Attentional modulation of auditory steady-state responses.

Manuel S Malmierca,Chris Davis,Yatin Mahajan,Jeesun Kim

doi:10.1371/journal.pone.0110902

Manuel S Malmierca, Chris Davis + Show 2 more

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https://doi.org/10.1371/journal.pone.0110902

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Journal: PloS one	Publication Date: Oct 21, 2014
Citations: 41	License type: CC BY 4.0

Affiliation: Western Sydney University

Abstract

Auditory selective attention enables task-relevant auditory events to be enhanced and irrelevant ones suppressed. In the present study we used a frequency tagging paradigm to investigate the effects of attention on auditory steady state responses (ASSR). The ASSR was elicited by simultaneously presenting two different streams of white noise, amplitude modulated at either 16 and 23.5 Hz or 32.5 and 40 Hz. The two different frequencies were presented to each ear and participants were instructed to selectively attend to one ear or the other (confirmed by behavioral evidence). The results revealed that modulation of ASSR by selective attention depended on the modulation frequencies used and whether the activation was contralateral or ipsilateral. Attention enhanced the ASSR for contralateral activation from either ear for 16 Hz and suppressed the ASSR for ipsilateral activation for 16 Hz and 23.5 Hz. For modulation frequencies of 32.5 or 40 Hz attention did not affect the ASSR. We propose that the pattern of enhancement and inhibition may be due to binaural suppressive effects on ipsilateral stimulation and the dominance of contralateral hemisphere during dichotic listening. In addition to the influence of cortical processing asymmetries, these results may also reflect a bias towards inhibitory ipsilateral and excitatory contralateral activation present at the level of inferior colliculus. That the effect of attention was clearest for the lower modulation frequencies suggests that such effects are likely mediated by cortical brain structures or by those in close proximity to cortex.

Highlights

A listener in a typical everyday situation receives multiple auditory inputs some of which may be relevant and others not
The purpose of the present research was to build on the above research that has used a frequency tagging paradigm with the aim of determining how selective sustained attention modulates cortical responses (ASSR) as a function of contralateral/ipsilateral activations across different modulation frequencies
As part of a pilot study conducted to determine the best combination of modulation frequencies, we found that when the difference in frequencies was large (e.g., 16 and 40 Hz) participants’ attention involuntarily switched to higher modulation frequency

Summary

Introduction

A listener in a typical everyday situation receives multiple auditory inputs some of which may be relevant and others not. The listener has to selectively attend to particular inputs and sustain this attention over time. It is through sustained selective attention that a listener is able to enhance task-relevant processing and suppress irrelevant processing [1,2]. Research on the attentional modulation of cortical responses typically examined event-related potentials (ERPs) and paralleled the early behavioral work on aural discrimination by using simple transient stimuli, such as tone bursts and tone pips. Use of these stimuli provided a high degree of control over stimulus properties and presentation times. Results showed larger auditory P1, N1 and T-complex responses to attended stimuli [3,4] and reduced activity to unattended stimuli [1,5]

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