scholarly journals Neural mechanisms of rhythmic masking release in monkey primary auditory cortex: implications for models of auditory scene analysis

2012 ◽  
Vol 107 (9) ◽  
pp. 2366-2382 ◽  
Author(s):  
Yonatan I. Fishman ◽  
Christophe Micheyl ◽  
Mitchell Steinschneider
Keyword(s):  
Auditory Cortex ◽  
Perceptual Organization ◽  
Primary Auditory Cortex ◽  
Auditory Scene Analysis ◽  
Neural Mechanisms ◽  
Stream Segregation ◽  
Scene Analysis ◽  
Neural Basis ◽  
Masking Release ◽  
Auditory Scene

The ability to detect and track relevant acoustic signals embedded in a background of other sounds is crucial for hearing in complex acoustic environments. This ability is exemplified by a perceptual phenomenon known as “rhythmic masking release” (RMR). To demonstrate RMR, a sequence of tones forming a target rhythm is intermingled with physically identical “Distracter” sounds that perceptually mask the rhythm. The rhythm can be “released from masking” by adding “Flanker” tones in adjacent frequency channels that are synchronous with the Distracters. RMR represents a special case of auditory stream segregation, whereby the target rhythm is perceptually segregated from the background of Distracters when they are accompanied by the synchronous Flankers. The neural basis of RMR is unknown. Previous studies suggest the involvement of primary auditory cortex (A1) in the perceptual organization of sound patterns. Here, we recorded neural responses to RMR sequences in A1 of awake monkeys in order to identify neural correlates and potential mechanisms of RMR. We also tested whether two current models of stream segregation, when applied to these responses, could account for the perceptual organization of RMR sequences. Results suggest a key role for suppression of Distracter-evoked responses by the simultaneous Flankers in the perceptual restoration of the target rhythm in RMR. Furthermore, predictions of stream segregation models paralleled the psychoacoustics of RMR in humans. These findings reinforce the view that preattentive or “primitive” aspects of auditory scene analysis may be explained by relatively basic neural mechanisms at the cortical level.

scholarly journals Functional brain networks underlying perceptual switching: auditory streaming and verbal transformations

2012 ◽  
Vol 367 (1591) ◽  
pp. 977-987 ◽  
Author(s):  
Makio Kashino ◽  
Hirohito M. Kondo
Keyword(s):  
Perceptual Organization ◽  
Brain Activity ◽  
Auditory Scene Analysis ◽  
Scene Analysis ◽  
Switching Frequency ◽  
Auditory Streaming ◽  
Auditory Scene ◽  
Functional Brain Networks ◽  
Fmri Analysis ◽  
Perceptual Changes

Recent studies have shown that auditory scene analysis involves distributed neural sites below, in, and beyond the auditory cortex (AC). However, it remains unclear what role each site plays and how they interact in the formation and selection of auditory percepts. We addressed this issue through perceptual multistability phenomena, namely, spontaneous perceptual switching in auditory streaming (AS) for a sequence of repeated triplet tones, and perceptual changes for a repeated word, known as verbal transformations (VTs). An event-related fMRI analysis revealed brain activity timelocked to perceptual switching in the cerebellum for AS, in frontal areas for VT, and the AC and thalamus for both. The results suggest that motor-based prediction, produced by neural networks outside the auditory system, plays essential roles in the segmentation of acoustic sequences both in AS and VT. The frequency of perceptual switching was determined by a balance between the activation of two sites, which are proposed to be involved in exploring novel perceptual organization and stabilizing current perceptual organization. The effect of the gene polymorphism of catechol- O -methyltransferase (COMT) on individual variations in switching frequency suggests that the balance of exploration and stabilization is modulated by catecholamines such as dopamine and noradrenalin. These mechanisms would support the noteworthy flexibility of auditory scene analysis.

The Intraparietal Sulcus and Perceptual Organization

2005 ◽  
Vol 17 (4) ◽  
pp. 641-651 ◽  
Author(s):  
Rhodri Cusack
Keyword(s):  
Auditory Cortex ◽  
Perceptual Organization ◽  
Stream Segregation ◽  
Intraparietal Sulcus ◽  
Neural Basis ◽  
General Role ◽  
Auditory Stream ◽  
Auditory Stream Segregation ◽  
Clinical Interest ◽  
Physical Changes

The structuring of the sensory scene (perceptual organization) profoundly affects what we perceive, and is of increasing clinical interest. In both vision and audition, many cues have been identified that influence perceptual organization, but only a little is known about its neural basis. Previous studies have suggested that auditory cortex may play a role in auditory perceptual organization (also called auditory stream segregation). However, these studies were limited in that they just examined auditory cortex and that the stimuli they used to generate different organizations had different physical characteristics, which per se may have led to the differences in neural response. In the current study, functional magnetic resonance imaging was used to test for an effect of perceptual organization across the whole brain. To avoid confounding physical changes to the stimuli with differences in perceptual organization, we exploited an ambiguous auditory figure that is sometimes perceived as a single auditory stream and sometimes as two streams. We found that regions in the intraparietal sulcus (IPS) showed greater activity when 2 streams were perceived rather than 1. The specific involvement of this region in perceptual organization is exciting, as there is a growing literature that suggests a role for the IPS in binding in vision, touch, and cross-modally. This evidence is discussed, and a general role proposed for regions of the IPS in structuring sensory input.

scholarly journals Integration of visual information in auditory cortex promotes auditory scene analysis through multisensory binding

2017 ◽  
Author(s):  
Huriye Atilgan ◽  
Stephen M. Town ◽  
Katherine C. Wood ◽  
Gareth P. Jones ◽  
Ross K. Maddox ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Visual Information ◽  
Field Potential ◽  
Auditory Scene Analysis ◽  
Visual Signals ◽  
Scene Analysis ◽  
Auditory Information ◽  
Amplitude Fluctuations ◽  
Auditory Scene ◽  
Stimulus Features

SummaryHow and where in the brain audio-visual signals are bound to create multimodal objects remains unknown. One hypothesis is that temporal coherence between dynamic multisensory signals provides a mechanism for binding stimulus features across sensory modalities. Here we report that when the luminance of a visual stimulus is temporally coherent with the amplitude fluctuations of one sound in a mixture, the representation of that sound is enhanced in auditory cortex. Critically, this enhancement extends to include both binding and non-binding features of the sound. We demonstrate that visual information conveyed from visual cortex, via the phase of the local field potential is combined with auditory information within auditory cortex. These data provide evidence that early cross-sensory binding provides a bottom-up mechanism for the formation of cross-sensory objects and that one role for multisensory binding in auditory cortex is to support auditory scene analysis.

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