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. 2015 Oct 27;27(1):625–634. doi: 10.1093/cercor/bhv241

Figure 1.

Figure 1.

Disinhibition of striatal local field potential (LFP) response to cortical train stimulation following chronic nigrostriatal DA lesion. (a) Forelimb stepping test assessed presurgery and 6 weeks postsurgery revealed that 6-OHDA injection into the medial forebrain bundle (n = 13) resulted in marked stepping deficits in the contralateral forelimb and >90% TH-positive (DA) cell loss in the ipsilateral substantia nigra (SN) relative to sham controls (n = 11). Insets show examples of TH staining illustrating the extent of DA lesion in the striatum. (b) Coronal sections of Nissl staining showing the location of the stimulating and recording electrodes. Inset shows traces of cortically evoked striatal LFP responses (calibration: 2 mv/25 ms). (c) Cortical train stimulation typically suppresses striatal LFP in sham controls. This inhibitory response was lacking or attenuated following DA lesion as revealed by two-way ANOVA and significant main effects of treatment at 10 Hz (F1,220 = 49.8, P < 0.0005), 20 Hz (F1,220 = 62.3, P < 0.0005), and 40 Hz (F1,220 = 71.4, P < 0.0005). Post hoc analyses showed a lack of LFP inhibition at 10 and 20 Hz, and an attenuated LFP inhibition at 40 Hz in the 6-OHDA group relative to sham controls (+P < 0.05/++P < 0.005/+++P < 0.0005 vs. 1st pulse, *P < 0.05/**P < 0.005/***P < 0.0005 vs. sham, LSD post hoc test). (d) Summary of the mean LFP response calculated from pulses 2 to 10 (*P < 0.05/***P < 0.0005 vs. sham or naïve, LSD post hoc test, one-way ANOVA; 10 Hz: F2,27 = 4.2, P < 0.05; 20 Hz: F2,27 = 5.4, P < 0.05; 40 Hz: F2,27 = 14.1, P < 0.0005). (e) Traces of cortically evoked striatal LFP illustrating the effects of 6-OHDA lesion (calibration: 2 mV/100 ms at 10 Hz, 2 mV/50 ms at 20 Hz, 2 mV/25 ms at 40 Hz).