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- An Immunological Approach to Increase the Brain’s Resilience to
Abstract: We have previously demonstrated the therapeutic potential of inducing a humoral response with autoantibodies to the N-methyl D-aspartate (NMDA) receptor using a genetic approach. In this study, we generated three recombinant proteins to different functional domains of the NMDA receptor, which is implicated in mediating brain tolerance, specifically NR1[21–375], NR1[313–619], NR1[654–800], and an intracellular scaffolding protein, Homer1a, with a similar anatomical expression pattern. All peptides showed similar antigenicity and antibody titers following systemic vaccination, and all animals thrived. Two months following vaccination, rats were administered the potent neurotoxin, kainic acid. NR1[21–375] animals showed an antiepileptic phenotype but no neuroprotection. Remarkably, despite ineffective antiepileptic activity, 6 of 7 seizing NR1[654–800] rats showed absolutely no injury with only minimal changes in the remaining animal, whereas the majority of persistently seizing rats in the other groups showed moderate to severe hippocampal injury. CREB, BDNF, and HSP70, proteins associated with preconditioning, were selectively upregulated in the hippocampus of NR1[654–800] animals, consistent with the observed neuroprotective phenotype. These results identify NR1 epitopes important in conferring anticonvulsive and neuroprotective effects and support the concept of an immunological strategy to induce a chronic state of tolerance in the brain.
PubDate: Thu, 24 Apr 2014 06:49:55 +000
- Prenatal Exposure to Lamotrigine: Effects on Postnatal Development and
Behaviour in Rat Offspring
Abstract: Use of antiepileptic drugs (AEDs) in pregnancy warrants various side effects and also deleterious effects on fetal development. The present study was carried out to assess the effects of prenatal exposure to lamotrigine (LTG) on postnatal development and behavioural alterations of offspring. Adult male and female Sprague Dawley rats weighing 150–180 g b. wt. were allowed to copulate and pregnancy was confirmed by vaginal cytology. Pregnant rats were treated with LTG (11.5, 23, and 46 mg/kg, p.o) from gestational day 3 (GND 3) and this treatment continued till postnatal day 11 (PND 11). Offspring were separated from their dam on day 21 following parturition. LTG, at 46 mg/kg, p.o, produced severe clinical signs of toxicity leading to death of dam between GND 15 and 17. LTG, at 11.5 and 23 mg/kg, p.o, showed significant alterations in offspring’s incisors eruption and vaginal opening when compared to age matched controls. LTG (23 mg/kg, p.o) exposed female offspring expressed hyperactive behaviour and decreased GABA-A receptor expression when compared to control rats. These results reveal that prenatal exposure to LTG may impart differential postnatal behavioural alterations between male and female rats which paves way for further investigations.
PubDate: Mon, 14 Apr 2014 07:48:34 +000
- Detection of Early Ischemic Changes in Noncontrast CT Head Improved with
Abstract: Introduction. Noncontrast head CT (NCCT) is the standard radiologic test for patients presenting with acute stroke. Early ischemic changes (EIC) are often overlooked on initial NCCT. We determine the sensitivity and specificity of improved EIC detection by a standardized method of image evaluation (Stroke Windows). Methods. We performed a retrospective chart review to identify patients with acute ischemic stroke who had NCCT at presentation. EIC was defined by the presence of hyperdense MCA/basilar artery sign; sulcal effacement; basal ganglia/subcortical hypodensity; and loss of cortical gray-white differentiation. NCCT was reviewed with standard window settings and with specialized Stroke Windows. Results. Fifty patients (42% females, 58% males) with a mean NIHSS of 13.4 were identified. EIC was detected in 9 patients with standard windows, while EIC was detected using Stroke Windows in 35 patients (18% versus 70%; ). Hyperdense MCA sign was the most commonly reported EIC; it was better detected with Stroke Windows (14% and 36%; ). Detection of the remaining EIC also improved with Stroke Windows (6% and 46%; ). Conclusions. Detection of EIC has important implications in diagnosis and treatment of acute ischemic stroke. Utilization of Stroke Windows significantly improved detection of EIC.
PubDate: Sun, 09 Mar 2014 08:41:45 +000
- Relationship between Neural Activity and Executive Function: An NIRS Study
Abstract: Objective. This study examined the relationship between neural activity and executive function (EF) by near-infrared spectroscopy (NIRS). In addition, an oral reading span test (RST) was used to explore this association. Methods. Fifteen adults participated in the study. We used the RST and simple reading as the two tasks. Results. The RST score and cortical hemodynamic response in the left inferior frontal gyrus were significantly correlated. Conclusion. Based on the oral RST performance assessment and NIRS examination, the present findings suggest a relationship between EF and cortical activation.
