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Pectoral fin kinematics and motor patterns are shaped by fin ray mechanosensation during steady swimming in Scarus quoyi

Citation

Aiello, Brett R. et al. (2020), Pectoral fin kinematics and motor patterns are shaped by fin ray mechanosensation during steady swimming in Scarus quoyi, Dryad, Dataset, https://doi.org/10.5061/dryad.gtht76hhb

Abstract

For many species of fish, rhythmic movement of the pectoral fins, or forelimbs, drives locomotion. In terrestrial vertebrates, normal limb- based rhythmic gaits require ongoing modulation with limb mechanosensors. Given the complexity of the fluid environment and dexterity of fish swimming through it, we hypothesize that mechanosensory modulation is also critical to normal fin-based swimming. Here, we examined the role of sensory feedback from the pectoral fin rays and membrane on the neuromuscular control and kinematics of pectoral fin-based locomotion. Pectoral fin kinematics and electromyograms of the six major fin muscles of the parrotfish, Scarus quoyi, a high-performance pectoral fin swimmer, were recorded during steady swimming before and after bilateral transection of the sensory nerves extending into the rays and surrounding membrane. Alternating activity of antagonistic muscles was observed and drove the fin in a figure-of-eight fin stroke trajectory before and after nerve transection. After bilateral transections, pectoral fin rhythmicity remained the same or increased. Differences in fin kinematics with the loss of sensory feedback also included fin kinematics with a significantly more inclined stroke plane angle, an increased angular velocity and fin beat frequency, and a transition to the body-caudal fin gait at lower speeds. After transection, muscles were active over a larger proportion of the fin stroke, with overlapping activation of antagonistic muscles rarely observed in the trials of intact fish. The increased overlap of antagonistic muscle activity might stiffen the fin system in order to enhance control and stability in the absence of sensory feedback from the fin rays. These results indicate that fin ray sensation is not necessary to generate the underlying rhythm of fin movement, but contributes to the specification of pectoral fin motor pattern and movement during rhythmic swimming.

 

Methods

EMG electrodes were inserted into each muscle and the fish were swam in a flow tank at a speed of 2 body lengths per second.

All other relevant information on data collection can be found in the materials and methods section of the manuscript.

Usage Notes

All code neccessary to analyze 3D kinemtics data is included in the "R functions.R" file.

The raw data to begin this process and re-generate all subsequent files in this data set is file: Raw motion data.csv.

All other kinematic data files can be reproduced using the R code file and this raw motion data file, but are also included in the data set for easy reference.

Funding

National Science Foundation, Award: DGE-0903637

Office of Naval Research Global, Award: N00014-0910352