Causal contribution of optic flow signal in Macaque extrastriate visual cortex for roll perception

Extrastriate visual cortex encodes optic flow, yet a direct link to perception has yet to be established. Here, the authors apply electrical microstimulation to reveal that roll signals in MSTd causally contribute to rotation perception around line-of-sight. Optic flow is a powerful cue for inferring self-motion status which is critical for postural control, spatial orientation, locomotion and navigation. In primates, neurons in extrastriate visual cortex (MSTd) are predominantly modulated by high-order optic flow patterns (e.g., spiral), yet a functional link to direct perception is lacking. Here, we applied electrical microstimulation to selectively manipulate population of MSTd neurons while macaques discriminated direction of rotation around line-of-sight (roll) or direction of linear-translation (heading), two tasks which were orthogonal in 3D spiral coordinate using a four-alternative-forced-choice paradigm. Microstimulation frequently biased animal's roll perception towards coded labeled-lines of the artificial-stimulated neurons in either context with spiral or pure-rotation stimuli. Choice frequency was also altered between roll and translation flow-pattern. Our results provide direct causal-link evidence supporting that roll signals in MSTd, despite often mixed with translation signals, can be extracted by downstream areas for perception of rotation relative to gravity-vertical.

Automated summary

The extrastriate visual cortex plays a role in encoding optic flow, but its direct link to perception has not been established. In this study, the authors used electrical microstimulation to reveal that roll signals in MSTd contribute to rotation perception. These findings provide important evidence for understanding the neural mechanisms underlying perception of rotation.