Abstract
Neuroethology seeks to uncover the neural mechanisms underlying natural behaviour. One of the major challenges in this field is the
need to correlate directly neural activity and behavioural output. In most cases, recording of neural activity in freely moving animals is
extremely difficult. However, electromyographic recording can often be used in lieu of neural recording to gain an understanding of the
motor output program underlying a well-defined behaviour. Electromyographic recording is less invasive than most other recording
methods, and does not impede the performance of most natural tasks. Using the opercular display of the Siamese fighting fish as a model,
we developed a protocol for correlating directly electromyographic activity and kinematics of opercular movement: electromyographic
activity was recorded in the audio channel of a video cassette recorder while video taping the display behaviour. By combining
computer-assisted, quantitative video analysis and spike analysis, the kinematics of opercular movement are linked to the motor output
program. Since the muscle that mediates opercular abduction in this fish, the dilator operculi, is a relatively small muscle with several
subdivisions, we also describe methods for recording from small muscles and marking the precise recording site with electrolytic
corrosion. The protocol described here is applicable to studies of a variety of natural behaviour that can be performed in a relatively
confined space. It is also useful for analyzing complex or rapidly changing behaviour in which a precise correlation between kinematics
and electromyography is required. 2001 Elsevier Science B.V. All rights reserved.