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Sensory Stimuli (sensory + stimulus)
Selected AbstractsVisuospatial attention disturbance in Duchenne muscular dystrophyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2 2010MARIA CLARA DRUMMOND SOARES DE MOURA Aim, The cognitive deficits present in the Duchenne muscular dystrophy (DMD) are not yet well characterized. Attention, considered to be the brain mechanism responsible for the selection of sensory stimuli, could be disturbed in DMD, contributing, at least partially, to the observed global cognitive deficit. The aim of this study was to investigate attentional function in individuals with DMD. Method, Twenty-five males (mean age 12y; SD 2y 2mo) with DMD and 25 healthy males (mean age 12y; SD 2y) were tested in a visuospatial task (Posner computerized test). They were instructed to respond as quickly as possible to a lateralized visual target stimulus with the ipsilateral hand. Their attention was automatically orientated by a peripheral prime stimulus or, alternatively, voluntarily orientated by a central spatially informative cue. Results, The main result obtained was that the attentional effect (sum of the benefit and the cost of attention) did not differ between the two groups in the case of automatic attention (p=0.846) but was much larger for individuals with DMD than for comparison individuals in the case of voluntary attention (p<0.001). Interpretation, The large voluntary attentional effect exhibited by the participants with DMD seems similar to that of younger children, suggesting that the disease is associated with delayed maturation of voluntary attention mechanisms. [source] Characterization of the plasticity-related gene, Arc, in the frog brainDEVELOPMENTAL NEUROBIOLOGY, Issue 12 2010Lisa A. Mangiamele Abstract In mammals, expression of the immediate early gene Arc/Arg3.1 in the brain is induced by exposure to novel environments, reception of sensory stimuli, and production of learned behaviors, suggesting a potentially important role in neural and behavioral plasticity. To date, Arc has only been characterized in a few species of mammals and birds, which limits our ability to understand its role in modifying behavior. To begin to address this gap, we identified Arc in two frog species, Xenopus tropicalis and Physalaemus pustulosus, and characterized its expression in the brain of P. pustulosus. We found that the predicted protein for frog Arc shared 60% sequence similarity with Arc in other vertebrates, and we observed high Arc expression in the forebrain, but not the midbrain or hindbrain, of female túngara frogs sacrificed at breeding ponds. We also examined the time-course of Arc induction in the medial pallium, the homologue of the mammalian hippocampus, in response to a recording of a P. pustulosus mating chorus and found that accumulation of Arc mRNA peaked 0.75 h following stimulus onset. We found that the mating chorus also induced Arc expression in the lateral and ventral pallia and the medial septum, but not in the striatum, hypothalamus, or auditory midbrain. Finally, we examined acoustically induced Arc expression in response to different types of mating calls and found that Arc expression levels in the pallium and septum did not vary with the biological relevance or acoustic complexity of the signal. © 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 813,825, 2010 [source] Cholecystokinin receptor antagonists increase the rat pup's preference toward maternal-odor and rug textureDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2001Michal Shayit Abstract The role of the cholecystokinin (CCK) system in mediating the infant's natural preferences toward maternal-related stimuli was examined by peripheral administration of selective CCKA and CCKB receptor antagonists (Devazepide and L-365,260, respectively) to 11,12-day-old rats and presenting them with a 3-minute preference test. In Experiment 1, the choice was between two floor textures, rug and plywood; the time spent on the relatively preferred side (rug) was measured. In Experiment 2, the odor of maternal faces emanated from one end of the test arena; time spent near that end was measured. These sensory stimuli were chosen as they represent olfactory and tactile aspects of the dam and nest. Compared to controls, both CCK receptor antagonists selectively increased the time spent on the preferred side, in both experiments, without affecting axillary temperature or locomotor activity. The results suggest that CCK may mediate and attenuate the infant's attraction toward naturally preferred stimuli. © 2001 John Wiley & Sons, Inc. Dev Psychobiol 38: 164,173, 2001 [source] Effects of urethane anaesthesia on sensory processing in the rat barrel cortex revealed by combined optical imaging and electrophysiologyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2010Ian M. Devonshire Abstract The spatiotemporal dynamics of neuronal assemblies evoked by sensory stimuli have not yet been fully characterised, especially the extent to which they are modulated by prevailing brain states. In order to examine this issue, we induced different levels of anaesthesia, distinguished by specific electroencephalographic indices, and compared somatosensory-evoked potentials (SEPs) with