Proceedings of The Physiological Society

Puerto de la Cruz, Tenerife (2003) J Physiol 548P, P166

Poster Communications

Interdependence between telencephalic nervous activity and respiratory activity in reptiles: a non-linear approach

Luis De Vera*, Ernesto Pereda† and Julián Jes

*Laboratory of Biophysics, Department of Physiology, Faculty of Medicine, University of La Laguna, Canary Islands and †Department of Basic Physics, Faculty of Physics, University of La Laguna, Canary Islands, Spain


Many physiological studies are interested in the complexity and non-linearity of the EEG and the respiratory activity (RA). Relationships between these signals in mammals, have been estimated using a non-linear approach (Burioka et al. 2001). Similar studies have been performed on the EEG of reptiles, in order to characterise its non-linear behaviour and to compare it with the human EEG during sleep (González et al. 1999). Nevertheless, no non-linear studies have been carried out in reptiles to describe the relationships between central nervous and respiratory activities. Therefore, cortical EEG and respiratory signals were simultaneously registered in six lizards (Gallotia galloti) at 25 °C, with the aim of studying the degree of interdependence between both physiological systems, by using a non-linear systems approach.

Monopolar cortical EEG recordings were carried out by means of electrodes implanted on the right medial cortex. Simultaneously, the RA was recorded from the EMG of intercostal muscles. All surgical procedures were performed under ether anaesthesia. Every second, the EEG was digitised at 128 Hz and the EMG at 1 kHz, and the corresponding power spectra (PSD) were obtained via FFT, in order to calculate the power of the EEG low-frequency band (0.1-4 Hz), as well as the power of the main respiratory peak. This procedure was repeated every second during a 10 min period. In this way, two 600-data-point power signals (EEG-LF and RAS) were obtained. Continuous recordings from 10.00-14.00 h provided 24 consecutive power signals of these characteristics for each lizard.The state space of each power signal was reconstructed using time delay embedding (

Where applicable, experiments conform with Society ethical requirements