The anterior cingulate cortex mediates processing selection in the Stroop attentional conflict paradigm.

Abstract

Regional cerebral blood flow, an index of local neuronal activity, was measured using positron emission tomography (PET) during the performance of the classic Stroop color/word task in eight healthy right-handed subjects.In the first condition of this paradigm, subjects name the color of the words presented on a video monitor. All the words are the color names congruent to the color presented (e.g., the noun "red" displayed in red color). In the second condition, subjects also name the color of the words presented on the monitor. However, during these trials all words are color names incongruent to the color presented (e.g., the noun "red" displayed in green color). The difference in brain activity between these two conditions (i.e., incongruent minus congruent) could reveal brain systems involved in the attentionally mediated resolution of the conflict between the habitual response of reading words vs. the task demands of naming the color of the words-i.e., the Stroop interference effect. The most robust responses occurred in the anterior cingulate cortex. Other responses noted were in the left premotor cortex, left postcentral cortex, left putamen, supplementary motor area, right superior temporal gyrus, and bilateral peristriate cortices. These data provide support for the role of the anterior cingulate cortex in attentional processing through the selection and recruitment of processing centers appropriate for task execution. Furthermore, the extensive distributed network of activated regions suggests that the Stroop interference effect cannot be explained simply in terms of stimulus encoding or response interference.The Stroop task (1, 2) is a classic experimental paradigm used in behavioral neuroscience in both clinical and research settings. Subjects note the strong interference of word reading upon color naming, called the Stroop interference effect, when a noun presented is a color name displayed visually using a different color (see Fig. 1 What are the likely anatomical loci and associated cognitive operations involved in attentional conflict paradigms such as the Stroop task? Two general areas are suggested on the basis of data from several sources: the prefrontal cortex and the anterior cingulate. The prefrontal cortex, based on experimental evidence from both monkeys as well as humans (4, 5), has been demonstrated to be important not only for memory buffering to permit "on-line" processing but also for inhibition of "prepotent" habitual, albeit sometimes inappropriate, responses. Lesions of the left prefrontal cortex result in impaired performance in the Stroop task (6). Linguistic tasks requiring the inhibition of reading a noun and the generation of a verb appropriate to the noun result not only in activation of the left prefrontal cortex but also the anterior cingulate (7,8). Some human diseases, such as schizophrenia, involving prefrontal (9) and anterior cingulate abnormalities (10) result in impairments in attentional conflict paradigms (11).Recent technological advances in nuclear medi...

Brain imaging of the central executive component of working memory

“…Different aspects of inhibitory control may be distinguished [56], especially those preventing access to goal-irrelevant information that may be partially activated, restraining access to strong but situationally inappropriate responses, and suppressing the activation of no longer relevant information. Most of the studies exploring inhibition processes have used different variants of the Stroop paradigm and showed increased activity during the interference condition (i.e., naming the font colour of letters that spell a colour word different than the colour-to-be-named) in the anterior cingulate gyrus and right orbitofrontal regions [15,70,91]. Moreover, increased activity has also been found in left inferior frontal regions [25,54,118] and in temporal and parietal areas [e.g., 25,118].…”

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