Noradrenaline: active in arousal, but not for the hippocampal-neocortical dialogue

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Tohidi, Setare
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Dept. of Neuroscience
Noradrenaline plays a role in modulating behaviors and memory. Memory can have short durations, or long durations. Long term memory, however, requires plastic changes for its permanent storage. Evidence suggests that neocortical-hippocampal dialogue during sharp wave ripples is essential for memory consolidation. Although studies suggest the importance of noradrenaline in memory formation and memory consolidation at cellular and synaptic level, less is known about the role of noradrenaline in system memory consolidation during neocortical-hippocampal dialogue. I conducted wide-field optical imaging of the mouse neocortical noradrenergic activity by recording fluorescent signal from GCaMP6s calcium sensors expressed in noradrenergic terminals of locus coeruleus in neocortex, combined with hippocampal electrophysiological recording. I found that neocortical noradrenaline deactivates around sleep and awake sharp wave ripples, with no significant differences between neocortical regions. These findings suggest either that noradrenaline is not necessary for hippocampal-neocortical memory transfer or that such transfer is only possible in the absence of noradrenaline. I also found that noradrenaline becomes active when the mice are aroused as indicated by pupil dilation. Parsimony suggests that noradrenaline is active in arousal but not in memory consolidation.
Noradrenaline , Norepinephrine , Sharp Wave Ripples , Hippocampus , Neocortex