Segmental processing in the human auditory dorsal stream

• Published in: Brain research 2008-07, Vol.1220 (18 July), p.179-190
• Main Authors: Zaehle, Tino, Geiser, Eveline, Alter, Kai, Jancke, Lutz, Meyer, Martin
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation - methods; Analysis of Variance; Auditory cortex; Auditory Cortex - blood supply; Auditory Cortex - physiology; Auditory Pathways - blood supply; Auditory Pathways - physiology; Auditory Perception - physiology; Brain Mapping; Discrimination; Dorsal processing stream; Functional Laterality; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging - methods; Neurology; Oxygen - blood; Psycholinguistics; Segmentation; Speech - physiology; Speech and non-speech; Speech Perception - physiology; Sublexical processing
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2007.11.013

Abstract In the present study we investigated the functional organization of sublexical auditory perception with specific respect to auditory spectro-temporal processing in speech and non-speech sounds. Participants discriminated verbal and nonverbal auditory stimuli according to either spectral or temporal acoustic features in the context of a sparse event-related functional magnetic resonance imaging (fMRI) study. Based on recent models of speech processing, we hypothesized that auditory segmental processing, as is required in the discrimination of speech and non-speech sound according to its temporal features, will lead to a specific involvement of a left-hemispheric dorsal processing network comprising the posterior portion of the inferior frontal cortex and the inferior parietal lobe. In agreement with our hypothesis results revealed significant responses in the posterior part of the inferior frontal gyrus and the parietal operculum of the left hemisphere when participants had to discriminate speech and non-speech stimuli based on subtle temporal acoustic features. In contrast, when participants had to discriminate speech and non-speech stimuli on the basis of changes in the frequency content, we observed bilateral activations along the middle temporal gyrus and superior temporal sulcus. The results of the present study demonstrate an involvement of the dorsal pathway in the segmental sublexical analysis of speech sounds as well as in the segmental acoustic analysis of non-speech sounds with analogous spectro-temporal characteristics.