Neuronal Synchrony during Anesthesia: A Thalamocortical Model (original) (raw)

There is growing evidence in favour of the temporal-coding hypothesis that temporal correlation of neuronal discharges may serve to bind distributed neuronal activity into unique representations and, in particular, that θ (3.5-7.5 Hz) and δ (0.5 <3.5 Hz) oscillations facilitate information coding. The θ and δ rhythms are shown to be involved in various sleep stages, and during anaesthesia, and they undergo changes with the depth of anaesthesia. We introduce a thalamocortical model of interacting neuronal ensembles to describe phase relationships between θ and δ oscillations, especially during deep and light anaesthesia. Asymmetric and long range interactions among the thalamocortical neuronal oscillators are taken into account. The model results are compared with the experimental observations of Musizza et al. J. Physiol. (London) 2007 580:315-326. The δ and θ activities are found to be separately generated and are governed by the thalamus and cortex respectively. Changes in the degree of intra-ensemble and interensemble synchrony imply that the neuronal ensembles inhibit information coding during deep anaesthesia and facilitate it during light anaesthesia.