Crayfish brain states characterization with wavelet transform

Behavioral and electrophysiological experiments show that crayfish have periods of rest with characteristics similar to sleep in vertebrates, a stereotyped body position, high threshold to mechanical stimuli, and specific brain electrical signals. The aim of this work is to characterize the brain electrical signals associated with sleep in crayfish. Electrical and behavioral recordings from individual crayfish were performed continuously during 24 hours. Videotapes from crayfish in aquaria under control conditions show three different behaviors: i) standing up, ii) lying on one side against the surface of the water, and iii) crouched and motionless. Brain electrical activity was different for each one of these positions. Wavelet analysis of brain electrical records show high power at all frequencies in the standing up crayfish, a decrease in the power of all frequencies, mainly for 30 to 45 Hz band, in the animal lying on one side (sleeping) and intermediate values for the crouched crayfish, the characteristics of this latter activity depended on the previous positions sequence.