TY - JOUR. T1 - Morphological variation of layer III pyramidal neurones in the occipitotemporal pathway of the macaque monkey visual cortex. AU - Elston, Guy N.. AU - Rosa, Marcello G.P.. PY - 1998/5/28. Y1 - 1998/5/28. N2 - We compared the morphological characteristics of layer III pyramidal neurones in different visual areas of the occipitotemporal cortical stream, which processes information related to object recognition in the visual field (including shape, colour and texture). Pyramidal cells were intracellularly injected with Lucifer Yellow in cortical slices cut tangential to the cortical layers, allowing quantitative comparisons of dendritic field morphology, spine density and cell body size between the blobs and interblobs of the primary visual area (V1), the interstripe compartments of the second visual area (V2), the fourth visual area (V4) and cytoarchitectonic area TEO. We found that the tangential dimension of basal dendritic fields of layer III pyramidal neurones increases from ...
Dopaminergic pathway and primary visual cortex are involved in the freezing of gait in Parkinsons disease: a PET-CT study Yongtao Zhou,1 Junwu Zhao,1,2 Yaqin Hou,3 Yusheng Su,3 Piu Chan,1 Yuping Wang11The Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, Peoples Republic of China; 2The Nuclear Medicine Department, Xuanwu Hospital of Capital Medical University, Beijing, Peoples Republic of China; 3The Department of Neurology, Weihai Municipal Hospital, Shandong, Peoples Republic of ChinaBackground: Freezing of gait (FOG) could be partly alleviated by dopaminergic drugs but the mechanism still needs to be elucidated. The purpose of this study is to explore the mechanisms of FOG by vesicular monoamine transporter VMAT2 distribution with the 18,F-AV133 tracer and 18-fludeoxyglucose positron emission tomography-computed tomography (18,F-FDG PET-CT).Methods: Clinical material and PET-CT data were collected from 20 patients with FOG and 147 patients without FOG from November
Cortical circuits are sensitive to experience during well-defined intervals of early postnatal development called critical periods (1). After the critical period, plasticity is reduced or absent. Monocular deprivation (MD) is a classic model of experience-dependent plasticity. MD during the critical period results in a shift of ocular dominance (OD) of cortical neurons in favor of the nondeprived eye (2, 3). No OD shift is seen after MD in adult animals. The factors responsible for the cessation of OD plasticity in adults are only partially known. There is some evidence that the developmental increase in intracortical inhibition reduces plasticity and contributes to the termination of the critical period (4-6). However, other factors present in the adult visual cortex could stabilize synaptic connections and limit experience-dependent plasticity. CSPGs are attractive candidates for this role. CSPGs are components of the ECM that inhibit axonal sprouting and growth (7-9). Their adult pattern of ...
CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): this article we investigate to what extent the statistical properties of natural images can be used to understand the variation of receptive field properties of simple cells in the mammalian primary visual cortex. The receptive fields of simple cells have been studied extensively (e.g., Hubel & Wiesel 1968, DeValois et al. 1982a, DeAngelis et al. 1993): they are localised in space and time, have band-pass characteristics in the spatial and temporal frequency domains, are oriented, and are often sensitive to the direction of motion of a stimulus. Here we will concentrate on the spatial properties of simple cells. Several hypotheses as to the function of these cells have been proposed. As the cells preferentially respond to oriented edges or lines, they can be viewed as edge or line detectors. Their joint localisation in both the spatial domain and the spatial frequency domain has led to the suggestion that they mimic Gabor
During development of the mammalian visual system, axon terminals of lateral geniculate nucleus (LGN) neurons, initially intermixed within layer 4 of the visual cortex, gradually segregate according to eye preference to form ocular dominance columns. In addition to LGN axons and layer 4 neurons, subplate neurons may also participate in interactions leading to column formation. Deletion of subplate neurons before the formation of ocular dominance columns prevents the segregation of LGN axons within layer 4. Thus, interactions between LGN axons and layer 4 neurons are not sufficient; subplate neurons are also required for formation of ocular dominance columns in the visual cortex. ...
Synaptic plasticity plays a key role in processes of learning and memory. Long-term potentiation (LTP) is a relatively stable enhancement of synaptic transmission following specific patterns of electrical stimulation. Some types of learning (e.g. motor learning, fear conditioning) result in LTP-like changes at synapses. However, no studies have examined LTP-like plasticity in the visual cortex as a result of visual discrimination learning. A visual discrimination task was used to examine changes in LTP in the primary visual cortex (V1) of adult rats. Rats were placed in a Y-shaped water maze and required to swim to one choice arm containing a hidden platform. Distinct visual cues indicated the presence (CS+) and absence (CS-) of the platform. Rats learned to reliably discriminate the visual cues to successfully navigate the maze. Control rats received the same procedure, but the visual cues did not have a predictive relation with the platform. Following training, trained, control, and ...
GENESIS Turtle Cortex Model README file ======================================= This is the large scale model of turtle visual cortex (the NGU model) described in: Nenadic, Z., Ghosh, B.K. and Ulinski. P. (2003) Propagating Waves in Visual Cortex: A Large Scale Model of Turtle Visual Cortex, J. Computational Neuroscience 14:161-184. and Nenadic, Z., Ghosh, B.K. and Ulinski. P. (2002) Modeling and Estimation Problems in the Turtle Visual Cortex, IEEE Trans. Bio-Med. Eng., 49:753-762 It is also described in considerable detail in the file TurtleVisCortex-descrip.pdf, which is included in this archive. This README file tells how to run the simulation with GENESIS. To run the simulation --------------------- 1. If you do not have the GENESIS simulator installed, download it from the GENESIS web site at http://genesis-sim.org/GENESIS. It is available in source and binary versions for UNIX/Linux, MAC OSX, and Windows with Cygwin. Follow the installation instructions provided with the GENESIS ...
