Following Figure 5—figure supplement 1, to further rule out the possibility that HF-LFP signals are related to eye movements, we include data recorded as T6 performed an auditory-cued task with her eyes closed as she attempted multiple single-joint movements. The task included a delay period in which she was prompted (via an auditory cue) about the upcoming movement attempt, but was asked to not attempt the movement until receiving a go cue. (a) Sample of the signals recorded on T6’s array during the attempted movement. Some channels show discernible single or multiunit activity (threshold crossings), while others do not. Neural data was processed as in Figure 5, with thresholds set to −4 times the r.m.s. voltage value for each channel. Scale bars (lower left corner) represent 150 µV (vertical) and 0.5 milliseconds (horizontal). (b) Threshold crossing rates as a function of time for attempted single-joint flexion movements (index finger: red, thumb: yellow, wrist: light green, elbow: darker green) for five example channels with discernable threshold crossing activity. Each trace represents the mean ± s.e.m. threshold crossing rate for a given condition, computed across 20 trials for each condition. Horizontal scale bar represents 500 ms, vertical scale bar represents 20 threshold crossings / sec. Red box denotes the time each movement was prompted, and blue box denotes the time of the go cue (break in the traces is due to the randomized delay period across trials). As shown, activity is indicative of both planning and movement attempt epochs. Traces from individual trials were smoothed by convolving with a Gaussian kernel with 50 ms s.d. prior to mean / standard deviation calculations. (d) Same plots, but depicting HF-LFP power instead of threshold crossing rates, for a different set of example channels that did not have discernible multiunit activity. Horizontal scale bar is again 500 ms, vertical scale (HF-LFP power) is in arbitrary units. The same trials as panel (c) above were used. Because there were no visual cues and the participant had her eyes closed, it is unlikely that the participant was making condition dependent eye movements. However, as shown, even in the absence of visual cues, HF-LFP power signals display a similar time course following target onset, degree of planning- and movement-related activity, and degree of condition dependence, as threshold crossing activity. Data are from T6’s post-implant day 488.