Definition
Inhibition
Inhibition is a synaptic signal that decreases the likelihood of a neuron firing.
Biologically, inhibition hyperpolarises the soma — it moves the membrane potential farther from the firing threshold. Inhibition is mediated by synapses and stands in opposition to excitation.
McCulloch–Pitts Model
In the McCulloch–Pitts model, a single active inhibitory input forces the output to regardless of excitatory input — an absolute veto.