The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Matteo Carandini - One of the best experts on this subject based on the ideXlab platform.
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effects of arousal on mouse Sensory Cortex depend on modality
Cell Reports, 2018Co-Authors: Daisuke Shimaoka, Kenneth D Harris, Matteo CarandiniAbstract:Summary Changes in arousal modulate the activity of mouse Sensory Cortex, but studies in different mice and different Sensory areas disagree on whether this modulation enhances or suppresses activity. We measured this modulation simultaneously in multiple cortical areas by imaging mice expressing voltage-sensitive fluorescent proteins (VSFP). VSFP imaging estimates local membrane potential across large portions of Cortex. We used temporal filters to predict local potential from running speed or from pupil dilation, two measures of arousal. The filters provided good fits and revealed that the effects of arousal depend on modality. In the primary visual Cortex (V1) and auditory Cortex (Au), arousal caused depolarization followed by hyperpolarization. In the barrel Cortex (S1b) and a secondary visual area (LM), it caused only hyperpolarization. In all areas, nonetheless, arousal reduced the phasic responses to trains of Sensory stimuli. These results demonstrate diverse effects of arousal across Sensory Cortex but similar effects on Sensory responses.
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population rate dynamics and multineuron firing patterns in Sensory Cortex
The Journal of Neuroscience, 2012Co-Authors: Michael S Okun, Matteo Carandini, Pierre Yger, Stephan L Marguet, Florian Gerardmercier, Andrea Benucci, Steffen Katzner, Laura BusseAbstract:Cortical circuits encode Sensory stimuli through the firing of neuronal ensembles, and also produce spontaneous population patterns in the absence of Sensory drive. This population activity is often characterized experimentally by the distribution of multineuron “words” (binary firing vectors), and a match between spontaneous and evoked word distributions has been suggested to reflect learning of a probabilistic model of the Sensory world. We analyzed multineuron word distributions in Sensory Cortex of anesthetized rats and cats, and found that they are dominated by fluctuations in population firing rate rather than precise interactions between individual units. Furthermore, cortical word distributions change when brain state shifts, and similar behavior is seen in simulated networks with fixed, random connectivity. Our results suggest that similarity or dissimilarity in multineuron word distributions could primarily reflect similarity or dissimilarity in population firing rate dynamics, and not necessarily the precise interactions between neurons that would indicate learning of Sensory features.
Fiorenzo Conti - One of the best experts on this subject based on the ideXlab platform.
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Synaptic localization of GLT-1a in the rat somatic Sensory Cortex.
Glia, 2008Co-Authors: Marcello Melone, Michele Bellesi, Fiorenzo ContiAbstract:GLT-1a, the major glutamate transporter, plays an important role in both physiological and pathological conditions. Uncertainty regarding its localization in the cerebral Cortex prompted us to re-examine its cellular and subcellular localization in the rat somatic Sensory Cortex. GLT-1a detection was sensitive to fixation; in optimal conditions � 25% of GLT-1a1 profiles were axon terminals. GLT-1a/VGLUT1 double-labeling and pre-embedding electron microscopy studies showed that � 50% of GLT-1a1 profiles were in the vicinity of asymmetric synapses. Using pre-embedding electron microscopy, we found that � 70% of GLT-1a located in the vicinity of asymmetric synapses was astrocytic and � 30% was neuronal. Post-embedding immunogold studies showed that the density of gold particles coding for GLT-1a was much higher in astrocytic processes than in axon terminals, and that in the latter they were never at the active zone. In both astrocytic processes and axon terminals most gold particles were localized in a membrane region extending for about 250 nm from active zone margin, with a peak at 140 nm for astrocytic processes and at 80 for axon terminals. We conclude that, although GLT-1a is expressed by both astrocytes and axon terminals, astrocytic GLT-1a predominates at asymmetric synapses, and that the perisynaptic localization of GLT-1a in Cortex is well-suited to modulate Glu concentrations at the cleft and also to restrict Glu spillover. V C 2008 Wiley-Liss, Inc.
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Changes in glutamate immunoreactivity in the somatic Sensory Cortex of adult monkeys induced by nerve cuts.