voltage-sensitive dye imaging (VSDI) responses in the rat barrel cortex evoked by whisker deflection. At deeper levels of anaesthesia, all responses were reduced in amplitude but, surprisingly, only VSDI responses exhibited prolonged activation resulting in a delayed return to baseline. Further analysis of the optical signal demonstrated that the reduction in response amplitude was constant across the area of activation, resulting in a global down-scaling of the population response. The manner in which the optical signal relates to the various neuronal generators that produce the SEP signal is also discussed. These data provide information regarding the impact of anaesthetic agents on the brain, and show the value of combining spatial analyses from neuroimaging approaches with more traditional electrophysiological techniques. [source] Cholinergic modulation of visuospatial responding in central thalamusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2007Lori A. Newman Abstract Central thalamus has extensive connections with basal ganglia and frontal cortex that are thought to play a critical role in sensory-guided goal-directed behavior. Central thalamic activity is influenced by cholinergic projections from mesopontine nuclei. To elucidate this function we trained rats to respond to lights in a reaction time (RT) task and compared effects of muscarinic (2.4, 7.3, 22 nmol scopolamine) and nicotinic (5.4, 16, 49, 98 nmol mecamylamine) antagonists with the GABAA agonist muscimol (0.1, 0.3, 1.0 nmol) in central thalamus. We compared this with subcutaneous (systemic) effects of mecamylamine (3.2, 9.7, 29 µmol/kg) and scopolamine (0.03, 0.09, 0.26 µmol/kg). Subcutaneous scopolamine increased omissions (failure to respond within a 3-s response window) at the highest dose tested. Subcutaneous mecamylamine increased omissions at the highest dose tested while impairing RT and per cent correct at lower doses. Intrathalamic injections of muscimol and mecamylamine decreased per cent correct at doses that did not affect omissions or RT. Intrathalamic scopolamine increased omissions and RT at doses that had little effect on per cent correct. Anatomical controls indicated that the effects of mecamylamine were localized in central thalamus and those of scopolamine were not. Drug effects did not interact with attention-demanding manipulations of stimulus duration, proximity of stimulus and response locations, or stimulus array size. These results are consistent with the hypothesis that central thalamus mediates decisional processes linking sensory stimuli with actions, downstream from systems that detect sensory signals. They also provide evidence that this function is specifically influenced by nicotinic cholinergic receptors. [source] Uremic pruritus: A reviewHEMODIALYSIS INTERNATIONAL, Issue 2 2005Jocemir R. Lugon Abstract Pruritus is a major disorder among the skin derangements in advanced renal failure. Its prevalence seems to be diminishing perhaps because of improvements in dialysis treatment. Recent information suggests that interactions between dermal mast cells and distal ends of nonmyelinated C fibers may be important in the precipitation and regulation of the sensory stimuli. The knowledge as to the control of pruritus transmission to cortex areas is still incomplete but endogenous opioid and opioid receptors may have a role in this regard. A recent classification was proposed for pruritus based on the level of its origin. Uremic pruritus, however, seems to be too complex to fit perfectly in any of the suggested modalities. Inflammation and malnutrition are recognized risk factors for cardiovascular death in end-stage renal disease patients, which may be related to the genesis of pruritus. Consistent with this concept, lower serum levels of albumin and higher serum levels of ferritin were found in pruritic patients when compared to nonpruritic ones. Newer treatments for this difficult clinical problem are being developed and tested. [source] "Automatism" and the emergence of dynamic psychiatryJOURNAL OF THE HISTORY OF THE BEHAVIORAL SCIENCES, Issue 1 2003Adam Crabtree FacultyArticle first published online: 21 JAN 200 This article is about the clash of two explanatory paradigms, each attempting to account for the same data of human experience. In the first half of the nineteenth century, physiologists investigated reflex actions and applied a recently coined word, "automatism," to describe actions which, although seeming to arise from higher centers, actually result from automatic reaction to sensory stimuli. Experiments with spinal reflexes led to the investigation of the reflex action of the brain or "cerebral automatisms." Reflex actions of this kind were used to explain everything from acting compulsively to composing symphonies. Physiological explanations of phenomena of this kind seemed insufficient to some and, in the 1880s, Frederic Myers and Pierre Janet developed psychological frameworks for understanding these phenomena, positing hidden centers of intelligence at work in the individual, outside ordinary awareness, which produce what came to be called "psychological automatisms." Their attempts to unify this psychological framework with the existing physiological one failed. Nevertheless, their work played