Differential behavioral responsiveness to ipsilateral and contralateral visual stimuli produced by unilateral...

Rats were trained to respond to a visual cue signalling availability of brain reward on the left or the right side of a small chamber. Most of the rats began to respond more accurately to the visual cue presented on the side contralateral to brain stimulation than to the ipsilateral cue as the training progressed. The facilitation of the rat's response to the contralaterally presented visual cue was more evident when tested with visual cues presented simultaneously in both ipsilateral and contralateral sides. However, when tested with visual cues removed from both sides, this tendency became unclear. Additionally, monocular training gave evidence of identifying the visual cue ipsilateral to the open eye, irrespective of the electrode side. The results are interpreted as signifying that the ipsilateral hemisphere is activated by the brain stimulus and leads to improved discrimination of the contralateral visual cue because the visual system in the rat is crossed.