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Thalamic input to mesial and superior area 6 in the macaque monkey
The Journal of Comparative Neurology
|August 12, 1996
Summary
This study maps thalamocortical projections to mesial and superior area 6. Different thalamic nuclei project to specific area 6 subregions, revealing distinct motor and non-motor circuit origins.
Area of Science:
- Neuroscience
- Motor Control
- Brain Mapping
Background:
- The mesial and superior area 6 regions are crucial for motor control.
- Understanding their thalamocortical input is essential for deciphering motor circuitry.
Purpose of the Study:
- To define the specific thalamic nuclei projecting to distinct subregions of mesial and superior area 6.
- To elucidate the origins of thalamocortical pathways in supplementary motor areas.
Main Methods:
- Restricted injections of neuronal tracers into physiologically identified areas F3, F6, F2, and F7.
- Tracing neuronal pathways from the thalamus to specific Brodmann areas in the frontal cortex.
Main Results:
- Each area 6 subregion receives unique thalamic inputs, varying quantitatively and qualitatively.
- Supplementary motor area proper (F3) and area F2 receive inputs from motor-related thalamic nuclei (VLo, VPLo, VLc).
- Pre-SMA (F6) and supplementary eye field (F7) receive inputs from different thalamic nuclei, including VApc, area X, and MD, reflecting distinct functional circuits.
Conclusions:
- Area 6 subregions are targets of both cerebellar and basal ganglia circuits.
- Specific basal ganglia and cerebellar circuits are differentially connected to distinct area 6 subregions, suggesting specialized roles in motor and oculomotor control.