Visual Neuroscience
1469-8714
0952-5238
Anh Quốc
Cơ quản chủ quản: Cambridge University Press , CAMBRIDGE UNIV PRESS
Lĩnh vực:
Sensory SystemsPhysiology
Phân tích ảnh hưởng
Thông tin về tạp chí
Visual Neuroscience is an international journal devoted to the publication of experimental and theoretical research on biological mechanisms of vision. A major goal of publication is to bring together in one journal a broad range of studies that reflect the diversity and originality of all aspects of neuroscience research relating to the visual system. Contributions may address molecular, cellular or systems-level processes in either vertebrate or invertebrate species. The journal publishes work based on a wide range of technical approaches, including molecular genetics, anatomy, physiology, psychophysics and imaging, and utilizing comparative, developmental, theoretical or computational approaches to understand the biology of vision and visuo-motor control. The journal also publishes research seeking to understand disorders of the visual system and strategies for restoring vision. Studies based exclusively on clinical, psychophysiological or behavioral data are welcomed, provided that they address questions concerning neural mechanisms of vision or provide insight into visual dysfunction.
Các bài báo tiêu biểu
Normalization of cell responses in cat striate cortex Abstract Simple cells in the striate cortex have been depicted as half-wave-rectified linear operators. Complex cells have been depicted as energy mechanisms, constructed from the squared sum of the outputs of quadrature pairs of linear operators. However, the linear/energy model falls short of a complete explanation of striate cell responses. In this paper, a modified version of the linear/energy model is presented in which striate cells mutually inhibit one another, effectively normalizing their responses with respect to stimulus contrast. This paper reviews experimental measurements of striate cell responses, and shows that the new model explains a significantly larger body of physiological data.
Tập 9 Số 2 - Trang 181-197 - 1992
Human symmetry detection exhibits reverse eccentricity scaling Human symmetry detection in dense patterns exhibits
a spatial integration range that becomes narrower with
distance of the symmetry axis from the fovea. This narrowing
violates the general properties of eccentricity that have
been found for all previous visual cortical areas, tasks,
and assessment techniques. This reverse eccentricity scaling
may, in conjunction with the long-range matching properties
for symmetry described in Tyler and Hardage (1996), imply
that symmetry is processed by a specialized cortical area
with non-retinotopic neural architecture.
Tập 16 Số 5 - Trang 919-922 - 1999
Activity correlates of cytochrome oxidase-defined compartments in granular and supragranular layers of primary visual cortex of the macaque monkey Abstract To determine if changes in metabolic capacity revealed by cytochrome oxidase (CO) histochemistry are related to sustained changes in energy-utilizing neuronal activity, we assayed CO levels and recorded multiunit firing rates along nearly tangential penetrations of V1 in seven adult macaque monkeys before and after single, monocular injections of TTX. Within as little as 14 h, TTX blockade began to reduce CO staining in zones of layer 4C that received dominant input from the injected eye. Since simple monocular occlusion has only minor effects on cortical CO levels (Trusk et al., 1990), the changes in activity that were specifically associated with CO depletion were isolated by comparing spike rates during monocular TTX blockade and during monocular occlusion. Five second samples of multiunit spike rate were obtained after 2-min adaptation to each of four adapting fields: black, gray, white, and textured. Results were similar for these four conditions. In layer 4C, ocular dominance zones with input from the TTX eye had ongoing spike rates that were 48% of the rates in zones with input from a normal but occluded eye. In six animals, it was possible to record activity at a single site before, during, and after the onset of TTX blockade. Background activity at these interpuff sites decreased as much as 3-fold in less than 1 h but stabilized within 3–4 h to an average of 53% of pre-TTX rates. These data support the interpretation that energy utilization linked to sustained spike rates partially regulates CO levels under normal conditions, at least in layer 4. Furthermore, changes in neuronal activity induced by retinal TTX preceded the detectable reduction in CO activity in V1 suggesting that the adjustment of CO levels was in response to the altered activity.
