title: Task-related preparatory modulations multiply with acoustic processing in monkey auditory cortex.
abstract: We characterised task-related top-down signals in monkey auditory cortex cells by comparing single-unit activity during passive sound exposure with neuronal activity during a predictable and unpredictable reaction-time task for a variety of spectral-temporally modulated broadband sounds. Although animals were not trained to attend to particular spectral or temporal sound modulations, their reaction times demonstrated clear acoustic spectral-temporal sensitivity for unpredictable modulation onsets. Interestingly, this sensitivity was absent for predictable trials with fast manual responses, but re-emerged for the slower reactions in these trials. Our analysis of neural activity patterns revealed a task-related dynamic modulation of auditory cortex neurons that was locked to the animal's reaction time, but invariant to the spectral and temporal acoustic modulations. This finding suggests dissociation between acoustic and behavioral signals at the single-unit level. We further demonstrated that single-unit activity during task execution can be described by a multiplicative gain modulation of acoustic-evoked activity and a task-related top-down signal, rather than by linear summation of these signals.
authors.affiliation: Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
authors.forename: Roohollah
authors.initials: R
authors.lastname: Massoudi
authors.forename: Marc M
authors.initials: MM
authors.lastname: Van Wanrooij
authors.forename: Sigrid M C I
authors.initials: SM
authors.lastname: Van Wetter
authors.forename: Huib
authors.initials: H
authors.lastname: Versnel
authors.forename: A John
authors.initials: AJ
authors.lastname: Van Opstal
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology; D008253:Macaca mulatta; D008297:Male; D009474:Neurons / Q000502:physiology*
keywords: amplitude-modulated noise; awake; electrophysiology; reaction time; ripple; top-down