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 sustem on units within the lentiform nucleus (LM), which is the avian equivalent of the pretectal nucleus of the optic trat. A prominent depression of the spontaneous firing rat 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 rolo of the LM in the coordinate transformation from visual imputs to a vestibular referense system

Evidence for recrossing of the pathway from the retina to the ipsilateral nucleus of the optic tract

Single-unit recordings of the nucleous of the optic tract (NOT) under visual stimulation were performed in 5 opossums. Most of the units were directionally selective. Receptive fields for the contralateral eye lie mainly in the contralateral field while those for the ipsilateral eye were mainly in the ipsilateral field. As the nasal does not project ipsilaterally, recrossing must occur in the pathway from the retina to the ipsilateral NOT. Possible sites for this recrossing are discussed