DOI: 10.5061/dryad.wdbrv162w
title: A data archive including processed spiking data, raw EMG datasets, and video data during locomotion behavior from six mice

description: During locomotion, the coordinated activity of dozens of muscles shapes
 the kinematic features of each stride, including systematic changes in
 limb movement across walking speed. Motor units, each of which consists of
 a single motor neuron and the muscle fibers it innervates, contribute to
 the total activation of each muscle through their recruitment and firing
 rate when active. However, it remains unknown how the nervous system
 controls locomotor speed by changing the firing of individual motor units.
 To address this, we combined quantitative behavioral analysis of mouse
 locomotion with single motor unit recordings from the lateral and long
 heads of the triceps brachii, which drive monoarticular extension of the
 elbow and biarticular movements of the elbow and shoulder, respectively.
 In contrast to prior studies employing bulk EMG to examine muscle
 activity, our recordings revealed the diversity of spike patterning across
 motor units as well as systematic differences in motor unit activity
 across muscles and locomotor speeds. First, motor unit activity differed
 significantly across the lateral and long heads, suggesting differential
 control of these two closely apposed elbow extensor muscles. Second, we
 found that individual units were recruited probabilistically (during only
 a subset of strides), showing that the highly repeatable bulk EMG signals
 observed across strides in fact reflect stochastically varying subsets of
 individual motor units. Finally, although recruitment probability and
 firing rate both increased at faster walking speeds, increases in
 recruitment were proportionally larger than rate changes, and recruitment
 of individual units accompanied changes in limb kinematics. Together,
 these results reveal how the firing of individual motor units varies
 systematically across muscles and walking speeds to produce flexible
 locomotor behavior.
description: # A data archive including processed spiking data, raw EMG datasets, and
 video data during locomotion behavior from six mice **1) allanimaldata.mat
 - processed data** * version – version number for this format of data
 storage * freqrange – bandpass filter range (Hz) for the EMG * impedances
 – impedance values (Ω) for electrode channel * animalID – unique Sober lab
 ID tag for animal * muscles – muscle location for each electrode channel *
 implantDate – date (yyyy-mm-dd) of electrode implant surgery *
 experimentDate – date (yyyy-mm-dd) of treadmill running experiment *
 experimental_rig – treadmill name * ntrials – number of trials *
 exclusion_trials – trials pre-excluded manually due to issues * comments –
 notes on experiment * units – 3xm matrix with info on m units (muscle
 location for each unit, noise floor on the most relevant channel for each
 unit, signal amplitude for each unit on that same channel) trialdata –
 each trial consisted of 1 minute of continuous running on the treadmill at
 a given speed * trialnum – trial number * beltSpeedL – left belt speed
 (m/s) for whole trial duration * beltSpeedR – right belt speed (m/s) for
 whole trial duration * right_forepaw_strides – stride times for the right
 forepaw (Each paw has an nx4 matrix ordered footstrike~1~, liftoff,
 footstrike~2~, stride number (n)) * elb_angle_min_stride – re-defined
 strides based on the elbow minimum angles because it better captures spike
 patterns from the elbow extensor muscles. This was only calculated for the
 right elbow. The nx5 matrix has n strides found through footstrike/liftoff
 definition, and columns are ordered as timestamps (s) for elbow
 minimum~1~, footstrike~1~, liftoff, elbow maximum, elbow minimum~2~. Since
 the elbow angle cannot always be reliably calculated, some strides have
 already been excluded * spikes_times – spike times for each unit. Units
 have been ordered previously from most to least total spikes
 stride_discrete_kinematics – discrete kinematic parameters for 6
 experimental mice. Each field contains n rows based on the right forepaw
 defined strides of the animal * stride_dur – stride duration (s) as time
 between footstrike~1~ and footstrike~2~ * stance_dur – stance duration (s)
 as time between footstrike~1~ and liftoff * swing_dur – swing duration (s)
 as time between liftoff and footstrike~2~ * elb_stride_dur – stride
 duration (s) as time between elbow minimum~1~ and elbow minimum~2~ *
 elb_stance – duration (s) between elbow minimum~1~ and footstrike~1~ * vel
 – body velocity (m/s) averaged over the duration from footstrike to
 footstrike * accel – body acceleration (m/s^2^) averaged over the duration
 from footstrike to footstrike * orientation – distance (m)between nose and
 tail, averaged over the duration from footstrike to footstrike – used to
 validate orientation, as values should be positive if the animal is
 walking forwards * speed_quart – nx4 matrix with n strides and true values
 in a single column based on evenly dividing all valid strides into 4
 groups based on speed. 1^st^ column is slowest and 4^th^ is fastest. This
 definition (which is the main one used) can be helpful to account for the
 natural variability of animals, with analyses based on equal group sizes *
 speed_range – nx4 matrix with n strides and true values in a single column
 based on pre-determined group speeds. 1^st^ column is 0.1-0.15 m/s. 2^nd^
 is 0.15-0.2 m/s. 3^rd^ is 0.2-0.25 m/s. 4^th^ is 0.25-0.3 m/s. This
 definition can be helpful for consistency across animals * speed_tread –
 first column is treadmill speed during each stride. The second column is
 whether body velocity falls within 90-110% of the treadmill speed.
 stride_discrete_spiking – discrete spiking parameters for 6 experimental
 mice. Each field is a nxm matrix with n rows based on right forepaw
 strides of the animal and m columns based on number of units * spike_count
 – number of spikes in each unit per stride * active_duration – duration
 (s) between first and last spikes within a stride * active_duration_zeros
 – duration (s) between first and last spikes within a stride where each
 spike is artificially given a duration of 4ms around the peak. Thus,
 strides with one spike have a time of 4ms instead of being excluded *
 duty_cycle – active duration divided by elbow stride duration, * ifr_med –
 median value (Hz) of the instantaneous firing rate for all spikes.
 Instantaneous firing rate was calculated as 1 divided by the inter-spike
 interval * ifr_max – maximum value (Hz) of the instantaneous firing rate
 for all spikes. Instantaneous firing rate was calculated as 1 divided by
 the inter-spike interval * first_spk – time (s) of first spike * last_spk
 – time (s) of last spike * fr_maxraw – maximum firing rate (Hz) within
 stride from firing rated defined by gaussian smoothed over spike times *
 fr_phaseraw – approximate phase of maximum firing rate based on scaling
 continuous firing rate trace over time to a 1-100 phase scale. Note that
 values of 1 are almost always erroneous from strides with no spiking from
 a unit **2) allmousekinematics.mat** Timeseries data for kinematic
 tracking of each mouse during the experiment. Each mouse's data is
 located in order in a table with the following information * beltspeed -
 vector of treadmill belt speed across all trials * session_time - vector
 of timepoints across all trials * trial_number - trial number * kinematics
 - labeled body parts with 'prob' representing the confidence of
 the tracked point along (x,y) dimensions. If choosing to look at the video
 files directly, skipped frames sometimes occur and can be identified in
 each trial based on when a confidence point has a NaN value. **3)
 mouseRawData.mat** Contains processed EMG data and timeseries information
 for mice A-F in struct trialdata_original with the following fields: * emg
 - mxn EMG data matrix of m data samples recorded at 30kHZ and n electrode
 channels * time - mx1 time vector * trial - start and stop indices for
 each trial **4) All_videos.zip** Locomotion videos for each mouse (mouse A
 to F) and trial contained within this dataset and the video files are
 named based on number of trials.