Figure 7.

Cortical microcircuit for coincidence detection underlying cognitive control. The simplified diagram of circuitry embedding a L5-PC (blue) in agranular cortex with soma (triangle) located in L5, dendrites that extend up to L1, and axons (blue arrows) that project both intrinsically, innervating inhibitory neurons (red) and other pyramidal neurons (data not shown) in the microcircuit, and extrinsically, innervating other brain areas. This figure illustrates how dendritic dynamics can contribute to an error signal. An efferent copy of a motor command is delivered through a feedforward thalamic pathway, terminating on the L5-PC soma and apical dendrites. A task rule signal from PFC is delivered through a feedback pathway, terminating on the L5-PC apical dendrites. The soma of a L5-PC (blue triangle) generates Na⁺-APs that propagate intracortically to Martinotti cells (ovals) and other inhibitory interneurons (star). The Martinotti cells terminate on the L5-PC apical dendrites, while the other interneuron terminates on the soma. Because inhibitory neurons in agranular cortex largely make intralaminar projections, the interlaminar inhibitory projections depicted here (dashed red lines) represent connections that are likely mediated by additional PCs and interneurons in L3 and L5 (data not shown). The dynamics of this connectivity induces Ca²⁺ spikes, which amplify the coincidence of the efferent copy and the task rule to generate an error signal. These neuronal events are signaled by the generation of theta band LFP from deeper layers and gamma band LFP from superficial layers (indicated by labeled oscillations).