Event boundaries drive norepinephrine release and distinctive neural representations of space in the rodent hippocampus

• DOI: 10.7554/elife.105183.1
• Publication Date: 2025-01-31T16:25:35Z
• Authors: Sam McKenzie; Alexandra L Sommer; Tia N Donaldson; Infania Pimentel; Meenakshi Kakani; Irene Jungyeon Choi; Ehren L Newman; Daniel F English
• Keywords: Place cell

Episodic memories are temporally segmented around event boundaries that tend to coincide with moments of environmental change. During these times, the state brain should change rapidly, or reset, ensure information encountered before and after an boundary is encoded in different neuronal populations. Norepinephrine (NE) thought facilitate this network reorganization. However, it unknown whether drive NE release hippocampus and, if so, how relates changes hippocampal firing patterns. The advent new GRAB sensor now allows for measurement binding sub-second resolution. Using tool mice, we tested released into dorsal during defined by unexpected transitions between spatial contexts presentations novel objections. We found dynamics were well explained time elapsed each changes, not related conditioned behaviors, exploratory bouts movement, reward. Familiarity a context accelerated rate which phasic decayed baseline. Knowing when elevated, coding space differs moments. Immediately observed relatively unique patterns neural spiking settled modal at similar returned These results consistent model wherein drives representations away from steady-state attractor. hypothesize distinctive codes may long-term memory contribute basis primacy effect.