Receptive field organization across multiple electrosensory maps. II. Computational analysis of the effects of receptive field size on prey localization

AbstractThe two-dimensional organization of receptive fields (RFs) of 44 cells in the cat visual cortex and four cells from the cat LGN was measured by stimulation with either dots or bars of light. The light bars were presented in different positions and orientations centered on the RFs. The RFs found were arbitrarily divided into four general types: Punctate, resembling DOG filters (11%); those resembling Gabor filters (9%); elongate (36%); and multipeaked-type (44%). Elongate RFs, usually found in simple cells, could show more than one excitatory band or bifurcation of excitatory regions. Although regions inhibitory to a given stimulus transition (e.g. ON) often coincided with regions excitatory to the opposite transition (e.g. OFF), this was by no means the rule. Measurements were highly repeatable and stable over periods of at least 1 h. A comparison between measurements made with dots and with bars showed reasonable matches in about 40% of the cases. In general, bar-based measurements revealed larger RFs with more structure, especially with respect to inhibitory regions. Inactivation of lower cortical layers (V-VI) by local GABA injection was found to reduce sharpness of detail and to increase both receptive-field size and noise in upper layer cells, suggesting vertically organized RF mechanisms. Across the population, some cells bore close resemblance to theoretically proposed filters, while others had a complexity that was clearly not generalizable, to the extent that they seemed more suited to detection of specific structures. We would speculate that the broadly varying forms of cat cortical receptive fields result from developmental processes akin to those that form ocular-dominance columns, but on a smaller scale.

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Role of Inhibition in Cortical Reorganization of the Adult Raccoon Revealed by Microiontophoretic Blockade of GABAAReceptors

Journal of Neurophysiology ◽

10.1152/jn.2001.86.1.94 ◽

2001 ◽

Vol 86 (1) ◽

pp. 94-103 ◽

Cited By ~ 38

Author(s):

Liisa Tremere ◽

T. Philip Hicks ◽

Douglas D. Rasmusson

Keyword(s):

Receptive Field ◽

Receptive Fields ◽

Cortical Reorganization ◽

Field Size ◽

Cortical Region ◽

Simple Expansion ◽

Field Organization ◽

Subcortical Regions ◽

Continuous Fields ◽

Receptive Field Organization

Cortical reorganization was induced by amputation of the 4th digit in 11 adult raccoons. Animals were studied at various intervals, ranging from 2 to 37 wk, after amputation. Recordings were made from a total of 129 neurons in the deafferented cortical region using multibarrel micropipettes. Several types of receptive fields were described in reorganized cortex: restricted fields were similar in size to the normal receptive fields in nonamputated animals; multi-regional fields included sensitive regions on both adjacent digits and/or the underlying palm and were either continuous over the entire field or consisted of split fields. The proportion of neurons with restricted fields increased with time after amputation and was greater than previously found in subcortical regions. A GABAAreceptor antagonist (bicuculline methiodide), glutamate, and GABA were administered iontophoretically to these neurons while determining their receptive fields and thresholds. Bicuculline administration resulted in expansion of the receptive field in 60% of the 93 neurons with cutaneous fields. In most cases (33 neurons) this consisted of a simple expansion around the borders of the predrug receptive field, and the average expansion (426%) was not different from that seen in nonamputated animals. In some neurons ( n = 4), bicuculline produced an expansion from one digit onto the adjacent palm or another digit, an effect never seen in control animals. Bicuculline also changed the split fields of seven neurons into continuous fields by exposing a responsive region between the split fields. Finally, bicuculline changed the internal receptive field organization of 10 neurons by revealing subfields with reduced thresholds. In contrast to the situation in nonamputated animals, iontophoretic administration of glutamate also produced receptive field expansion in some neurons ( n = 6), but the size and/or shape of the change was different from that produced by bicuculline, indicating that the effects of bicuculline were not due to an overall facilitation of neuronal activity. These results are consistent with the hypotheses that an important component of long-term cortical reorganization is the gradual reduction in effective receptive field size and that intracortical inhibitory networks are partially responsible for these changes.

