Figure 6: Selective synaptic dysfunction of cortical layer-4 PV cells in PV-Mecp2−/y mice.
(a) Diagram depicting the configuration for recording monosynaptic IPSCs in a PC (Vclamp=−40 mV) in response to electric stimulation to a neighbouring PV cell in acute V1 slices. Traces: sample IPSCs recorded from postsynaptic PCs in WT, PV-Cre(;Ai9), flox-Mecp2 and PV-Mecp2−/y(;Ai9) mice, elicited by five consecutive PV cell action potentials (APs) at 20 Hz, followed by a single spike after 0.5 s. Scale bar, 10 pA, 25 ms. (b) Left: Cumulative distribution and the mean value (inset) of amplitudes of the first IPSC evoked by a train stimulation of all recorded pairs; Right: Short-term depression and synaptic recovery rate of recurrent inhibitory PV–PC synapses from the experiments shown in a. n, number of examined cells. (c,d) Diagram depicting the configuration for recording monosynaptic EPSCs in a PV cell (Vclamp=−70 mV) in response to electric stimulation of projection axons in the white matter region below layer 6. Scale bar, 50 pA, 25 ms. The asterisk indicates occasional transmission failure during the minimal stimulation. Data depicted in the same manner as in a,b. (e,f) Diagram depicting the configuration for the recording of monosynaptic EPSCs in a PV cell (Vclamp=−70 mV) in response to stimulation of a neighbouring PC. Scale bar, 20 pA, 25 ms. The EPSC amplitudes from PV-Mecp2−/y(;Ai9) mice showed significant reduction in comparison with WT, (P=0.0003, t-test), but not at the same synapse from PV-Cre(;Ai9) and flox-Mecp2 mice (P=0.43 and 0.57, respectively). Average data are presented as mean±s.e.m.
