Advances in Neuroscience
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Open Access journal
ISSN (Print) 2356-6787 - ISSN (Online) 2314-789X
Published by Hindawi [333 journals]
- Contemporary Review of the Management of Brain Metastasis with Radiation
Abstract: Brain metastases are an important cause of morbidity and mortality, afflicting approximately 200,000 Americans annually. The prognosis for these patients is poor, with median survivals typically measured in months. In this review article, we present the standard treatment approaches with whole brain radiation and as well as novel approaches in the prevention of neurocognitive deficits.
PubDate: Wed, 18 Mar 2015 09:07:05 +000
- Corrigendum to “How Basal Ganglia Outputs Generate Behavior”
PubDate: Mon, 09 Feb 2015 08:54:56 +000
- The Effect of Simple Melodic Lines on Aesthetic Experience: Brain Response
to Structural Manipulations
Abstract: This fMRI study investigates the effect of melody on aesthetic experience in listeners naïve to formal musical knowledge. Using simple melodic lines, whose syntactic structure was manipulated, we created systematic acoustic dissonance. Two stimulus categories were created: canonical (syntactically “correct,” in the Western culture) and modified (made of an altered version of the canonical melodies). The stimuli were presented under two tasks: listening and aesthetic judgment. Data were analyzed as a function of stimulus structure (canonical and modified) and stimulus aesthetics, as appraised by each participant during scanning. The critical contrast modified versus canonical stimuli produced enhanced activation of deep temporal regions, including the parahippocampus, suggesting that melody manipulation induced feelings of unpleasantness in the listeners. This was supported by our behavioral data indicating decreased aesthetic preference for the modified melodies. Medial temporal activation could also have been evoked by stimulus structural novelty determining increased memory load for the modified stimuli. The analysis of melodies judged as beautiful revealed that aesthetic judgment of simple melodies relied on a fine-structural analysis of the stimuli subserved by a left frontal activation and, possibly, on meaning attribution at the charge of right superior temporal sulcus for increasingly pleasurable stimuli.
PubDate: Tue, 30 Dec 2014 00:10:06 +000
- Treatments for Neurological Gait and Balance Disturbance: The Use of
Noninvasive Electrical Brain Stimulation
Abstract: Neurological gait disorders are a common cause of falls, morbidity, and mortality, particularly amongst the elderly. Neurological gait and balance impairment has, however, proved notoriously difficult to treat. The following review discusses some of the first experiments to modulate gait and balance in healthy adults using anodal transcranial direct current stimulation (tDCS) by stimulating both cerebral hemispheres simultaneously. We review and discuss published data using this novel tDCS approach, in combination with physical therapy, to treat locomotor and balance disorders in patients with small vessel disease (leukoaraiosis) and Parkinson’s disease. Finally, we review the use of bihemispheric anodal tDCS to treat gait impairment in patients with stroke in the subacute phase. The findings of these studies suggest that noninvasive electrical stimulation techniques may be a useful adjunct to physical therapy in patients with neurological gait disorders, but further mutlicentre randomized sham-controlled studies are needed to evaluate whether experimental tDCS use can translate into mainstream clinical practice for the treatment of neurological gait disorders.
PubDate: Wed, 03 Dec 2014 09:11:05 +000
- How Basal Ganglia Outputs Generate Behavior
Abstract: The basal ganglia (BG) are a collection of subcortical nuclei critical for voluntary behavior. According to the standard model, the output projections from the BG tonically inhibit downstream motor centers and prevent behavior. A pause in the BG output opens the gate for behavior, allowing the initiation of actions. Hypokinetic neurological symptoms, such as inability to initiate actions in Parkinson’s disease, are explained by excessively high firing rates of the BG output neurons. This model, widely taught in textbooks, is contradicted by recent electrophysiological results, which are reviewed here. In addition, I also introduce a new model, based on the insight that behavior is a product of closed loop negative feedback control using internal reference signals rather than sensorimotor transformations. The nervous system is shown to be a functional hierarchy comprising independent controllers occupying different levels, each level controlling specific variables derived from its perceptual inputs. The BG represent the level of transition control in this hierarchy, sending reference signals specifying the succession of body orientations and configurations. This new model not only explains the major symptoms in movement disorders but also generates a number of testable predictions.
