How transient a??remappinga?? of neuronal receptive fields mediates perceptual stability

摘要

It is well known that saccades cause transient but profound changes to the receptive fields of parietal cortical cells and also to human perception. It remains unclear, however, how these events contribute to stability. One critical but largely overlooked fact is that as receptive fields shift, responses to the a??new receptive fielda?? are delayed in time, creating a receptive field oriented in space-time (Binda et al., J. Neurosc., 2009). We studied mislocalization of pairs of bars (6 ?? 1deg, one white, one black) briefly presented successively (temporal separations 20a??160 ms) at the same or different positions, at various times relative to the onset of a 20?° horizontal saccade. Single perisaccadic bars, and also pairs of bars of different orientation, were strongly mislocalized, by up to half saccade amplitude. However, when the bars were of the same orientation and displayed within 40a??120 ms of each other, no mislocalization occurred with either, provided at least one bar was presented outside the crucial interval ?±20 ms from saccadic onset. The stabilization occurred only for bars nearby in external space (within 5?°) even though the separation on the retina could be over 20?°. There was also a strong compression of apparent time. We modeled the interaction between the bars with a neuronal mechanism extending over space and time that responds to both stimuli: as the response to the bar displayed to the a??future receptive fielda?? is delayed, it arrives simultaneously with the response to stimuli displayed later to the classic receptive field, and are therefore fused. This transient perisaccadic space-time orientation of the future receptive field generates a response profile that is broad, but anchored to external space, and this is the key to perceptual stability.