The visual cortical association field: A Gestalt concept or a psychophysiological entity?

• Published in: Journal of physiology, Paris Vol. 94; no. 5; pp. 333 - 342
• Main Authors: Chavane, F., Monier, C., Bringuier, V., Baudot, P., Borg-Graham, L., Lorenceau, J., Frégnac, Y.
• Format: Journal Article
• Language: English
• Published: France Elsevier Ltd 01-12-2000; Elsevier
• Subjects: Animals; apparent motion; binding; Brain Mapping; Cats; collinearity; Electrophysiology; Electrophysiology - methods; Evoked Potentials, Visual; Evoked Potentials, Visual - physiology; Gestalt Theory; horizontal connectivity; Humans; intracellular recording; Life Sciences; Membrane Potentials; Models, Neurological; Neurons; Neurons - physiology; Neurons and Cognition; patch-clamp; Photic Stimulation; Psychophysics; Psychophysics - methods; Reaction Time; Retina; Retina - physiology; Synapses; Synapses - physiology; synaptic integration field; Visual Cortex; Visual Cortex - physiology; Visual Pathways; Visual Pathways - physiology; intracellular recording; horizontal connectivity; apparent motion; synaptic integration field; patch-clamp; binding; collinearity; psychophysics
• DOI: 10.1016/S0928-4257(00)01096-2
• EISSN: 1769-7115
• ISSN: 0928-4257

The receptive field of a visual neurone is classically defined as the region of space (or retina) where a visual stimulus evokes a change in its firing activity. Intracellular recordings in cat area 17 show that the visually evoked synaptic integration field extends over a much larger area than that established on the basis of spike activity. Synaptic depolarizing (dominant excitation) responses decrease in strength for stimuli that are flashed at increasing distances away from the centre of the discharge field, while their onset latency increases. A detailed spatio-temporal analysis of these electrophysiological data shows that subthreshold synaptic responses observed in the ‘silent’ surround of cortical receptive fields result from the intracortical spread of activation waves carried by slowly conducting horizontal axons within primary visual cortex. They also predict that a perceptual facilitation may occur when feedforward activation produced by the motion signal in the retina travels in phase in the primary visual cortex with the visually induced spread of horizontal activation. A psychophysical correlate has been obtained in humans, showing that apparent motion produced by a sequence of co-linear Gabor patches, known to preferentially activate V1 orientation selective cells, are perceived by human observers as much faster than non co-linear sequences of the same physical speed.