Related Experiment Video

Updated: Sep 24, 2025

Investigating Long-term Synaptic Plasticity in Interlamellar Hippocampus CA1 by Electrophysiological Field Recording
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Investigating Long-term Synaptic Plasticity in Interlamellar Hippocampus CA1 by Electrophysiological Field Recording

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A critical period for learning and plastic changes at hippocampal CA1 synapses

Yuya Sakimoto1, Ako Shintani2, Daiki Yoshiura2

  • 1Department of Physiology, Yamaguchi University Graduate School of Medicine, Ube, 755-8505, Japan. ysaki@yamaguchi-u.ac.jp.

Scientific Reports
|May 3, 2022
PubMed

Insights

This study reveals a critical period for hippocampal synaptic plasticity in rats. Learning and synaptic changes mature from infancy to adulthood, with specific plasticity patterns emerging at different developmental stages.

Area of Science:

  • Neuroscience
  • Developmental Biology
  • Synaptic Plasticity

Background:

  • Postnatal development of hippocampal function is crucial for learning and memory across mammalian species.
  • Understanding the developmental trajectory of synaptic plasticity provides insights into learning capabilities.
  • Previous research indicates changes in hippocampal function during postnatal development, but synaptic evidence is limited.

Purpose of the Study:

  • To investigate developmental changes in hippocampal synaptic plasticity following an inhibitory avoidance task in rats.
  • To identify specific time windows for learning and synaptic modifications in the hippocampus.
  • To correlate behavioral performance with synaptic changes at different postnatal ages.

Main Methods:

  • Rats of different ages (2, 3, 4, and 8 weeks) were trained on an inhibitory avoidance task.
  • Following training, miniature excitatory and inhibitory postsynaptic currents (mEPSCs and mIPSCs) were recorded from hippocampal CA1 neurons in brain slices.
  • Sensory-motor functions and emotional states were assessed to rule out confounding factors.

Main Results:

  • Learning performance improved significantly from infancy (2 weeks) to adulthood (8 weeks).
  • Synaptic plasticity, specifically increased mEPSC amplitude, was observed at 3 weeks, while both mEPSC and mIPSC amplitudes increased at 4 weeks.
  • At 8 weeks, only mIPSC amplitude showed training-induced increases, indicating age-dependent plasticity.
  • Developmental changes in task performance were task-dependent, and sensory-motor functions remained adequate throughout development.

Conclusions:

  • A critical period for hippocampal learning and synaptic plasticity exists, extending from juvenile to adult stages.
  • The maturation of hippocampal CA1 synaptic plasticity is a gradual process, with distinct changes in excitatory and inhibitory neurotransmission occurring at different developmental time points.
  • These findings highlight the dynamic nature of hippocampal circuit development and its impact on cognitive functions.

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