Figure 6. Three-site stimulation to examine identity of synaptic input.

A and B, Characteristic neuronal EPSCs in response to extracellular electrical stimulation at varying frequencies for highly overlapping (A) and less overlapping (B) conditions in the oddball paradigm. Placement of stimulating electrodes was modified from that shown in Fig. 1A. Electrodes S1 and S2 were separately placed to activate less overlapping areas, whereas electrodes S2 and S3 were closely placed to activate highly overlapping areas. Insets show responses expanded in time scale. C, Comparison of normalized responses to the deviant stimulus between less overlapping and highly overlapping conditions (n = 5, 6, 7, and 7 for 10, 20, 50, and 100 Hz, respectively). D, NIs for EPSCs in highly overlapping and less overlapping conditions. The diagonal line represents the equiprobable line, with most points biased toward the less overlapping condition.