Figure 7.

Non-synchronized cells showed synchronized push-pull synaptic excitation and inhibition. a) Vector strength for membrane potential was significantly greater than that for synaptic currents at 4 ms ICI (p < 10⁻⁹, filled dots), but not for 256 ms ICI (n. s., open dots). Group data for 12 non-synchronized neurons for which we were able to record both current-clamp (I=0) and voltage-clamp data. Synaptic currents were measured at hyperpolarized holding potentials (−83 ± 20 mV). Dashed line indicates unity slope. b) Cycle averages of excitatory (green) and inhibitory (red) synaptic conductances along with sinusoidal fits (same neuron as Fig 1a,4a,5a). Arrowheads indicate stimulus artifact. c) Phase difference between excitation and inhibition extracted from the sinusoidal fits in b. Dashed line is a linear regression fit (p < 10⁻²). Note that excitation and inhibition were in-phase at the longest ICI (256 ms) but nearly out of phase at the shortest ICIs (4–8 ms). d) Across all 11 non-synchronized neurons for which we were able to measure both excitation and inhibition, the phase difference between them depended significantly on ICI (p < 0.05). e) Across synchronized neurons (n=12), excitatory-inhibitory phase difference did not depend on ICI. Dashed lines in d–e are linear regression fits.