Neural Substrates of Attentive Listening Assessed with a Novel Auditory Stroop Task

Elena Plante,Julie L Lockwood,Kyle R Almryde,Thomas A Christensen

doi:10.3389/fnhum.2010.00236

Abstract

A common explanation for the interference effect in the classic visual Stroop test is that reading a word (the more automatic semantic response) must be suppressed in favor of naming the text color (the slower sensory response). Neuroimaging studies also consistently report anterior cingulate/medial frontal, lateral prefrontal, and anterior insular structures as key components of a network for Stroop-conflict processing. It remains unclear, however, whether automatic processing of semantic information can explain the interference effect in other variants of the Stroop test. It also is not known if these frontal regions serve a specific role in visual Stroop conflict, or instead play a more universal role as components of a more generalized, supramodal executive-control network for conflict processing. To address these questions, we developed a novel auditory Stroop test in which the relative dominance of semantic and sensory feature processing is reversed. Listeners were asked to focus either on voice gender (a more automatic sensory discrimination task) or on the gender meaning of the word (a less automatic semantic task) while ignoring the conflicting stimulus feature. An auditory Stroop effect was observed when voice features replaced semantic content as the “to-be-ignored” component of the incongruent stimulus. Also, in sharp contrast to previous Stroop studies, neural responses to incongruent stimuli studied with functional magnetic resonance imaging revealed greater recruitment of conflict loci when selective attention was focused on gender meaning (semantic task) over voice gender (sensory task). Furthermore, in contrast to earlier Stroop studies that implicated dorsomedial cortex in visual conflict processing, interference-related activation in both of our auditory tasks was localized ventrally in medial frontal areas, suggesting a dorsal-to-ventral separation of function in medial frontal cortex that is sensitive to stimulus context.

Highlights

In the classic visual Stroop test, interference arises when behavioral responses are contingent upon selecting the task-relevant dimension over the task-irrelevant information embedded in an incongruent sensory stimulus
Results consistently point to the involvement of a frontal lobe network comprising the anterior cingulate cortex, lateral prefrontal cortex, and anterior insula, but they indicate some regional variation across different Stroop tasks and studies
To help clarify the unresolved issues surrounding task- vs. modality-dependent neural activation in Stroop tasks, we developed a novel auditory Stroop-conflict paradigm for use in conjunction with functional magnetic resonance imaging

Summary

Introduction

In the classic visual Stroop test, interference arises when behavioral responses are contingent upon selecting the task-relevant dimension (ink color) over the task-irrelevant information (word meaning) embedded in an incongruent sensory stimulus. Results consistently point to the involvement of a frontal lobe network comprising the anterior cingulate cortex, lateral prefrontal cortex, and anterior insula, but they indicate some regional variation across different Stroop tasks and studies. These same brain regions are often identified in studies that use other paradigms to measure response inhibition, such as go/no-go, flanker, and stimulus-response incompatibility tasks (MacDonald et al, 2000; Buchsbaum et al, 2005; Thompson-Schill et al, 2005; Wager et al, 2005; Simmonds et al, 2008). An open question is whether these frontal lobe regions consistently associated with Stroop and other conflict tasks are components of a domain-general network, or if these areas can be further dissociated through manipulations that target specific cognitive processes

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Discussion

Conclusion