The Journal of Comparative Neurology, 1996Co-Authors: Fiorenzo Conti, Andrea Minelli, Tim P. PonsAbstract:: Antibodies to glutamate (Glu) were used to study the effects of reduced afferent input on excitatory neurons in the somatic Sensory Cortex of adult monkeys. In each monkey, immunocytochemical staining was compared to thionin and cytochrome oxidase (CO) staining in adjacent sections. In the cervical spinal cord, dorsal column nuclei, ventroposterior thalamus, and primary somatic Sensory Cortex (SI), Glu immunoreactivity (Glu-ir) was analogous to that described in normal animals; regions with reduced or absent Glu-ir were never observed and no appreciable differences were noted between the experimental and normal side. There were also no differences in CO or thionin-stained sections from the affected hemisphere. In the insuloparietal operculum, sections in the hemisphere contralateral to the nerve cut showed that most cortical fields had a normal pattern of Glu-ir (pattern a), some exhibited a reduction of Glu-ir (pattern b), and that in the central portion of the upper bank of the central sulcus, which corresponds to the general location of the hand representation of the second somatic Sensory Cortex (SII), Glu-ir had virtually disappeared (pattern c). Adjacent sections processed for CO or stained with thionin showed that in the regions corresponding to those characterized by pattern c, CO was slightly decreased and that glial cells had increased in number. In the regions of SII characterized by pattern c, small intensely stained glial cells displayed Glu-ir. These findings indicate that Glu-ir is regulated by afferent activity and suggest that changes in Glu levels in neurons as well as in glial cells may trigger the biochemical processes underlying the functional and structural changes occurring during a slow phase of reorganizational plasticity in the cerebral Cortex of adult monkeys.
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Substance P‐containing pyramidal neurons in the cat somatic Sensory Cortex
The Journal of Comparative Neurology, 1992Co-Authors: Fiorenzo Conti, Silvia De Biasi, Mara Fabri, Lubna H. Abdullah, Tullio Manzoni, Peter PetruszAbstract:Light and electron microscopic immunocytochemical methods were used to verify the possibility that neocortical pyramidal neurons in the first somatic Sensory Cortex of cats contain substance P. At the light microscopic level, substance P-positive neurons accounted for about 3% of all cortical neurons, and the vast majority were nonpyramidal cells. However, 10% of substance P-positive neurons had a large conical cell body, a prominent apical dendrite directed toward the pia, and basal dendrites, thus suggesting they are pyramidal neurons. These neurons were in layers III and V. At the electron microscopic level, the majority of immunoreactive axon terminals formed symmetric synapses, but some substance P-positive axon terminals made asymmetric synapses. Labelled dendritic spines were also present. Combined retrograde transport-immunocytochemical experiments were also carried out to study whether substance P-positive neurons are projection neurons. Colloidal gold-labelled wheat germ agglutinin conjugated to enzymatically inactive horseradish peroxidase was injected either in the first somatic Sensory Cortex or in the dorsal column nuclei. In the somatic Sensory Cortex contralateral to the injection sites, a few substance P-positive neurons in layers III and V also contained black granules, indicative of retrograde transport. This indicates that some substance P-positive neurons project to cortical and subcortical targets. We have therefore identified a subpopulation of substance P-positive neurons that have most of the features of pyramidal neurons, are the probable source of immunoreactive axon terminals forming asymmetric synapses on dendritic spines, and project to the contralateral somatic Sensory Cortex and dorsal column nuclei. These characteristics fulfill the criteria required for classifying a cortical neuron as pyramidal. © 1992 Wiley-Liss, Inc.
Barry R Komisaruk - One of the best experts on this subject based on the ideXlab platform.
