title: Brain bases for auditory stimulus-driven figure-ground segregation.
abstract: Auditory figure-ground segregation, listeners' ability to selectively hear out a sound of interest from a background of competing sounds, is a fundamental aspect of scene analysis. In contrast to the disordered acoustic environment we experience during everyday listening, most studies of auditory segregation have used relatively simple, temporally regular signals. We developed a new figure-ground stimulus that incorporates stochastic variation of the figure and background that captures the rich spectrotemporal complexity of natural acoustic scenes. Figure and background signals overlap in spectrotemporal space, but vary in the statistics of fluctuation, such that the only way to extract the figure is by integrating the patterns over time and frequency. Our behavioral results demonstrate that human listeners are remarkably sensitive to the appearance of such figures. In a functional magnetic resonance imaging experiment, aimed at investigating preattentive, stimulus-driven, auditory segregation mechanisms, naive subjects listened to these stimuli while performing an irrelevant task. Results demonstrate significant activations in the intraparietal sulcus (IPS) and the superior temporal sulcus related to bottom-up, stimulus-driven figure-ground decomposition. We did not observe any significant activation in the primary auditory cortex. Our results support a role for automatic, bottom-up mechanisms in the IPS in mediating stimulus-driven, auditory figure-ground segregation, which is consistent with accumulating evidence implicating the IPS in structuring sensory input and perceptual organization.
authors.affiliation: Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, United Kingdom. s.teki@fil.ion.ucl.ac.uk
authors.forename: Sundeep
authors.initials: S
authors.lastname: Teki
authors.forename: Maria
authors.initials: M
authors.lastname: Chait
authors.forename: Sukhbinder
authors.initials: S
authors.lastname: Kumar
authors.forename: Katharina
authors.initials: K
authors.lastname: von Kriegstein
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Griffiths
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001306:Auditory Pathways / Q000098:blood supply; D001307:Auditory Perception / Q000502:physiology*; D001921:Brain / Q000098:blood supply / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010100:Oxygen / Q000097:blood; D011571:Psychoacoustics; D017603:Signal Detection, Psychological / Q000502:physiology*
chemical_list: D010100:Oxygen