Incomplete synaptic vesicle priming functionally disconnects CA1 pyramidal cells.

About 25% of CA1 pyramidal cell output boutons innervate CA1PC spines but show very low release probability or complete failure, indicating incomplete synaptic vesicle priming.

• Why it matters: CA1 is treated as a nonrecurrent circuit, yet whether local CA1PCs form functional excitatory connections is unclear.
• What they did: Using in vitro two-photon glutamate imaging with iGluSnFR3 across individual boutons, followed by post hoc electron microscopy, they mapped bouton structure to release behavior during action-potential trains.
• The result: Phorbol 12,13-dibutyrate and elevated calcium (2+) converted silent synapses into properly functioning ones, implying intact glutamatergic synapses are functionally disconnected by impaired vesicle priming.

AI summary of the abstract · may contain errors · not medical advice · read the paper.