title: Auditory cortex tracks the temporal regularity of sustained noisy sounds.
abstract: Neuroimaging studies have revealed dramatic asymmetries between the responses to temporally regular and irregular sounds in the antero-lateral part of Heschl's gyrus. For example, the magnetoencephalography (MEG) study of Krumbholz et al. [Cereb. Cortex 13, 765-772 (2003)] showed that the transition from a noise to a similar noise with sufficient temporal regularity to provoke a pitch evoked a pronounced temporal-regularity onset response (TRon response), whereas a comparable transition in the reverse direction revealed essentially no temporal-regularity offset response (TRoff response). The current paper presents a follow-up study in which the asymmetry is examined with much greater power, and the results suggest an intriguing reinterpretation of the onset/offset asymmetry. The TR-related activity in auditory cortex appears to be composed of a transient (TRon) and a TR-related sustained response (TRsus), with a highly variable TRon/TRsus amplitude ratio. The TRoff response is generally dominated by the break-down of the TRsus activity, which occurs so rapidly as to preclude the involvement of higher-level cortical processing. The time course of the TR-related activity suggests that TR processing might be involved in monitoring the environment and alerting the brain to the onset and offset of behaviourally relevant, animate sources.
authors.affiliation: Section of Experimental Audiology, ENT Clinic, Münster University Hospital, Kardinal-von-Galen-Ring 10, D-48129 Münster, Germany. Lutkenh@uni-muenster.de
authors.forename: Bernd
authors.initials: B
authors.lastname: Lütkenhöner
authors.forename: Annemarie
authors.initials: A
authors.lastname: Seither-Preisler
authors.forename: Katrin
authors.initials: K
authors.lastname: Krumbholz
authors.forename: Roy D
authors.initials: RD
authors.lastname: Patterson
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception; D001309:Auditory Threshold; D005072:Evoked Potentials, Auditory; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D009622:Noise; D046709:Pattern Recognition, Physiological; D010507:Periodicity; D011930:Reaction Time; D013997:Time Factors; D013998:Time Perception; D055815:Young Adult