PubDate: Sun, 09 Mar 2014 06:56:24 +000
- Methods of EEG Signal Features Extraction Using Linear Analysis in
Frequency and Time-Frequency Domains
Abstract: Technically, a feature represents a distinguishing property, a recognizable measurement, and a functional component obtained from a section of a pattern. Extracted features are meant to minimize the loss of important information embedded in the signal. In addition, they also simplify the amount of resources needed to describe a huge set of data accurately. This is necessary to minimize the complexity of implementation, to reduce the cost of information processing, and to cancel the potential need to compress the information. More recently, a variety of methods have been widely used to extract the features from EEG signals, among these methods are time frequency distributions (TFD), fast fourier transform (FFT), eigenvector methods (EM), wavelet transform (WT), and auto regressive method (ARM), and so on. In general, the analysis of EEG signal has been the subject of several studies, because of its ability to yield an objective mode of recording brain stimulation which is widely used in brain-computer interface researches with application in medical diagnosis and rehabilitation engineering. The purposes of this paper, therefore, shall be discussing some conventional methods of EEG feature extraction methods, comparing their performances for specific task, and finally, recommending the most suitable method for feature extraction based on performance.
PubDate: Thu, 13 Feb 2014 16:04:42 +000
- A Recurrent Increase of Synchronization in the EEG Continues from Waking
throughout NREM and REM Sleep
Abstract: Pointwise transinformation (PTI) provides a quantitative nonlinear approach to spatiotemporal synchronization patterns of the rhythms of coupled cortical oscillators. We applied PTI to the waking and sleep EEGs of 21 healthy sleepers; we calculated the mean levels and distances of synchronized episodes and estimated the dominant frequency shift from unsynchronized to synchronized EEG segments by spectral analysis. Recurrent EEG synchronization appeared and ceased abruptly in the anterior, central, and temporal derivations; in the posterior derivations it appeared more fluctuating. This temporal dynamics of synchronization remained stable throughout all states of vigilance, while the dominant frequencies of synchronized phases changed markedly. Mean synchronization had high frontal and occipital levels and low central and midtemporal levels. Thus, a fundamental coupling pattern with recurrent increases of synchronization in the EEG (“RISE”) seems to exist during the brain’s resting state. The generators of RISE could be coupled corticocortical neuronal assemblies which might be modulated by subcortical structures. RISE designates the recurrence of transiently synchronized cortical microstates that are independent of specific EEG waves, the spectral content of the EEG, and especially the current state of vigilance. Therefore, it might be suited for EEG analysis in clinical situations without stable vigilance.
PubDate: Thu, 06 Feb 2014 06:27:37 +000
- Effect of Coadministration of Neurovite and Lamivudine on the
Histomorphology of the Cerebellum of Wistar Rats
Abstract: Introduction. Lamivudine is a nucleoside reverse transcriptase inhibitor antiretroviral agent used in the treatment of human immunodeficiency virus type 1 infection. This study was to investigate the effects of coadministration of neurovite and lamivudine on the histomorphology of the cerebellum of Wistar rats. Materials and Methods. Twenty Wistar rats were divided equally into four groups. Group A animals were the control treated with distilled water. Groups B, C, and D animals were treated, respectively, with therapeutic dose of lamivudine (4.28 mg/kg), a combination of lamivudine (4.28 mg/kg) and neurovite (7.05 mg/kg), and neurovite (7.05 mg/kg) alone, daily. The rats were sacrificed using chloroform inhalation, processed, and stained using H&E method. Results. There was severe cellular degeneration with dystrophic changes, vacuolization in the molecular and granular layers, and aggregation of swollen Purkinje cells in group B animals compared with group C animals which showed only slight cellular dystrophy and inflammation. The mean cellular population was significantly () higher in the treatment groups compared with the control. Conclusion. There was amelioration of damage of the cerebellum in the animals treated with neurovite and lamivudine combination compared to animals treated with only lamivudine. Therefore, there is need to give neurovite to patients on lamivudine therapy.
PubDate: Thu, 16 Jan 2014 09:18:35 +000
- What Guides Visual Overt Attention under Natural Conditions' Past and
Abstract: In the last decade, overt attention under natural conditions became a prominent topic in neuroscientific and psychological research. In this context, one central question is “what guides the direction of gaze on complex visual scenes'” In the present review recent research on bottom-up influences on overt attention is presented first. Against this background, strengths and limitations of the bottom-up approach are discussed and future directions in this field are outlined. In addition to that, the current scope on top-down factors in visual attention is enlarged by discussing the impact of emotions and motivational tendencies on viewing behavior. Overall, this review highlights how behavioral and neurophysiological research on overt attention can benefit from a broader scope on influential factors in visual attention.
