Abstract
Primate ventral intra-parietal (VIP) area is a key region for judging heading direction, especially when pursuit eye movements are involved. In previous studies, monkeys had been well trained in heading discrimination task before neuronal data collection. Although behavioral training can significantly improve monkeys' performance in heading discrimination task during pursuit eye movements, it still remains unclear whether this behavioral change can be sufficiently supported by the neuronal plasticity in VIP or not. We recorded neuronal responses of macaques' VIP to the same heading stimuli before and during heading discrimination training. Behavioral performance was collected simultaneously during training. Visual stimuli were constructed by simulating monkey moving toward a 3D cloud of points. Heading angle was varied along horizontal line. To evaluate the contributions of retina and extra-retina signals, we included simulated pursuit eye movements condition besides fixation and real pursuit eye movements. We found that the behavioral improvement in training involved real pursuit eye movements couldn't be transferred to the simulated pursuit condition, even their visual inputs were identical. Then, we found that training significantly increased the sensitivity of VIP neurons at all eye movements conditions (Two-way Anova, training main effect, p< 0.001). On the other hand, training didn't reduce the separation of heading tuning among different pursuit eye movements conditions, suggesting no additional contribution to solve compensation problem (Two-way Anova, training main effect = n.s.). Our results suggest that the neural system can use visual cues solely to compensate smooth pursuit eye movements, but the strategy is not the same as in real eye movements scenario. Training can gradually increase the VIP neurons' sensitivity at all eye movements conditions, but has no direct contribution in eye movements compensation. Therefore, eye movements compensation might rely on the rapid and flexible change of read-out rule, instead of neural tuning plasticity of sensory system.
Meeting abstract presented at VSS 2017