Cutting rostral trigeminal nuclear complex projections preferentially affects perioral nociception in the rat

Sagittal knife cuts were made medial to rostral trigeminal brainstem nuclei in 11 rats. These cuts resulted in significant group deficits in facial thermal nociception at only two of the 5 ipsilateral sites tested. The affected sites were close to the vibrissa and oral cavity, suggesting that rostral trigeminal projections signal anterior rather than more caudal facial nociception. Three rats were also tested for EEG arousal responsiveness to innocuous air puffs before and after the cuts at the same facial sites. Only one of the rats demonstrated a significant deficit at one of the 5 sites tested, suggesting that the rostral projections interrupted in this study are not necessary for innocuous facial sensation.