Visual selectivity for heading in monkey area MST

The control of self-motion is supported by visual, vestibular, and proprioceptive signals. Recent research has shown how these signals interact in the monkey medio-superior temporal area (area MST) to enhance and disambiguate the perception of heading during self-motion. Area MST is a central stage for self-motion processing from optic flow, and integrates flow field information with vestibular self-motion and extraretinal eye movement information. Such multimodal cue integration is clearly important to solidify perception. However to understand the information processing capabilities of the brain, one must also ask how much information can be deduced from a single cue alone. This is particularly pertinent for optic flow, where controversies over its usefulness for self-motion control have existed ever since Gibson proposed his direct approach to ecological perception. In our study, we therefore, tested macaque MST neurons for their heading selectivity in highly complex flow fields based on the purely visual mechanisms. We recorded responses of MST neurons to simple radial flow fields and to distorted flow fields that simulated a self-motion plus an eye movement. About half of the cells compensated for such distortion and kept the same heading selectivity in both cases. Our results strongly support the notion of an involvement of area MST in the computation of heading.