Tập 12 Số 4 - Trang 629-639 - 1995
Spatial and temporal coherence in cortico-cortical connections: A cross-correlation study in areas 17 and 18 in the cat Abstract Visual cortical areas are richly but selectively connected by “patchy” projections. We characterized these connections physiologically with cross-correlograms (CCHs), calculated for neuron pairs or small groups located one each in visual areas 17 and 18 of the cat. The CCHs were then compared to the visuotopic and orientation match of the neurons' receptive fields (RFs). For both spontaneous and visually driven activity, most non-flat correlograms were centered; i.e. the most likely temporal relationship between spikes in the two areas is a synchronous one. Although spikes are most likely to occur simultaneously, area 17 spikes may occur before area 18 orvice versa , giving the cross-correlogram peak a finite width (temporal dispersion). Cross-correlograms fell into one of three groups according to their full-width at half peak height: 1–8 ms (modal width, 3 ms), 15–65 ms (modal width 30 ms), or 100–1000 ms (modal width 400 ms). These classificatory groups are nonoverlapping; the three types of coupling appeared singly and in combination. Neurons whose receptive fields (RFs) are nonoverlapping or cross-oriented may yet be coupled, but the coupling is more likely to be the broadest type of coupling than the medium-dispersed type. The sharpest type of coupling is found exclusively between neurons with at least partially overlapping RFs and mostly between neurons whose stimulus orientation preferences matched to within 22.5 deg. The maximum spatial dispersion observed in the RFs of coupled neurons compares well with the maximum divergence seen anatomically in the A18/A17 projection system. We suggest three different mechanisms to produce each of the three different degrees of observed spatial and temporal coherence. All mechanisms use common input of cortical origin. For medium and broad coupling, this common input arises from cell assemblies split between both sides of the 17/18 projection system, but acting synchronously. Such distributed common-input cell assemblies are a means of overcoming sparse connectivity and achieving synaptic transmission in the pyramidal network.
Tập 9 Số 1 - Trang 21-37 - 1992
Modeling corticofugal feedback and the sensitivity of lateral geniculate neurons to orientation discontinuity We model feedback from primary visual cortex to the dorsal
lateral geniculate nucleus (dLGN). This feedback makes dLGN
neurons sensitive to orientation discontinuity (Sillito et al.,
1993; Cudeiro & Sillito, 1996). In the model, each dLGN
neuron receives retinotopic input driven by layer 6 cortical
neurons in a full set of orientation columns. Excitation is
monosynaptic, while inhibition is through perigeniculate neurons
and dLGN interneurons. The stimulus consists of drifting gratings,
one within and the other outside a circular region centered
over the receptive field of the model dLGN relay neuron we study.
They appear as a single grating when they are aligned with equal
contrast. The model reproduces experimental results showing
an increasing inhibitory effect of feedback on the firing rate
of dLGN neurons as the two gratings move towards the aligned
position. Moreover, enhancement of dLGN cell center-surround
antagonism by feedback is revealed by measuring the responses
to drifting gratings inside a circular window, as a function
of window radius. This effect is related to the observed length
tuning of dLGN cells. Sensitivity to orientation discontinuity
could be mediated in the model by feedback from either simple
or complex cells. The model puts constraints on the feedback
synaptic footprint and shows that its elongated shape does not
play a crucial role in sensitivity to orientation discontinuity.
The inhibitory component of feedback must predominate overall,
but the feedback signal from a cortical neuron to a dLGN neuron
with the same or nearby receptive-field center can be dominated
by excitation. Predictions of the model include (1) robust stimuli
for layer 6 cortical neurons give pronounced nonlinearities
in the responses of dLGN neurons; (2) the sensitivity to
orientation discontinuity at low contrast is twice that at high
contrast.
