FIGURE 10.

A proposed model of cortical excitatory circuitry. (A) L3d and L4 spiny neurons receive abundant core-type or core-like thalamic inputs, whereas L2/3 and L5 pyramidal neurons accept matrix-type inputs on their apical tufts. L2/3 pyramidal and L3d/L4 spiny neurons send axons to L5 pyramidal neurons, and L2/3 and L5 pyramidal neurons project to other cortical areas and subcortical regions, respectively (blue circuit). In contrast, L6 CTNs receive thalamic inputs directly and indirectly via L3d/L4 neurons, and then send their activity back to the thalamic neurons (red circuit). (B) It is likely that these two circuits are embedded in the cortical microcircuit with relative independence. The blue circuit may behave like a feedforward information-processing system, whereas the red one may serve as a dynamical system because of its recurrent nature. w, subcortical or cortical “driver” afferent vector; x, state vector of thalamic neurons; y, output vector of L2/3 pyramidal neurons; z, output vector of L5 pyramidal neurons.