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Dopamine-dependent memory consolidation and locus coeruleus

DANDRITE Topical Seminar by Tomonori Takeuchi

2016.11.02 | Emilie Marie Niebuhr Aagaard

Date Fri 25 Nov
Time 13:45 15:15
Location Auditorium 6 (Building 1170 room 347)

The retention of episodic-like memory is enhanced when something novel happens shortly before or after encoding. Using an everyday memory task in mice, we sought the neurons mediating this dopamine-dependent novelty effect, previously thought to originate from the tyrosine hydroxylase-expressing (TH+) neurons in the ventral tegmental area (VTA). We find that neuronal firing in the locus coeruleus (LC) is especially sensitive to environmental novelty, LC-TH+ neurons project more profusely than VTA-TH+ neurons to the hippocampus, optogenetic activation of LC-TH+neurons mimics the novelty effect, and this novelty-associated memory enhancement is unaffected by VTA inactivation. Surprisingly, two effects of LC-TH+ photoactivation are sensitive to hippocampal dopamine D1/D5 receptor blockade and resistant to adrenoceptor blockade – memory enhancement and long lasting potentiation of synaptic transmission in CA1 ex vivo. Thus, LC-TH+ neurons, typically defined by noradrenergic signalling, can mediate post-encoding memory enhancement in a manner consistent with possible co-release of dopamine in hippocampus.