Inferior parietal lobule neurones related to eye and hand reach movements in rhesus monkey.
Analysis was made on neuronal responses of the inferior parietal lobule to visual, jump, or 'reach' behavioral paradigm in 2 awake, trained rhesus monkeys. Preconditioning and antidromic electrical stimulation of medial and oral pulvinar LP nuclei and the arcuate gyrus aided the study. The results reveal two reach cell categories: one with no definable visual sensitivity (NVHRN) and one with visual receptive field responsiveness (VHRN). The VHRN reach cell firing is characterized by an early component. As the latter was observed only when the monkey reached loci inside but not outside of the cell-receptive field, it was equated with the cell visual receptive field response. This component could be voided by preconditioning stimulation of medial pulvinar or LP, the latencies of the VHRN responses becoming longer and comparable to NVHRN. If the consequences of reaching were nulled in any of a few different ways, such as preventing the monkey from reaching, disenabling the panel key, or denying the reward, a reach cell biphasic firing response showed no change in the first burst, but the second burst was absent, suggesting the latter's relation to satiation. If a jump cell's visual responses enhanced by the 'jump' paradigm were negated by preconditioning stimulation, the saccadic eye movement that otherwise followed the enhanced signals was replaced by another saccade, different in direction and amplitude, as if of other frames of reference. It seems, therefore, that the inferior parietal lobe system subserves in two types of reach behaviour: one with and one without visual guidance, playing perhaps a role in selecting strategies such as the dynamic option to do away with the visual guidance, if circumstances demand.
Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Israel.
B
B
Blum
D000818:Animals; D001931:Brain Mapping; D004558:Electric Stimulation; D005074:Evoked Potentials, Visual; D006225:Hand / Q000294:innervation; D008253:Macaca mulatta; D009474:Neurons / Q000502:physiology; D010296:Parietal Lobe / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012160:Retina / Q000502:physiology; D012438:Saccades; D014795:Visual Pathways / Q000502:physiology