Fig. 7

(a) Simplified sketch of the neuronal discharges in TCC following vibrissal stimulation (black horizontal bars; magenta vertical bars) and GON stimulation (arrowheads; blue vertical bars). Gray vertical bars indicate the resting, spontaneous discharge of the same TCC units studied after vibrissal stimuli. For better visualization, spontaneous and evoked responses are represented at different time scales (spontaneous activity compressed 10x; interstimulus interval, stimulus duration and firing responses expanded 3-5x). The bottom recordings show the effect of a conditioning GON stimuli on the following response to facial stimuli. (b) Similar sketch summarizing the effects of blocking inhibitory GABAergic (Bic), Glycinergic (Str) or both GABA- and Glycinergic transmission (Bic + Str) on the conditioning effect of GON stimulation on the response to vibrissal stimulation. The number of vertical bars under each of these three conditions represent comparisons with the values observed just prior to the application of the drug(s) shown in (a). (c) Simplified view of a minimal local circuitry in laminae III of TCC that could help explain, at a circuital level only, the effects of GON stimulation on the successive response of TCC units to light stimulation of the vibrissal pad under control or CCI-IoN conditions. Units responding to GON could be different (R1, more likely) or the same (R2, less likely) units recorded after vibrissal stimulation. Color codes and geometric figures identify different excitatory and inhibitory neurons and synapses. Other possible excitatory neurons interposed in the circuit are omitted