PubDate: Thu, 12 Dec 2013 14:47:54 +000
- Traveled Distance Is a Sensitive and Accurate Marker of Motor Dysfunction
in a Mouse Model of Multiple Sclerosis
Abstract: Multiple sclerosis (MS) is a common central nervous system disease associated with progressive physical impairment. To study the mechanisms of the disease, we used experimental autoimmune encephalomyelitis (EAE), an animal model of MS. EAE is induced by myelin oligodendrocyte peptide, and the severity of paralysis in the disease is generally measured using the EAE score. Here, we compared EAE scores and traveled distance using the open-field test for an assessment of EAE progression. EAE scores were obtained with a 6-step observational scoring system for paralysis, and the traveled distance was obtained by automatic trajectory analysis of natural exploratory behaviors detected by a computer. The traveled distance of the EAE mice started to decrease significantly at day 7 of the EAE process, when the EAE score still did not reflect a change. Moreover, in the relationship between the traveled distance and paralysis as measured by the EAE score after day 14, there was a high coefficient of determination between the distance and the score. The results suggest that traveled distance is a sensitive marker of motor dysfunction in the early phases of EAE progression and that it reflects the degree of motor dysfunction after the onset of paralysis in EAE.
PubDate: Tue, 10 Dec 2013 14:01:07 +000
- Trigeminal Medullary Dorsal Horn Neurons Activated by Nasal Stimulation
Coexpress AMPA, NMDA, and NK1 Receptors
Abstract: Afferent information initiating the cardiorespiratory responses during nasal stimulation projects from the nasal passages to neurons within the trigeminal medullary dorsal horn (MDH) via the anterior ethmoidal nerve (AEN). Central AEN terminals are thought to release glutamate to activate the MDH neurons. This study was designed to determine which neurotransmitter receptors (AMPA, kainate, or NMDA glutamate receptor subtypes or the Substance P receptor NK1) are expressed by these activated MDH neurons. Fos was used as a neuronal marker of activated neurons, and immunohistochemistry combined with epifluorescent microscopy was used to determine which neurotransmitter receptor subunits were coexpressed by activated MDH neurons. Results indicate that, during nasal stimulation with ammonia vapors in urethane-anesthetized Sprague-Dawley rats, activated neurons within the superficial MDH coexpress the AMPA glutamate receptor subunits GluA1 (95.8%) and GluA2/3 (88.2%), the NMDA glutamate receptor subunits GluN1 (89.1%) and GluN2A (41.4%), and NK1 receptors (64.0%). It is therefore likely that during nasal stimulation the central terminals of the AEN release glutamate and substance P that then produces activation of these MDH neurons. The involvement of AMPA and NMDA receptors may mediate fast and slow neurotransmission, respectively, while NK1 receptor involvement may indicate activation of a nociceptive pathway.
PubDate: Sun, 08 Dec 2013 11:03:42 +000
- The Effect of Performing a Dual Task on Postural Control in Children with
Abstract: The aim of the study was to explore the effect of eye movements (saccades and pursuits) on postural stability in children with autism versus typically developing children of comparable age. Postural stability was recorded with a platform (Techno Concept) in seven children with autism (mean age: 6 ± 0.8) while fixating a target or making saccades or pursuit eye movements. Data was compared to that of seven age-matched typically developing children. Surface area and mean speed of the center of pressure (CoP) were measured. Autistic children (AC) were more instable than typically developing children (TD), both in simple as well as dual task conditions. Performing a dual task thus affects AC and TD children in a different way. AC stability is not improved during saccades or pursuit eye movements in the dual task condition; in contrast, saccades significantly improve postural stability in TD children. The postural instability observed in AC during simple as well as dual task supports the hypothesis that such children have deficits in cerebellar functions.
PubDate: Wed, 30 Oct 2013 17:50:58 +000
- A Review of Hypothalamic-Pituitary-Adrenal Axis Function in Chronic
Abstract: Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has been found in a high proportion of chronic fatigue syndrome (CFS) patients and includes enhanced corticosteroid-induced negative feedback, basal hypocortisolism, attenuated diurnal variation, and a reduced responsivity to challenge. A putative causal role for genetic profile, childhood trauma, and oxidative stress has been considered. In addition, the impact of gender is demonstrated by the increased frequency of HPA axis dysregulation in females. Despite the temporal relationship, it is not yet established whether the endocrine dysregulation is causal, consequent, or an epiphenomenon of the disorder. Nonetheless, given the interindividual variation in the effectiveness of existing biological and psychological treatments, the need for novel treatment strategies such as those which target the HPA axis is clear.