Primary cortical areas normally have a single mapping of the receptor array arising from a point-to-point projection from the thalamus. We show that, for the visual cortex, this simple mapping rule breaks down when retinal input to the thalamus is altered. We utilize the monocular enucleation paradigm, which alters subcortical mappings ipsilateral to the remaining eye. We show that this manipulation produces an altered visuotopic map in area 17 with two separated, mirror-imaged representations of the central visual field. Furthermore, thalamic point-to-point connectivity is dramatically changed. There are now two overlapping geniculocortical projections: the predominant projection maps with apparently normal topography, and a second projection maps with the opposite polarity. The plane of symmetry of the duplicated anatomical projection coincides precisely with the functional map reversal and, notably, geniculocortical magnification factors are identical in the two projections. We suggest that the
We report the application of Optical coherence tomography (OCT) for visualizing a one dimensional depth resolved functional structure of cat brain in vivo. The OCT system is based on the known fact that neural activation induces structural changes such as capillary dilation and cellular swelling. Detecting these changes as an amplitude change of the scattered light, an OCT signal reflecting neural activity i.e., fOCT (functional OCT) could be obtained. Experiments have been done to obtain a depth resolved stimulus-specific profile of activation in cat visual cortex. Our results in one dimension indicate that indeed an orientation dependent functional signal could be obtained. Further, we show that this depth resolved fOCT signal is well correlated with the stimulus dependent column determined by OISI. Based on the results, the smallest functional unit in depth, resolved by the proposed system is around 40 micrometers . We are extending our system to perform two dimensional functional imaging ...
TY - JOUR. T1 - Population receptive field shapes in early visual cortex are nearly circular. AU - Lerma-Usabiaga, Garikoitz. AU - Winawer, Jonathan. AU - Wandell, Brian A.. N1 - Funding Information: Received Dec. 3, 2020; revised Jan. 3, 2021; accepted Jan. 10, 2021. Author contributions: G.L.-U., J.W., and B.A.W. designed research; G.L.-U., J.W., and B.A.W. performed research; G.L.-U. analyzed data; G.L.-U., J.W., and B.A.W. wrote the paper. This work was supported by the European Unions Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie Grant 795807 (to G.L.-U.) and by National Institutes of Health Grants EY027401, EY027964, and MH111417 (to J.W.). We thank E. Silson, C. Baker, and R. Reynolds. We also thank R. Reynolds for help with the AFNI software. The authors declare no competing financial interests. Correspondence should be addressed to Garikoitz Lerma-Usabiaga at [email protected]. https://doi.org/10.1523/JNEUROSCI.3052-20.2021 Copyright © 2021 the ...
Behavioral studies have reported reduced spatial attention in amblyopia, a developmental disorder of spatial vision. However, the neural populations in the visual cortex linked with these behavioral spatial attention deficits have not been identified. Here, we use functional MRI-informed electroencephalography source imaging to measure the effect of attention on neural population activity in the visual cortex of human adult strabismic amblyopes who were stereoblind. We show that compared with controls, the modulatory effects of selective visual attention on the input from the amblyopic eye are substantially reduced in the primary visual cortex (V1) as well as in extrastriate visual areas hV4 and hMT+. Degraded attentional modulation is also found in the normal-acuity fellow eye in areas hV4 and hMT+ but not in V1. These results provide electrophysiological evidence that abnormal binocular input during a developmental critical period may impact cortical connections between the visual cortex and ...
Background. Our previous studies have implicated the primary visual cortex (V1) as the putative visuo-spatial sketchpad for working-memory, but in a supramodal form. To establish this memory-related role for V1, we need to determine the source of its top-down modulation from higher-order memory mechanisms, including medial-temporal lobe (MTL) structures such as the hippocampus and perirhinal cortex (PRC) (Likova, 2012, 2013), which has direct anatomical connection to V1 (Clavagnier et al., 2004). Indeed, V1 and the hippocampus exhibited correlated changes under a memory-based training intervention (Likova, 2015); moreover, the representations for both memory and perception were confirmed as supramodal in PRC (Cacciamani & Likova, 2016). Now, to address the key question of the direction and significance of influence between these memory areas and V1, we ran Granger Causality analysis. Methods. Using fMRI in blind subjects before and after a unique memory-guided drawing intervention ...
For years, neural activity in the brains visual cortex was thought to have only one job: to create visual perceptions. A new study by researchers at MITs Picower Institute for Learning and Memory shows that visual cortical activity can serve another purpose -- connecting visual experience with non-visual events.. The study, slated to appear in the March 17 issue of Science, implies that sensory parts of the brain may be able to accomplish more complex tasks than previously imagined, according to co-authors Marshall G. Shuler, MIT research affiliate, and Mark F. Bear, professor of brain and cognitive sciences. The findings have implications for understanding how our brains imbue sensory experience with behavioral meaning.. Electrodes were implanted in the visual cortex of adult rats. Initially, as expected, their neurons responded only to light. However, as the animal repeatedly experienced a light stimulus with the delivery of a drop of water, the neuronal activity changed. And in many cases, ...
Anatomical and physiological studies of the primate visual system have suggested that the signals relayed by the magnocellular and parvocellular subdivisions of the LGN remain segregated in visual cortex. It has been suggested that this segregation may account for the known differences in visual function between the parietal and temporal cortical processing streams in extrastriate visual cortex. To test directly the hypothesis that the temporal stream of processing receives predominantly parvocellular signals, we recorded visual responses from the superficial layers of V1 (striate cortex), which give rise to the temporal stream, while selectively inactivating either the magnocellular or parvocellular subdivisions of the LGN. Inactivation of the parvocellular subdivision reduced neuronal responses in the superficial layers of V1, but the effects of magnocellular blocks were generally as pronounced or slightly stronger. Individual neurons were found to receive contributions from both pathways. We ...