a crucial role in paving the way for what Ellenberger called dynamic psychiatry, which accepts the reality of an unconscious dynamic of the psyche. © 2003 Wiley Periodicals, Inc. [source] Role of the somatosensory system in primary dystoniaMOVEMENT DISORDERS, Issue 6 2003Michele Tinazzi MD Abstract The pathophysiology of dystonia is still not fully understood, but it is widely held that a dysfunction of the corticostriatal,thalamocortical motor circuits plays a major role in the pathophysiology of this syndrome. Although the most dramatic symptoms in dystonia seem to be motor in nature, marked somatosensory perceptual deficits are also present in this disease. In addition, several lines of evidence, including neurophysiological, neuroimaging and experimental findings, suggest that both motor and somatosensory functions may be defective in dystonia. Consequently, abnormal processing of the somatosensory input in the central nervous system may lead to inefficient sensorimotor integration, thus contributing substantially to the generation of dystonic movements. Whether somatosensory abnormalities are capable of triggering dystonia is an issue warranting further study. Although it seems unlikely that abnormal somatosensory input is the only drive to dystonia, it might be more correlated to the development of focal hand than generalized dystonia because local somesthetic factors are more selectively involved in the former than in the latter where, instead it seems to be a widespread deficit in processing sensory stimuli of different modality. Because basal ganglia and motor areas are heavily connected not only with somatosensory areas, but also with visual and acoustic areas, it is possible that abnormalities of other sensory modalities, such as visual and acoustic, may also be implicated in the pathophysiology of more severe forms of primary dystonia. Further studies have to be addressed to the assessment of the role of sensory modalities and their interaction on the pathophysiology of different forms of primary dystonia. © 2003 Movement Disorder Society [source] Patterns of response to sensory stimuli encountered in daily activities: a comparison between 3,10-year-old Israeli and American children without disabilitiesOCCUPATIONAL THERAPY INTERNATIONAL, Issue 2 2006Ariela Neuman Abstract The purpose of this study was to examine the extent to which patterns of response of typical children aged 3 to 10 in Israel, as reported in the Sensory Profile (Dunn, 1999), were similar to typical children in the United States. The Sensory Profile is a caregiver questionnaire designed to assess sensory processing abilities. A translated Hebrew version of the Sensory Profile was completed by parents of 714 typically developing children who were recruited from across Israel. The mean scores of the Israeli children were compared to the published mean scores of the American children at the section and factor level to determine whether the scoring system of the Sensory Profile would be applicable for Israeli children. The findings revealed that, in some sections and factor clusters, the scores of Israeli children were lower than the scores of the American children across all ages. Although the Israeli children scored lower, overall, their scores were within the established range of typical performance. Initial support for the application of the scoring system of the Sensory Profile in Israel is suggested. Due to the nature of the sample of Israeli children, future studies are recommended with a national representative sample and with specific disability groups to further validate the clinical use of the Sensory Profile in Israel. Copyright © 2006 John Wiley & Sons, Ltd [source] Annotation: What do we know about sensory dysfunction in autism?THE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 12 2005A critical review of the empirical evidence Background:, Unusual responses to sensory stimuli are seen in many children with autism. Their presence was highlighted both in early accounts of autism and in more recent first-person descriptions. There is a widespread belief that sensory symptoms characterize autism and differentiate it from other disorders. This paper examines the empirical evidence for this assumption. Method:, All controlled experimental laboratory investigations published since 1960 were identified through systematic searches using Medline/PubMed and PsycInfo search engines. A total of 48 empirical papers and 27 theoretical or conceptual papers were reviewed. Results:, Sensory symptoms are more frequent and prominent in children with autism than in typically developing children, but there is not good evidence that these symptoms differentiate autism from other developmental disorders. Certain groups, including children with fragile X syndrome and those who are deaf-blind, appear to demonstrate higher rates of sensory symptoms than children with autism. In reviewing the evidence relevant to two theories of sensory dysfunction in autism, over- and under-arousal theory, we find that there is very little support for hyper-arousal and failure of habituation in autism. There is more evidence that children with autism, as a group, are hypo-responsive to sensory stimuli, but there are also multiple failures to replicate findings