Original Article: https://doi.org/10.1038/s41586-020-2771-1
- The ability to recognize information that is unsuitable with previous experience is critical for survival.
- Enhanced attention, perception and memory in mammalian brain may be due to the evolution of these novelty signals.
- The importance of brain regions such as the ventral tegmental area and locus coeruleus in broadly signaling novelty is well documented.
- However, these diffuse monoaminergic transmitters have yet to be shown to deliver specific information on the type of stimuli that drive them.
- Ventral tegmental area is a structure in the midbrain which sends dopaminergic neural projections to both the limbic and cortical areas.
- The locus coeruleus is a heavily pigmented nucleus located in the dorsal wall of the rostral pons in the lateral floor of the fourth ventricle.
- Whether distinct types of novelty, such as contextual and social novelty, are differently processed and routed in the brain is unknown.
- Researchers identify the supramammillary nucleus as a novelty hub in the hypothalamus.
- Supramammillary nucleus of the posterior hypothalamus serves as an important relay in the brainstem to septum/hippocampus pathway involved in the generation of hippocampal theta rhythm.
- The supramammillary nucleus region is unique in that it does not only responds broadly to novel stimuli, but also separates and selectively routes different types of information to discrete cortical target for the modulation of mnemonic processing.
- Using a new transgenic mouse line, we found that in supramammillary neurons that project to the dentate gyrus are activated by contextual novelty.
- The supramammillary nucleus–CA2 circuit is preferentially activated by novel social encounters.
- Circuit-based manipulation showed that divergent novelty channeling in these projections modifies hippocampal contextual or social memory.
- This content-specific routing of novelty signals represents a previously unknown mechanism that enables the hypothalamus to flexibly regulate select components of cognition.
Chen, S., He, L., Huang, A.J.Y. et al. A hypothalamic novelty signal modulates hippocampal memory. Nature (2020). https://doi.org/10.1038/s41586-020-2771-1