The sensory recruitment model envisages visual working memory (VWM) as an emergent property that is encoded and maintained in sensory (visual) regions. The model implies that enhanced sensory-perceptual functions, as in synaesthesia, entail a dedicated VWM-system, showing reduced visual cortex activity as a result of neural specificity. By contrast, sensory-perceptual decline, as in old age, is expected to show enhanced visual cortex activity as a result of neural broadening. To test this model, young grapheme-color synaesthetes, older adults and young controls engaged in a delayed pair-associative retrieval and a delayed matching-to-sample task, consisting of achromatic fractal stimuli that do not induce synaesthesia. While a previous analysis of this dataset (Pfeifer et al., 2016) has focused on cued retrieval and recognition of pair-associates (i.e., long-term memory), the current study focuses on visual working memory and considers, for the first time, the crucial delay period in which no visual
Introduction. According to recent behavioral studies, people with schizophrenia are poor at filling-in between collinear elements because of impaired long-range horizontal connections in early visual cortex. However, patients also poorly process low spatial frequencies (SFs), which is thought to arise from dysfunction along the magnocellular pathway. In this study, we aimed to replicate the finding of impaired lateral interactions in schizophrenia and also to determine whether such impairments can be improved by employing high SF elements. Method. We had 24 persons with schizophrenia and 25 well-matched controls repeatedly detect a low-contrast element flanked by collinear or orthogonal high-contrast elements. An up/down staircase governed the contrast of the central target so that subjects detected the target 79.4% of the time. The three element display (target + flankers) was scaled in size to produce a lower and higher spatial frequency condition (4 and 10 cycles/deg, respectively). Results. ...
The characterisation of the extravascular (EV) contribution to the blood oxygenation level-dependent (BOLD) effect is important for understanding the spatial specificity of BOLD contrast and for modelling approaches that aim to extract quantitative metabolic parameters from the BOLD signal. Using bipolar crusher gradients, total (b = 0 s/mm(2) ) and predominantly EV (b = 100 s/mm(2) ) gradient echo BOLD ΔR(2)* and signal changes (ΔS/S) in response to visual stimulation (flashing checkerboard; f = 8 Hz) were investigated sequentially (within | 3 h) at 1.5, 3.0 and 7.0 T in the same subgroup of healthy volunteers (n = 7) and at identical spatial resolutions (3.5 × 3.5 × 3.5 mm(3)). Total ΔR(2)* (z-score analysis) values were -0.61 ± 0.10 s(-1) (1.5 T), -0.74 ± 0.05 s(-1) (3.0 T) and -1.37 ± 0.12 s(-1) (7.0 T), whereas EV ΔR(2)* values were -0.28 ± 0.07 s(-1) (1.5 T), -0.52 ± 0.07 s(-1) (3.0 T) and -1.25 ± 0.11 s(-1) (7.0 T). Although EV ΔR(2)* increased linearly with field, as expected, it
Experimental evidence concerning plasticity of orientation selectivity in visual cortex poses an apparent dilemma. There are strong indications that orientation selectivity of single cells in visual cortex is experience-dependent and dependent on synaptic plasticity. On the other hand, preferred orientation seems very stable. Moreover, preferred orientation is identical for both eyes, even if they never experience common visual input.. To account for this, we propose that a scaffold is embedded in the structure of the long-range lateral connectivity. Its structure determines the initial orientation preference observed in animals with no visual experience and accounts for the stability in the orientation maps that develop in eyes with no common visual experience. The scaffold model is consistent with the broadly tuned, low-spatial frequency orientation selectivity seen in very young animals (DeAngelis et al., 1993). It is also consistent with the observation that orientation selectivity increases ...
The distribution of orientation-selective cells in the primary visual cortex has been found to reflect the first-order statistics of visual inputs, i.e. which orientations are most common during a critical period [1]. Similarly, some properties of the lateral connections between these cells have been found to reflect the second-order statistics of images, i.e. the coocurrence statistics of oriented edge elements, but the results have differed by species. Specifically, horizontal connections have been found to be elongated along the axis of preferred orientation in tree shrew [2] and owl monkey [3], but not in macaque [4]. It is unclear whether these results indicate genuine species differences, or perhaps differences in the visual environments in which these animals were raised. Here we analyse the effect of input statistics on lateral excitatory connectivity in a developmental model of primary visual cortex, by relating differences in co-occurence statistics of distinct image datasets, analysed ...
In the fetal and neonatal monkey, periodically organized regions of high activity of acetylcholinesterase were found in the visual cortical area V2 (Area 18). The acetylcholinesterase bands, like the thin and thick stripes of cytochrome oxidase, were found to run orthogonal to the area 17/18 border. During neonatal development these bands progressively narrow and finally disappear shortly after four months of age.
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Neocortical interneurons display great morphological and physiological variability and are ideally positioned to control circuit dynamics, although their exact role is still poorly understood. To better understand this diversity, we have performed a detailed anatomical and physiological characterization of 3 subtypes of visual cortex interneurons, isolated from transgenic mice which express green fluorescent protein in somatostatin, parvalburnin, and neuropeptide Y positive neurons. We find that these 3 groups of interneurons have systematic differences in dendritic and axonal morphologies and also characteristically differ in the frequencies, amplitude, and kinetics of the spontaneous excitatory and inhibitory synaptic currents they receive. Moreover, we detect a correlation between the kinetics of their synaptic inputs and quantitative aspects of their axonal arborizations. This suggests that different interneuron types could channel different temporal patterns of activity. Our results also ...
Research Interest Visual neurophysiology and perception. Publications Lopour Beth A, Tavassoli Abtine, Fried Itzhak, Ringach Dario L Coding of information in the phase of local field potentials within human medial temporal lobe Neuron, 2013; 79(3): 594-606.. Paik Se-Bum, Ringach Dario L Link between orientation and retinotopic maps in primary visual cortex Proceedings of the National Academy of Sciences of the United States of America, 2012; 109(18): 7091-6.. Nauhaus Ian, Busse Laura, Ringach Dario L, Carandini Matteo Robustness of traveling waves in ongoing activity of visual cortex The Journal of neuroscience : the official journal of the Society for Neuroscience, 2012; 32(9): 3088-94.. Frey Jared, Ringach Dario L Binocular eye movements evoked by self-induced motion parallax The Journal of neuroscience : the official journal of the Society for Neuroscience, 2011; 31(47): 17069-73.. Paik Se-Bum, Ringach Dario L Retinal origin of orientation maps in visual cortex Nature neuroscience, 2011; ...
