Injecting Instructions into Premotor Cortex Kevin A. Mazurek, Marc H. Schieber  Neuron  Volume 96, Issue 6, Pages 1282-1289.e4 (December 2017) DOI: 10.1016/j.neuron.2017.11.006 Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 1 Task, Instructions, and Electrode Locations (A) Monkeys initially performed the reach-grasp-manipulate task instructed by blue LEDs. (B) Monkeys then learned to perform the same task instructed by ICMS delivered in either the PM or S1. (C) Sequence of task epochs. (D and E) Floating microelectrode array locations in monkey L (D) and monkey X (E). Light gray squares with dark outlines represent arrays in the PM, dark gray squares with light outlines represent arrays in the S1, and black squares represent arrays in the M1. AS, arcuate sulcus; CS, central sulcus; IPS, intraparietal sulcus. Orientation arrows: C, caudal; M, medial. (F and G) Typical unit activity recorded from a PM electrode in monkey L (F) and in monkey X (G) during RGM movements (LED instructions) involving each object: perpendicular cylinder (Perp; purple), coaxial cylinder (Coax; yellow), button (red), and sphere (blue). Only five trials of each movement are shown in the raster display, whereas ∼20 trials of each are averaged in the histograms. Trials have been aligned at the instruction onset (time = 0, black squares in the raster trials). Additional markers indicate the time of movement onset (black circle) and target object contact (black triangle) in each trial. Neuron 2017 96, 1282-1289.e4DOI: (10.1016/j.neuron.2017.11.006) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 2 Learning to Use PM- or S1-ICMS Instructions (A–D) In early sessions, only LED instructions were delivered. Beginning at session 0 (solid vertical line), both LED and ICMS instructions were delivered concurrently. Instruction LEDs then were gradually dimmed (beginning at dotted vertical line) and eventually turned off completely (dashed vertical line). Monkey L first learned to use S1-ICMS (A) and then PM-ICMS (B). Monkey X first learned to use PM-ICMS (C) and then S1-ICMS (D). Reaction times are displayed as medians. The shaded regions represent the 25th–75th percentile. See also Tables S1 and S2. Neuron 2017 96, 1282-1289.e4DOI: (10.1016/j.neuron.2017.11.006) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 3 Parameter Sweeps (A–I) Three parameters of PM-ICMS instructions were varied for each monkey: pulse frequency (A–C), current amplitude (D–F), and train duration (G–I). Success rates (A, D, and G), reaction times (B, E, and H), and movement times (C, F, and I) are plotted as a function of the swept parameter. In (G), the vertical dotted lines represent the median reaction time across all swept durations for each monkey (H), and the corresponding horizontal dotted lines indicate the success rate at this median reaction time, based on the fitted logistic functions. X’s (monkey L, blue) and O’s (monkey X, red) indicate medians; error bars represent the 25th and 75th percentiles. See also Table S3. Neuron 2017 96, 1282-1289.e4DOI: (10.1016/j.neuron.2017.11.006) Copyright © 2017 Elsevier Inc. Terms and Conditions

Figure 4 Stimulus-Triggered Averages of EMG Activity (A and B) Averages of rectified EMG activity from four upper extremity muscle groups (triceps, biceps, forearm extensors, and forearm flexors) were compiled for monkey L (A) and monkey X (B) using individual ICMS pulses as triggers. ICMS parameters used for these sessions are given in Table S4. Separate averages (colors) were compiled using n pulses delivered through the PM electrode instructing the sphere, button, coaxial cylinder, or perpendicular cylinder, as well as for catch-trial pulses delivered in the M1. The vertical gray bar indicates the interval during which the aligned stimulation artifacts have been blanked. Each trace has been Z scored. The dashed horizontal black lines represent ± 3 SDs from the bootstrap-adjusted baseline (i.e., the solid black horizontal line). See also Table S4 and Figure S1. Neuron 2017 96, 1282-1289.e4DOI: (10.1016/j.neuron.2017.11.006) Copyright © 2017 Elsevier Inc. Terms and Conditions