PubDate: Mon, 30 Sep 2013 11:56:38 +000
- Myosins Are Differentially Expressed under Oxidative Stress in Chronic
Streptozotocin-Induced Diabetic Rat Brains
Abstract: Diabetes mellitus is a disease characterized by persistent hyperglycemia, which may lead to brain tissue damage due to oxidative stress and also contributes to neuronal death and changes in synaptic transmission. This study evaluated the effect of oxidative stress and the use of antioxidants supplementation on myosins expression levels in the brains of chronic diabetic rats induced by streptozotocin. Lipid peroxidation, antioxidant enzymes activities, and myosins-IIB and -Va expressions at transcriptional and translational levels were examined after 90 days induction. The chronic effect of the diabetes led to the upregulation of superoxide dismutase (SOD) and catalase (CAT) activities, and the downregulation of glutathione peroxidase (GPx), but there was no statistically significant increase in the malondialdehyde (MDA) levels. These alterations were accompanied by high myosin-IIB and low myosin-Va expressions. Although the antioxidant supplementation did not interfere on MDA levels, the oxidative stress caused by chronic hyperglycemia was reduced by increasing SOD and restoring CAT and GPx activities. Interestingly, after supplementation, diabetic rats recovered only myosin-Va protein levels, without interfering on myosins mRNA levels expressed in diabetic rat brains. Our results suggest that antioxidant supplementation reduces oxidative stress and also regulates the myosins protein expression, which should be beneficial to individuals with diabetes/chronic hyperglycemia.
PubDate: Tue, 24 Sep 2013 15:56:09 +000
- A Tool to Investigate Symmetry Properties of Newborns Brain: The
Newborns’ Symmetric Brain Atlas
Abstract: It is well established that the two hemispheres of the human brain exhibit a certain degree of asymmetry. Postmortem studies of developing brains of pre- and postpartum infants have shown that already in this early stage of development Heschl gyrus, planum temporale and superior temporal sulcus (STS) exhibit pronounced asymmetry. Advances in acquisition and computational evaluation of high-resolution magnetic resonance images provide enhanced tools for noninvasive studies of brain asymmetry in newborns. Until now most atlases used for image processing contain themselves asymmetry and may thus introduce and/or increase asymmetry already contained in the original data of brain structural or functional images. So, it is preferable to avoid the application of these asymmetric atlases. Thus, in this paper we present our framework to create a symmetric brain atlas from a group of newborns aged between 39 and 42 weeks after gestation. The resulting atlas demonstrates no difference between its original and its flipped version as should be the case for an asymmetric atlas. Consequently, the resulting symmetric atlas can be used for applications such as analysis of development of brain asymmetry in the context of language development.
PubDate: Wed, 18 Sep 2013 11:45:44 +000
- Quantification of Neocortical Slice Diffusion Characteristics Using
Pharmacokinetic and Pharmacodynamic Modelling
Abstract: Pharmacological brain slice experiments are complicated by the need to ensure adequate drug delivery deep into the healthy layers of the tissue. Because tissue slices have no blood supply, this is achieved solely by passive drug diffusion. The aim of this study was to determine whether pharmacokinetic/pharmacodynamic (PKPD) modeling could be adapted to estimate drug diffusion times in neocortical brain slices. No-magnesium seizure-like event (SLE) activity was generated in 41 slices (400 μm). Two anesthetic agents, etomidate (24 μM, ) and thiopental (250 μM, ), and magnesium ions () were delivered to effect reversible reductions in SLE frequency. Concentration-effect hysteresis loops were collapsed using a first order rate constant model and equilibrium half-lives () derived. The values obtained were consistent with expectations. The median (range) of 83.1 (19.4–330.1) min for etomidate is in keeping with its known slow diffusion into brain slice tissue. Values for etomidate and thiopental (111.8 (27.8–198.0) min) were similar, while magnesium had a significantly faster equilibration rate ( of 26.1 (8.6–77.0) min) compared to the anesthetics, as expected for a simple ion. In conclusion, PKPD modeling is a simple and practical method that can be applied to brain slice experiments for investigating drug diffusion characteristics.
