Lateral Habenula regulates the maintenance of fear long-term memory

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

Huerta Grande

Congreso; Reunión Anual de la Sociedad Argentina de Neurociencias; 2013

Sociedad Argentina de Neurociencias

Memory definition implies the temporal persistence of a mnemonic trace; howeverthe mechanisms that ensure memory stability over time are not well understood.One crucial finding in this regard was that a dopaminergic signal arriving from theVentral Tegmental Area (VTA) to the hippocampus during a defined period of timeafter acquisition is critical for the definition of how long a memory will persist(Rossatto et al., 2009). Lateral Habenula (LHb) is a small epithalamic structure thatcodifies negative motivational value and exerts a powerful control over VTAdopaminergic neurons. Recently it has been shown that LHb activation is sufficientto induce aversive associative learning; however the key question about whetherLHb activation is required for a memory to be formed during adversive associativelearning has not been addressed. In our experiments we used the InhibitoryAvoidance (IA), a protocol in which a single electric shock exposure induces apersistent contextual aversive memory, to study the relationship between LHb andmemory formation in rats. Our results show that inhibition of LHb during memoryacquisition does not impair IA memory formation but reduces its temporal stability.This effect posses a striking parallelism to reducing IA memory salience by reducingelectric shock intensity suggesting that LHb activation during training conveys asalience signal that ensures temporal stability of the newly formed memory.