In:
Cerebral Cortex, Oxford University Press (OUP), Vol. 29, No. 10 ( 2019-09-13), p. 4067-4076
Abstract:
Clarifying learning-induced synaptic plasticity in hippocampal circuits is critical for understanding hippocampal mechanisms of memory acquisition and storage. Many in vitro studies have demonstrated learning-associated plasticity at hippocampal synapses. However, as a neural basis of memory encoding, the nature of synaptic plasticity underlying hippocampal neuronal responses to memorized stimulation remains elusive. Using in vivo whole-cell recording in anaesthetized adult rats and mice, we investigated synaptic activity of hippocampal CA1 pyramidal cells (PCs) in response to a flash of visual stimulation as the conditioned stimulus (CS) in associative fear conditioning. We found that shortly ( 〈 3 days) after conditioning, excitatory synaptic responses and spiking responses to the flash CS emerged in a large number (~70%) of CA1 PCs, a neuronal population previously unresponsive to the flash before conditioning. The learning-induced CA1 excitatory responsiveness was further indicated to result from postsynaptic unsilencing at flash-associated silent synapses, with NMDA receptor-gated responses we recently reported in naive animals. Our findings suggest that associative fear learning can induce excitatory responsiveness to the memorized CS in a large population of CA1 neurons, via a process of postsynaptic unsilencing at CA1 silent synapses, which may be critical for hippocampal acquisition and storage of associative memory.
Type of Medium:
Online Resource
ISSN:
1047-3211
,
1460-2199
DOI:
10.1093/cercor/bhy288
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
2019
detail.hit.zdb_id:
1077450-6
detail.hit.zdb_id:
1483485-6
SSG:
12
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