Object representation in a gravitational reference frame

Abstract

When your head tilts laterally, as in sports, reaching, and resting, your eyes counterrotate less than 20%, and thus eye images rotate, over a total range of about 180°. Yet, the world appears stable and vision remains normal. We discovered a neural strategy for rotational stability in anterior inferotemporal cortex (IT), the final stage of object vision in primates. We measured object orientation tuning of IT neurons in macaque monkeys tilted +25 and –25° laterally, producing ~40° difference in retinal image orientation. Among IT neurons with consistent object orientation tuning, 63% remained stable with respect to gravity across tilts. Gravitational tuning depended on vestibular/somatosensory but also visual cues, consistent with previous evidence that IT processes scene cues for gravity’s orientation. In addition to stability across image rotations, an internal gravitational reference frame is important for physical understanding of a world where object position, posture, structure, shape, movement, and behavior interact critically with gravity.

Role of the right middle occipital gyrus in egocentric spatial orientation in reference to gravitational information: Evidence from a pre-registered rTMS study

“…Also, in non-human primates, neural activity in response to visual inputs in the lower visual cortex, including V1 (Horn et al, 1972;Tomko et al, 1981) and V2/3 (Sauvan and Peterhans, 1999), is found to be affected by the direction of gravity. Furthermore, higher association areas such as the caudal intraparietal area (Rosenberg and Angelaki, 2014) and inferotemporal cortex (Emonds et al, 2023) have been found to visually encode the tilt orientation of an object with respect to the gravitational vertical. When combining the present results with previous neurophysiological findings, it is possible to speculate that orientation information about visual objects might be integrated with vestibular-derived gravitational information at multiple stages of bottom-up visual processing, including the MOG.…”