DOI: 10.5061/dryad.76hdr7t4f
title: Data from: Flight power muscles have a coordinated, causal role in controlling hawkmoth pitch turns

description: Flying insects solve a daunting control problem of generating a patterned
 and precise motor program to stay airborne and generate agile maneuvers.
 In this motor program, consisting of every action potential controlling
 wing musculature, each muscle encodes significant information about
 movement in precise spike timing down to the millisecond scale. While
 individual muscles share information about movement, we do not yet know if
 they have separable effects on an animal's motion, or if muscles
 functionally interact such that the effects of any muscle's timing
 depend heavily on the state of the entire musculature. To answer these
 questions, we performed spike-resolution electromyography and precise
 stimulation of individual spikes in the hawkmoth Manduca sexta during
 tethered flapping. We specifically explored how the flight power muscles
 themselves may contribute to pitch control, which is necessary to
 stabilize flight. Combining a correlational study of visually-induced
 turns with causal manipulation of spike timing, we discovered likely
 coordination patterns for pitch turns, investigated whether these
 correlational patterns can individually drive pitch control, and studied
 whether the precise spike timing of power muscles can lead to pitch
 maneuvers. We observed significant timing changes of the main downstroke
 muscles, the dorsolongitudinal muscles (DLMs), associated with whether a
 moth was pitching up or down. Causally inducing this timing change in the
 DLMs with electrical stimulation produced a consistent, mechanically
 relevant feature in pitch torque, establishing that power muscles in
 Manduca have a control role in pitch. Because changes were evoked in
 unconstrained flapping in only the DLMs, however, these pitch torque
 features left a large unexplained variation. We find this unexplained
 variation indicates significant functional overlap in pitch control, such
 that precise timing of one power muscle does not produce a precise turn,
 demonstrating the importance of coordination across the entire motor
 program for flight.
description: Moths attached to a 6-axis load cell tether would freely engage
 in bouts of flapping flight, during which the DLMs would be stimulated
 with a specific timing relative to the DVMs. Stimulus delay times were
 chosen at random from a range of 4-40 ms after DVM spike detection, with
 each delay time applied for a 20 second recording period with EMG and F/T
 transducer recorded at 10 kHz. Single 0.25 ms pulses of either constant
 current or constant voltage were applied to silver wires placed on either
 end of each DLM, with each stimulation separated by at least 4 seconds to
 avoid entrainment. Timing of stimulus was achieved by passing either the
 left or right DVM voltage recording through a custom analog
 spike-detection circuit and microcontroller. The controller would trigger
 a stimulator (A-M Systems Model 3800) with a stimulus isolation unit (A-M
 Systems Model 2200) on a controlled delay time from the onset of a
 detected DVM spike.  All stimulus pulses were biphasic,
 but specific stimulus features such as whether constant current or voltage
 were used and of what amplitude, were calibrated for each moth
 individually. Stimulus was repeatedly applied while the moth was in a
 quiescent state, with stimulation amplitude steadily increased until
 evoked motor action potentials were observed in both DLMs with no evoked
 action potentials observed in surrounding muscles. While most individuals
 had their best response from constant current stimulation, differences in
 electrode placement and individual anatomy and physiology resulted in
 better results for some individuals from constant voltage stimulation.
 After calibration, stimuli ranged from 0.05-0.1 mA for constant current
 stimulation and 5-10 V for constant voltage. Note that evoked action
 potentials occur roughly 4 milliseconds after a pulse of current is
 applied.
description: # Flight power muscles have a coordinated, causal role in controlling
 hawkmoth pitch turns
 [https://doi.org/10.5061/dryad.76hdr7t4f](https://doi.org/10.5061/dryad.76hdr7t4f) This repository contains data of Manduca sexta hawkmoths flapping on a dorsal tether, with electrical stimulation applied periodically to the dorsolongitudinal muscles (DLMs) to elicit muscle action potentials at specific times. Contained here are .h5 files for each individual moth in the dataset, named according to the date the data was collected (with an appending \_1 if multiple moths were run on that same data). The .h5 files can be read by any standard hdf5 library, but we did all of our processing using Python and the Pandas library specifically. Reading each .h5 file, you will find a dataframe of all relevant time-series information from a given moth, sampled at 10kHz. This includes spike times of when the DLM and DVM muscles fired, the six time-varying forces and torques produced by the moth flapping on the tether, and some additional variables from data processing such as wingstroke number. The column names for these dataframes are as follows: `Time` -- Self explanatory, time column in seconds `LDVM` through `RDVM` -- EMG voltage traces from all four power muscles (left and right DVM and DLM). The DorsoLongitudinalMuscle (DLM) on each side produces the downstroke, and the DorsoVentralMuscle (DVM) on each side produces the upstroke. `stim` -- Analog trace of when stimulus trigger, in the form of a 0-5V signal that is normally zero, but goes high when stimulus is triggered `fx` through `mz` -- Forces and moments (torques) measured, adjusted to match each moth's calculated center of mass `trig` -- Similar to stimulus trigger, but signal used to trigger the end of each trial. Likely not needed in analysis `wb` -- Unique wingbeat identifiers, denotes what wingbeat a given point in time/dataframe row belongs to. Wingbeats are found using hilbert transform of Z force `trial` -- Unique trial identifiers, denotes what trial (short 20 second recording) a given point in time/dataframe row belongs to. `phase` -- Phase for each wingstroke a given row belongs to. Phase is 0 at the start and 1 at the end of each wingstroke, so denotes what fraction or percentage of a wingstroke a given row occurs at `wbstate` -- Signifier for what stimulus is doing in a given wingstroke. Can either be 'pre', 'stim', or 'post', denoting pre-stimulus wingstroke, stimulus wingstroke, and post-stimulus winstroke, respectively `pulse` -- Unique identifier for each time stimulus is applied. Pre- and post-stimulus wingstrokes around a stimulus wingstroke are associated to a given unique pulse `stimphase` -- Phase at which stimulus was applied `LDVM_st` through `RDVM_st` -- Boolean value indicating whether a spike for that muscle occurred at that given row. Results of spike sorting, use this for actual spike times `date` -- Unique date/moth code to indicate individual moth Alongside the main data for each individual, there is a `vars_datenumber.pkl` file, containing some additional information. These are mainly just used to store the unique translations used to transform forces and torques recorded on the load cell to a reference frame centered at each moth's center of mass.