Robust discrimination between EEG responses to categories of environmental sounds in early coma
Open Access
- 1 January 2014
- journal article
- research article
- Published by Frontiers Media SA in Frontiers in Psychology
Abstract
Humans can recognize categories of environmental sounds, including vocalizations produced by humans and animals and the sounds of man-made objects. Most neuroimaging investigations of environmental sound discrimination have studied subjects while consciously perceiving and often explicitly recognizing the stimuli. Consequently, it remains unclear to what extent auditory object processing occurs independently of task demands and consciousness. Studies in animal models have shown that environmental sound discrimination at a neural level persists even in anesthetized preparations, whereas data from anesthetized humans has thus far provided null results. Here, we studied comatose patients as a model of environmental sound discrimination capacities during unconsciousness. We included nineteen comatose patients treated with therapeutic hypothermia during the first two days of coma, while recording nineteen-channel electroencephalography (EEG). At the level of each individual patient, we applied a decoding algorithm to quantify the differential EEG responses to human versus animal vocalizations as well as to sounds of living vocalizations versus man-made objects. Discrimination between vocalization types was accurate in eleven patients and discrimination between sounds from living and man-made sources in ten patients. At the group level, the results were significant only for the comparison between vocalization types. These results lay the groundwork for disentangling truly preferential activations in response to auditory categories, and the contribution of awareness to auditory category discrimination.Keywords
This publication has 67 references indexed in Scilit:
- Masked Priming of Conceptual Features Reveals Differential Brain Activation during Unconscious Access to Conceptual Action and Sound InformationPLOS ONE, 2013
- Voice Cells in the Primate Temporal LobeCurrent Biology, 2011
- Identifying Object Categories from Event-Related EEG: Toward Decoding of Conceptual RepresentationsPLOS ONE, 2010
- Cortical Representation of Natural Complex Sounds: Effects of Acoustic Features and Auditory Object CategoryJournal of Neuroscience, 2010
- Opposing effects of attention and consciousness on afterimagesProceedings of the National Academy of Sciences of the United States of America, 2010
- Electrophysiological evidence for an early processing of human voicesBMC Neuroscience, 2009
- The Primate Cortical Auditory System and Neural Representation of Conspecific VocalizationsAnnual Review of Neuroscience, 2009
- Machine learning classifiers and fMRI: A tutorial overviewNeuroImage, 2009
- "Who" Is Saying "What"? Brain-Based Decoding of Human Voice and SpeechScience, 2008
- Functional Imaging Reveals Numerous Fields in the Monkey Auditory CortexPLoS Biology, 2006