The calcarine fissure (or calcarine sulcus) is an anatomical landmark located at the caudal end of the medial surface of the brain. Its name comes from the Latin calcar meaning spur.. It is a complete sulcus. The calcarine sulcus begins near the occipital pole in two converging rami and runs forward to a point a little below the splenium of the corpus callosum, where it is joined at an acute angle by the medial part of the parietooccipital sulcus. The anterior part of this fissure gives rise to the prominence of the calcar avis in the posterior cornu of the lateral ventricle. The calcarine sulcus is where the primary visual cortex (V1) is concentrated. The central visual field is located in the posterior portion of the calcarine sulcus and the peripheral visual field in the anterior portion. ...
The organization and connections of the primary visual area (V1) were examined in mice that lacked functional rods (Gnat-/-), but had normal cone function. Because mice are nocturnal and rely almost exclusively on rod vision for normal behaviors, the Gnat-/- mice used in the present study are considered functionally blind. Our goal was to determine if visual cortex is reorganized in these mice, and to examine the neuroanatomical connections that may subserve reorganization. We found that most neurons in V1 responded to auditory, or some combination of auditory, somatosensory, and/or visual stimulation. We also determined that cortical connections of V1 in Gnat-/- mice were similar to those in normal animals, but even in normal animals, there is sparse input from auditory cortex to V1. An important observation was that most of the subcortical inputs to V1 were from thalamic nuclei that normally project to V1 such as the lateral geniculate (LG), lateral posterior (LP), and lateral dorsal (LD) nuclei.
CiteSeerX - Scientific documents that cite the following paper: Antibody labeling of functional subdivisions in visual cortex: cat-301 immunoreactivity in striate and extrastriate cortex of the macaque. Vis Neurosci. 5:67--81
Matrix metalloproteinases play a crucial role in adult visual plasticity in the brains of healthy and stroke-affected mice and their activity has to be within a narrow window for experience-induced plasticity to occur.
Color perception in macaque monkeys and humans depends on the visually evoked activity in three cone photoreceptors and on neuronal post-processing of cone signals. Neuronal post-processing of cone signals occurs in two stages in the pathway from retina to the primary visual cortex. The first stage, in in P (midget) ganglion cells in the retina, is a single-opponent subtractive comparison of the cone signals. The single-opponent computation is then sent to neurons in the Parvocellular layers of the Lateral Geniculate Nucleus (LGN), the main visual nucleus of the thalamus. The second stage of processing of color-related signals is in the primary visual cortex, V1, where multiple comparisons of the single-opponent signals are made. The diversity of neuronal interactions in V1cortex causes the cortical color cells to be subdivided into classes of single-opponent cells and double-opponent cells. Double-opponent cells have visual properties that can be used to explain most of the phenomenology of color
Sensory experience has a profound influence in shaping the functional organization of the cerebral cortex. Over 30 years ago, Hubel and Wiesel described a critical period of postnatal development for the formation of binocular connections in cat visual cortex. They demonstrated that thisconnectivity can be dramatically altered by simple forms of sensory deprivation, such as the temporary closure of one eyelid (monoculardeprivation). Besides the obvious relevance of this neural plasticity to the development of visual capabilities in humans and animals, it seems likely hat similar processes form the basis for some forms of learning and memory in the adult brain. Indeed, visual cortical plasticity, like learning andmemory formation decreases with age and depend on the internal state of the animal. The research in this lab is directed toward elucidating thebasic mechanisms by which visual experience can modify cortical connections in the visual cortex, and how those mechanisms are regulated.. We ...
Home , Papers , Evidence of an increased neuronal activation-to-resting glucose uptake ratio in the visual cortex of migraine patients: a study comparing FDG-PET and visual evoked potentials. ...
Much of the visual cortex is organized into visual field maps: nearby neurons have receptive fields at nearby locations in the image. Mammalian species generally have multiple visual field maps with each species having similar, but not identical, maps. The introduction of functional magnetic resonan …
Purpose: Patients with early onset retinal dysfunction have abnormal V1 fMRI responses when passively viewing a stimulus. In contrast, patients with adult onset dysfunction do not have significant V1 responses unless they are engaged in a demanding task (Masuda et al., 2008). The development of abnormal cortical responses appears to depend on the timing of the onset of retinal dysfunction. To measure the critical period for the development of abnormal V1 responses, we used fMRI in subjects with congenital, critical period onset, and adult onset macular degeneration (MD).. Methods: We recruited MD patients with similar central retinal lesions. The retinal damage deprives a zone in the posterior of V1 of its normal input projections. We refer to this as the lesion projection zone, LPZ. In the MD and healthy controls we used moving-bar stimuli and a model-based analytical method (Dumoulin and Wandell, 2008) to measure visual field maps and population receptive field (pRF) sizes. We made the ...
TY - JOUR. T1 - Subcellular Localization of Intercellular Adhesion Molecule-5 (Telencephalin) in the Visual Cortex Is Not Developmentally Regulated in the Absence of Matrix Metalloproteinase-9. AU - Kelly, Emily A.. AU - Tremblay, Marie-Eve. AU - Gahmberg, Carl G.. AU - Tian, Li. AU - Majewska, Ania K.. PY - 2014. Y1 - 2014. KW - ICAM-5. KW - dendrite. KW - electron microscopy. KW - plasticity. KW - telencephalin. KW - MMP-9. KW - LONG-TERM POTENTIATION. KW - MATRIX METALLOPROTEINASES. KW - MEMBRANE GLYCOPROTEIN. KW - NEURONAL GLYCOPROTEIN. KW - LEUKOCYTE ADHESION. KW - RAT HIPPOCAMPUS. KW - BRAIN. KW - EXPRESSION. KW - EPHA4. KW - MICROGLIA. KW - 1182 Biochemistry, cell and molecular biology. U2 - 10.1002/cne.23440. DO - 10.1002/cne.23440. M3 - Article. VL - 522. SP - 676. EP - 688. JO - Journal of Comparative Neurology. JF - Journal of Comparative Neurology. SN - 0021-9967. IS - 3. ER - ...