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Male Urogenital System Mapped Onto the Sensory Cortex: Functional Magnetic Resonance Imaging Evidence
The Journal of Sexual Medicine, 2020Co-Authors: Kachina Allen, Eleni Frangos, N Wise, Barry R KomisarukAbstract:Abstract Introduction The projection of the human male urogenital system onto the paracentral lobule has not previously been mapped comprehensively. Aim To map specific urogenital structures onto the primary somatoSensory Cortex toward a better understanding of sexual response in men. Methods Using functional magnetic resonance imaging, we mapped primary somatoSensory cortical responses to self-stimulation of the penis shaft, glans, testicles, scrotum, rectum, urethra, prostate, perineum, and nipple. We further compared neural response with erotic and prosaic touch of the penile shaft. Main Outcome Measure We identified the primary mapping site of urogenital structures on the paracentral lobule and identified networks involved in perceiving touch as erotic. Results We mapped sites on the primary somatoSensory Cortex to which components of the urogenital structures project in men. Evidence is provided that penile cutaneous projection is different from deep penile projection. Similar to a prior report in women, we show that the nipple projects to the same somatoSensory cortical region as the genitals. Evidence of differential representation of erotic and nonerotic genital self-stimulation is also provided, the former activating Sensory networks other than the primary Sensory Cortex, indicating a role of “top-down” activity in erotic response. Clinical Implications We map primary sites of projection of urogenital structures to the primary somatoSensory Cortex and differentiate cortical sites of erotic from nonerotic genital self-stimulation. Strength & Limitations To our knowledge, this is the first comprehensive mapping onto the primary somatoSensory Cortex of the projection of the components of the urogenital system in men and the difference in cortical activation in response to erotic vs nonerotic self-stimulation. The nipple was found to project to the same cortical region as the genitals. Evidence is provided that superficial and deep penile stimulation project differentially to the Cortex, suggesting that Sensory innervation of the penis is provided by more than the (pudendal) dorsal nerve. Conclusion This study reconciles prior apparently conflicting findings and offers a comprehensive mapping of male genital components to the paracentral lobule. We provide evidence of differential projection of light touch vs pressure applied to the penile shaft, suggesting differential innervation of its superficial, vs deep structure. Similar to the response in women, we found nipple projection to genital areas of the paracentral lobule. We also provide evidence of differential representation of erotic and nonerotic genital self-stimulation, the former activating Sensory networks other than the primary Sensory Cortex, indicating a role of top-down activity in erotic response. Allen K, Wise N, Frangos E, et al. Male Urogenital System Mapped Onto the Sensory Cortex: Functional Magnetic Resonance Imaging Evidence. J Sex Med 2020;17:603–613.
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Activation of Sensory Cortex by imagined genital stimulation: an fMRI analysis.
Socioaffective Neuroscience & Psychology, 2016Co-Authors: N Wise, Eleni Frangos, Barry R KomisarukAbstract:Background : During the course of a previous study, our laboratory made a serendipitous finding that just thinking about genital stimulation resulted in brain activations that overlapped with, and differed from, those generated by physical genital stimulation. Objective : This study extends our previous findings by further characterizing how the brain differentially processes physical ‘touch’ stimulation and ‘imagined’ stimulation. Design : Eleven healthy women (age range 29–74) participated in an fMRI study of the brain response to imagined or actual tactile stimulation of the nipple and clitoris. Two additional conditions – imagined dildo self-stimulation and imagined speculum stimulation – were included to characterize the effects of erotic versus non-erotic imagery. Results : Imagined and tactile self-stimulation of the nipple and clitoris each activated the paracentral lobule (the genital region of the primary Sensory Cortex) and the secondary somatoSensory Cortex. Imagined self-stimulation of the clitoris and nipple resulted in greater activation of the frontal pole and orbital frontal Cortex compared to tactile self-stimulation of these two bodily regions. Tactile self-stimulation of the clitoris and nipple activated the cerebellum, primary somatoSensory Cortex (hand region), and premotor Cortex more than the imagined stimulation of these body regions. Imagining dildo stimulation generated extensive brain activation in the genital Sensory Cortex, secondary somatoSensory Cortex, hippocampus, amygdala, insula, nucleus accumbens, and medial prefrontal Cortex, whereas imagining speculum stimulation generated only minimal activation. Conclusion : The present findings provide evidence of the potency of imagined stimulation of the genitals and that the following brain regions may participate in erogenous experience: primary and secondary Sensory cortices, Sensory-motor integration areas, limbic structures, and components of the ‘reward system’. In addition, these results suggest a mechanism by which some individuals may be able to generate orgasm by imagery in the absence of physical stimulation. Keywords: human female; tactile imagery; clitoris; nipple; self-stimulation; homunculus; sexual arousal; genitalia; primary somatoSensory Cortex; secondary somatoSensory Cortex (Published: 25 October 2016) Citation: Socioaffective Neuroscience & Psychology 2016, 6 : 31481 - http://dx.doi.org/10.3402/snp.v6.31481 This paper is part of the Special Issue: Orgasm: Neurophysiological, psychological, and evolutionary perspectives. More papers from this issue can be found at www.socioaffectiveneuroscipsychol.net
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women s clitoris vagina and cervix mapped on the Sensory Cortex fmri evidence
The Journal of Sexual Medicine, 2011Co-Authors: Barry R Komisaruk, N Wise, Eleni Frangos, Kachina Allen, Stuart BrodyAbstract:Introduction The projection of vagina, uterine cervix, and nipple to the Sensory Cortex in humans has not been reported.
