DOI: 10.5061/dryad.s7h44j1g4
title: Data from: An output-null signature of inertial load in motor cortex

description: This dataset contains electrophysiological recordings from the forelimb
 muscles and motor cortex of mice performing treadmill locomotion subject
 to manipulation of limb inertial load and optogenetic perturbation of
 neural activity in the cerebellum and motor cortex. Results and
 experimental methods are described in Kirk et al., Nature Communications
 2024 (forthcoming) and Kirk et al., bioRxiv 2023.
description: # Data for Kirk et al., "An output-null signature of inertial load in
 motor cortex," Nature Communications 2024. ## 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](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](mailto: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'