List of causes of Babinskis reflex and Lesions of the visual cortex in children, alternative diagnoses, rare causes, misdiagnoses, patient stories, and much more.
New research is challenging the long-held belief that stroke-induced blindness is untreatable and therefore permanent.. Though speech and motor impairments following stroke are routinely treated with great success, therapies for recovering vision have historically been thought impossible. Many stroke survivors have been consigned to permanent blindness as a result. Fortunately, a new study demonstrates that by stimulating healthy parts of the brain, vision recovery following a stroke is possible.. Krystel Huxlin, Ph.D., a neuroscientist and associate professor at the University of Rochester Eye Institute, helmed the study with seven stroke survivors of various ages who had all suffered severe damage to their primary visual cortex, an area of the brain responsible for making sense of visual stimuli so that a recognizable image can be perceived.. Primary visual cortex damage leaves stroke survivors with a vague awareness of visual stimuli but no way to make sense of what they are seeing or discern ...
Researchers at the Wellcome Trust Centre for Neuroimaging at UCL used non-invasive, real-time brain imaging that enabled participants to watch their own brain activity on a screen, a technique known as neurofeedback. During the training phase, they were asked to try to increase activity in the area of the brain that processes visual information, the visual cortex, by imagining images and observing how their brains responded.. After the training phase, the participants visual perception was tested using a new task that required them to detect very subtle changes in the contrast of an image. When they were asked to repeat this task while clamping brain activity in the visual cortex at high levels, those who had successfully learned to control their brain activity could improve their ability to detect even very small changes in contrast.. This improved performance was only observed when participants were exercising control over their brain activity.. Lead author Dr Frank Scharnowski, who is now ...
Our overarching interest is in the question of how experience and deprivation modify synaptic connections in the brain. Experience-dependent synaptic plasticity is the physical substrate of memory, sculpts connections during postnatal development to determine the capabilities and limitations of brain functions, is responsible for the reorganization of the brain after damage, and is vulnerable in numerous psychiatric and neurological diseases and contributes to their symptoms.. Historically, our major efforts to address this question have been focused on the visual cortex and hippocampus. The visual cortex is a site of robust experience-dependent synaptic plasticity, exemplified by the consequences of temporary monocular deprivation (MD) during childhood. MD sets in motion a stereotyped choreography of synaptic modification whereby the deprived-eye inputs to visual cortex rapidly lose strength and, with a delay, the open-eye inputs undergo a compensatory gain in strength. The behavioral ...
A key research direction in the lab examines visual cortex plasticity in blindness. In sighted primate, much of the occipital lobe is dedicated to visual perception. What happens to this part of the brain when it does not receive its species typical input during development? Previous research finds that in blindness, occipital areas are active during tactile and auditory tasks. One of our goals is to uncover the cognitive functions that are supported by the occipital cortex in blind people. Are these functions similar to vision? We find that in blindness visual areas become involved in higher-cognitive functions, including language, mathematical reasoning and non-verbal executive control. These functions recruit different parts of visual cortex within a single blind individuals. Studying the repurposing of visual cortex for higher-order cognition provides insights into the mechanisms that determine cortical specialization in humans. The lab is interested in how experience changes the ...
While the effects of visual deprivation have been well studied in animal models, much less is known about the effects of blindness on human early visual pathway...
Neuroscience research articles are provided.. What is neuroscience? Neuroscience is the scientific study of nervous systems. Neuroscience can involve research from many branches of science including those involving neurology, brain science, neurobiology, psychology, computer science, artificial intelligence, statistics, prosthetics, neuroimaging, engineering, medicine, physics, mathematics, pharmacology, electrophysiology, biology, robotics and technology. ...
A fundamental property of neuronal circuits is the ability to adapt to altered sensory inputs. It is well established that the functional synaptic changes underlying this adaptation are reflected by structural modifications in excitatory neurons. In contrast, the degree to which structural plasticity in inhibitory neurons accompanies functional changes is less clear. Here, we use two-photon imaging to monitor the fine structure of inhibitory neurons in mouse visual cortex after deprivation induced by retinal lesions. We find that a subset of inhibitory neurons carry dendritic spines, which form glutamatergic synapses. Removal of visual input correlates with a rapid and lasting reduction in the number of inhibitory cell spines. Similar to the effects seen for dendritic spines, the number of inhibitory neuron boutons dropped sharply after retinal lesions. Together, these data suggest that structural changes in inhibitory neurons may precede structural changes in excitatory circuitry, which ...
TY - JOUR. T1 - Attentional control of the processing of neutral and emotional stimuli. AU - Pessoa, Luiz. AU - Kastner, Sabine. AU - Ungerleider, Leslie G.. PY - 2002/12/1. Y1 - 2002/12/1. N2 - A typical scene contains many different objects that compete for neural representation due to the limited processing capacity of the visual system. At the neural level, competition among multiple stimuli is evidenced by the mutual suppression of their visually evoked responses and occurs most strongly at the level of the receptive field. The competition among multiple objects can be biased by both bottom-up sensory-driven mechanisms and top-down influences, such as selective attention. Functional brain imaging studies reveal that biasing signals due to selective attention can modulate neural activity in visual cortex not only in the presence but also in the absence of visual stimulation. Although the competition among stimuli for representation is ultimately resolved within visual cortex, the source of ...
