Fig. 4.
Repeated burst stimulation of the MD potentiates FF-evoked firing in PFC neurons. A, In neurons that did not fire in response to MD stimulation, tetanic burst stimulation of the MD (25 4-pulse 20 Hz trains; interburst interval of 5 sec; arrow) potentiated FF-evoked firing for ∼10 min (black squares). In contrast, repeated single-pulse stimulation of the FF alone had no effect (gray circles). Symbols represent mean percentage change (+SEM) in baseline FF-evoked firing. B, Peristimulus time histograms showing a typical response from a single PFC neuron at baseline (B1) 2 min before and 1 min after MD tetanus (B2) (25 sweeps each). In this cell, MD tetanus substantially potentiated FF-evoked firing probability. Arrows represent time points at which single pulses were administered to the FF (450 μA stimulation intensity for both). * p < 0.05 and ** p < 0.01, respectively, versus baseline.