are closely coordinated. The highly polarized radial glial cells (RGCs) serve both as progenitor cells to generate neurons and as support for the migration of these neurons. After their generation, neurons transiently assume a multipolar morphology before they polarize and begin their migration along the RGCs. Here, we show that Rap1 GTPases perform essential functions for cortical organization as master regulators of cell polarity. Conditional deletion of Rap1 GTPases leads to a complete loss of cortical lamination. In RGCs, Rap1 GTPases are required to maintain their polarized organization. In newborn neurons, the loss of Rap1 GTPases prevents the formation of axons and leading processes and thereby interferes with radial migration. Taken together, the loss of RGC and neuronal polarity results in the disruption of cortical organization.
      PubDate: 2016-01-04
  • Adaptive Engagement of Cognitive Control in Context-Dependent Decision
    • Authors: Waskom ML; Frank MC, Wagner AD.
      Abstract: AbstractMany decisions require a context-dependent mapping from sensory evidence to action. The capacity for flexible information processing of this sort is thought to depend on a cognitive control system in frontoparietal cortex, but the costs and limitations of control entail that its engagement should be minimized. Here, we show that humans reduce demands on control by exploiting statistical structure in their environment. Using a context-dependent perceptual discrimination task and model-based analyses of behavioral and neuroimaging data, we found that predictions about task context facilitated decision making and that a quantitative measure of context prediction error accounted for graded engagement of the frontoparietal control network. Within this network, multivariate analyses further showed that context prediction error enhanced the representation of task context. These results indicate that decision making is adaptively tuned by experience to minimize costs while maintaining flexibility.
      PubDate: 2016-01-04
  • Protracted Development of the Proprioceptive Brain Network During and
           Beyond Adolescence
    • Authors: Cignetti F; Fontan A, Menant J, et al.
      Abstract: AbstractProprioceptive processing is important for appropriate motor control, providing error-feedback and internal representation of movement for adjusting the motor command. Although proprioceptive functioning improves during childhood and adolescence, we still have few clues about how the proprioceptive brain network develops. Here, we investigated developmental changes in the functional organization of this network in early adolescents (n = 18, 12 ± 1 years), late adolescents (n = 18, 15 ± 1), and young adults (n = 18, 32 ± 4), by examining task-evoked univariate activity and patterns of functional connectivity (FC) associated with seeds placed in cortical (supramarginal gyrus) and subcortical (dorsal rostral putamen) regions. We found that although the network is already well established in early adolescence both in terms of topology and functioning principles (e.g., long-distance communication and economy in wiring cost), it is still undergoing refinement during adolescence, including a shift from diffuse to focal FC and a decreased FC strength. This developmental effect was particularly pronounced for fronto-striatal connections. Furthermore, changes in FC features continued beyond adolescence, although to a much lower extent. Altogether, these findings point to a protracted developmental time course for the proprioceptive network, which breaks with the relatively early functional maturation often associated with sensorimotor networks.
      PubDate: 2016-01-04
  • Adolescent Cannabinoid Exposure Induces a Persistent Sub-Cortical
           Hyper-Dopaminergic State and Associated Molecular Adaptations in the
           Prefrontal Cortex
    • Authors: Renard J; Rosen LG, Loureiro M, et al.
      Abstract: AbstractConsiderable evidence suggests that adolescent exposure to delta-9-tetrahydrocanabinol (THC), the psychoactive component in marijuana, increases the risk of developing schizophrenia-related symptoms in early adulthood. In the present study, we used a combination of behavioral and molecular analyses with in vivo neuronal electrophysiology to compare the long-term effects of adolescent versus adulthood THC exposure in rats. We report that adolescent, but not adult, THC exposure induces long-term neuropsychiatric-like phenotypes similar to those observed in clinical populations. Thus, adolescent THC exposure induced behavioral abnormalities resembling positive and negative schizophrenia-related endophenotypes and a state of neuronal hyperactivity in the mesocorticolimbic dopamine (DA) pathway. Furthermore, we observed profound alterations in several prefrontal cortical molecular pathways consistent with sub-cortical DAergic dysregulation. Our findings demonstrate a profound dissociation in relative risk profiles for adolescent versus adulthood exposure to THC in terms of neuronal, behavioral, and molecular markers resembling neuropsychiatric pathology.
