Extended Data Fig. 6. In vitro and ex vivo changes in local connection strength and probability.

a, mEPSP frequency, nor amplitude significantly changed following Hebbian association of pre- and postsynaptic activity in vitro (black and white bars) when presynaptic neurons are non-accommodating nor in recruited (green) versus non-recruited (red) neurons ex vivo, suggesting that plasticity and CFC-mediated recruitment both have a presynaptic site of expression (Two-tailed Student’s t-tests, top-left: t₇ = 1.2, n = 11; bottom-left: t₇ = 1.5, n = 11; top-right: t₄ = 0.4, n = 7 GFP⁺ and 5GFP⁻; bottom-right: t₄ = 1.7, n = 7 GFP⁺ and 6 GFP⁻, P > 0.05 in all cases). Bars are means + sd. b, No mEPSP amplitude or frequency changes were observed in vitro when the presynaptic cell was accommodating (n = 6) or when no plasticity induction protocol was applied (n = 10). Bars are means + sd. c, Example relationship between voltage-variance for one connection (also known as Non-stationary fluctuation analysis): the variance of the fluctuation of the decays for each EPSP in comparison to the mean is plotted as a function of the mean EPSP decay amplitude, during baseline (circles) and after Hebbian induction (squares); d, The conductance (γ) is estimated from the voltage-variance relationship for each cell during baseline and after Hebbian induction of plasticity for naïve slices (left, as in Fig. 4a; n = 11), non-recruited connections (middle, red; n = 6) and recruited connections (right, green; n = 7); Two-tailed Student’s t-test, P > 0.05. Bars are means + sd. e, Rise times (20–80%, open circles) and decay times (62%, filled circles) for all EPSPs used for non-stationary fluctuation analysis. Hebbian pre- and post- synaptic pairing affected neither rise time nor decay time. To note: although we did not find any changes in mEPSP/mEPSC characteristics after changes in synaptic strength, mEPSP/mEPSC may also originate from projections outside of the LA.