The Buzsaki Lab
Selection of memories. Experiences need to be tagged
during learning for further consolidation. However, neurophysiological mechanisms that select experiences for lasting memory are not known. By combining large-scale neural recordings in mice with dimensionality reduction
techniques, we observed that successive maze traversals were tracked by continuously drifting populations of neurons, providing neuronal signatures of both places visited and events encountered. When the brain state changed during reward consumption, sharp wave ripples (SPW-Rs) occurred on some trials, and their specific spike content decoded the trial blocks that surrounded them.
During postexperience sleep, SPW-Rs continued to replay those trial blocks that were reactivated most frequently during waking SPW-Rs. Replay content of awake SPW-Rs thus provides a neurophysiological tagging mechanism to
select aspects of experience that are preserved and consolidated for future use (Yang et al., Science 2024). Neuromodulation. In our previous study, we have reported that the neuromodulator acetylcholine (ACh) suppresses SPW-Rs. Ye, the mechanisms by which different neuroma dilators compete or cooperate at various temporal scales remain an open question. We investigated the
interaction between Ach and oxytocin (OXT) at slow and fast timescales during different brain states. Although these neurodilators fluctuated in parallel during NREM packets, transitions from NREM to REM were characterized by a surge of ACh but a continued decrease of OXT. OXT signaling lagged behind ACh. High ACh was correlated with population synchrony and gamma oscillations during active waking, whereas minimum ACh predicts SPW-Rs. Optogenetic control of ACh and OXT neurons confirmed the active role of these neuromodulators in the observed correlations. Synchronous hippocampal activity consistently reduced OXT activity, whereas inactivation of the lateral septum-hypothalamus path attenuated this effect. Our findings demonstrate how cooperative actions of these
neuromodulators allow target circuits to perform specific functions
(Zhang et al., Neuron 2024)