Neurophysiological mechanisms of auditory selective attention in humans

Abstract

This chapter reviews the main data on the physiological substrates of auditory selective attention and their contribution to theoretical models of cognitive psychology.While event-related potentials, magnetoencephalography, and more recently neuroimaging techniques have provided fundamental information on the neural correlates of attention in the central cortical system, measurements of the frequency-following responses in the brainstem and evoked otoacoustic emissions at the cochlea strongly suggest attentional phenomena at the auditory periphery. We propose an adaptive filtering mechanism for selective auditory attention that can be flexibly and dynamically tuned depending on the attentional demand. INTRODUCTIONKnowledge of the psychophysiological mechanisms of modality-specific attention closely depends on knowledge of the corresponding sensory system. In spite of extensive research these last decades on audition and sound analysis, the neural basis of automatic and controlled processing in audition remains poorly understood compared to that in the visual system. We do not pretend here to make an exhaustive list of the studies of auditory attention, but rather give some landmarks of the hypotheses, orientations, and main findings that have contributed to the knowledge of the brain mechanisms of auditory selective attention in humans.Interestingly, the literature on this topic shows an evolution in the theoretical and experimental approaches, the questions raised, and of course the techniques used. Research in the 1960's has been characterized by the elaboration of theoretical models of attention based on behavioral measurements. Since the pilot experiment by Hillyard et al. in 1973 (1), the chronometric measures provided by event-related potentials (ERPs) and later by magnetoencephalographic recordings (MEG) have enriched the psychological theories and physiological models of selective attention. These models, in turn, have been improved with the development of ERP mapping systems and electrical source analysis methods. Likewise promising is the recent use of neuroimaging techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomogaphy (PET), which provide better spatial resolution for locating the brain structures activated. However, as will be discussed, the variety of experimental paradigms and the empirical approaches frequently used have often made it difficult to interpret the findings within the framework of theoretical models of attention. On the other hand, the recent discovery of active mechanical processes in the cochlea that are directly connected with the efferent auditory system has given a new impetus to the peripheral gating hypothesis.These various aspects of attentional research are illustrated below. PSYCHOLOGICAL MODELS OF AUDITORY SELECTIVE ATTENTIONAuditory selective attention refers to the mental ability to resist distractor stimuli and select relevant information from the surrounding acoustic events, as illustrated in the "cocktail party effect". ...

Intracranial Electrophysiology of Auditory Selective Attention Associated with Speech Classification Tasks

“…Specifically, our findings generally support the “gain” theory of auditory selective attention at the level of the auditory cortex (Hillyard et al, 1973). The “gain” theory posits that attended stimuli or stimulus attributes elicit larger responses whereas unattended stimuli or their attributes are associated with a reduction or inhibitory gating of neural activity at an early stage of sensory processing (Giard et al, 2000). Empirical investigations supporting the “gain” theory of auditory selective attention have generally been performed using dichotic listening paradigms wherein the listener attends to one stream and ignores the other (e.g., Hillyard et al, 1973; Mesgarani and Chang, 2012).…”

“…The model predicts that stimuli that are more closely related to the target (e.g., words in a semantic categorization task) will require a longer comparison process than stimuli that are highly dissimilar (e.g., tones in a semantic categorization task; Giard et al, 2000). It would thus be predicted that responses to words would be graded based upon both the task demands and the target status.…”

“…Non-invasive studies examining auditory averaged evoked potentials (AEPs) and neuromagnetic fields have demonstrated enhanced responses to components of the attended stream and dampened responses to the simultaneously presented unattended stream (e.g., Ding and Simon, 2012; Simon, 2015). Functional neuroimaging studies have similarly shown that activity within regions of the auditory cortex involved in processing a specific acoustic stream is enhanced when attention is directed to that stream (Giard et al, 2000; Paltoglou et al, 2009, 2011; Lee et al, 2013; Alho et al, 2014). …”

“…Despite the important findings obtained using non-invasive methods, limitations inherent to indirect measures of neural activity hamper detailed understanding of the mechanisms underlying auditory selective attention within the human brain (Giard et al, 2000; Lee et al, 2014). AEPs and neuromagnetic fields are limited in their ability to identify the specific brain regions modulated by auditory selective attention.…”

Early Auditory Evoked Potential Is Modulated by Selective Attention and Related to Individual Differences in Visual Working Memory Capacity

“…In general, the earliest component of the human auditory ERP that is consistently modulated by selective attention in adults is the N1 at 80–140 msec (for reviews, see Herrmann & Knight, 2001; Giard, Fort, Mouchetant-Rostaing, & Pernier, 2000; Hillyard, Mangun, Woldorff, & Luck, 1995), although there is evidence of an earlier P20-50 modulation in studies where auditory attention was highly focused on rapidly presented tone pips (Woldorff & Hillyard, 1991; Woldorff, Hansen, & Hillyard, 1987) and during intermodal selective attention (Karns & Knight, 2009; Hackley, Woldorff, & Hillyard, 2007). Here, employing dichotic presentations to emphasize early selection using naturalistic language stimuli, we report a robust effect of attention on the first major positive peak (P1) in the auditory evoked potential at around 80–90 msec.…”