Role of the Parabrachial Nucleus on Taste Memory Formation in the Rat

This paper explores the research conducted to understand the role of the rat parabrachial nucleus (PBN) in taste-mediated behavior. Gustatory information of the PBN is modulated by three key principles: taste-visceral input from the NST, descending projections from corticofugal areas, as well as indirect signals from inhibitory GABAergic mechanisms. While these three components modify PBN activity, the convergence of signals in the PBN is significant for changes in palatability. In regards to appetitive taste formation, nutritional solutions paired with taste stimuli can increase the hedonic value of the tastant. Brain areas responsible for taste preferences include the PBN, in particular the lPBN, as demonstrated in lesion and electrical stimulation studies. On the other hand, taste aversions occur when the taste stimulus is associated with negative gastrointestinal consequences. Excitotoxic and ibotenic acid lesions of the PBN also impaired formation of taste avoidance behavior. Therefore, the PBN, with input from its complex neural circuitry, can be considered as a principal brain structure in learning and memory process of taste formation.