Figure 10.

The relationship between plasticity and inhibition. A, The electrical 3D maps compare distribution of plasticity and inhibition. After a control period, synaptic plasticity was induced with TBS. Then, after allowing plasticity to attain a steady level (30 min), 10 μm bicuculline was perfused. It was therefore possible to obtain a plasticity map (post-TBS − control) and the corresponding inhibition map (post-TBS − bicuculline) in the same MEA recording experiment. B, The plot shows the relationship between synaptic plasticity and inhibition for MEA recordings in which inhibition was evaluated after TBS (closed circles; n = 4 MEA recordings, n = 23 electrodes) (e.g., see A) or before TBS (open circles; n = 4 MEA recordings, n = 22 electrodes). The colored points code plasticity for the slice shown in A. LTP prevails with little inhibition, LTD with large inhibition. The dotted line is a biexponential fitting to the data [y₀ = −25, x₀ = 0, A₁ = 142.15, τ₁ = 90, A₂ = −100, τ₂ = 160; p(χ²) < 0.01]. C, The plot shows the relationship between synaptic plasticity and the excitatory/inhibitory balance (E/I) (definition in the text) for the same recordings used in B. Whereas LTP occurs only at high E/I, LTD occurs at all values. The colored points code plasticity for the slice shown in A. To complete the dataset representation, the white dots show results recorded within the plasticity rejection threshold (less than ±10% change).