UCL Speech Science Forum 17 March 2016 Daniel Bendor

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.