PubDate: Tue, 18 Nov 2014 08:01:02 +000
- Neck Flexion Induces Larger Deformation of the Brain Than Extension at a
Rotational Acceleration, Closed Head Trauma
Abstract: A closed head trauma induces incompletely characterized temporary movement and deformation of the brain, contributing to the primary traumatic brain injury. We used the pressure patterns recorded with light-operated miniature sensors in anaesthetized adult rabbits exposed to a sagittal plane rotational acceleration of the head, lasting 1 ms, as a measure of brain deformation. Two exposure levels were used and scaled to correspond to force levels reported to cause mild and moderate diffuse injury in an adult man, respectively. Flexion induced transient, strong, extended, and predominantly negative pressures while extension generated a short positive pressure peak followed by a minor negative peak. Low level flexion caused as strong, extended negative pressures as did high level extension. Time differences were demonstrated between the deformation of the cerebrum, brainstem, and cerebellum. Available X-ray and MRI techniques do not have as high time resolution as pressure recordings in demonstrating complex, sequential compression and stretching of the brain during a trauma. The exposure to flexion caused more protracted and extensive deformation of the brain than extension, in agreement with a published histopathological report. The severity and extent of the brain deformation generated at a head trauma thus related to the direction at equal force.
PubDate: Mon, 03 Nov 2014 11:11:27 +000
- Understanding Neural Population Coding: Information Theoretic Insights
from the Auditory System
Abstract: In recent years, our research in computational neuroscience has focused on understanding how populations of neurons encode naturalistic stimuli. In particular, we focused on how populations of neurons use the time domain to encode sensory information. In this focused review, we summarize this recent work from our laboratory. We focus in particular on the mathematical methods that we developed for the quantification of how information is encoded by populations of neurons and on how we used these methods to investigate the encoding of complex naturalistic sounds in auditory cortex. We review how these methods revealed a complementary role of low frequency oscillations and millisecond precise spike patterns in encoding complex sounds and in making these representations robust to imprecise knowledge about the timing of the external stimulus. Further, we discuss challenges in extending this work to understand how large populations of neurons encode sensory information. Overall, this previous work provides analytical tools and conceptual understanding necessary to study the principles of how neural populations reflect sensory inputs and achieve a stable representation despite many uncertainties in the environment.
PubDate: Sun, 19 Oct 2014 09:38:28 +000
- The Potentiation of Associative Memory by Emotions: An Event-Related FMRI
Abstract: Establishing associations between pieces of information is related to the medial temporal lobe (MTL). However, it remains unclear how emotions affect memory for associations and, consequently, MTL activity. Thus, this event-related fMRI study attempted to identify neural correlates of the influence of positive and negative emotions on associative memory. Twenty-five participants were instructed to memorize 90 pairs of standardized pictures during a scanned encoding phase. Each pair was composed of a scene and an unrelated object. Trials were neutral, positive, or negative as a function of the emotional valence of the scene. At the behavioral level, participants exhibited better memory retrieval for both emotional conditions relative to neutral trials. Within the right MTL, a functional dissociation was observed, with entorhinal activation elicited by emotional associations, posterior parahippocampal activation elicited by neutral associations, and hippocampal activation elicited by both emotional and neutral associations. In addition, emotional associations induced greater activation than neutral trials in the right amygdala. This fMRI study shows that emotions are associated with the performance improvement of associative memory, by enhancing activity in the right amygdala and the right entorhinal cortex. It also provides evidence for a rostrocaudal specialization within the MTL regarding the emotional valence of associations.
PubDate: Sun, 14 Sep 2014 12:15:02 +000
- The Role of Habenula in Motivation and Reward
Abstract: Located centrally along the dorsal diencephalic system, the habenula is divided into two structures: the medial and the lateral portions. It serves as an important relay between the forebrain and several hindbrain sites. In the last few years, a huge attention has been devoted to this structure, especially the lateral habenula (LHb), which seems to play an important role in emotion, motivation, and reward. Recent studies using techniques such as electrophysiology and neuroimaging have shown that the LHb is involved in motivational control of behavior. Its dysfunction is often associated with depression, schizophrenia, and mood disorder. This review focuses on providing a neuroanatomical and behavioral overview of some of the research previously done on the LHb. First, we describe the anatomical structure of the habenula and we explain how it is involved in reward and motivation. Then, we will discuss how this structure is linked to the limbic system, to finally provide a comparison between several studies that have used electrolytic lesions.
