UCL Speech Science Forum
17th March 2016
The role of inhibition in auditory cortex for encoding temporal information
Daniel Bendor
In auditory cortex, temporal information within a sound is represented by two
complementary neural codes: a temporal representation based on stimulus-locked
firing and a rate representation, where discharge rate co-varies with the timing
between acoustic events but lacks a stimulus-synchronized response. Using a
computational neuronal model, we find that stimulus-locked responses are generated
when sound-evoked excitation is combined with strong, delayed inhibition. In
contrast to this, a non-synchronized rate representation is generated when the net
excitation evoked by the sound is weak, which occurs when excitation is coincident
and balanced with inhibition. Using single-unit recordings from awake marmosets
(Callithrix jacchus), we validate several model predictions, including differences in
the temporal fidelity, discharge rates and temporal dynamics of stimulus-evoked
responses between neurons with rate and temporal representations. Together these
data suggest that feedforward inhibition provides a parsimonious explanation of the
neural coding dichotomy observed in auditory cortex.