Direction- and Velocity-Specific Responses from beyond the Classical Receptive Field in the Middle Temporal Visual Area (MT)

TLDR

MT neurons have receptive fields that extend far beyond the classical region, with large directional and velocity‑selective surrounds that are antagonistic to the core response and are organized topographically, allowing integration of local and global visual context. The study investigates whether these extensive surrounds contribute to figure‑ground discrimination, preattentive vision, perceptual constancies, and depth perception via motion cues. The authors simultaneously stimulated the core receptive field and its surround with moving stimuli to reveal the surround’s influence.

Abstract

The true receptive field of more than 90% of neurons in the middle temporal visual area (MT) extends well beyond the classical receptive field (crf), as mapped with conventional bar or spot stimuli, and includes a surrounding region that is 50 to 100 times the area of the crf. These extensive surrounds are demonstrated by simultaneously stimulating the crf and the surround with moving stimuli. The surrounds commonly have directional and velocity-selective influences that are antagonistic to the response from the crf. The crfs of MT neurons are organized in a topographic representation of the visual field. Thus MT neurons are embedded in an orderly visuotopic array, but are capable of integrating local stimulus conditions within a global context. The extensive surrounds of MT neurons may be involved in figure-ground discrimination, preattentive vision, perceptual constancies, and depth perception through motion cues.