Lateral parabrachial lesions impair intraperitoneal but not intraventricular methylscopolamine-induced taste aversion learning

The role of the lateral parabrachial area (lPB) in the acquisition of a del ayed taste aversion learning task (TAL) was examined by delivering the peri pherally acting aversive compound, methylscopolamine (MSP), through two dif ferent routes, intraperitoneal and intraventricular. Consistent with previo us anatomical, behavioral and molecular work, electrolytic lesions centered at the IPB did impair TAL when the MSP was injected intraperitoneally. How ever, lPB-lesioned animals exhibited intact learning capacities when MSP wa s administered intraventricularly. These results are interpreted in terms o f the lPB as a critical anatomical relay involved in bottom-up visceral pro cessing of aversive stimuli and also in relation to the relevance of forebr ain structures in TAL. (C) 2000 Elsevier Science BN. All rights reserved.