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. Author manuscript; available in PMC: 2009 Aug 15.
Published in final edited form as: Nat Neurosci. 2009 Jan 25;12(2):190–199. doi: 10.1038/nn.2245

Figure 7.

Figure 7

Repeated cocaine treatment reduces the mGluR5/burst-mediated conversion of subthreshold input to suprathreshold action potential output and D1/5R modulation. (a) Whole-cell patch clamp recording of a layer 5 pyramidal neuron given a burst of 5 suprathreshold simulated synaptic current injections at 20 Hz followed by a single subthreshold simulated current injection delivered at 85% of threshold at different times from 1 second to 4 seconds post burst (Overlay) in the presence of DHPG (50 µM; Gray Traces) and after SKF81297 (10 µM; Black Traces). DHPG elicited a dADP that converted the fast subthreshold input to suprathreshold spike output in the first 3 seconds post burst. Inset shows the superimposed fast EPSP responses before and after DHPG (Gray trace) and SKF (Black trace) when measured prior to the burst of five action potentials (scale bar is 5 mV and 10 ms). Right panel shows the average spike probability in response to subthreshold simulated postsynaptic input in the presence of DHPG (50 µM; Open squares, Control) and SKF81297 (10 µM; Filled Squares; n = 8, p < 0.01 at 2 and 3 seconds). (b) Short (2 day) withdrawal from repeated cocaine treatment reduces the spike probability (Left Panel; Open squares, Saline/Control, n = 8 and Open circles, Cocaine, n = 11,p < 0.001 at 1 and 2 seconds). The right panel shows the normalized spike probability following DHPG and SKF81297 in the untreated/saline-treated control group (Filled squares, Cont SKF; n = 8) and the cocaine-treated group given DHPG alone (Open circles, COC Cont) or DHPG and SKF81297 (Filled Squares, COC SKF). (c) Late (14 Day) withdrawal from repeated cocaine treatment does not alter the burst triggered dADP (Left Panel; Saline/Control, n = 6 and Cocaine, n = 6; p > 0.05). The right panel shows lack of D1/5R modulation of the normalized spike probability for the cocaine treated group in response to DHPG (Open circles, COC Cont) and after SKF81297 (Filled circles, COC SKF; p > 0.05) compared to non-treated cocaine controls (Filled Squares; Cont SKF).