Auditory perceptual decision-making based on semantic categorization of environmental sounds
Marzia De Lucia1, Athina Tzovara, Fosco Bernasconi
1Electroencephalography Brain Mapping Core, Center for Biomedical Imaging (CIBM) of Lausanne and Geneva, University of Lausanne, Lausanne, Switzerland. marzia.de-lucia@chuv.ch
Neuroimage
|February 15, 2012
Summary
The brain can distinguish between sound categories early on, even before conscious perception. Explicit sound categorization involves later brain processing stages, independent of initial sensory discrimination.
Area of Science:
- Neuroscience
- Auditory Perception
- Cognitive Science
Background:
- Complex sound discrimination involves multiple brain activity stages.
- Understanding the roles of these stages and their link to perception is crucial.
Purpose of the Study:
- To investigate when and how the brain discriminates sound categories, even without behavioral awareness.
- To differentiate early sensory processing from later perceptual decision-making in auditory discrimination.
Main Methods:
- 160-channel electroencephalography (EEG) was used to record brain activity.
- Subjects categorized sounds from living and man-made objects.
- A single-trial classifier analyzed voltage topographies and latencies for discriminative brain responses.
Main Results:
- Brain activity successfully decoded semantic categories for uncategorized sounds between 116-174 ms post-stimulus.
- Correctly categorized sounds showed differential brain activity starting at 112 ms and again at ~270 ms.
- Early brain activity (112 ms) suggests implicit sound representation tuning, while later activity (~270 ms) relates to perceptual decisions.
Conclusions:
- The brain discriminates environmental sounds at early stages, irrespective of behavioral accuracy.
- Explicit sound categorization relies on a distinct, later processing stage.
- Early auditory processing is independent of, and precedes, conscious perceptual categorization.
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