Macaque Lateral Intraparietal Cortex Depends on the Forebrain

25 Our eyes are constantly moving, allowing us to attend to different visual objects in our 26 environment. With each eye movement, a given object activates an entirely new set of visual 27 neuron, yet we perceive a stable scene. One potential neural mechanism for stable perception is 28 the phenomenon of remapping. Neurons in lateral intraparietal cortex (area LIP), frontal eye 29 fields (FEF), extrastriate cortex, and the superior colliculus (SC) respond to visual stimuli 30 outside their receptive field if a impending eye movement will bring the stimulus location into 31 their receptive field. Remapping depends on neurons receiving visual information from outside 32 their classic receptive field, even when the initially salient location is in the opposite visual field. 33 If the forebrain commissures are transected, behavior dependent on accurate spatial updating is 34 impaired but recovers over time. Additionally, neurons in LIP continue to remap information 35 across hemifields even in the absence of the forebrain commissures. One possible explanation 36 for the across hemifield remapping in split-brain animals is that neurons in a single hemisphere 37 could represent visual information from both visual fields. We measured receptive fields of LIP 38 neurons in split-brain monkeys and compared them to receptive fields in intact monkeys. We 39 found a small number of neurons with bilateral receptive fields in the intact monkey. In 40 comparison, we found no such neurons in the split-brain animals. We conclude that bilateral 41 representations in area LIP following forebrain commissures transection cannot account for 42 remapping across hemifields. 43