PubDate: Tue, 26 Aug 2014 11:37:11 +000
- Effect of Resveratrol as Caloric Restriction Mimetic and Environmental
Enrichment on Neurobehavioural Responses in Young Healthy Mice
Abstract: Caloric restriction and environmental enrichment have been separately reported to possess health benefits such as improvement in motor and cognitive functions. Resveratrol, a natural polyphenolic compound, has been reported to be caloric restriction mimetic. This study therefore aims to investigate the potential benefit of the combination of resveratrol as CR and EE on learning and memory, motor coordination, and motor endurance in young healthy mice. Fifty mice of both sexes were randomly divided into five groups of 10 animals each: group I animals received carboxymethylcellulose (CMC) orally per kg/day (control), group II animals were maintained on every other day feeding, group III animals received resveratrol 50 mg/kg, suspended in 10 g/L of (CMC) orally per kg/day, group IV animals received CMC and were kept in an enriched environment, and group V animals received resveratrol 50 mg/kg and were kept in EE. The treatment lasted for four weeks. On days 26, 27, and 28 of the study period, the animals were subjected to neurobehavioural evaluation. The results obtained showed that there was no significant change in neurobehavioural responses in all the groups when compared to the control which indicates that 50 mg/kg of resveratrol administration and EE have no significant effects on neurobehavioural responses in young healthy mice over a period of four weeks.
PubDate: Mon, 18 Aug 2014 07:28:05 +000
- Improving Cognitive Function from Children to Old Age: A Systematic Review
of Recent Smart Ageing Intervention Studies
Abstract: Background. Cognitive functions are important for daily life at any age. One purpose of Smart Ageing is to investigate how to improve cognitive functions. This systematic review evaluates beneficial effects of the intervention on cognitive functions. Method. We conducted a systematic review of intervention studies of improvements of cognitive functions published or in press before December 2013. Because of the heterogeneity of the intervention programs, a systematic and critical review of the interventions and outcomes was conducted instead of a meta-analysis. Results. We identified nine completed and published studies, which were divided into four categories: cognitive training using video game, cognitive training using PC, cognitive training using paper and pencil, and exercise training. Review results showed that various intervention programs can improve cognitive functions such as executive functions, working memory, episodic memory, processing speed, and general cognitive ability/IQ. Conclusions. The systematic review demonstrated that some intervention programs can be effective for improving various aspects of cognitive functioning at any age. Some limitations to this review include its small sample size and heterogeneity of programs and cognitive function measures, in addition to unresolved issues such as transfer of everyday skills and effectiveness for nonhealthy people.
PubDate: Mon, 11 Aug 2014 12:32:39 +000
- Structure-Function Relationships behind the Phenomenon of Cognitive
Resilience in Neurology: Insights for Neuroscience and Medicine
Abstract: The phenomenon of cognitive resilience, that is, the dynamical preservation of normal functions despite neurological disorders, demonstrates that cognition can be highly robust to devastating brain injury. Here, cognitive resilience is considered across a range of neurological conditions. Simple computational models of structure-function relationships are used to discuss hypotheses about the neural mechanisms of resilience. Resilience expresses functional redundancies in brain networks and suggests a process of dynamic rerouting of brain signals. This process is underlined by a global renormalization of effective connectivity, capable of restoring information transfer between spared brain structures via alternate pathways. Local mechanisms of synaptic plasticity mediate the renormalization at the lowest level of implementation, but it is also driven by top-down cognition, with a key role of self-awareness in fostering resilience. The presence of abstraction layers in brain computation and networking is hypothesized to account for the renormalization process. Future research directions and challenges are discussed regarding the understanding and control of resilience based on multimodal neuroimaging and computational neuroscience. The study of resilience will illuminate ways by which the brain can overcome adversity and help inform prevention and treatment strategies. It is relevant to combating the negative neuropsychological impact of aging and fostering cognitive enhancement.