Kenneth D Harris - One of the best experts on this subject based on the ideXlab platform.
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effects of arousal on mouse Sensory Cortex depend on modality
Cell Reports, 2018Co-Authors: Daisuke Shimaoka, Kenneth D Harris, Matteo CarandiniAbstract:Summary Changes in arousal modulate the activity of mouse Sensory Cortex, but studies in different mice and different Sensory areas disagree on whether this modulation enhances or suppresses activity. We measured this modulation simultaneously in multiple cortical areas by imaging mice expressing voltage-sensitive fluorescent proteins (VSFP). VSFP imaging estimates local membrane potential across large portions of Cortex. We used temporal filters to predict local potential from running speed or from pupil dilation, two measures of arousal. The filters provided good fits and revealed that the effects of arousal depend on modality. In the primary visual Cortex (V1) and auditory Cortex (Au), arousal caused depolarization followed by hyperpolarization. In the barrel Cortex (S1b) and a secondary visual area (LM), it caused only hyperpolarization. In all areas, nonetheless, arousal reduced the phasic responses to trains of Sensory stimuli. These results demonstrate diverse effects of arousal across Sensory Cortex but similar effects on Sensory responses.
Uri Kramer - One of the best experts on this subject based on the ideXlab platform.
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interhemispheric correlations of slow spontaneous neuronal fluctuations revealed in human Sensory Cortex
Nature Neuroscience, 2008Co-Authors: Roy Mukamel, Ilan Dinstein, Eran Privman, Michal Harel, Lior Fisch, Hagar Gelbardsagiv, Svetlana Kipervasser, Fani Andelman, Miri Y Neufeld, Uri KramerAbstract:Spontaneous cortical waves have been widely observed, although previous evidence from humans has been indirect, using functional magnetic resonance imaging. This study reports that there are slow modulations in neuronal firing rates and gamma local field potentials in human auditory Cortex in the absence of Sensory stimuli or task. Animal studies have shown robust electrophysiological activity in the Sensory Cortex in the absence of stimuli or tasks. Similarly, recent human functional magnetic resonance imaging (fMRI) revealed widespread, spontaneously emerging cortical fluctuations. However, it is unknown what neuronal dynamics underlie this spontaneous activity in the human brain. Here we studied this issue by combining bilateral single-unit, local field potentials (LFPs) and intracranial electrocorticography (ECoG) recordings in individuals undergoing clinical monitoring. We found slow (<0.1 Hz, following 1/f-like profiles) spontaneous fluctuations of neuronal activity with significant interhemispheric correlations. These fluctuations were evident mainly in neuronal firing rates and in gamma (40–100 Hz) LFP power modulations. Notably, the interhemispheric correlations were enhanced during rapid eye movement and stage 2 sleep. Multiple intracranial ECoG recordings revealed clear selectivity for functional networks in the spontaneous gamma LFP power modulations. Our results point to slow spontaneous modulations in firing rate and gamma LFP as the likely correlates of spontaneous fMRI fluctuations in the human Sensory Cortex.
