Spatiotemporal Properties of Vestibular Responses in Area MSTd

Abstract

Recent studies have shown that many neurons in the primate dorsal medial superior temporal area (MSTd) show spatial tuning during inertial motion and that these responses are vestibular in origin. Given their well-studied role in processing visual self-motion cues (i.e., optic flow), these neurons may be involved in the integration of visual and vestibular signals to facilitate robust perception of self-motion. However, the temporal structure of vestibular responses in MSTd has not been characterized in detail. Specifically, it is not known whether MSTd neurons encode velocity, acceleration, or some combination of motion parameters not explicitly encoded by vestibular afferents. In this study, we have applied a frequency-domain analysis to single-unit responses during translation in three dimensions (3D). The analysis quantifies the stimulus-driven temporal modulation of each response as well as the degree to which this modulation reflects the velocity and/or acceleration profile of the stimulus. We show that MSTd neurons signal a combination of velocity and acceleration components with the velocity component being stronger for most neurons. These two components can exist both within and across motion directions, although their spatial tuning did not show a systematic relationship across the population. From these results, vestibular responses in MSTd appear to show characteristic features of spatiotemporal convergence, similar to previous findings in the brain stem and thalamus. The predominance of velocity encoding in this region may reflect the suitability of these signals to be integrated with visual signals regarding self-motion perception.

Spatiotopic Coding of BOLD Signal in Human Visual Cortex Depends on Spatial Attention

“…It has been shown that the presence of vestibular signals anchored in an inertial frame of reference affects the retinotopic heading tuning of neurons in MSTd [46]. This result is consistent with the general notion that spatial selectivity in MT/MST is flexible, and can adapt its reference frame for the specific task being performed.…”

A Comparison of Vestibular Spatiotemporal Tuning in Macaque Parietoinsular Vestibular Cortex, Ventral Intraparietal Area, and Medial Superior Temporal Area

“…As concluded previously using different analyses, neural activity in MSTd is mostly related to stimulus velocity (Gu et al, 2006; Fetsch et al, 2010). This property may reflect the need to match the temporal dynamics of vestibular signals with those of visual signals (optic flow) related to self-motion perception, as visual responses to motion typically represent velocity instead of acceleration (Rodman and Albright, 1987; Lisberger and Movshon, 1999; Gu et al, 2006).…”

A Neural Signature of Divisive Normalization at the Level of Multisensory Integration in Primate Cortex

“…1a) assumes that MSTd neurons receive purely visual inputs from area MT, which is consistent with previous studies that did not find vestibular signals in MT (Chowdhury et al, 2009; Smith et al, 2012). In contrast to the well characterized pathway by which visual signals propagate to area MSTd, the source of vestibular inputs to MSTd remains unclear, and it is likely that MSTd receives vestibular input through other cortical areas (Chen et al, 2010, 2011a, b, c, 2013; Fetsch et al, 2010). Although our normalization model assumes that MSTd neurons receive visual and vestibular inputs from separate sources (Fig.…”