抄録
To understand how the MT/MST areas are involved in vergence tracking, we examined activity of MT/MST neurons during smooth pursuit in frontal planes and vergence eye movements in two head-fixed Japanese monkeys. As a search stimulus, the monkeys tracked a 0.5° stereo spot moving sinusoidally in virtual space created using frame-sequential presentation and shutter glasses. We tested 143 neurons in MT/MST during both frontal-pursuit and vergence tracking. The majority of MT/MST neurons (69%) responded only during frontal-pursuit, 16% responded during both frontal-pursuit and vergence tracking, and the remaining 15% responded only during vergence tracking. Visual response to sinusoidal motion of a stereo spot or optic flow was tested while the monkeys fixated a stationary spot. The majority of neurons tested responded to optic flow (82/132) with large receptive fields, and preferred directions of visual response of the majority of them were opposite to those during tracking. About half of neurons tested also responded to spot motion (22/47). Using disparity step target motion, we examined latencies of neuron discharge. Some of them (10/26) discharged before the onset of vergence eye movements even after subtraction of visual components. These results suggest that MT/MST contains neurons that are involved in the initiation of vergence tracking. Supported in part by Japanese MEXT and NIH grants (EY006069; RR00156). [Jpn J Physiol 54 Suppl:S182 (2004)]
