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

Area of Science:

• Neuroscience
• Computational Neuroscience
• Visual Neuroscience

Background:

• Optic flow is crucial for self-motion perception, influencing balance, orientation, and navigation.
• Neurons in the primate extrastriate visual cortex (MSTd) respond to complex optic flow patterns, but their direct perceptual role is unclear.

Purpose of the Study:

• To investigate the causal role of MSTd neurons in the perception of self-motion, specifically rotational (roll) and translational (heading) components of optic flow.
• To determine if manipulating MSTd activity can bias perceptual decisions related to self-motion.

Main Methods:

• Electrical microstimulation was used to selectively activate populations of MSTd neurons in macaques.
• Macaques performed a four-alternative-forced-choice task to discriminate the direction of roll or heading.
• Stimulation effects on perceptual choices were analyzed in relation to optic flow stimuli (spiral or pure rotation).

Main Results:

• Microstimulation of MSTd neurons biased macaque perception of roll direction, regardless of the optic flow context (spiral or pure rotation).
• Stimulation also altered the choice frequency between roll and translation perception.
• These findings demonstrate a direct causal link between MSTd activity and the perception of rotational self-motion.

Conclusions:

• MSTd neurons' roll signals, even when mixed with translation signals, can be extracted by downstream brain areas for perceptual interpretation.
• This study provides causal evidence for MSTd's role in processing optic flow for spatial orientation and self-motion perception.
• The findings support the idea that specific neural populations in MSTd contribute directly to conscious perception of self-motion.