The role of the frontal pursuit area in learning in smooth pursuit eye movements.

The frontal pursuit area (FPA) in the cerebral cortex is part of the circuit for smooth pursuit eye movements. The present paper asks whether the FPA is upstream, downstream, or at the site of learning in pursuit eye movements. Learning was induced by having monkeys repeatedly pursue targets that moved at one speed for 150 msec before changing speed.

Evidence for object permanence in the smooth-pursuit eye movements of monkeys.

We recorded the smooth-pursuit eye movements of monkeys in response to targets that were extinguished (blinked) for 200 ms in mid-trajectory. Eye velocity declined considerably during the target blinks, even when the blinks were completely predictable in time and space. Eye velocity declined whether blinks were presented during steady-state pursuit of a constant-velocity target, during initiation of pursuit before target velocity was reached, or during eye accelerations induced by a change in target velocity.

Directional anisotropies reveal a functional segregation of visual motion processing for perception and action.

Human exhibits an anisotropy in direction perception: discrimination is superior when motion is around horizontal or vertical rather than diagonal axes. In contrast to the consistent directional anisotropy in perception, we found only small idiosyncratic anisotropies in smooth pursuit eye movements, a motor action requiring accurate discrimination of visual motion direction. Both pursuit and perceptual direction discrimination rely on signals from the middle temporal visual area (MT), yet analysis of multiple measures of MT neuronal responses in the macaque failed to provide evidence of a directional anisotropy.

Spatial generalization of learning in smooth pursuit eye movements: implications for the coordinate frame and sites of learning.

We have examined the underlying coordinate frame for pursuit learning by testing how broadly learning generalizes to different retinal loci and directions of target motion. Learned changes in pursuit were induced using double steps of target speed. Monkeys tracked a target that stepped obliquely away from the point of fixation, then moved smoothly either leftward or rightward.