Nested calcium dynamics support daily cell unity and diversity in the suprachiasmatic nuclei of free-behaving mice.
PNAS Nexus
; 1(3): pgac112, 2022 Jul.
Article
en En
| MEDLINE
| ID: mdl-36741435
ABSTRACT
The suprachiasmatic nuclei (SCN) of the anterior hypothalamus host the circadian pacemaker that synchronizes mammalian rhythms with the day-night cycle. SCN neurons are intrinsically rhythmic, thanks to a conserved cell-autonomous clock mechanism. In addition, circuit-level emergent properties confer a unique degree of precision and robustness to SCN neuronal rhythmicity. However, the multicellular functional organization of the SCN is not yet fully understood. Indeed, although SCN neurons are well-coordinated, experimental evidences indicate that some neurons oscillate out of phase in SCN explants, and possibly to a larger extent in vivo. Here, to tackle this issue we used microendoscopic Ca2+ i imaging and investigated SCN rhythmicity at a single cell resolution in free-behaving mice. We found that SCN neurons in vivo exhibited fast Ca2+ i spikes superimposed upon slow changes in baseline Ca2+ i levels. Both spikes and baseline followed a time-of-day modulation in many neurons, but independently from each other. Daily rhythms in basal Ca2+ i were highly coordinated, while spike activity from the same neurons peaked at multiple times of the light cycle, and unveiled clock-independent coactivity in neuron subsets. Hence, fast Ca2+ i spikes and slow changes in baseline Ca2+ i levels highlighted how multiple individual activity patterns could articulate within the temporal unity of the SCN cell network in vivo, and provided support for a multiplex neuronal code in the circadian pacemaker.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
PNAS Nexus
Año:
2022
Tipo del documento:
Article
País de afiliación:
Francia