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ENLARGEMENT OF THE RECEPTIVE FIELD SIZE TO LOW INTENSITY MECHANICAL STIMULATION IN THE RAT SPINAL NERVE LIGATION MODEL OF NEUROPATHY

Journal of the Peripheral Nervous System ◽

10.1046/j.1529-8027.2000.00022-48.x ◽

2000 ◽

Vol 5 (4) ◽

pp. 248-248

Author(s):

R Suzuki ◽

Vk Kontinen ◽

E Matthews ◽

E Williams ◽

Ah Dickenson

Keyword(s):

Receptive Field ◽

Mechanical Stimulation ◽

Spinal Nerve ◽

Spinal Nerve Ligation ◽

Field Size ◽

Receptive Field Size ◽

Low Intensity

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Comparison of the responses of AII amacrine cells in the dark- and light-adapted rabbit retina

Visual Neuroscience ◽

10.1017/s0952523899164058 ◽

1999 ◽

Vol 16 (4) ◽

pp. 653-665 ◽

Cited By ~ 78

Author(s):

DAIYAN XIN ◽

STEWART A. BLOOMFIELD

Keyword(s):

Receptive Field ◽

Light Adaptation ◽

Amacrine Cells ◽

Bipolar Cells ◽

Rabbit Retina ◽

Response Component ◽

Synaptic Inputs ◽

Field Organization ◽

Receptive Field Organization ◽

Aii Amacrine Cells

We studied the light-evoked responses of AII amacrine cells in the rabbit retina under dark- and light-adapted conditions. In contrast to the results of previous studies, we found that AII cells display robust responses to light over a 6–7 log unit intensity range, well beyond the operating range of rod photoreceptors. Under dark adaptation, AII cells showed an ON-center/OFF-surround receptive-field organization. The intensity–response profile of the center-mediated response component followed a dual-limbed sigmoidal function indicating a transition from rod to cone mediation as stimulus intensities were increased. Following light adaptation, the receptive-field organization of AII cells changed dramatically. Light-adapted AII cells showed both ON- and OFF-responses to stimulation of the center receptive field, but we found no evidence for an antagonistic surround. Interestingly, the OFF-center response appeared first following rapid light adaptation and was then replaced gradually over a 1–4 min period by the emerging ON-center response component. Application of the metabotropic glutamate receptor agonist APB, the ionotropic glutamate blocker CNQX, 8-bromo-cGMP, and the nitric oxide donor SNAP all showed differential effects on the various center-mediated responses displayed by dark- and light-adapted AII cells. Taken together, these pharmacological results indicated that different synaptic circuits are responsible for the generation of the different AII cell responses. Specifically, the rod-driven ON-center responses are apparently derived from rod bipolar cell synaptic inputs, whereas the cone-driven ON-center responses arise from signals crossing the gap junctions between AII cells and ON-center cone bipolar cells. Additionally, the OFF-center response of light-adapted AII cells reflects direct synaptic inputs from OFF-center cone bipolar cells to AII dendritic processes in the distal inner plexiform layer.

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Receptive Field Size and Response Latency Are Correlated Within the Cat Visual Thalamus

Journal of Neurophysiology ◽

10.1152/jn.00847.2004 ◽

2005 ◽

Vol 93 (6) ◽

pp. 3537-3547 ◽

Cited By ~ 20

Author(s):

Chong Weng ◽

Chun-I Yeh ◽

Carl R. Stoelzel ◽

Jose-Manuel Alonso

Keyword(s):

Receptive Field ◽

Spatial Frequency ◽

Response Latency ◽

Time Course ◽

Frequency Tuning ◽

Receptive Fields ◽

Cortical Cell ◽

Field Size ◽

Receptive Field Size ◽

Spatial Frequency Tuning

Each point in visual space is encoded at the level of the thalamus by a group of neighboring cells with overlapping receptive fields. Here we show that the receptive fields of these cells differ in size and response latency but not at random. We have found that in the cat lateral geniculate nucleus (LGN) the receptive field size and response latency of neighboring neurons are significantly correlated: the larger the receptive field, the faster the response to visual stimuli. This correlation is widespread in LGN. It is found in groups of cells belonging to the same type (e.g., Y cells), and of different types (i.e., X and Y), within a specific layer or across different layers. These results indicate that the inputs from the multiple geniculate afferents that converge onto a cortical cell (approximately 30) are likely to arrive in a sequence determined by the receptive field size of the geniculate afferents. Recent studies have shown that the peak of the spatial frequency tuning of a cortical cell shifts toward higher frequencies as the response progresses in time. Our results are consistent with the idea that these shifts in spatial frequency tuning arise from differences in the response time course of the thalamic inputs.

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