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. 2014 Aug 4;9(8):e103596. doi: 10.1371/journal.pone.0103596

Figure 1. The intrinsic excitability of IL pyramidal neurons increased within 4 hours after extinction and reversed with the spontaneous recovery of fear.

Figure 1

A. Percent of time that rats spent freezing to the tone in groups that were conditioned (Cond; n = 13 rats, black), and fear extinguished (Ext-0; n = 9 rats, red; Ext-4; n = 6 rats, blue; SR; n = 8 rats, green). The Ext-0 group was sacrificed immediately after extinction, and the Ext-4 group was sacrificed 4 hours after extinction. B. Average freezing of the SR group on day 3 and day 21 to two tones. SR rats were sacrificed immediately after testing on day 21. C. Sample traces showing responses of IL neurons from each group to a 200 pA depolarizing current step. D. Number of spikes evoked in IL neurons by increasing depolarizing steps in the Cond (n = 34), Ext-0 (n = 22), Ext-4 (n = 18), and SR (n = 18) groups. E. Average maximum number of spikes evoked in each group. F. Average first interspike interval (ISI). ***p<0.001, *p<0.05.