PubDate: Thu, 05 Sep 2013 09:22:28 +000
- Xanthine Oxidase Does Not Contribute to Apoptosis after Brain
Hypoxia-Ischemia in Immature Rabbits
Abstract: Background. The mechanisms involving the initiation of apoptosis after brain hypoxia-ischemia through caspase activation are not fully defined. Oxygen free radicals may be an important mediator of caspase initiation with reactive oxygen species generated by xanthine oxidase (XO) being one potential source. The purpose of this study was to examine the role of XO in apoptosis after global cerebral injury. Methods. Immature rabbits were subjected to 8 minutes hypoxia and 8 minutes ischemia and then 4 hours of reperfusion. In one group (), the XO substrate xanthine was infused to generate more oxygen free radicals to promote apoptosis while in another (), the XO inhibitor allopurinol was given to reduce apoptosis by preventing free radical production (). Control animals () received the vehicles. Caspase 3, 8, and 9 enzyme activities were measured in the cerebral cortex, hippocampus, cerebellum, thalamus, and caudate. Results. Administration of xanthine increased () caspase 3 activity but only in the hippocampus, and pretreatment with allopurinol did not reduce it. No differences () were found in any other region nor were there any changes in caspases 8 or 9 activities. Conclusion. We conclude that XO is not a major factor in inducing apoptosis after hypoxic-ischemic brain injury.
PubDate: Thu, 01 Aug 2013 12:02:30 +000
- The Role of Neurotransmitters in Protection against Amyloid-β
Toxicity by KiSS-1 Overexpression in SH-SY5Y Neurons
Abstract: Recent studies have suggested that the kisspeptin (KP) and kissorphin (KSO) peptides have neuroprotective actions against the Alzheimer’s amyloid-β (Aβ) peptide. Overexpression of the human KiSS-1 gene that codes for KP and KSO peptides in SH-SY5Y neurons has also been shown to inhibit Aβ neurotoxicity. The in vivo actions of KP include activation of neuroendocrine and neurotransmitter systems. The present study used antagonists of KP, neuropeptide FF (NPFF), opioids, oxytocin, estrogen, adrenergic, cholinergic, dopaminergic, serotonergic, and γ-aminobutyric acid (GABA) receptors plus inhibitors of catalase, cyclooxygenase, nitric oxide synthase, and the mitogen activated protein kinase cascade to characterize the KiSS-1 gene overexpression neuroprotection against Aβ cell model. The results showed that KiSS-1 overexpression is neuroprotective against Aβ and the action appears to involve the KP or KSO peptide products of KiSS-1 processing. The mechanism of neuroprotection does not involve the activation of the KP or NPFF receptors. Opioids play a role in the toxicity of Aβ in the KiSS-1 overexpression system and opioid antagonists naloxone or naltrexone inhibited Aβ toxicity. The mechanism of KiSS-1 overexpression induced protection against Aβ appears to have an oxytocin plus a cyclooxygenase dependent component, with the oxytocin antagonist atosiban and the cyclooxygenase inhibitor SC-560 both enhancing the toxicity of Aβ.
PubDate: Wed, 17 Jul 2013 10:52:28 +000
- Nonsocial Functions of Hypothalamic Oxytocin
Abstract: Oxytocin (OXT) is a hypothalamic neuropeptide composed of nine amino acids. The functions of OXT cover a variety of social and nonsocial activity/behaviors. Therapeutic effects of OXT on aberrant social behaviors are attracting more attention, such as social memory, attachment, sexual behavior, maternal behavior, aggression, pair bonding, and trust. The nonsocial behaviors/functions of brain OXT have also received renewed attention, which covers brain development, reproduction, sex, endocrine, immune regulation, learning and memory, pain perception, energy balance, and almost all the functions of peripheral organ systems. Coordinating with brain OXT, locally produced OXT also involves the central and peripheral actions of OXT. Disorders in OXT secretion and functions can cause a series of aberrant social behaviors, such as depression, autism, and schizophrenia as well as disturbance of nonsocial behaviors/functions, such as anorexia, obesity, lactation failure, osteoporosis, diabetes, and carcinogenesis. As more and more OXT functions are identified, it is essential to provide a general view of OXT functions in order to explore the therapeutic potentials of OXT. In this review, we will focus on roles of hypothalamic OXT on central and peripheral nonsocial functions.
PubDate: Sun, 07 Jul 2013 09:31:19 +000
- The Special Role of Higher-Frequency Neighbors at the Phonological Level:
An Event-Related Potential Study of Chinese Character Naming
Abstract: The present study explored the time course of neighborhood frequency effect at the early processing stages, examining whether orthographic neighbors with higher frequency exerted an influence on target processing especially at the phonological stage by using the event-related potential (ERP). Thirteen undergraduate students were recruited in this study, and they were required to covertly name Chinese characters with or without higher-frequency neighbors (HFNs); meanwhile, their brain activity was recorded. Results showed that the effect of neighborhood frequency was significant in frontocentral P2 amplitude, with a reduction for naming characters with HFNs compared to those without HFNs; while there was no effect in posterior N1 amplitude. The only neighborhood frequency effect in P2 component suggested a special role for the HFNs in phonological access of Chinese characters. The decrease in amplitude for naming with-HFN characters might be associated with the phonological interference of higher-frequency neighbors due to their different pronunciations from the target characters.
