Neuronal activity in primate parietal cortex area 5 varies with intended movement direction during an instructed-delay period.
A monkey was trained to make arm movements to visual targets immediately after presentation of a GO signal, either in a visual reaction-time paradigm (CONTROL task), or after an instructed-delay period of variable duration, during which a CUE stimulus signalled the direction of the impending movement (DELAY task). The activity of 98 area 5 cells recorded in 2 hemispheres varied with movement direction in the CONTROL task. This included 60 "early" cells which showed directional activity changes prior to movement onset. In the DELAY task, 54/98 cells (55%) showed activity changes during the instructed-delay period which varied with the direction of the impending movement. Most of these (45/54, 83%) were "early" cells. Forty proximal arm-related cells were recorded in adjacent area 2. In contrast to area 5, only 2/40 area 2 cells showed any evidence of changes in activity varying with intended movement direction during the instructed-delay period. The origin of area 5 activity changes during an instructed-delay period which are related to intended direction of a delayed movement is uncertain, but its presence is consistent with a number of proposed roles for area 5.
Centre de Recherche en Sciences Neurologiques, Faculté de Médecine, Université de Montréal, Québec, Canada.
D J
DJ
Crammond
J F
JF
Kalaska
D000818:Animals; D005071:Evoked Potentials; D008251:Macaca / Q000502:physiology*; D008253:Macaca mulatta / Q000502:physiology*; D009039:Motion Perception / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*