Fronto-parietal connectivity changes following noxious stimulation during anesthesia

RATIONALE The aim of our study was to assess the changes in the fronto-parietal connectivity estimated by the cross approximate entropy (XAppEn) during noxious stimulation while under chloral hydrate anaesthesia, in rats. METHOD A group of 11 Wistar rats chronically implanted with Ni-Cr electrodes, which were placed on the dura mater of the right hemisphere (over the olfactory cortex, the frontal and the parietal lobes), were used in the present study. Noxious stimuli of a mechanical and thermal nature were applied on the left hindpaw during chloral hydrate anesthesia. The anesthetic depth was estimated through median frequency computation, which in that instance was of 2-3 Hz. Fronto-parietal functional cortical connectivity was assessed by using XAppEn. RESULTS After data processing and analysis we observed an increase of fronto-parietal functional connectivity during mechanical and thermal noxious stimulation. In addition, MEF increased both in frontal and parietal areas during the mechanical and thermal stimulation compared to baseline. CONCLUSION Mechanical and thermal stimulation induces an increase in the fronto-parietal connectivity during chloral hydrate anesthesia in rats.