Running reorganizes the circuitry of one-week-old adult-born hippocampal neurons
Abstract
Adult
hippocampal neurogenesis is an important form of structural and
functional plasticity in the mature mammalian brain. The existing
consensus is that GABA regulates the initial integration of adult-born
neurons, similar to neuronal development during embryogenesis.
Surprisingly, virus-based anatomical tracing revealed that very young,
one-week-old, new granule cells in male C57Bl/6 mice receive input not
only from GABAergic interneurons, but also from multiple glutamatergic
cell types, including mature dentate granule cells, area CA1-3 pyramidal
cells and mossy cells. Consistently, patch-clamp recordings from
retrovirally labeled new granule cells at 7-8 days post retroviral
injection (dpi) show that these cells respond to NMDA application with
tonic currents, and that both electrical and optogenetic stimulation can
evoke NMDA-mediated synaptic responses. Furthermore, new dentate
granule cell number, morphology and excitatory synaptic inputs at 7 dpi
are modified by voluntary wheel running. Overall, glutamatergic and
GABAergic innervation of newly born neurons in the adult hippocampus
develops concurrently, and excitatory input is reorganized by exercise.
- PMID:
- 28883658
- PMCID:
- PMC5589841
- DOI:
- 10.1038/s41598-017-11268-z
Gretchen Reynolds points to work by van Praag and collaborators
showing that a week of activity rather than inactivity (in adult male
rats) increases both the formation of new nerve cells in the hippocampus
and the richness of their interactions. The new cells had more and
longer dendrites, more of which led to spatial memory areas.
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