Tập 18 Số 6 - Trang 865-877 - 2001
Nonlagged relay cells and interneurons in the cat lateral geniculate nucleus: Receptive-field properties and retinal inputs Abstract Simultaneous recording in the cat's retina and lateral geniculate nucleus (LGN) was used to find excitatory inputs to LGN cells. These recordings, correlated with measurements of LGN cell receptive-field properties, suggested new functional subdivisions of LGN cells. Distinctions between lagged and nonlagged cells were described before (Mastronarde, 1987a,b ; Mastronarde et al., 1991), classification of nonlagged cells is examined here. The Xs -type relay cells described before (Mastronarde, 1987a,b ) each had detectable excitatory input from only one retinal X cell. Cells that received significant input from more than one retinal X cell were of three kinds: relay cells with pure X input (XM ); relay cells with mixed X and Y input (X/Y); and cells that could not be antidromically activated from visual cortex (XI ). In the series of relay cells, XS -XM -X/Y-Y, cells had progressively larger receptive-field centers, lower spatial resolution, and faster and more Y-like responses to various stimuli. XI cells resembled XM and X/Y cells in some respects but tended to have higher maintained firing rates, more sustained responses, and weaker surround suppression of the center response. The distinctness of XS , XM , X/Y, XI , and Y from each other was examined with a modification of discriminant analysis that allowed cells to lack measurements for some parameters. Any given pair of categories could be distinguished reliably with only three parameters, although less so for X/Y-Y. In particular, XI cells were distinguishable from relay cells by properties other than the results of cortical stimulation, thus supporting the identity of XI cells as a separate class of X interneurons. Two discontinuities in the behavior of retinal input suggest that XM cells are a separate class from XS and X/Y cells: (1) LGN X cells received either no detectable input from any of the retinal X cells adjacent to their main input, or an easily detectable amount from several such cells; and (2) cells received either no Y input or a certain minimum amount. No such discontinuity in input underlies the distinction between X/Y and Y cells. LGN Y cells were also heterogeneous. Those with substantial input from more than one retinal Y cell had larger receptive fields and a greater preference for fast-moving stimuli than did Y cells dominated by a single input. Three Y cells could not be antidromically activated. They tended to differ from Y relay cells and resemble X interneurons in several ways. These shared properties, and the general reliability of cortical stimulation for nonlagged cells, indicate that the cells were Y interneurons. The strength of excitatory input extrapolated to zero at a separation between LGN and ganglion cell receptive fields equivalent to the radius of a retinal X axonal arbor for X input to XM , XI , and X/Y cells, or to the radius of a Y arbor for Y input to X/Y and Y cells. Thus, a retinal axon appears to be selective in providing input primarily to cells with somata within its arbor, rather than to all cells with overlapping dendrites. Coverage, the number of receptive-field centers overlapping a single point, was estimated for each kind of LGN cell described here. Each had a coverage of at least 6, comparable to that of retinal Y cells; most kinds had coverages of 15–35. These estimates support the idea that these subdivisions of LGN cells are functionally significant. XM and X/Y cells fill in the functional gap that is present between retinal X and Y cells and make the distribution of spatial properties more continuous, while multiple-input Y cells broaden the range of spatial properties. One role of LGN circuitry might thus be to provide a substrate for the correspondingly broad and continuous range of spatial-frequency tuning in the visual cortex.
Tập 8 Số 5 - Trang 407-441 - 1992
Spatial sensitivity, responsivity, and surround suppression of LGN cell responses in the macaque Abstract Responses of cells in the lateral geniculate nucleus (LGN) of the macaque monkey have been measured for different sizes of chromatic and achromatic stimuli, with relative luminance spanning a range of 3–6 log units. Homogeneous illuminated test fields, centered on the receptive field, were used. Responses to these stimuli deviated from what is expected for the grating stimuli used to study the contrast-sensitive mechanisms in the visual pathway. For test fields smaller than the center of the receptive field, both the excitatory and the inhibitory cone-opponent components were present in the response, and the sensitivity to both components increased with the same factor when the test field increased in size (area summation). For test field areas extending into the suppressive surround of the extraclassical receptive field, the excitatory and the inhibitory cone opponents were both suppressed, again by the same factor. This suppression of the cell’s responsiveness, as a function of test spot area, was described by a logarithmic function, and the spatial sensitivity of attenuation could therefore be described by a power function of radius. The logarithmic suppression was clear for parvocellular and koniocellular cells but was more prominent for magnocellular cells. The surround field suppression was also found for the prepotential inputs to LGN cells, indicating a retinal origin. The difference of Gaussian (DOG) model has been used successfully to describe the cells’ contrast behavior for grating stimuli. However, this model fails to describe the constant excitatory/inhibitory response balance needed to obtain color (hue) stability for light stimuli of different sizes but with the same Commission Internationale de l’Eclairage (CIE) chromaticity and luminance factor. Neither the constant responsiveness found in the center of the receptive field nor the suppressive response in the surround can be described by the DOG model.
