Description of the data and file structure

• emg_data.mat
  Electromyographic (EMG) recordings during treadmill locomotion. The structure out(k) contains data for the kth experimental session. The structures LFL and RFL contain kinematic data for the left and right forelimbs. The key array in these structures is x_finger_step, which contains the position of the fingertip and has dimensions (# steps) x (# bins within a step) x (# spatial dimensions: 1-forward, 2-right, 3-up). The logical vectors has_laser and has_load indicate which experimental conditions occur on each step. The cell arrays out(k).emg_step_LFL and out(k).emg_step_RFL contain the rectified and smoothed EMG traces for each muscle and step cycle, segmented with respect to the left and right forelimb strides, respectively.
• emg_data_home_cage.mat
  EMG recordings from mouse forelimb muscles under optogenetic perturbation of motor cortex and cerebellum as mice were standing quietly in their home cages. The structure out(k) contains data for the kth experimental session. Rectified and smoothed EMG traces are in the array data_smooth, which has dimensions (# muscles) x (#trials) x (# time points). The vector which_block indicates which trials correspond to which stimulation conditions, and side_block and power_block specify which side of the brain was perturbed and at what power level, respectively.
• motor_unit_data.mat
  Recordings from single motor units during treadmill locomotion. Data were acquired with Myomatrix arrays and conventional fine wire electrodes. The structure data(k) contains motor unit data from the kth experimental session. The cell arrays peri_step.st_R and peri_step.st_L contain the phase of the right and left forelimb locomotor cycles at which motor unit action potential occurred, and have dimensions (# right forelimb steps) x (# motor units in the session) and (# left forelimb steps) x (# motor units in the session), respectively. The arrays peri_step.r_R and peri_step.r_L contain stride-locked motor unit firing rates, and have dimensions (# motor units) x (# steps) x (# phase bins). The experimental conditions (load on / off and laser on / off) for each right and left stride are indicated in data(k).kin.LFL.has_load, data(k).kin.LFL.has_laser, data(k).kin.RFL.has_load, and data(k).kin.RFL.has_laser.
• pop_data_MC.mat
  Motor cortex factors obtained from demixed principal component analysis (dPCA), formatted using the dPCA toolbox at https://github.com/machenslab/dPCA, described in Kobak et al. (eLife, 2016). The array data_MC.Z_pop contains all 20 dPCA factors for each condition, and has dimensions (# factors: 20) x (# load conditions: 2) x (# laser conditions: 2) x (# speed conditions: 5) x (# step phase bins: 100). The arrays Z_{ci, lo, la, sp} contain factors for condition-invariant, load, laser, and speed dimensions, respectively.
• pop_data_MU.mat
  Motor unit factors obtained from dPCA. The formatting is identical to the formatting for motor cortical data in pop_data_MC.mat.
• processed_M014_MC_load_PC_stim.mat
• processed_M015_MC_load_PC_stim.mat
  Motor cortex recordings from each mouse during treadmill locomotion. The step-locked spike times and firing rates for the kth session are contained in data(k).peri_step.st and data(k).peri_step.r, and have dimensions (# steps) x (# units) and (# units) x (# steps) x (# step phase bins), respectively. The experimental conditions (load and laser) for the step cycles contralateral to the recorded units are in logical vectors data(k).kin.RFL.has_load and data(k).kin.RFL.has_laser.

Sharing/Access information

All data were obtained from experiments in the Sauerbrei Lab at Case Western Reserve University. Please direct all inquiries to Britton Sauerbrei (bxs561@case.edu).

Code/Software

• compare_cortex_and_mu.m
  Runs a comparison of neural trajectories in motor cortex and spinal motor units.
• emg_analyses.m
  Analyzes the dependence of step-locked EMG activity on experimental variables.
• motor_cortex_analyses.m
  Analyzes motor cortical single-unit and population activity during treadmill locomotion.
• motor_unit_analyses.m
  Analyzes single-unit and population activity in spinal motor units during treadmill locomotion.
• opto_calibration_home_cage.m
  Plots EMG aligned to optogenetic perturbation of motor cortex and cerebellum during standing in the home cage.
• utils
  This folder contains Matlab helper functions required to run the main scripts.

All analyses were performed with Matlab R2022a. The following toolboxes were used:
‘Signal Processing Toolbox’
‘Statistics and Machine Learning Toolbox’
‘Automated Driving Toolbox’
‘Lidar Toolbox’
‘Navigation Toolbox’
‘Robotics System Toolbox’
‘ROS Toolbox’
‘UAV Toolbox’