Multi-input synapses, but not LTP-strengthened synapses, correlate with hippocampal memory storage in aged mice

Aziz, Wajeeha, Kraev, Igor, Mizuno, Keiko, Kirby, Alaistair, Fang, Ton, Rupawala, Huzefa, Kasbi, Kamillia, Rothe, Stephanie, Josza, Felix, Rosenblum, Kobi, Stewart, Michael G and Giese, Karl Peter (2019) Multi-input synapses, but not LTP-strengthened synapses, correlate with hippocampal memory storage in aged mice. Current Biology, 29 (21). pp. 3600-3610. ISSN 0960-9822

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Long-lasting changes at synapses enable memory storage in the brain. Although aging is associated with impaired memory formation, it is not known whether the synaptic underpinnings of memory storage differ with age. Using a training schedule that results in the same behavioral memory formation in young and aged mice, we examined synapse ultrastructure and molecular signaling in hippocampus after contextual fear conditioning. Only in young, but not old mice contextual fear memory formation was associated with synaptic changes that characterize well-known long-term potentiation,a strengthening of existing synapses with one input. Instead old age memory was correlated with generation of multi-innervated dendritic spines (MIS), which are predominantly two-input synapses formed by the attraction of an additional excitatory, presynaptic terminal onto an existing synapse. Accordingly, a blocker used to inhibit MIS generation impaired contextual fear memory only in old mice. Our results reveal how the synaptic basis of hippocampal memory storage changes with age and they suggest that these distinct memory-storing mechanisms may explain impaired updating in old age.

Item Type: Article
Keywords: memory storage, normal aging, structural plasticity at synapses
Schools and Departments: Brighton and Sussex Medical School > Division of Medical Education
Research Centres and Groups: Sussex Neuroscience
Subjects: Q Science > QP Physiology > QP0351 Neurophysiology and neuropsychology > QP0361 Nervous system > QP0364 Synapses
Depositing User: Wajeeha Aziz
Date Deposited: 20 Sep 2019 16:35
Last Modified: 25 Nov 2019 15:15

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