scholarly journals Optimum spatiotemporal receptive fields for vision in dim light

2009 ◽  
Vol 9 (4) ◽  
pp. 18-18 ◽  
Author(s):  
A. Klaus ◽  
E. J. Warrant
Keyword(s):  
Receptive Fields ◽  
Dim Light ◽  
Spatiotemporal Receptive Fields

Spatiotemporal receptive fields: a dynamical model derived from cortical architectonics

1986 ◽  
Vol 226 (1245) ◽  
pp. 421-444 ◽  
Keyword(s):  
Cortical Neurons ◽  
Receptive Fields ◽  
Pyramidal Cells ◽  
Tuning Curves ◽  
Cell Responses ◽  
Intrinsic Connectivity ◽  
Output System ◽  
Spatiotemporal Receptive Fields ◽  
External Connections ◽  
Insight Into

We assume that the mammalian neocortex is built up out of some six layers which differ in their morphology and their external connections. Intrinsic connectivity is largely excitatory, leading to a considerable amount of positive feedback. The majority of cortical neurons can be divided into two main classes: the pyramidal cells, which are said to be excitatory, and local cells (most notably the non-spiny stellate cells), which are said to be inhibitory. The form of the dendritic and axonal arborizations of both groups is discussed in detail. This results in a simplified model of the cortex as a stack of six layers with mutual connections determined by the principles of fibre anatomy. This stack can be treated as a multi-input-multi-output system by means of the linear systems theory of homogeneous layers. The detailed equations for the simulation are derived in the Appendix. The results of the simulations show that the temporal and spatial behaviour of an excitation distribution cannot be treated separately. Further, they indicate specific processing in the different layers and some independence from details of wiring. Finally, the simulation results are applied to the theory of visual receptive fields. This yields some insight into the mechanisms possibly underlying hypercomplexity, putative nonlinearities, lateral inhibition, oscillating cell responses, and velocity-dependent tuning curves.

Visuomotor functions of central thalamus in monkey. II. Unit activity related to visual events, targeting, and fixation

1984 ◽  
Vol 51 (6) ◽  
pp. 1175-1195 ◽  
Author(s):  
J. Schlag ◽  
M. Schlag-Rey
Keyword(s):  
Eye Movement ◽  
Receptive Fields ◽  
Stimulus Onset ◽  
Visual Responses ◽  
Visual Events ◽  
Response Enhancement ◽  
Dim Light ◽  
Central Thalamus ◽  
Thalamic Region ◽  
Sustained Responses

In alert monkeys, single-unit responses to visual stimuli were recorded in the central thalamic region where eye movement-related activity has been observed (33). Usually, the stimuli were 1 degree annulus patterns of dim light presented at unpredictable locations on a tangent screen. The animals were trained on two tasks: one in which they delivered the stimulus themselves by pressing a panel that they had to release immediately when the stimulus shape changed to a square, and another one in which the stimulus was turned on by the experimenter and the monkeys were rewarded for fixating this target for a predetermined length of time. In both tasks, continuous stimulus fixation was required. Receptive fields were tested with and without a fixation point. Retinal coordinates of stimuli were obtained by subtracting eye-position coordinates from stimulus coordinates in space, the monkey's head being fixed. Unit responses in the cases where targeting occurred or did not occur were analyzed separately. Transient responses were observed in 63 units and sustained responses in 44 units. Among the 63 units responding transiently, 42 did so irrespective of targeting. Their receptive fields were very large, generally including the fovea, and predominantly contralateral when the fields were asymmetric. The responses of the other 21 units depended on the occurrence of targeting. They were called visually triggered eye movement-related responses (VTEM). VTEM units were further subdivided in 9 units active only with targeting and 12 units showing the classical phenomenon of "response enhancement" under this condition. VTEM units were contrasted to six units that were both passively visually responsive and bursting with saccades, either spontaneous or visually triggered. The latencies of passive visual and VTEM responses to stimulus onset were comprised between 77 and 135 ms in 80% of the units. VTEM units also fired prior to retargeting saccades. Presaccadic units active with spontaneous saccades also discharged with visually elicited saccades. The earliest sign of activation after stimulus onset eliciting a saccade appeared between 80 and 100 ms, that is, in the same range of latencies as passive visual and VTEM units. Sustained visual responses consisted of activation in 18 units and inactivation in 26 units. The occurrence of these patterns of firing was related to stimulus fixation. In the majority of cases, the changes in discharge frequency started before fixation was achieved by a targeting saccade. They terminated before fixation was broken by a saccade away from the stimulus.(ABSTRACT TRUNCATED AT 400 WORDS)

Development of spatiotemporal receptive fields of simple cells: I. Model formulation

1997 ◽  
Vol 77 (6) ◽  
pp. 453-461 ◽  
Author(s):  
S. Wimbauer ◽  
O.G. Wenisch ◽  
K.D. Miller ◽  
J.L. van Hemmen
Keyword(s):  
Receptive Fields ◽  
Model Formulation ◽  
Simple Cells ◽  
Spatiotemporal Receptive Fields

scholarly journals Spatiotemporal receptive fields of barrel cortex revealed by reverse correlation of synaptic input

2014 ◽  
Vol 17 (6) ◽  
pp. 866-875 ◽  
Author(s):  
Alejandro Ramirez ◽  
Eftychios A Pnevmatikakis ◽  
Josh Merel ◽  
Liam Paninski ◽  
Kenneth D Miller ◽  
...  
Keyword(s):  
Synaptic Input ◽  
Barrel Cortex ◽  
Receptive Fields ◽  
Reverse Correlation ◽  
Spatiotemporal Receptive Fields

scholarly journals The Berkeley Wavelet Transform: A Biologically Inspired Orthogonal Wavelet Transform

2008 ◽  
Vol 20 (6) ◽  
pp. 1537-1564 ◽  
Author(s):  
Ben Willmore ◽  
Ryan J. Prenger ◽  
Michael C.-K. Wu ◽  
Jack L. Gallant
Keyword(s):  
Wavelet Transform ◽  
Spatial Frequency ◽  
Orthonormal Basis ◽  
Receptive Fields ◽  
Constant Term ◽  
Two Dimensions ◽  
Gabor Wavelet ◽  
Scale Invariant ◽  
V1 Neurons ◽  
Spatiotemporal Receptive Fields

We describe the Berkeley wavelet transform (BWT), a two-dimensional triadic wavelet transform. The BWT comprises four pairs of mother wavelets at four orientations. Within each pair, one wavelet has odd symmetry, and the other has even symmetry. By translation and scaling of the whole set (plus a single constant term), the wavelets form a complete, orthonormal basis in two dimensions. The BWT shares many characteristics with the receptive fields of neurons in mammalian primary visual cortex (V1). Like these receptive fields, BWT wavelets are localized in space, tuned in spatial frequency and orientation, and form a set that is approximately scale invariant. The wavelets also have spatial frequency and orientation bandwidths that are comparable with biological values. Although the classical Gabor wavelet model is a more accurate description of the receptive fields of individual V1 neurons, the BWT has some interesting advantages. It is a complete, orthonormal basis and is therefore inexpensive to compute, manipulate, and invert. These properties make the BWT useful in situations where computational power or experimental data are limited, such as estimation of the spatiotemporal receptive fields of neurons.

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