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An oculomotor representation area within the ventral premotor cortex
1Department of Physiology, Tohoku University School of Medicine, Sendai, 980, Japan.
Abstract:
We explored the ventral part of the premotor cortex (PMV) with intracortical microstimulation (ICMS) while monkeys performed a visual fixation task, to see whether the PMV is involved in oculomotor control. ICMS evoked saccades from a small-restricted region in the PMV, without evoking movements in the limbs, neck, or body. We found the saccade-evoking site in the PMV in a total of three hemispheres in two monkeys. Quantitative analysis of the effects of eye position on saccades evoked by microstimulation of the PMV characterized the evoked saccades as goal directed. The nature of the saccades evoked in the PMV contrasted with the fixed vector nature of saccades evoked by ICMS of the frontal eye field. We also found that neurons in this restricted area of the PMV were active while the animals were performing a saccade task that required them to make saccades toward targets without arm movements. These data provide evidence for the presence of an oculomotor-specific subregion within the PMV. This subregion and the surrounding skeletomotor-representing regions of the PMV seem to coordinate oculomotor and skeletomotor control in performing goal-directed motor tasks.
Insights
Researchers found a specific area in the ventral premotor cortex (PMV) that controls eye movements (oculomotor control). This region coordinates eye and body movements for goal-directed tasks.
Area of Science:
- Neuroscience
- Motor Control
- Primate Research
Background:
- The ventral premotor cortex (PMV) is known for its role in motor control.
- Its specific involvement in oculomotor control has been less understood.
Purpose of the Study:
- To investigate whether the PMV plays a role in oculomotor control.
- To identify specific subregions within the PMV involved in eye movement control.
Main Methods:
- Intracortical microstimulation (ICMS) was applied to the PMV in monkeys during a visual fixation task.
- Analysis of evoked saccades and neuronal activity during oculomotor tasks.
Main Results:
- A restricted region within the PMV evoked goal-directed saccades, distinct from limb or neck movements.
- These saccades differed from those evoked by ICMS of the frontal eye field.
- Neurons in this PMV region showed activity during saccade tasks without arm movements.
Conclusions:
- Evidence suggests an oculomotor-specific subregion exists within the PMV.
- This subregion likely coordinates oculomotor and skeletomotor control for goal-directed actions.