LATERAL HABENULA DETERMINES LONG-TERM STORAGE OF AVERSIVE MEMORIES

MICOL TOMAIUOLO; CAROLINA GONZALEZ; JORGE H MEDINA; JOAQUIN PIRIZ

Milan

Congreso; 9th FENS forum of Neurosciences; 2014

Federation of European Neuroscience Societies (FENS)

Lateral Habenula (LHb) is a small epithalamic structure that exerts a powerful control over dopaminergic brain stem centers and conveys negative motivational signals. It has been shown recently that LHb activation is sufficient to induce aversive associative learning; however the key question about whether LHb activation is required for an aversive memory to be formed has not been addressed. We studied in rats the function of LHb in memory formation using the inhibitory avoidance task (IA). We found that LHb inactivation during IA training does not disrupt memory when assessed 24 hours after, but abolishes it 7 days later, indicating that LHb activity during memory acquisition is not necessary for memory formation, but regulates its temporal stability. This effect was reversed by several manipulations that increase temporal stability of the IA memory formed by weak shock training, standing out a similarity between this memory and the memory formed during LHb inactivation. Consequently, our results indicate that LHb activity is not necessary for the formation of an aversive memory, but ensures its temporal maintenance. In addition our results suggest that during aversive associative learning, activity of the LHb modulates the subjective negative value attributed to the experience.