Wiener, S.I., Arleo, A., Déjean, C., Boucheny, C., Khamassi, M. and Zugaro M. Optic field flow signals update the activity of head direction cells in the rat anterodorsal thalamus. Society For Neuroscience Abstracts, 2004

Sony CSL authors: Angelo Arleo, Christian Boucheny

Abstract

Head direction (HD) neurons fire selectively as an animal orients its head in different directions relative to the environment. The subset of active neurons updates as the head rotates. Normally as a subject moves about, turning the head in one direction produces an opposite shift of the visual image. Hence rotations of the visual scene convey information about rotations of the head in space. Our working hypothesis is that the optic flow of the visual scene during movements helps to update the directional firing of HD neurons. To test whether this may result from optic field flow cues, we altered them relative to head rotations. In 7 Long-Evans rats, 14 anterodorsal thalamic HD neurons were recorded. The animals were placed on a circular platform (diam 75 cm) surrounded by a large cylindrical black curtain (diam 3 m). A planetarium-like projector presented a field of points evenly distributed on the curtains of the otherwise dark room. First, preferred directions (PD) were recorded with the points still. Then, they were rotated at constant velocity for 90 s, while directional firing was recorded. In 28 sessions for a total of 42 rotations at 4.5 deg/s (i. e., about 405 deg over the 90 s period) yielded a mean coherent drift of 204 deg (SD=54 deg) in the PD of the neurons relative to the room reference frame. The HD system registers this optic field rotation as a shift in the animal's orientation. This could be the basis of a vection-like phenomenon that humans experience as the visually evoked sensation of movement. This would conflict with other information received by the HD system (e.g. vestibular, motor command and efferent copy signals) indicating no such self-rotation. Consistent with this, the optic field flow signals provoked directional shifts only when the animal was actively moving, not when it was immobile, where the intermodality discrepancy would be highly salient. Support Contributed By: ACI, CNES

BibTeX entry

@INPROCEEDINGS { wiener:04b, AUTHOR="Wiener, S.I. and Arleo, A. and Déjean, C. and Boucheny, C. and Khamassi, M. and Zugaro M.", BOOKTITLE="Society For Neuroscience Abstracts", TITLE="Optic field flow signals update the activity of head direction cells in the rat anterodorsal thalamus", YEAR="2004", }