In NetLab and biological networks facilitation describes a post-synaptic response that closely tracks pre-synaptic stimulus.

In biological terms facilitation describes a progressive increase in a synapse's response to successive action potentials during a train of stimulus pulses. Typically the input train of pulses could last up to a few seconds.

In NetLab's abstraction, facilitation describes a direct response to higher input levels with some level of attack and decay built in to the transfer function.

Facilitation was called reactive stimulus or reactive feedback in NetLab v0.1.