PubDate: Mon, 04 Aug 2014 00:00:00 +000
- Synthetic Cathinones and Their Rewarding and Reinforcing Effects in
Abstract: Synthetic cathinones, colloquially referred to as “bath salts,” are derivatives of the psychoactive alkaloid cathinone found in Catha edulis (Khat). Since the mid-to-late 2000s, these amphetamine-like psychostimulants have gained popularity amongst drug users due to their potency, low cost, ease of procurement, and constantly evolving chemical structures. Concomitant with their increased use is the emergence of a growing collection of case reports of bizarre and dangerous behaviors, toxicity to numerous organ systems, and death. However, scientific information regarding the abuse liability of these drugs has been relatively slower to materialize. Recently we have published several studies demonstrating that laboratory rodents will readily self-administer the “first generation” synthetic cathinones methylenedioxypyrovalerone (MDPV) and methylone via the intravenous route, in patterns similar to those of methamphetamine. Under progressive ratio schedules of reinforcement, the rank order of reinforcing efficacy of these compounds is MDPV ≥ methamphetamine > methylone. MDPV and methylone, as well as the “second generation” synthetic cathinones α-pyrrolidinovalerophenone (α-PVP) and 4-methylethcathinone (4-MEC), also dose-dependently increase brain reward function. Collectively, these findings indicate that synthetic cathinones have a high abuse and addiction potential and underscore the need for future assessment of the extent and duration of neurotoxicity induced by these emerging drugs of abuse.
PubDate: Wed, 04 Jun 2014 06:47:47 +000
- Developing Attention: Behavioral and Brain Mechanisms
Abstract: Brain networks underlying attention are present even during infancy and are critical for the developing ability of children to control their emotions and thoughts. For adults, individual differences in the efficiency of attentional networks have been related to neuromodulators and to genetic variations. We have examined the development of attentional networks and child temperament in a longitudinal study from infancy (7 months) to middle childhood (7 years). Early temperamental differences among infants, including smiling and laughter and vocal reactivity, are related to self-regulation abilities at 7 years. However, genetic variations related to adult executive attention, while present in childhood, are poor predictors of later control, in part because individual genetic variation may have many small effects and in part because their influence occurs in interaction with caregiver behavior and other environmental influences. While brain areas involved in attention are present during infancy, their connectivity changes and leads to improvement in control of behavior. It is also possible to influence control mechanisms through training later in life. The relation between maturation and learning may allow advances in our understanding of human brain development.
PubDate: Thu, 08 May 2014 00:00:00 +000
- Rett Syndrome: Coming to Terms with Treatment
Abstract: Rett syndrome (RTT) has experienced remarkable progress over the past three decades since emerging as a disorder of worldwide proportions, particularly with discovery of the linkage of RTT to MECP2 mutations. The advances in clinical research and the increasing pace of basic science investigations have accelerated the pattern of discovery and understanding. Clinical trials are ongoing and others are planned. A review of these events and the prospects for continued success are highlighted below. The girls and women encountered today with RTT are, overall, in better general, neurologic, and behavioral health than those encountered earlier. This represents important progress worldwide from the concerted efforts of a broadly based and diverse clinical and basic research consortium as well as the efforts of parents, family, and friends.
PubDate: Thu, 10 Apr 2014 08:22:54 +000
- Neurocognitive Basis of Schizophrenia: Information Processing
Abnormalities and Clues for Treatment
Abstract: Schizophrenia is a chronic and severe psychiatric disorder that affects all aspects of patients’ lives. Over the past decades, research applying methods from psychology and neuroscience has increasingly been zooming in on specific information processing abnormalities in schizophrenia. Impaired activation of and connectivity between frontotemporal, frontoparietal, and frontostriatal brain networks subserving cognitive functioning and integration of cognition and emotion has been consistently reported. Major issues in schizophrenia research concern the cognitive and neural basis of hallucinations, abnormalities in cognitive-emotional processing, social cognition (including theory of mind), poor awareness of illness, and apathy. Recent findings from cognitive neuroscience studies in these areas are discussed. The findings may have implications for treatment, for example, noninvasive neurostimulation of specific brain areas. Ultimately, a better understanding of the cognitive neuroscience of schizophrenia will pave the way for the development of effective treatment strategies.
PubDate: Sun, 09 Feb 2014 09:41:06 +000
- Reelin in the Years: Controlling Neuronal Migration and Maturation in the
Abstract: The extracellular protein Reelin was initially identified as an essential factor in the control of neuronal migration and layer formation in the developing mammalian brain. In the years following its discovery, however, it became clear that Reelin is a multifunctional protein that controls not only the positioning of neurons in the developing brain, but also their growth, maturation, and synaptic activity in the adult brain. In this review, we will highlight the major discoveries of the biological activities of Reelin and the underlying molecular mechanisms that affect the development and function of the mammalian brain, from embryonic ages to adulthood.
PubDate: Sun, 05 Jan 2014 08:53:41 +000