Imagine if memory could be tuned in such a way where good memories are enhanced for those suffering from dementia or bad memories are wiped away for individuals with post-traumatic stress disorder. A Stony Brook University research team has taken a step toward the possibility of tuning the strength of memory by manipulating one of the brain’s natural mechanisms for signaling involved in memory, a neurotransmitter called acetylcholine. Their findings are published in the journal Neuron.
Ref: Cholinergic Signaling Controls Conditioned Fear Behaviors and Enhances Plasticity of Cortical-Amygdala Circuits. Neuron (5 May 2016) | DOI: 10.1016/j.neuron.2016.04.028
We examined the contribution of endogenous cholinergic signaling to the acquisition and extinction of fear- related memory by optogenetic regulation of cholinergic input to the basal lateral amygdala (BLA). Stimulation of cholinergic terminal fields within the BLA in awake-behaving mice during training in a cued fear-conditioning paradigm slowed the extinction of learned fear as assayed by multi-day retention of extinction learning. Inhibition of cholinergic activity during training reduced the acquisition of learned fear behaviors. Circuit mechanisms underlying the behavioral effects of cholinergic signaling in the BLA were assessed by in vivo and ex vivo electrophysiological recording. Photostimulation of endogenous cholinergic input (1) enhances firing of putative BLA principal neurons through activation of acetylcholine receptors (AChRs), (2) enhances glutamatergic synaptic transmission in the BLA, and (3) induces LTP of cortical-amygdala circuits. These studies support an essential role of cholinergic modulation of BLA circuits in the inscription and retention of fear memories.