Convergence of aversive pathways and function onto the rostromedial tegmental nucleus (RMTg) a major target of habenular efferents
演題番号 : S1-10-1-2
Thomas C Jhou:1
1:National Institute on Drug Abuse
Numerous brain structures have been implicated in aversive behavior, including the amygdala, septum, central gray, and most recently the lateral habenula. It has not been well understood how these regions interact with each other, or with appetitive systems such as dopamine neurons. However, we recently identified and characterized a brain region, the rostromedial tegmental nucleus (RMTg), which receives inputs from the lateral habenula (LHb), central gray, and other regions implicated in affective behavior, and projects strongly to dopamine neurons of the ventral tegmental area (VTA) and substantia nigra pars compacta. Neurons in the RMTg, also called the "tail" of the VTA, are largely GABAergic, and occupy a wedge of tissue extending from the caudal edge of the VTA to the rostral edge of the cholinergic pedunculopontine nucleus. RMTg neurons are activated by aversive stimuli and inhibited by appetitive stimuli, similarly to LHb neurons and oppositely from dopamine neurons. Furthermore, lesions encompassing the RMTg severely reduce fear behavior in at least three paradigms which are mediated by separate forebrain structures. Hence, the RMTg may be a convergent target of multiple aversive brain systems, as well as a crucial link between aversive and appetitive brain systems. We are now investigating several follow-up topics, including the RMTg role in opioid reward, functions of RMTg afferents, and genomic analysis of RMTg gene expression.