Enhanced frontal cortex activation in rats by convergent amygdaloid and noxious sensory signals

The modulation of frontal cortical EEG activation to noxious somatosensory (tail pressure) and olfactory (acetone) stimulation by the basal amygdala w as examined in urethane-anesthetized rats. Mild tail pressure produced no E EG activation, while acetone (sniffed by freely breathing rats or drawn acr oss the olfactory epithelium in tracheotomized rats) produced a moderate su ppression of large-amplitude synchronized EEG patterns. Concurrent, low-int ensity 100 Hz stimulation of the basal amygdala permitted EEG activation to tail pressure to occur, and strongly enhanced olfactory-induced cortical a ctivation. These results indicate that excitation of the basal amygdala pot entiates frontal cortical responsiveness to aversive sensory events. This m ay provide a mechanism to facilitate cortical excitability and processing b y amygdaloid neuronal activity. NeuroReport 12:2395-2398 (C) 2001 Lippincot t Williams & Wilkins.