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. 2015 Feb 4;113(7):2537–2548. doi: 10.1152/jn.00701.2014

Fig. 2.

Fig. 2.

Stimulation artifact rejection and behavioral response to deep brain stimulation (DBS). Ai: neuronal signal from M1 acquired just before and during GPi-DBS, but with artifact subtraction disabled. Note the presence of large voltage transients during DBS (black) preventing discrimination of single unit spikes. Aii: expanded view of a short time period during DBS showing the large voltage transients that occurred time locked to the delivery of the stimulation pulse (vertical dashed lines; 150-Hz, 1-mA, 200-μs pulse width). Aiii: same microelectrode signal acquired on a parallel acquisition channel with artifact subtraction working shows no evidence of shock artifacts while action potentials and recording noise are preserved. (Note the different voltage scales in Aii and Aiii.) Action potentials that were completely obscured by artifacts in the unsubtracted data stream were easily detected in the processed data stream. Aiv: peristimulus sweeps (n = 4,500) of the recorded signal (top trace) demonstrate that it was possible to record and discriminate action potentials across the entire peristimulus period, including times close to stimulus pulse delivery (time zero). The bottom traces show statistical tests of the efficacy of the artifact rejection. The mean waveforms of spikes discriminated during DBS (thick black lines; ±SE indicated by light gray shading) were required to fall within the 95% confidence interval for all spikes discriminate during nonstimulation periods (dark gray shading). The test was conducted separately for four 2-ms epochs, defined by the vertical dashed lines. Bi: clinical testing using the torque motor. The figure shows one unprocessed record of constant angular displacement (gray trace) ±20° at 1 Hz and corresponding torque trace (black trace) off- and on-stimulation. Bii: measure of elbow rigidity calculated as cycle-by-cycle work derived from the integrated resistive torque (i.e., “work”) required to move the elbow joint through a ± 20° cycle at 1 Hz from one recording session that consisted of ten 30-s long periods of stimulation. Note the large reduction of work during application of GPi-DBS and the persistence of the effect after stimulation has stopped. Biii: postural transients (*) increased in frequency during GPi-DBS. This particular example shows raw torque (black traces) for 7 successive blocks of GPi-DBS (gray shading) sampled from monkey C.