Facilitation and suppression of single striate-cell activity by spatially discrete pattern stimuli presented beyond the receptive field

Abstract

Visual stimulation of a region outside the receptive field of single cells in visual cortex often results in the modulation of their responses. The modulatory effects are thought to be mediated through lateral connections within visual cortex. Research on lateral interactions commonly shows suppression. There has been no systematic study of the optimal conditions for facilitation. Here we have studied the nature of the modulation using a new type of compound stimulus: contrast reversal of pattern stimuli made of three discrete grating patches. The middle patch, optimally fitted to the receptive field in orientation, size, and spatial as well as temporal frequencies, was flanked by two similar patches presented well outside the receptive field. We found that (1) both facilitation and suppression occurred often in the same cells, when orientations of the target and flankers matched the receptive-field's optimal orientation; (2) facilitation with collinear flankers occurred most frequently at target contrasts just above the cell's firing threshold and suppression prevailed at high contrasts; (3) facilitative or suppressive modulation was obtained with target-flankers separation of up to 12 deg or more; (4) collinear facilitation was lost when flankers' orientation was rotated by 90 deg, while keeping all other parameters the same; and (5) neither the modulation mode nor the proportion of modulated cells was related to the cell types (simple vs. complex cells) and cells' laminar locations. Here we have provided physiological evidence for contrast-dependent, collinear facilitation probably underlying perceptual grouping in humans.

On the functions, mechanisms, and malfunctions of intracortical contextual modulation

“…They also showed that these effects were not due to the flankers encroaching within the distal RF of the recorded cell, but were due to modulatory interactions between cells with non-overlapping distal RFs. Such facilitation is greatest at target contrasts just above the cell's firing threshold (Polat and Norcia, 1996;Polat et al 1998), and includes cases where the flankers are placed at separations of 12 degrees or more (Mizobe et al, 2001), which is beyond the furthest extent of the cell's distal RF (Angelucci et al, 2002). This facilitation is mediated both by long-range intra-regional connections (Stettler et al, 2002) and by feedback from higher regions (Angelucci et al, 2002).…”

Intersubject variability and induced gamma in the visual cortex: DCM with empirical Bayes and neural fields

“…We found that the absolute magnitude of the gamma‐band response increased with size, despite considerably varying across participants. This stimulus‐dependence, could have important implications for the role of gamma oscillations in neuronal processing [Ray and Maunsell, 2010] and extra‐classical receptive field effects have been shown to depend on stimulus context and spatial configuration, for example, [Akasaki et al, 2002; Mizobe et al, 2001]. Surround suppression is a (well‐known) reduction of neural responses that emerges as the size of the stimulus becomes larger and encroaches on regions outside the classical receptive field [Allman et al, 1985; DeAngelis et al, 1994].…”

Time Course and Time-Distance Relationships for Surround Suppression in Macaque V1 Neurons

“…Therefore, we present results for complex cells only. There is strong evidence that surround suppression operates similarly for simple and complex cells (Dreher, 1972;Rose, 1977;Kato et al, 1978;Nelson and Frost, 1978;Walker et al, 2000;Mizobe et al, 2001;Cavanaugh et al, 2002;Levitt and Lund, 2002). We studied surround suppression in 92 orientation-tuned complex cells.…”