and studies that demonstrate lack of group differences. Conclusions:, The use of different methods, the study of different sensory modalities, and the changing scientific standards across decades complicate interpretation of this body of work. We close with suggestions for future research in this area. [source] Prolonged stimulus exposure reveals prolonged neurobehavioral response patternsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 10 2010Brett A. Johnson Abstract Although it has been shown repeatedly that minimum response times in sensory systems can be quite short, organisms more often continue to respond to sensory stimuli over considerably longer periods of time. The continuing response to sensory stimulation may be a more realistic assessment of natural sensory responses, so we determined for how long a stimulus would evoke a response in naïve, freely moving animals. Specifically, we determined for how long such rats responded to odorants during continuous passive exposures by monitoring their sniffing with whole-body plethysmography. We found that naïve rats continue to sniff odorants vigorously for up to 3 minutes, much longer than what has been reported for highly trained, highly motivated rats. Patterns of 2-deoxyglucose (2-DG) uptake in the glomerular layer of the rat olfactory bulb also were seen after only 1,5 minutes of odorant exposure, overlapping with the period of increased respiration to odorants. Moreover, these 2-DG uptake patterns closely resembled the patterns that emerge from prolonged odorant exposures, suggesting that activity mapping over prolonged periods can identify areas of activity that are present when rats are still attending and responding to odorant stimuli. Given these findings, it seems important to consider the possibility that prolonged exposure to other sensory stimuli will reveal more realistic neural response patterns. J. Comp. Neurol. 518:1617,1629, 2010. © 2009 Wiley-Liss, Inc. [source] Extended analysis and treatment of self-injurious behaviorBEHAVIORAL INTERVENTIONS, Issue 3 2001John J. Healey In experiment 1, an extended functional analysis of self-injury was conducted with a 21-year-old male diagnosed with autism and profound mental retardation. The multielement phase yielded undifferentiated results. Subsequent blocking of conditions plus the addition of a component allowing access to multiple sensory stimuli suggested that self-injury was unrelated to programmed positive or negative reinforcement contingencies. The behavior appeared to be automatically reinforced; its occurrence decreased when access to alternative sensory stimuli was provided. Experiment 2 evaluated a treatment condition in which response-independent access to these sensory stimuli was provided within the participant's everyday environment. Baseline and treatment frequencies of self-injury were compared in a combined, multiple-baseline-across-settings and ABAB design. The level of self-injury decreased substantially during treatment. These results support the use of extended analog analyses of aberrant behavior in instances in which undifferentiated responding occurs in the initial analogue analysis. Additionally, a procedure is described for generalizing the intervention derived from the experimental analysis into the participant's everyday environment. Copyright © 2001 John Wiley & Sons, Ltd. [source] Glutamate-induced post-activation inhibition of locus coeruleus neurons is mediated by AMPA/kainate receptors and sodium-dependent potassium currentsBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2009Teresa Zamalloa Background and purpose:, Locus coeruleus (LC) neurons respond to sensory stimuli with a glutamate-triggered burst of spikes followed by an inhibition. The aim of our work was to characterize the inhibitory effect of glutamate in the LC. Experimental approach:, Single-unit extracellular and patch-clamp recordings were performed to examine glutamate responses in rat brain slices containing the LC. Key results:, Glutamate caused an initial activation followed by a late post-activation inhibition (PAI). Both effects were blocked by an AMPA/kainate receptor antagonist but not by NMDA or metabotropic glutamate receptor antagonists. All glutamate receptor agonists were able to activate neurons, but only AMPA and quisqualate caused inhibition. In neurons clamped at ,60 mV, glutamate and AMPA induced inward, followed by outward, currents, with the latter reversing polarity at ,110 mV. Glutamate-induced PAI was not modified by ,2 -adrenoceptor, µ opioid, A1 adenosine and GABAA/B receptor antagonists or Ca2+ -dependent release blockade, but it was reduced by raising the extracellular K+ concentration. Glutamate-induced PAI was not affected by several potassium channel, Na+/K+ pump, PKC and neuronal NO synthase inhibitors or lowering the extracellular Ca2+ concentration. The Na+ -activated K channel opener bithionol concentration-dependently potentiated glutamate-induced PAI, whereas partial (80%) Na+ replacement reduced glutamate- and AMPA-induced PAI. Finally, reverse transcription polymerase chain reaction assays showed the presence of mRNA for the Ca2+ -impermeable GluR2 subunit in the LC. Conclusions and implications:, Glutamate induces a late PAI in the LC, which may be