Figure 6

Diagram of TC circuits. Panels A, B and C show three TC modules which we consider to be identical [7]. Module A is depicted in more detail [30]. One module includes, first, cortical layers (I, IV, V and VI) with pyramidal cells and one grey GABAergic inhibitory cell; second, nucleus reticularis (RT, grey GABAergic inhibitory cells); and third, thalamus (TH), represented by one specific cell in medial geniculate body (MGB) and one non-specific cell (e.g. in CL). The specific thalamic cell projects to the apical dendrites of both layers V and VI pyramidal cells and collaterals sustain reticular feedback and cortical feed-forward inhibitions. The non-specific thalamic cell projects to RT and to the layer V pyramidal neuron and has a divergent connection onto the neighboring module. The corticothalamic feedback connection is depicted as intramodular onto RT and its thalamic relay cell, and divergent intra- and cross-modular onto 3 thalamic relay cells. There are also divergent cross-modular reticulothalamic projections. Arrows 1, 2 and 3 indicate the sequence of 1) auditory deafferentation, 2) theta cross-modular spread, and 3) beta activation edge.