PubDate: Tue, 02 Jul 2013 10:59:53 +000
- Off the Beaten Path: Drug Addiction and the Pontine Laterodorsal Tegmentum
Abstract: Drug addiction is a multileveled behavior controlled by interactions among many diverse neuronal groups involving several neurotransmitter systems. The involvement of brainstem-sourced, cholinergic neurotransmission in the development of addiction and in the persistent physiological processes that drive this maladaptive behavior has not been widely investigated. The major cholinergic input to neurons in the midbrain which are instrumental in assessment of reward and assignment of salience to stimuli, including drugs of abuse, sources from acetylcholine- (ACh-) containing pontine neurons of the laterodorsal tegmentum (LDT). Excitatory LDT input, likely cholinergic, is critical in allowing behaviorally relevant neuronal firing patterns within midbrain reward circuitry. Via this control, the LDT is positioned to be importantly involved in development of compulsive, addictive patterns of behavior. The goal of this review is to present the anatomical, physiological, and behavioral evidence suggesting a role of the LDT in the neurobiology underlying addiction to drugs of abuse. Although focus is directed on the evidence supporting a vital participation of the cholinergic neurons of the LDT, data indicating a contribution of noncholinergic LDT neurons to processes underlying addiction are also reviewed. While sparse, available information of actions of drugs of abuse on LDT cells and the output of these neurons as well as their influence on addiction-related behavior are also presented. Taken together, data from studies presented in this review strongly support the position that the LDT is a major player in the neurobiology of drug addiction. Accordingly, the LDT may serve as a future treatment target for efficacious pharmaceutical combat of drug addiction.
PubDate: Sun, 23 Jun 2013 14:03:02 +000
- Memory and Self–Neuroscientific Landscapes
Abstract: Relations between memory and the self are framed from a number of perspectives—developmental aspects, forms of memory, interrelations between memory and the brain, and interactions between the environment and memory. The self is seen as dividable into more rudimentary and more advanced aspects. Special emphasis is laid on memory systems and within them on episodic autobiographical memory which is seen as a pure human form of memory that is dependent on a proper ontogenetic development and shaped by the social environment, including culture. Self and episodic autobiographical memory are seen as interlocked in their development and later manifestation. Aside from content-based aspects of memory, time-based aspects are seen along two lines—the division between short-term and long-term memory and anterograde—future-oriented—and retrograde—past-oriented memory. The state dependency of episodic autobiographical is stressed and implications of it—for example, with respect to the occurrence of false memories and forensic aspects—are outlined. For the brain level, structural networks for encoding, consolidation, storage, and retrieval are discussed both by referring to patient data and to data obtained in normal participants with functional brain imaging methods. It is elaborated why descriptions from patients with functional or dissociative amnesia are particularly apt to demonstrate the facets in which memory, self, and personal temporality are interwoven.
PubDate: Tue, 14 May 2013 17:53:42 +000
- Slack, Slick, and Sodium-Activated Potassium Channels
Abstract: The Slack and Slick genes encode potassium channels that are very widely expressed in the central nervous system. These channels are activated by elevations in intracellular sodium, such as those that occur during trains of one or more action potentials, or following activation of nonselective cationic neurotransmitter receptors such as AMPA receptors. This review covers the cellular and molecular properties of Slack and Slick channels and compares them with findings on the properties of sodium-activated potassium currents (termed KNa currents) in native neurons. Human mutations in Slack channels produce extremely severe defects in learning and development, suggesting that KNa channels play a central role in neuronal plasticity and intellectual function.
PubDate: Mon, 13 May 2013 10:28:01 +000
- Does the Volume and Localization of Intracerebral Hematoma Affect
Short-Term Prognosis of Patients with Intracerebral Hemorrhage'
Abstract: The aim of this study was to determine whether volume and localization of intracerebral hematoma affects the six-month prognosis of patients with intracerebral hemorrhage (ICH). Patients and Methods. The study included 75 patients with ICH of both sex and all age groups. ICH, based on CT scan findings, was divided in the following groups: lobar, subcortical, infratentorial, intraventricular haemorrhage and multiple hematomas. Volume of intracerebral hematoma was calculated according to formula . Intracerebral hematomas, according to the volume, are divided in three groups (0–29 mL, 30–60 mL, and >60 mL). Results. The highest mortality rate was recorded in the group with multiple hematomas (41%), while the lowest in infratentorial (12.8%). The best six-month survival was in patients with a volume up to 29 mL, 30 of them (64%) survived. The highest mortality rate was recorded in patients with the hematoma volume >60 mL (85%). Kaplan-Meier’s analysis showed that there was statistical significance between the size of the hematoma and the six-month survival (). More than half of patients (61.1%) who survived 6 months after ICH were functionally independent (Rankin scale ≤2). Conclusion The volume of hematoma significantly affects six-month prognosis in patients with intracerebral hemorrhage, while localization does not.
