Figure 6.

CB1 receptor activation potentiates the frequency of burst events specifically in response to CS+ odor presentations. A, ISI histogram from a single BLA-responsive mPFC saline control rat showing the distribution of ISIs over the 2 min baseline, CS−, and CS+ recording epochs. A moderate shift in ISI frequency occurring below the 45 ms burst criterion (see Materials and Methods) takes place in response to the CS+ presentation relative to baseline. B, An ISI histogram from a single BLA-responsive mPFC neuron pretreated with the effective dose of WIN 55,212-2 (0.5 mg/kg) shows a strong shift toward ISI frequencies occurring below the 45 ms burst ISI criterion relative to baseline and CS− recording epochs, demonstrating that CB1 receptor activation can strongly potentiate associative bursting in response to emotionally salient conditioned stimuli. For all panels, the black arrows indicate the 45 ms burst ISI threshold cutoff point (see Materials and Methods).