Interaction between transcallosal and thalamocortical excitation.

The view is argued that the transcallosal flow of excitation performs three basic and closely interconnected functions: modulation of the size, concentration, and displacement of the thalamocortical flow of excitation. To express the situation in its general form, this amounts to filtration of the afferent flow. It is done by means of a mosaic of functional units, consisting mainly of a constellation of neurons with facilitatory center and depressing periphery, converting the ascending flow into a special kind of "funnel."