      PubDate: 2016-01-04
  • Mechanisms of Neuronal Silencing After Cortical Spreading Depression
    • Authors: Sawant-Pokam PM; Suryavanshi PP, Mendez JM, et al.
      Abstract: AbstractCortical spreading depression (CSD) is associated with migraine, stroke, and traumatic brain injury, but its mechanisms remain poorly understood. One of the major features of CSD is an hour-long silencing of neuronal activity. Though this silencing has clear ramifications for CSD-associated disease, it has not been fully explained. We used in vivo whole-cell recordings to examine the effects of CSD on layer 2/3 pyramidal neurons in mouse somatosensory cortex and used in vitro recordings to examine their mechanism. We found that CSD caused a reduction in spontaneous synaptic activity and action potential (AP) firing that lasted over an hour. Both pre- and postsynaptic mechanisms contributed to this silencing. Reductions in frequency of postsynaptic potentials were due to a reduction in presynaptic transmitter release probability as well as reduced AP activity. Decreases in postsynaptic potential amplitude were due to an inhibitory shift in the ratio of excitatory and inhibitory postsynaptic currents. This inhibitory shift in turn contributed to the reduced frequency of APs. Thus, distinct but complementary mechanisms generate the long neuronal silence that follows CSD. These cellular changes could contribute to wider network dysfunction in CSD-associated disease, while the pre- and postsynaptic mechanisms offer separate targets for therapy.
      PubDate: 2016-01-04
  • Neural Processing of Second-Order Motion in the Suprasylvian Cortex of the
    • Authors: Bussières LL; Casanova CC.
      Abstract: AbstractNeuronal responses to second-order motion, that is, to spatiotemporal variations of texture or contrast, have been reported in several cortical areas of mammals, including the middle-temporal (MT) area in primates. In this study, we investigated whether second-order responses are present in the cat posteromedial lateral suprasylvian (PMLS) cortex, a possible homolog of the primate area MT. The stimuli used were luminance-based sine-wave gratings (first-order) and contrast-modulated carrier stimuli (second-order), which consisted of a high-spatial-frequency static grating (carrier) whose contrast was modulated by a low-spatial-frequency drifting grating (envelope). Results indicate that most PMLS neurons responded to second-order motion and for the vast majority of cells, first- and second-order preferred directions were conserved. However, responses to second-order stimuli were significantly reduced when compared to those evoked by first-order gratings. Circular variance was increased for second-order stimuli, indicating that PMLS direction selectivity was weaker for this type of stimulus. Finally, carrier orientation selectivity was either absent or very broad and had no influence on the envelope's orientation selectivity. In conclusion, our data show that PMLS neurons exhibit similar first- and second-order response profiles and that, akin primate area MT cells, they perform a form-cue invariant analysis of motion signals.
      PubDate: 2016-01-04
  • Socio-Cognitive Phenotypes Differentially Modulate Large-Scale Structural
           Covariance Networks
    • Authors: Valk SL; Bernhardt BC, Böckler A, et al.
      Abstract: AbstractFunctional neuroimaging studies have suggested the existence of 2 largely distinct social cognition networks, one for theory of mind (taking others' cognitive perspective) and another for empathy (sharing others' affective states). To address whether these networks can also be dissociated at the level of brain structure, we combined behavioral phenotyping across multiple socio-cognitive tasks with 3-Tesla MRI cortical thickness and structural covariance analysis in 270 healthy adults, recruited across 2 sites. Regional thickness mapping only provided partial support for divergent substrates, highlighting that individual differences in empathy relate to left insular-opercular thickness while no correlation between thickness and mentalizing scores was found. Conversely, structural covariance analysis showed clearly divergent network modulations by socio-cognitive and -affective phenotypes. Specifically, individual differences in theory of mind related to structural integration between temporo-parietal and dorsomedial prefrontal regions while empathy modulated the strength of dorsal anterior insula networks. Findings were robust across both recruitment sites, suggesting generalizability. At the level of structural network embedding, our study provides a double dissociation between empathy and mentalizing. Moreover, our findings suggest that structural substrates of higher-order social cognition are reflected rather in interregional networks than in the the local anatomical markup of specific regions per se.
      PubDate: 2016-01-04
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
Home (Search)
Subjects A-Z
Publishers A-Z
Your IP address:
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2016