PubDate: Wed, 08 May 2013 18:27:04 +000
- The Mind-Brain Relationship as a Mathematical Problem
Abstract: This paper aims to frame certain fundamental aspects of the human mind (content and meaning of mental states) and foundational elements of brain computation (spatial and temporal patterns of neural activity) so as to enable at least in principle their integration within one and the same quantitative representation. Through the history of science, similar approaches have been instrumental to bridge other seemingly mysterious scientific phenomena, such as thermodynamics and statistical mechanics, optics and electromagnetism, or chemistry and quantum physics, among several other examples. Identifying the relevant levels of analysis is important to define proper mathematical formalisms for describing the brain and the mind, such that they could be mapped onto each other in order to explain their equivalence. Based on these premises, we overview the potential of neural connectivity to provide highly informative constraints on brain computational process. Moreover, we outline approaches for representing cognitive and emotional states geometrically with semantic maps. Next, we summarize leading theoretical framework that might serve as an explanatory bridge between neural connectivity and mental space. Furthermore, we discuss the implications of this framework for human communication and our view of reality. We conclude by analyzing the practical requirements to manage the necessary data for solving the mind-brain problem from this perspective.
PubDate: Sun, 14 Apr 2013 15:08:11 +000
- Biopsychosocial Aspects of Atypical Odontalgia
Abstract: Background. A few studies have found somatosensory abnormalities in atypical odontalgia (AO) patients. The aim of the study is to explore the presence of specific abnormalities in facial pain patients that can be considered as psychophysical factors predisposing to AO. Materials and Methods. The AO subjects () have been compared to pain-free (), trigeminal neuralgia (), migraine (), and temporomandibular disorder (). The neurometer current perception threshold (CPT) was used to investigate somatosensory perception. Structured clinical interviews based on the DSM-IV axis I and DSM III-R axis II criteria for psychiatric disorders and self-assessment questionnaires were used to evaluate psychopathology and aggressive behavior among subjects. Results. Subjects with AO showed a lower Aβ, Aδ, and C trigeminal fiber pain perception threshold when compared to a pain-free control group. Resentment was determined to be inversely related to Aβ (rho: 0.62, ), Aδ (rho: 0.53, ) and C fibers (rho: 0.54, ), and depression was inversely related with C fiber (rho: 0.52, ) perception threshold only in AO subjects. Conclusion. High levels of depression and resentment can be considered predictive psychophysical factors for the development of AO after dental extraction.
PubDate: Tue, 05 Mar 2013 10:18:52 +000
- Measurement of Blood-Brain Barrier Permeability with T1-Weighted Dynamic
Contrast-Enhanced MRI in Brain Tumors: A Comparative Study with Two
Abstract: The purpose of this study was to assess the feasibility of measuring different permeability parameters with T1-weighted dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) in order to investigate the blood brain-barrier permeability associated with different brain tumors. The Patlak algorithm and the extended Tofts-Kety model were used to this aim. Twenty-five adult patients with tumors of different histological grades were enrolled in this study. MRI examinations were performed at 1.5 T. Multiflip angle, fast low-angle shot, and axial 3D T1-weighted images were acquired to calculate T1 maps, followed by a DCE acquisition. A region of interest was placed within the tumor of each patient to calculate the mean value of different permeability parameters. Differences in permeability measurements were found between different tumor grades, with higher histological grades characterized by higher permeability values. A significant difference in transfer constant () values was found between the two methods on high-grade tumors; however, both techniques revealed a significant correlation between the histological grade of tumors and their values. Our results suggest that DCE acquisition is feasible in patients with brain tumors and that maps can be easily obtained by these two algorithms, even if the theoretical model adopted could affect the final results.
PubDate: Wed, 20 Feb 2013 13:34:33 +000
- An Emerging Dimension in Psychosomatic Research: The Nocebo Phenomenon in
the Management of Chronic Pain
Abstract: Introduction. The nocebo effect consists in delivering verbal suggestions of negative outcomes so that the subject expects clinical worsening. Several studies indicate that negative verbal suggestions may result in the amplification of pain. Amplification style is one of the most important dimensions in psychosomatic research. Methods. One group of pain therapy unit patients was evaluated at baseline and again after 6 months from the beginning of the pain treatment. Results. Only 43% of 86 chronic pain patients respond positively to the expectation of sham pain. This group shows at baseline higher pain intensity (t value: 2.72, ) and lower cold pain threshold (t value: 2.18, ) than the group of subjects with any response to sham pain stimulus. Somatoform dimensions influence positively the strength of nocebo response in those predisposed to it. Conclusion. Our study shows that the power of the nocebo phenomenon seems to be a dimension belonging to the investigation in psychosomatic. In contrast to what one might expect, the presence of the nocebo phenomenon affects positively pain relief and the outcome of pain treatment. In a clinical setting, and the meaning of nocebo response does not seem to be different from placebo response.
