Description:

The functional organization of primary motor cortex (M1) across the cortical sheet remains obscure. Aside from the crude and static somatotopic organization of M1, there is little evidence of spatially organized dynamic patterning across the motor cortical sheet. We have previously demonstrated that spatially organized propagating patterns of excitability along a rostro-caudal axis in non-human primates signal the initiation of movement but do not specify the details of the movement (Balasubramanian, Arce-McShane, Dekleva, Collinger, & Hatsopoulos, 2023). These propagating patterns of excitability were observed in the attenuation of low frequency beta oscillation (15-35 Hz) amplitude of the local field potential (LFP). We are now investigating patterns of high frequency components of the LFP (200-400 Hz referred to as high gamma) that propagate intermittently across M1 during reaching behaviors and have found that the propagation direction carries kinematic information (Liang, Balasubramanian, Papadourakis, & Hatsopoulos, 2023; unpublished data). Given that the high gamma signal serves as an accurate proxy for multi-unit activity (Ray & Maunsell, 2011), these results suggest that a spatially organized recruitment order of multi-unit activity provides behaviorally relevant information.