Format

Send to

Choose Destination
See comment in PubMed Commons below
Front Cell Neurosci. 2014 Feb 14;8:44. doi: 10.3389/fncel.2014.00044. eCollection 2014.

Electrophysiological characterization of granule cells in the dentate gyrus immediately after birth.

Author information

  • 1Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati Trieste, Italy.
  • 2Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati Trieste, Italy ; European Brain Research Institute Rome, Italy.

Abstract

Granule cells (GCs) in the dentate gyrus are generated mainly postnatally. Between embryonic day 10 and 14, neural precursors migrate from the primary dentate matrix to the dentate gyrus where they differentiate into neurons. Neurogenesis reaches a peak at the end of the first postnatal week and it is completed at the end of the first postnatal month. This process continues at a reduced rate throughout life. Interestingly, immediately after birth, GCs exhibit a clear GABAergic phenotype. Only later they integrate the classical glutamatergic trisynaptic hippocampal circuit. Here, whole cell patch clamp recordings, in current clamp mode, were performed from immature GCs, intracellularly loaded with biocytin (in hippocampal slices from P0 to P3 old rats) in order to compare their morphological characteristics with their electrophysiological properties. The vast majority of GCs were very immature with small somata, few dendritic branches terminating with small varicosities and growth cones. In spite of their immaturity their axons reached often the cornu ammonis 3 area. Immature GCs generated, upon membrane depolarization, either rudimentary sodium spikes or more clear overshooting action potentials that fired repetitively. They exhibited also low threshold calcium spikes. In addition, most spiking neurons showed spontaneous synchronized network activity, reminiscent of giant depolarizing potentials (GDPs) generated in the hippocampus by the synergistic action of glutamate and GABA, both depolarizing and excitatory. This early synchronized activity, absent during adult neurogenesis, may play a crucial role in the refinement of local neuronal circuits within the developing dentate gyrus.

KEYWORDS:

dentate gyrus granule cells; giant depolarizing potentials; immature hippocampus; low threshold calcium spikes; neurogenesis; postnatal development; sodium spikes; synchronized network activity

PMID:
24592213
PMCID:
PMC3924035
DOI:
10.3389/fncel.2014.00044
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Frontiers Media SA Icon for PubMed Central
    Loading ...
    Support Center