PubDate: Tue, 12 Feb 2013 09:14:15 +000
- The (Real) Neurogenic/Gliogenic Potential of the Postnatal and Adult Brain
Abstract: During the last two decades basic research in neuroscience has remarkably expanded due to the discovery of neural stem cells (NSCs) and adult neurogenesis in the mammalian central nervous system (CNS). The existence of such unexpected plasticity triggered hopes for alternative approaches to brain repair, yet deeper investigation showed that constitutive mammalian neurogenesis is restricted to two small “neurogenic sites” hosting NSCs as remnants of embryonic germinal layers and subserving homeostatic roles in specific neural systems. The fact that in other classes of vertebrates adult neurogenesis is widespread in the CNS and useful for brain repair sometimes creates misunderstandings about the real reparative potential in mammals. Nevertheless, in the mammalian CNS parenchyma, which is commonly considered as “nonneurogenic,” some processes of gliogenesis and, to a lesser extent, neurogenesis also occur. This “parenchymal” cell genesis is highly heterogeneous as to the position, identity, and fate of the progenitors. In addition, even the regional outcomes are different. In this paper the heterogeneity of mammalian parenchymal neurogliogenesis will be addressed, also discussing the most common pitfalls and misunderstandings of this growing and promising research field.
PubDate: Wed, 06 Feb 2013 09:49:30 +000
- Magnetic Resonance Imaging versus Electrophysiologic Tests in Clinical
Diagnosis of Lower Extremity Radicular Pain
Abstract: Introduction. Radicular low back pain is one of the most common medical problems. The aim of this study was to evaluate the diagnostic accuracy of MRI and electrodiagnosis in lower extremity radicular pain in relation to history and clinical findings. Methods. In this cross-sectional study, we studied 165 sciatalgic subjects. A comprehensive history and physical examinations were taken from the subjects and recorded, and then MRI scanning and electrodiagnostic (nerve conduction velocity and electromyography) tests were performed. Results. From 152 subjects who remained in the study, 67 cases (44.1%) had radicular pain in left lower limb, 46 (30.3%) in right, and 39 (25.6%) in both lower limbs. 104 cases (68.4%) had shown some type of abnormalities in both MRI and electrodiagnosis, 30 (19.7%) had shown this abnormality only in MRI, and 21 (13.8%) only in electrodiagnosis, while 10 cases (6.5%) had both normal MRI and electrodiagnostic studies. Coordination rates of MRI and electrodiagnosis with clinical findings were 58.6% and 89.5%, respectively. Conclusion. In many MRI negative but symptomatic subjects, electrodiagnosis has an important diagnostic value.
PubDate: Tue, 15 Jan 2013 11:53:21 +000
- Caspase-3 and Survivin Expression in Primary Atypical and Malignant
Abstract: Objective. Information about possible prognostic factors of the survival of patients with atypical and malignant meningiomas (AMM) is sparse. The aim of our study was to evaluate prognostic significance of apoptotic marker caspase-3 and apoptotic inhibitor survivin in a series of primary AMM. Methods. 86 AMM (76 atypical and 10 malignant) were analyzed. Caspase-3 and survivin expression was evaluated immunohistochemically. The correlation between caspase-3, survivin, and other possible factors of meningioma recurrence was evaluated. Uni- and multivariate recurrence-free survival (RFS) and overall survival (OS) analyses were performed. Results. The intensity of caspase-3 expression correlated with the tumor grade (), the proliferation index (), and the mitotic count (). Survivin tended to be more expressed in female patients (). Survivin expression was stronger in malignant compared to atypical meningiomas, however, the difference was not statistically important (). Neither survivin nor caspase-3 expression significantly predicted OS or RFS in patients with AMM. Conclusions. Strong caspase-3 expression on AMM cells could reflect a cellular attempt at the homeostatic autoregulation of the tumor size. Survivin expression on AMM cells is similar to the survivin expression reported on benign meningiomas. Caspase-3 and survivin expression has no prognostic significance on the survival of patients with AMM.
PubDate: Wed, 19 Dec 2012 11:43:09 +000