Cognitive Neuroscience and Neuropsychology

Auditory attention has been examined extensively over the years, primarily by means of event-related brain potentials (ERPs). Sustained attention to specific targets embedded in a series of non-targets (e.g. the ‘oddball’ paradigm) causes an increase in the amplitudes of various components of the auditory ERP after about 80 ms and results in the appearance of new waveforms, such as the N2B and the P3.1,2 Selective attention, or attention to one set of items while ignoring others, also affects the auditory ERP.3–5 Most of the experiments examining auditory attention have used simple stimuli, such as clicks or tones, but attention effects have also been found with speech stimuli6 and voices.7 It has been difficult to identify the sources for these attentional ERPs.8,9 The frontal lobes have been implicated due to the frontocentral topography of some attentional components,3 and the fact that the early attention-related negativity in the ERP is reduced by lesions in the frontal lobes.10 Other experiments have suggested that auditory association cortex,11,12 medial temporal cortex13 and parietal cortex14 are also involved in the modulation of auditory potentials by attention. There is other evidence to suggest that these attention effects are more likely to occur in auditory association cortex than in primary cortex. For example, early peaks in the auditory ERP that are not affected by attention show changes in scalp distribution depending on the pitch of the presented tones, i.e. a tonotopic change, whereas the peaks elicited by attention show no changes related to pitch, suggesting recruitment of non-tonotopic (association) auditory cortex.15 In addition, a greater proportion of cells in auditory association cortex of the monkey have been shown to increase firing rates to an attended auditory stimulus, compared to a non-attended stimulus, than was seen in primary auditory cortex.16 Auditory attention has remained relatively unexplored with the more recent neuroimaging techniques. While visual attention has been addressed to some extent in the neuroimaging literature,17 only one early study examined auditory attention.18 In addition, in this experiment auditory attention was examined only in the context of intermodal attention, i.e. switching attention between auditory, visual and somatosensory modalities. Activity in auditory Cognitive Neuroscience and Neuropsychology