Spatio-temporal organization of neural activity in frontal motor areas

 

We use optical imaging in behaving macaque monkeys to determine the spatial organization of populations of M1 neurons that encode reaching and grasping. Then we strategically place linear electrode arrays into cortical patches that were identified with optical imaging. This step allows us to recording neural activity from all layers of cortex for insight into how neural populations code movement. Combining optical imaging and neurophysiology reveals the spatial-temporal organization of neural activity in sensorimotor cortex. 

 

Reach-to-grasp

Head fixed macaque monkeys perform an instructed reach-to-grasp task. Variations in the target object motivate different grip postures. 

 

 

 

Optical window

A chronic chamber provides access to frontal motor areas and somatosensory areas. The native dura is replaced with a transparent membrane to create an optical window that is compatible with both optical imaging and microelectrode penetrations.  

 

Motor mapping

Intracortical microstimulation (ICMS) is deployed in hundreds of microelectrode sites. The objective is to map somatotopy  and define the border between M1 and premotor cortex. 

 

Intrinsic signal optical imaging (ISOI)

Cortical activity during movement is recorded with ISOI, which provides a wide field-of-view and high spatial resolution. Cortical microvessels and sulci are exploited as landmarks for co-registering the activity patterns to the motor map.   

 

 

 

 

Single unit recording

32-channel linear electrode arrays are acutely inserted into motor and premotor cortex for recording single unit activity during the reach-to-grasp task. The configuration of the array ensures that most recording channels are in cortex (red) and only a few channels are in white matter (dark gray) or in pia matter (light gray). Spikes from the voltage traces are aligned to behavioral events for insight into the neural code of movement.