Figure 7.

Direct Activation of Intercalated Neurons by Projections from the mPFC (A) ChR2-eYFP-expressing mPFC fibers (green) in dorsolateral (dITC, left) and ventromedial clusters of ITC neurons (vITC, right). Putative synaptic contacts are indicated as arrowheads. Ast, amygdalostriatal transition. (B) Left, EPSCs in an intercalated neuron at −80 mV evoked by photostimulation of mPFC fibers. EPSCs were inhibited by NBQX (10 μM). Right, synaptic latencies of EPSCs in ITC neurons or BLA neurons (n = 21, 17, and 9 cells for BLA/PN, dITC, and vITC, respectively). (C) EPSCs in the mPFC-ITC pathway in mice from each group induced by photostimuli of increasing intensity. EPSCs were recorded at −80 mV. (D) Input-output curves of EPSCs in mPFC-dITC (left) and mPFC-vITC pathways (right) (mPFC-dITC: n = 20-33 cells from 7-10 mice per group; mPFC-vITC: n = 8-9 cells from 3-4 mice per group). (E) EPSCs in the mPFC-ITC pathway at holding potentials from −80 to +40 mV in the presence of bicuculline (30 μM). (F) I-V plots of EPSCs in the mPFC-ITC pathway. AMPAR- and NMDAR-mediated EPSCs were measured and normalized as in Figure 3D (data from both ITC clusters were pulled together; n = 8-11 cells from 5-7 mice per each group). (G) AMPAR/NMDAR EPSC amplitude ratios in the mPFC-ITC pathway in different behavioral groups. (H) Sparse innervation of the CeA by ChR2-eYFP-expressing mPFC fibers (green). CeL and CeM, lateral and medial divisions of the CeA, respectively. st, the stria terminalis. (I) Left, EPSC (black) and IPSC (red) recorded in a CeM neuron in voltage-clamp mode at −80 mV and 0 mV, respectively. Inset shows spiking response of a CeM neuron to depolarizing current injection. Right, IPSCs had longer latencies compared to EPSCs (n = 13 and 30 neurons for EPSCs and IPSCs, respectively; p < 0.0001). (J) A summary plot of EPSC/IPSC ratios in BLA/PN, ITC neurons and CeM neurons (n = 21, 9, and 28 cells for BLA/PN, ITC neurons, and CeM neurons, respectively). Error bars are SEM.