  Fast-spiking (FS) interneurons in the brain are self-innervated by powerful
inhibitory GABAergic autaptic connections. By computational modelling, we
investigate how autaptic inhibition regulates the firing response of such
interneurons. Our results indicate that autaptic inhibition both boosts the
current threshold for action potential generation as well as modulates the
input-output gain of FS interneurons. The autaptic transmission delay is
identified as a key parameter that controls the firing patterns and determines
multistability regions of FS interneurons. Furthermore, we observe that
neuronal noise influences the firing regulation of FS interneurons by autaptic
inhibition and extends their dynamic range for encoding inputs. Importantly,
autaptic inhibition modulates noise-induced irregular firing of FS
interneurons, such that coherent firing appears at an optimal autaptic
inhibition level. Our result reveal the functional roles of autaptic inhibition
in taming the firing dynamics of FS interneurons.