mediated by a novel postsynaptic Na+ -dependent K+ current triggered by AMPA/kainate receptors. Mandarin translation of abstract [source] Migraine: a review and future directions for treatmentACTA NEUROLOGICA SCANDINAVICA, Issue 2 2006M. Linde Migraine is a chronic, neurological disorder generally manifesting itself in attacks with severe headache, nausea and an increased reactivity to sensory stimuli. A low migraine threshold is set by genetic factors, although the phenotype also modulates the manifestations. The 1-year prevalence is approximately 13% and is higher among women. Patients usually experience neuropsychological dysfunction, and sometimes also reversible focal neurological symptoms. The trajectories of the characteristic symptoms of acute migraine usually follow a similar time course, indicating a reciprocal underlying mechanism. A central nervous system hyperexcitability has been demonstrated in neurophysiological studies. The dibilitating effects of migraine are not confined to the attacks per se. Many individuals do not recover completely between the attacks and most report a negative impact on the most important life domains, and an interest in testing other treatments. Young persons have a higher frequency of attacks. Acute treatment should routinely be initiated with an analgesic plus a prokinetic anti-emetic. Triptans must not be provided early during the attack to ensure their efficacy. The natural course of attacks is commonly only temporarily altered by acute treatment. Non-pharmacological treatment and drugs may be equally viable in prophylaxis for migraine. In more complicated cases, conjoint therapy should be considered. New strategies to improve adherence with existing therapeutic regimens might yield greater benefits than will new pharmacological agents. [source] MULTIPLE LEVELS OF SENSORY INTEGRATION IN THE INTRINSIC SENSORY NEURONS OF THE ENTERIC NERVOUS SYSTEMCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2004Paul P Bertrand SUMMARY 1.,The enteric nervous system (ENS) is present in the wall of the gastrointestinal tract and contains all the functional classes of neuron required for complete reflex arcs. One of the most important and intriguing classes of neuron is that responsive to sensory stimuli: sensory neurons with cell bodies intrinsic to the ENS. 2.,These neurons have three outstanding and interrelated features: (i) reciprocal connections with each other; (ii) a slow excitatory post-synaptic potential (EPSP) resulting from high-speed firing in other sensory neurons; and (iii) a large after-hyperpolarizing potential (AHP) at the soma. Slow EPSP depolarize the cell body, generate action potentials (APs) and reduce the AHP. Conversely, the AHP limits the firing rate and, hence, reduces transmission of slow EPSP. 3.,Processing of sensory information starts at the input terminals as different patterns of APs depending on the sensory modality and recent sensory history. At the soma, the ability to fire APs and, hence, drive outputs is also strongly determined by the recent firing history of the neuron (through the AHP) and network activity (through the slow EPSP). Positive feedback within the population of intrinsic sensory neurons means that the network is able to drive outputs well beyond the duration of the stimuli that triggered them. 4.,Thus, sensory input and subsequent reflex generation are integrated over several hierarchical levels within the network on intrinsic sensory neurons. [source] Covert attention allows for continuous control of brain,computer interfacesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2010Ali Bahramisharif Abstract While brain-computer interfaces (BCIs) can be used for controlling external devices, they also hold the promise of providing a new tool for studying the working brain. In this study we investigated whether modulations of brain activity by changes in covert attention can be used as a continuous control signal for BCI. Covert attention is the act of mentally focusing on a peripheral sensory stimulus without changing gaze direction. The ongoing brain activity was recorded using magnetoencephalography in subjects as they covertly attended to a moving cue while maintaining fixation. Based on posterior alpha power alone, the direction to which subjects were attending could be recovered using circular regression. Results show that the angle of attention could be predicted with a mean absolute deviation of 51° in our best subject. Averaged over subjects, the mean deviation was ,70°. In terms of information transfer rate, the optimal data length used for recovering the direction of attention was found to be 1700 ms; this resulted in a mean absolute deviation of 60° for the best subject. The results were obtained without any subject-specific feature selection and did not require prior subject training. Our findings demonstrate that modulations of posterior alpha activity due to the direction of covert attention has potential as a control signal for continuous control in a BCI setting. Our approach will have several applications, including a brain-controlled computer mouse and improved methods for neuro-feedback that allow direct training of subjects' ability to modulate posterior alpha activity. [source] | ||||||||||||||||||||||||||||