Poster #: 7
Topic: Attention and distraction
Wednesday, Sep 9, 2015
Using adaptation to investigate the neural mechanisms of attention in the human auditory cortex
1MRC Institute of Hearing Research, Nottingham, United Kingdom
Single neuron recordings in auditory cortex have suggested that attention causes a sharpening of neural frequency selectivity . In humans, neuroimaging studies have reported similar effects when using notched-noise masking to estimate cortical frequency selectivity. There is a possibility, however, that these results were confounded by differences in attentional load between different masking conditions.
Here, we tested the effect of selective attention on cortical frequency tuning directly, using an adaptation paradigm previously used in the visual system . In this paradigm, the feature selectivity of cortical neurons is assessed by measuring the degree of stimulus-specific adaptation of the gross evoked response as a function of the difference between the adapting stimulus and the subsequently presented probe stimulus. If attention causes an increase in neural selectivity, it would be expected that adaptation becomes more stimulus specific, that is, more strongly dependent on the adapter-probe difference.
Tone-evoked auditory-evoked potentials (AEPs) were recorded from 23 participants performing a dichotic listening task. As expected, selective attention increased the amplitude of the N1 and P2, but not the P1, components of the AEP. The P2, but not the N1, exhibited a sharper frequency-specific release from adaptation under attention. These results support the view that neural sharpening mechanisms contribute to selective attention, particularly at higher stages of processing.
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