Figure 3.

Schematic Model of Connectivity between AIP, PMv, and M1

PMv is connected with M1 corticospinal neurons (CSN; black pyramids) via indirect inhibitory (red) and facilitatory (blue) pathways (late I-wave pathways). The PMv output neurons (orange pyramids) giving rise to these pathways receive inhibitory and facilitatory connections from canonical neurons in PMv (orange diamond). Object-related neurons in AIP (green diamond) make facilitatory projections to canonical neurons in PMv. At rest, conditioning TMS over PMv reveals net inhibitory PMv-M1 interactions. When grasping the disc, the corresponding object-related neurons in AIP increase their firing rate, which facilitates in turn the appropriate canonical neurons in PMv. In this example, activation of the PMv canonical cell yields facilitation of the ADM muscle representation by inhibition of the PMv-M1 inhibitory connections and facilitation of the facilitatory PMv-M1 connections.