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. 2018 Apr 25;120(2):662–680. doi: 10.1152/jn.00862.2017

Fig. 8.

Fig. 8.

A: effect of subthalamic nucleus (STN) deep brain stimulation (DBS) frequency on the heterogeneous cortical evoked potential (cEP) response found in a subset of healthy, awake rats (n = 4 rats, 5 hemispheres). Stimulation parameters for electrocorticographic (ECoG) recordings: charge-balanced, symmetric biphasic pulses with a duration of 90 µs/phase and an amplitude range of 50–70 µA. A1: 4.5 Hz. A2: 9 Hz. A3: 50 Hz. A4: 130 Hz. STN DBS at low frequencies evoked R1, R2, and R3 responses. STN DBS at 50 Hz evoked R1 and R2 responses, whereas STN DBS at 130 Hz evoked only an R1 response. Shading shows the range of cEP responses across several rats, whereas black trace shows the mean cEP response across rats. This cEP differed from the response shown in Fig. 4, although postmortem histology or contact testing confirmed the stimulating electrode to be within STN. B: quantification of cEP features (peak amplitude and latency of peak amplitude) across STN DBS frequencies. On each box, the central mark indicates the median and bottom and top edges of box indicate the 25th and 75th percentiles, respectively. Whiskers extend to 1.5 times the interquartile range. B1, B2, and B3: peak amplitude of R1, R2, and R3 responses at different STN DBS frequencies. Note a decrease in R1 peak amplitude at 130 Hz compared with lower frequencies. Friedman’s ANOVA identified effects of stimulation frequency on R1 peak amplitude (P = 0.026). B4, B5, and B6: latency of peak amplitude of R1, R2, and R3 responses at different STN DBS frequencies. Note an increase in the latency of peak amplitude of R1 response at higher compared with lower frequencies, although the results were not statistically significant (P = 0.050, Friedman’s ANOVA). *P < 0.05, significant difference between DBS frequencies (Dunn-Bonferroni method).