Preferential activity of dentate neurons during limb movements guided by vision.

1. We recorded the activity of dentate neurons while monkeys (n = 2) performed sequential pointing movements under two task conditions: visually guided and remembered. For both conditions, a monkey faced a panel with five touch pads. The animal began a trial by placing his right hand on a hold key in front of him. In the Remembered Sequence Task, light-emitting diodes (LEDs) over three touch pads were illuminated in a sequence as an instruction to the monkey. At the end of a variable instruction period, an auditory "Go" signal told the monkey to release the hold key and press the touch pads according to the instructed sequence. In the Tracking Task, the monkey was required to press three touch pads immediately after the LED over each of them was illuminated. 2. We recorded from 172 neurons in the dentate that showed task-related changes in activity during the reaction time (RT) period (i.e., the interval between the onset of the Go signal and the release of the hold key). Approximately 40% of these neurons were considered task-dependent because they displayed exclusive or enhanced (> +/- 50%) changes in peak activity during the RT period for one of the two task conditions. Almost 80% of the task-dependent neurons displayed exclusive or enhanced activity changes during the Tracking Task. Many of these neurons were located ventral and lateral to dentate neurons, which were not task-dependent. 3. These results suggest that a portion of the dentate nucleus is preferentially involved in the generation and/or guidance of movement based on visual cues.(ABSTRACT TRUNCATED AT 250 WORDS)