Fig. 13.
Influence of intracortical IN→CX inhibition on thalamocortical augmenting responses. A, B, CX-IN pair responding to a repetitive 10 Hz stimulation (Fig. 7A). Parameters are the same as in Fig. 7A, except as noted below. A, Decreasing the IN-evoked inhibition produced strong augmentation of CX responses (from 1 to 3–5 spikes) accompanied by progressive depolarization of the membrane potential (gGABAA = 0.01 μS from IN to CX cells). B, Weak inhibition produced strong depolarization during a train of stimuli and elicited tonic firing in CX cells that terminated after the train (gGABAA = 0.005 μS from IN to CX cells). C, Shift in the balance between excitation and inhibition in CX cells toward excitation accompanied by strengthening of the afferent TC→CX synaptic connections prolonged the slow poststimulus oscillations (compare C, Fig. 7A) (gGABAA = 0.01 μS from IN to CX cells, and gAMPA = 0.014 μS from TC to CX cells). Open circles indicate the time of thalamic stimulation.