Astrocytic connection to engram neurons Increased after learning

Abstract

Astrocytes directly participate in learning and memory. However, the structural association between astrocytes and memory-encoding engram neurons after learning remains to be elucidated. We developed astrocyte-enhanced green fluorescent protein reconstitution across synaptic partners (eGRASP) to examine tripartite synapses between astrocytes and engram neurons. Using astrocyte-eGRASP, we found that astrocytes had increased connections to engram neurons after learning. Dendritic spines with astrocytic contacts showed enhanced morphology. Live-cell imaging of astrocyte-eGRASP revealed that astrocytic connections are stabilized by neuronal activity. These results indicate that astrocytes distinguish contact between engram neurons and generate engram-specific contact patterns during learning.

Prolonged partner separation erodes nucleus accumbens transcriptional signatures of pair bonding in male prairie voles

“…While there is an emerging appreciation for the role of glia in mediating behavior ( Thornton and Hughes, 2020 ; Bacmeister et al, 2022 ; Auguste et al, 2022 ; Hughes et al, 2018 ; Duncan and Emery, 2023 ; Kim et al, 2023 ), these effects are largely due to modulation of neuronal activity, and we reasoned that the prominence of glial-related terms may have masked important neuronal transcriptional changes in our dataset. To home in on neuronal transcriptional changes specifically, we developed vole-optimized translating ribosome affinity purification in prairie voles (vTRAP).…”

Early-life stress induces persistent astrocyte dysfunction associated with fear generalisation

“…Evidence of this mechanism whereby increased c-Fos levels inversely correlate with memory accuracy have been recently shown in hippocampal circuits (38). In addition, astrocyte-engram neuron interactions have recently been identified (45) suggesting a potential participation of astrocytes in engram stabilisation. Our data are in line with previous reports that have demonstrated clear roles for astrocytes in memory formation and consolidation (29,46,47) and reveal that astrocytes participate in the neurobiological mechanisms by which stress influences emotional memory.…”