Area MST and Heading Perception in Macaque Monkeys

Abstract

The macaque medial superior temporal area (MST) is proposed to be specialized for analyzing complex 'optic flow' information. Such space-varying motion patterns provide a rich source of information about self motion, scene structure and object shape. We report the performance of rhesus macaques on a two-alternative 'heading' task, in which they reported whether horizontally varying, simulated trajectories were to left or right of center. Monkeys were sensitive to small heading angles; thresholds averaged 1.5-3 degrees. Heading estimates were stable in the face of changing stimulus location and smooth pursuit eye movements. In addition, we tested the role of area MST in heading judgements by electrically activating columns of neurons in this area while the monkeys performed the heading task. Activation of MST frequently affected performance, usually causing choice biases. These induced biases were often large and usually concordant with the preference of the neurons being activated. In addition, the induced biases were often larger in the presence of smooth pursuit eye movements. These results favor the hypothesis that MST is involved in recovering self-motion direction from optic flow cues and in the process by which heading perception is compensated for ongoing eye movements.

A Functional Architecture of Optic Flow in the Inferior Parietal Lobule of the Behaving Monkey

“…The functional architecture for optic flow revealed for areas 7a and DP could underlie heading perception [32]–[37]. Four orthogonal navigational optic flow selectivities were observed in agreement with electrical recordings in area 7a [8], [19].…”

Linking Neural Representation to Function in Stereoscopic Depth Perception: Roles of the Middle Temporal Area in Coarse versus Fine Disparity Discrimination

“…If a coding strategy such as vector averaging is used (Groh et al, 1997;Nichols and Newsome, 2002), neurons with preferred disparities close to the reference will also contribute to perceptual decisions. Importantly, however, microstimulation would still shift the "hill" of activity in MT toward the preferred disparity of the stimulated neurons; thus, the predicted outcome would be the same if the monkey uses a vector-average strategy instead of a lower-envelope principle (Britten and Van Wezel, 2002). Fourth, it is unlikely that our results are an artifact of eye movements.…”

Optimal multisensory decision-making in a reaction-time task

“…Further evidence against such models is provided by neurophysiological studies which demonstrate that visual and vestibular cues to heading converge in various cortical areas, including areas MSTd (Gu et al, 2006), VIP (Schlack et al, 2005; Chen et al, 2011b), and VPS (Chen et al, 2011a). Activity in area MSTd can account for sensitivity-based cue weighting in a fixed-duration task (Fetsch et al, 2011), and MSTd activity is causally related to multi-modal heading judgments (Britten and van Wezel, 1998, 2002; Gu et al, 2012). These physiological studies strongly suggest that visual and vestibular signals are integrated in sensory representations prior to decision-making, inconsistent with parallel race models.…”