Figure 5. Different cortical mechanisms may influence MEP amplitudes in the context of movement preparation and execution.

Filled triangles represent inhibitory inputs and open triangles represent excitatory inputs. PTN depicted in colours represents cells that are targeted in each scenario. A, global inhibition of motor cortical outputs that is task‐unspecific (e.g. in the context of a stop‐signal reaction time task). B, selective inhibition of circuits projecting to specific PTN muscle representations. This occurs in the scenario where selective activation of hand muscles is intended and is accompanied by a ‘surround inhibition’ effect suppressing cortical outputs to neighbouring, non‐activated muscles. C, when TMS is given with different current directions, changes in MEP amplitudes may result in less effective depolarization of intracortical neurons due to network properties.