Accessory optic-pretectal interactions in the pigeon.

This electrophysiological study analyzes the influence of the nucleus of the basal optic root (nBOR) of the avian accessory optic system on units within the lentiform nucleus (LM), which is the avian equivalent of the pretectal nucleus of the optic tract. A prominent depression of the spontaneous firing rate of neurons within the LM occurred following electrical stimulation of the ipsilateral nBOR. A close correlation was also found between the directional selectivity of LM units and the apparent displacements generated by rotations of the head around the horizontal semicircular canal axis. This is consistent with a possible role of the LM in the coordinate transformation from visual inputs to a vestibular reference system.