The radial unit hypothesis provides a framework for global (proliferation) and regional (distribution) expansion of the primate cerebral cortex. Using principal component analysis (PCA), we have identified cortical regions with shared variance in their surface area and cortical thickness, respectively, segmented from magnetic resonance images obtained in 23,800 participants. We then carried out meta-analyses of genome-wide association studies of the first two principal components for each phenotype. For surface area (but not cortical thickness), we have detected strong associations between each of the components and single nucleotide polymorphisms in a number of gene loci. The first (global) component was associated mainly with loci on chromosome 17 (9.5e-32 ≤ p ≤ 2.8e-10), including those detected previously as linked with intracranial volume and/or general cognitive function. The second (regional) component captured shared variation in the surface area of the primary and adjacent secondary ...
Visual imagery is mediated via top-down activation of visual cortex. Similar to stimulus-driven perception, the neural configurations associated with visual imagery are differentiated according to content. For example, imagining faces or places differentially activates visual areas associated with perception of actual face or place stimuli. However, while top-down activation of topographically specific visual areas during visual imagery is well established, the extent to which internally generated visual activity resembles the fine-scale population coding responsible for stimulus-driven perception remains unknown. Here, we sought to determine whether top-down mechanisms can selectively activate perceptual representations coded across spatially overlapping neural populations. We explored the precision of top-down activation of perceptual representations using neural pattern classification to identify activation patterns associated with imagery of distinct letter stimuli. Pattern analysis of the neural
Sensory areas. There is a general rule that one cerebral hemisphere handles sensory inputs from the opposite side of the body. This is true of the somatosensory cortex, and the visual system, where each visual area processes information relating to the opposite visual field of both eyes. The auditory cortex is an exception however, because localisation of sound requires comparison of the times of arrival of sounds at both ears; hence each auditory cortex receives inputs from both cochleas.. Sensory inputs to the cortex arise from the thalamic nuclei, including the medial and lateral geniculate bodies. There is a topographic map of one half of the bodys surface on the contralateral somatosensory cortex, and a map of the contralateral visual fields of both eyes on the visual cortex. There is also a map of the cochlear basilar membranes on the auditory cortex, in keeping with the need to localise sounds. The cortical area given over to the fovea in the primary visual cortex is much larger that ...
Most brain gene expression studies of schizophrenia have been conducted in the frontal cortex or hippocampus. The extent to which alterations occur in other cortical regions is not well established. We investigated primary visual cortex (Brodmann area 17) from the Stanley Neuropathology Consortium collection of tissue from 60 subjects with schizophrenia, bipolar disorder, major depression, or controls. We first carried out a preliminary array screen of pooled RNA, and then used RT-PCR to quantify five mRNAs which the array identified as differentially expressed in schizophrenia (myelin basic protein [MBP], myelin-oligodendrocyte glycoprotein [MOG], β-actin [ACTB], thymosin β-10 [TB10], and superior cervical ganglion-10 [SCG10]). Reduced mRNA levels were confirmed by RT-PCR for MBP, ACTB and TB10. The MBP reduction was limited to transcripts containing exon 2. ACTB and TB10 mRNAs were also decreased in bipolar disorder. None of the transcripts were altered in subjects with major depression. Reduced MBP
Objective: Vestibular signals are involved in higher cortical functions like spatial orientation and its disorders. Vestibular dysfunction contributes, for example, to spatial neglect which can be transiently improved by caloric stimulation. The exact roles and mechanisms of the vestibular and visual systems for the recovery of neglect are not yet known. Methods: Resting-state functional connectivity (fc) magnetic resonance imaging was recorded in a patient with hemispatial neglect during the acute phase and after recovery 6 months later following a right middle cerebral artery infarction before and after caloric vestibular stimulation. Seeds in the vestibular [parietal operculum (OP2)], the parietal [posterior parietal cortex (PPC);7A, hIP3], and the visual cortex (VC) were used for the analysis. Results: During the acute stage after caloric stimulation the fc of the right OP2 to the left OP2, the anterior cingulum, and the para/hippocampus was increased bilaterally (i.e., the vestibular ...
We used the rat visual cortex as a model system to examine the changes in protein synthesis during experience-induced synaptic plasticity. Dark-rearing rats from birth results in a relatively immature visual cortex that maintains the high de- gree of synaptic plasticity characteristic of the critical period (Kirkwood et al., 1995). Exposure of dark-reared rats to light results in a rapid, robust and coordinated burst of experience- driven synaptic plasticity that can be readily monitored at the biochemical and electrophysiological level (Quinlan et al., 1999). In previous work, we showed that visual experience evokes the polyadenylation of ␣-CaMKII mRNA in visual cortex and the elevation of ␣-CaMKII protein in synaptic fractions from this brain region. Moreover, this increase was a direct result of new synthesis because it was sensitive to the translation inhibitor cycloheximide (Wu et al., 1998). Here we show that the experience-induced increase of ␣-CaMKII pro- tein does not require new ...
TITLE stochastic release probability COMMENT Milstein 2015. When this point process receives a spike, it requests a random number from a random number generator and compares it to an internal release probability variable P to decide if a single vesicle should be released at this synapse. The release probability is then updated to follow specified dynamics of facilitation and depression. In order to make use of this event, additional synaptic mechanisms must be connected to this point process via a NetCon object. Dynamics based on: Implementation of the model of short-term facilitation and depression described in Varela, J.A., Sen, K., Gibson, J., Fost, J., Abbott, L.R., and Nelson, S.B. A quantitative description of short-term plasticity at excitatory synapses in layer 2/3 of rat primary visual cortex Journal of Neuroscience 17:7926-7940, 1997 ENDCOMMENT NEURON { POINT_PROCESS Pr RANGE P, P0, random, f, tau_F, d1, tau_D1, F, D1, tlast THREADSAFE POINTER randObjPtr } PARAMETER { : the (1) is ...
