Cortical encoding of auditory space during cued attention

Jury

Jennifer Bizley (rapporteur, UCL)
Stephen David (rapporteur, OHSU)
Elia Formisano (examinateur, Maastricht University)
Jean-François Léger (examinateur, ENS)
Yves Boubenec (co-encadrant, ENS)
Shihab Shamma (directeur de thèse, ENS)

The ability to localize sounds have clear behavioral benefits. Normal spatial hearing is known to be dependent on auditory cortex, but how auditory cortex represents sound location is still a matter of debate. Additionally, auditory neurons show broad tuning which is surprising given the existing behavioral evidence of high spatial accuracy. Here we hypothesize that continuous mapping of auditory spatial responses during cued attention might reveal improved spatial tuning. We trained two ferrets on a behavioral task involving spatially cued auditory attention. We present evidence of sound source spatial separation being reflected in behavioral reaction times. We recorded more than 900 cortical units and show auditory responses to spatially mapping stimuli can broadly be classified as functionally inhibitory or excitatory to sounds. We demonstrate excitatory neurons are the principal encoders of cue-modulation, and that spatial contrast between hemifields increase with task-engagement. We propose a model by which spatial encoding during cueing is inferred from the relative activity between the two hemispheres, and how spatial cueing is associated with repulsion of auditory space.