Tập 30 Số 4 - Trang 153-167 - 2013
Independence and merger of thalamocortical channels within macaque monkey primary visual cortex: Anatomy of interlaminar projections Abstract An important issue in understanding the function of primary visual cortex in the macaque monkey is how the several efferent neuron groups projecting to extrastriate cortex acquire their different response properties. To assist our understanding of this issue, we have compared the anatomical distribution of VI intrinsic relays that carry information derived from magno- (M) and parvocellular (P) divisions of the dorsal lateral geniculate nucleus between thalamic recipient neurons and interareal efferent neuron groups within area VI. We used small, iontophoretic injections of biocytin placed in individual cortical laminae of area VI to trace orthograde and retrograde inter- and intralaminar projections. In either the same or adjacent sections, the tissue was reacted for cytochrome oxidase (CO), which provides important landmarks for different efferent neuron populations located in CO rich blobs and CO poor interblobs in laminae ⅔, as well as defining clear boundaries for the populations of efferent neurons in laminae 4A and 4B. This study shows that the interblobs, but not the blobs, receive direct input from thalamic recipient 4C neurons; the interblobs receive relays from mid 4C neurons (believed to receive convergent M and P inputs), while blobs receive indirect inputs from either M or P (or both) pathways through layers 4B (which receives M relays from layer 4Cα) and 4A (which receives P relays directly from the thalamus as well as from layer 4Cβ). The property of orientation selectivity, most prominent in the interblob regions and in layer 4B, may have a common origin from oriented lateral projections made by mid 4C spiny stellate neurons. While layer 4B efferents may emphasize M characteristics and layer 4A efferents emphasize P characteristics, the dendrites of their constituent pyramidal neurons may provide anatomical access to the other channel since both blob and interblob regions in layers ⅔ have anatomical access to M and P driven relays, despite functional differences in the way these properties may be expressed in the two compartments.
Tập 11 Số 3 - Trang 467-489 - 1994
Contributions of individual layer 2–5 spiny neurons to local circuits in macaque primary visual cortex Abstract We studied excitatory local circuits in the macaque primary visual cortex (V1) to investigate their relationships to the magnocellular (M) and parvocellular (P) streams. Sixty-two intracellularly labeled spiny neurons in layers 2–5 were analyzed. We made detailed observations of the laminar and columnar specificity of axonal arbors and noted correlations with dendritic arbors. We find evidence for considerable mixing of M and P streams by the local circuitry in V1. Such mixing is provided by neurons in the primary geniculate recipient layer 4C, as well as by neurons in both the supragranular and infragranular layers. We were also interested in possible differences in the axonal projections of neurons with different dendritic morphologies. We found that layer 4B spiny stellate and pyramidal neurons have similar axonal arbors. However, we identified two types of layer 5 pyramidal neuron. The majority have a conventional pyramidal dendritic morphology, a dense axonal arbor in layers 2–4B, and do not project to the white matter. Layer 5 projection neurons have an unusual “backbranching” dendritic morphology (apical dendritic branches arc downward rather than upward) and weak or no axonal arborization in layers 2–4B, but have long horizontal axonal projections in layer 5B. We find no strong projection from layer 5 pyramidal neurons to layer 6. In macaque V1 there appears to be no single source of strong local input to layer 6; only a minority of cells in layers 2–5 have axonal branches in layer 6 and these are sparse. Our results suggest that local circuits in V1 mediate interactions between M and P input that are complex and not easily incorporated into a simple framework.
Tập 13 Số 5 - Trang 907-922 - 1996
First order connections of the visual sector of the thalamic reticular nucleus in marmoset monkeys (<i>Callithrix jacchus</i>) The thalamic reticular nucleus (TRN) supplies an important inhibitory input to the dorsal thalamus. Previous studies in non-primate mammals have suggested that the visual sector of the TRN has a lateral division, which has connections with first-order (primary) sensory thalamic and cortical areas, and a medial division, which has connections with higher-order (association) thalamic and cortical areas. However, the question whether the primate TRN is segregated in the same manner is controversial. Here, we investigated the connections of the TRN in a New World primate, the marmoset (Callithrix jacchus ). The topography of labeled cells and terminals was analyzed following iontophoretic injections of tracers into the primary visual cortex (V1) or the dorsal lateral geniculate nucleus (LGNd). The results show that rostroventral TRN, adjacent to the LGNd, is primarily connected with primary visual areas, while the most caudal parts of the TRN are associated with higher order visual thalamic areas. A small region of the TRN near the caudal pole of the LGNd (foveal representation) contains connections where first (lateral TRN) and higher order visual areas (medial TRN) overlap. Reciprocal connections between LGNd and TRN are topographically organized, so that a series of rostrocaudal injections within the LGNd labeled cells and terminals in the TRN in a pattern shaped like rostrocaudal overlapping “fish scales.” We propose that the dorsal areas of the TRN, adjacent to the top of the LGNd, represent the lower visual field (connected with medial LGNd), and the more ventral parts of the TRN contain a map representing the upper visual field (connected with lateral LGNd).
Tập 24 Số 6 - Trang 857-874 - 2007