Our perception of time constrains our experience of the world and exerts a pivotal influence over a myriad array of cognitive and motor functions. There is emerging evidence that the perceived duration of subsecond intervals is driven by sensory-specific neural activity in human and nonhuman animals, but the mechanisms underlying individual differences in time perception remain elusive. We tested the hypothesis that elevated visual cortex GABA impairs the coding of particular visual stimuli, resulting in a dampening of visual processing and concomitant positive time-order error (relative underestimation) in the perceived duration of subsecond visual intervals. Participants completed psychophysical tasks measuring visual interval discrimination and temporal reproduction and we measured in vivo resting state GABA in visual cortex using magnetic resonance spectroscopy. Time-order error selectively correlated with GABA concentrations in visual cortex, with elevated GABA associated with a rightward
Looking for occipital pole TA of cerebrum? Find out information about occipital pole TA of cerebrum. The tip of the occipital lobe of the brain Explanation of occipital pole TA of cerebrum
wait…what? Esref was born without the privilege of sight. As a result, he never developed the thalamo-cortical projections from the lateral geniculate nucleus (LGN) to the primary visual cortex necessary for sight perception. However, instead of letting his occipital lobe go to waste, Esrefs brain adapted by using that same cortical real estate for other senses, primarily touch.. With Esrefs enhanced sense of touch he claims he can, see more with his fingers than sighted people can see with their eyes. A bold statement: after all, Esref has no idea what seeing is like. Conversely, sighted people dont know what the sense of touch is like when the visual cortex becomes involved, so can we really deny his claim? The circular nature of this subjective discussion renders both opinions null but it does raise the question: is a subjective experience a product of the sensory modality involved or is it a product of the cortical area involved? And what exactly is Esref subjectively perceiving when ...
To reach and grasp an object in space on the basis of its image cast on the retina requires different coordinate transformations that take into account gaze and limb positioning. Eye position in the orbit influences the images conversion from retinotopic (eye-centered) coordinates to an egocentric frame necessary for guiding action. Neuroimaging studies have revealed eye position-dependent activity in extrastriate visual, parietal and frontal areas that is along the visuo-motor pathway. At the earliest vision stage, the role of the primary visual area (V1) in this process remains unclear. We used an experimental design based on pattern-onset visual evoked potentials (VEP) recordings to study the effect of eye position on V1 activity in humans. We showed that the amplitude of the initial C1 component of VEP, acknowledged to originate in V1, was modulated by the eye position. We also established that putative spontaneous small saccades related to eccentric fixation, as well as retinal disparity cannot
Damage to the visual system can result in (a partial) loss of vision, in response to which the visual system may functionally reorganize. Yet the timing, extent, and conditions under which this occurs are not well understood. Hence, studies in individuals with diverse congenital and acquired conditions and using various methods are needed to better understand this. In the present study, we examined the visual system of a young girl who received a hemispherectomy at the age of three and who consequently suffered from hemianopia. We did so by evaluating the corticocortical and retinocortical projections in the visual system of her remaining hemisphere. For the examination of these aspects, we analyzed the characteristics of the connective fields (“neural-referred” receptive fields) based on both resting-state (RS) and retinotopy data. The evaluation of RS data, reflecting brain activity independent from visual stimulation, is of particular interest as it is not biased by the patient’s
Microdeletion of a region in chromosome 16p11.2 increases susceptibility to autism. Although this region contains exons of 29 genes, disrupting only a small segment of the region, which spans five genes, is sufficient to cause autistic traits. One candidate gene in this critical segment is MVP, which encodes for the major vault protein (MVP) that has been implicated in regulation of cellular transport mechanisms. MVP expression levels in MVP+/- mice closely phenocopy those of 16p11.2 mutant mice, suggesting that MVP+/- mice may serve as a model of MVP function in 16p11.2 microdeletion. Here we show that MV Pregulates the homeostatic component of ocular dominance (OD) plasticity in primary visual cortex. MVP+/- mice of both sexes show impairment in strengthening of open-eye responses after several days of monocular deprivation (MD), whereas closed-eye responses are weakened as normal, resulting in reduced overall OD plasticity. The frequency of miniature EPSCs (mEPSCs) in pyramidal neurons is ...
The posterior parietal cortex (PPC) has been implicated in perceptual decisions, but whether its role is specific to sensory processing or sensorimotor transformation is not well understood. Here, we trained mice to perform a go/no-go visual discrimination task and imaged the activity of neurons in primary visual cortex (V1) and PPC during engaged behavior and passive viewing. Unlike V1 neurons, which respond robustly to stimuli in both conditions, most PPC neurons respond exclusively during task engagement. To test whether signals in PPC primarily encoded the stimulus or the animals impending choice, we image the same neurons before and after re-training mice with a reversed sensorimotor contingency. Unlike V1 neurons, most PPC neurons reflect the animals choice of the new target stimulus after re-training. Mouse PPC is therefore strongly task-dependent, reflects choice more than stimulus, and may play a role in the transformation of visual inputs into motor commands. The precise role of PPC in
A nonspecific term referring to impaired vision. Major subcategories include stimulus deprivation-induced amblyopia and toxic amblyopia. Stimulus deprivation-induced amblyopia is a developmental disorder of the visual cortex. A discrepancy between visual information received by the visual cortex from each eye results in abnormal cortical development. Strabismus and refractive errors may cause this condition. Toxic amblyopia is a disorder of the optic nerve which is associated with alcoholism, tobacco smoking, and other toxins and as an adverse effect of the use of some medications ...
A nonspecific term referring to impaired vision. Major subcategories include stimulus deprivation-induced amblyopia and toxic amblyopia. Stimulus deprivation-induced amblyopia is a developmental disorder of the visual cortex. A discrepancy between visual information received by the visual cortex from each eye results in abnormal cortical development. Strabismus and refractive errors may cause this condition. Toxic amblyopia is a disorder of the optic nerve which is associated with alcoholism, tobacco smoking, and other toxins and as an adverse effect of the use of some medications ...
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Neurons in the primate medial temporal lobe (MTL) respond selectively to visual categories such as faces, contributing to how the brain represents stimulus meaning. However, it remains unknown whether MTL neurons continue to encode stimulus meaning when it changes flexibly as a function of variable task demands imposed by goal-directed behavior. While classically associated with long-term memory, recent lesion and neuroimaging studies show that the MTL also contributes critically to the online guidance of goal-directed behaviors such as visual search. Do such tasks modulate responses of neurons in the MTL, and if so, do their responses mirror bottom-up input from visual cortices or do they reflect more abstract goal-directed properties? To answer these questions, we performed concurrent recordings of eye movements and single neurons in the MTL and medial frontal cortex (MFC) in human neurosurgical patients performing a memory-guided visual search task. We identified a distinct population of ...
