neural-circuits
Do ensembles form by excitability, not just synapses?
Open access · cc by · source: Europe PMC
Coactivating mouse L2/3 pyramids raised correlated firing with only small biphasic synaptic changes but large, persistent increases in intrinsic excitability.
Key findings
Coactivated cells increased correlated activity. Presynaptic plasticity was small and biphasic (depression then potentiation). Spontaneous EPSP frequency/amplitude rose even after single-cell stimulation. Strong lasting excitability gains (higher Rm, lower threshold) appeared and reversed when membrane-resistance changes were blocked pharmacologically—supporting an ‘iceberg’ model where subthreshold connections become suprathreshold.
Methodology
Replicated an in vivo optogenetic imprinting protocol in mouse visual-cortex slices, coactivating L2/3 pyramids and measuring pair correlations, EPSPs, membrane resistance, and spike threshold with whole-cell and perforated patch recordings.
Limitations
Slice coactivation may not fully recapitulate in vivo ensemble learning; human cortical ensembles and long-term behavior were not tested.
How this study connects
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