Data from: Precise excitation-inhibition balance controls gain and timing in the hippocampus

Excitation-inhibition (EI) balance controls excitability, dynamic range,
and input gating in many brain circuits. Subsets of synaptic input can be
selected or 'gated' by precise modulation of finely tuned EI
balance, but assessing the granularity of EI balance requires
combinatorial analysis of excitatory and inhibitory inputs. Using
patterned optogenetic stimulation of mouse hippocampal CA3 neurons, we
show that hundreds of unique CA3 input combinations recruit excitation and
inhibition with a nearly identical ratio, demonstrating precise EI balance
at the hippocampus. Crucially, the delay between excitation and inhibition
decreases as excitatory input increases from a few synapses to tens of
synapses. This creates a dynamic millisecond-range window for postsynaptic
excitation, controlling membrane depolarization amplitude and timing via
subthreshold divisive normalization. We suggest that this combination of
precise EI balance and dynamic EI delays forms a general mechanism for
millisecond-range input gating and subthreshold gain control in
feedforward networks.