Motion perception is fundamental to survival. Until recently, research on motion perception emphasized such basic aspects of motion as sampling and filtering. In the past decade, however, the emphasis has gradually shifted to higher-level motion processing-i.e., processing that takes place not only in the primary visual cortex but also in the higher or more complicated parts of the brain. The contributors to this book focus on such key aspects of motion processing as interaction and integration between locally measured motion units, structure from motion, heading in an optical flow, and second-order motion. They also discuss the interaction of motion processing with other high-level visual functions such as surface representation and attention.The book is divided into three sections: (1) interactive aspects of motion, (2) motion coherence and grouping, and (3) heading and structure from motion. Each section begins with computational aspects, proceeds to the neuropsychological/neurophysiological, and
We tested the hypothesis that the differences in performance between developmental dyslexics and controls on visual tasks are specific for the detection of dynamic stimuli. We found that dyslexics were less sensitive than controls to coherent motion in dynamic random dot displays. However, their sensitivity to control measures of static visual form coherence was not significantly different from that of controls. This dissociation of dyslexics performance on measures that are suggested to tap the sensitivity of different extrastriate visual areas provides evidence for an impairment specific to the detection of dynamic properties of global stimuli, perhaps resulting from selective deficits in dorsal stream functions.
Motion perception is fundamental to survival. Until recently, research on motion perception emphasized such basic aspects of motion as sampling and filtering. In the past decade, however, the emphasis has gradually shifted to higher-level motion processing--i.e., processing that takes place not only in the primary visual cortex but also in the higher or more complicated parts of the brain. The contributors to this book focus on such key aspects of motion processing as interaction and integration between locally measured motion units, structure from motion, heading in an optical flow, and second-order motion. They also discuss the interaction of motion processing with other high-level visual functions such as surface representation and attention. The book is divided into three sections: (1) interactive aspects of motion, (2) motion coherence and grouping, and (3) heading and structure from motion. Each section begins with computational aspects, proceeds to the ...
Individual neurons can undergo drastic structural changes, known as neuronal remodeling or structural plasticity. One example of this is in response to hormones, such as during puberty in mammals or metamorphosis in insects. However, in each of these examples, it remains unclear whether the remodeled neuron resumes prior patterns of connectivity, and if so, whether the persistent circuits drive similar behaviors. Here, we utilize a well-characterized neural circuit in the Drosophila larva: the moonwalker descending neuron (MDN) circuit. We previously showed that larval MDN induces backward crawling, and synapses onto the Pair1 interneuron to inhibit forward crawling (Carreira-Rosario et al., 2018). MDN is remodeled during metamorphosis and regulates backward walking in the adult fly. We investigated whether Pair1 is remodeled during metamorphosis and functions within the MDN circuit during adulthood. We assayed morphology and molecular markers to demonstrate that Pair1 is remodeled during ...
Single pulses of transcranial magnetic stimulation (TMS) result in distal and long-lasting oscillations, a finding directly challenging the virtual lesion hypothesis. Previous research supporting this finding has primarily come from stimulation of the motor cortex.
A large extent of the posterior cortex of the primate brain is devoted to vision, and it contains two general streams that process visual information. The one stream is situated more ventrally in the cortex and is important for object recognition, pattern recognition, color perception, and shape perception. These attributes of visual analysis we associate with visual awareness or seeing, and thus this stream has been referred to as the what system because it recognizes objects (Ungerleider and Mishkin 1982). A second, more dorsal stream is associated with visual-motor transformations-that is, the routing of sensory information into motor areas for the purpose of action. This dorsal stream plays an important role in attention, decisions, and movement planning. It also plays an important role in spatial awareness, which is crucial for planning movements to locations in space and for transforming visually defined locations into movement coordinates to accomplish accurate motor behaviors. This ...
Most blind people wear sunglasses, but what if their glasses could actually restore their vision? Such a feat seems miraculous, but the development of new bionic prostheses may make such miracles a reality. These devices work in two ways: by replacing non-functional parts of the visual pathway or by creating alternative neural avenues to provide vision. When attempting to repair or restore lost vision, it is important to understand how we normally receive and process visual information. Light enters the eye and is refracted by the cornea to the lens, which focuses the light onto the retina. The cells of the retina, namely photoreceptors, convert the light into electrical impulses, which are transmitted to the primary visual cortex by the optic nerve. In short, this process serves to translate light energy into electrical energy that our brain can interpret. For patients suffering from impaired or lost vision, one of the steps in this process is either malfunctioning or not functioning at ...
Cacciamani, L., Wager, E., Peterson, M. A., & Scalf, P. E. (2014, November). Connectivity between the perirhinal cortex and the visual cortex in young and older adults. Society for Neuroscience Annual Meeting, Washington, D.C.. Cacciamani, L., Scalf, P. E., & Peterson, M. A. (2014, May). Competition-based ground suppression in extrastriate cortex and the role of attention. Vision Sciences Society Meeting, St. Petersburg, FL.. Cacciamani, L., Scalf, P. E., & Peterson, M. A. (2013, November). Evidence of top-down mediated ground suppression in extrastriate cortex. Society for Neuroscience Annual Meeting, San Diego, CA.[PDF]. Cacciamani, L., Mojica, A. J., Sanguinetti, J. L., & Peterson, M. A. (2013, May). Accessing meaning for the groundside of a figure: How long does it last? Vision Sciences Society Meeting, Naples, FL. Journal of Vision, 13(9): 71. doi:10.1167/13.9.71. Scalf, P. E., Cacciamani, L., Barense, M. D., & Peterson, M. A. (2013, May). Representation of object parts and wholes in V2 ...