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Modulation of ventral prefrontal cortex functional connections reflects the interplay of cognitive processes and stimulus characteristics.

Protzner AB, McIntosh AR - Cereb. Cortex (2008)

Bottom Line: Emerging ideas of brain function emphasize the context-dependency of regional contributions to cognitive operations, where the function of a particular region is constrained by its pattern of functional connectivity.Analysis of right ventral PFC functional connectivity, however, suggested these activity patterns interact.These results underscore the interactive nature of brain processing, where modality-specific and process-specific networks interact for normal cognitive operations.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuropsychology, Toronto Western Hospital and Research Institute, Toronto, M5G 2M9 ON, Canada. protzner@uhnres.utoronto.ca

ABSTRACT
Emerging ideas of brain function emphasize the context-dependency of regional contributions to cognitive operations, where the function of a particular region is constrained by its pattern of functional connectivity. We used functional magnetic resonance imaging to examine how modality of input (auditory or visual) affects prefrontal cortex (PFC) functional connectivity for simple working memory tasks. The hypothesis was that PFC would show contextually dependent changes in functional connectivity in relation to the modality of input despite similar cognitive demands. Participants were presented with auditory or visual bandpass-filtered noise stimuli, and performed 2 simple short-term memory tasks. Brain activation patterns independently mapped onto modality and task demands. Analysis of right ventral PFC functional connectivity, however, suggested these activity patterns interact. One functional connectivity pattern showed task differences independent of stimulus modality and involved ventromedial and dorsolateral prefrontal and occipitoparietal cortices. A second pattern showed task differences that varied with modality, engaging superior temporal and occipital association regions. Importantly, these association regions showed nonzero functional connectivity in all conditions, rather than showing a zero connectivity in one modality and nonzero in the other. These results underscore the interactive nature of brain processing, where modality-specific and process-specific networks interact for normal cognitive operations.

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Behavior measures for the 4 experimental tasks. (A) Mean proportion correct. (B) Mean threshold. (C) Mean reaction time. Error bars show standard error.
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fig1: Behavior measures for the 4 experimental tasks. (A) Mean proportion correct. (B) Mean threshold. (C) Mean reaction time. Error bars show standard error.

Mentions: Measures of reaction time, accuracy, and threshold are summarized in Figure 1. We performed a 2 (modality) × 2 (experimental tasks) repeated measures analysis of variance on reaction time, accuracy, and threshold data from the day of scanning. For percent correct data (see Fig. 1A), all effects were statistically nonsignificant, indicating that task difficulty, as indicated by response accuracy, was equated across all experimental tasks. For threshold data (see Fig. 1A), the main effects of modality (F1,11 = 36.40, P < 0.001) and task (F1,11 = 41.59, P < 0.001) were significant. The main effect of modality indicates that auditory thresholds were generally lower than visual thresholds. The main effect of task indicates that comparison thresholds were generally higher than temporal sequencing thresholds. The interaction between modality and task also was significant (F1,11 = 9.27, P < 0.05), indicating that the difference between comparison and temporal sequencing thresholds was bigger for visual than for auditory tasks. For reaction time data (see Fig. 1A), the main effects of modality (F1,11 = 49.78, P < 0.001) and task (F1,11 = 12.13, P < 0.01) were significant. The main effect of modality indicates that auditory tasks were performed with longer reaction times than visual tasks. Finally, the main effect of task indicates that comparison tasks were associated with longer reaction times than sequencing tasks. The interaction term was nonsignificant.


Modulation of ventral prefrontal cortex functional connections reflects the interplay of cognitive processes and stimulus characteristics.

Protzner AB, McIntosh AR - Cereb. Cortex (2008)

Behavior measures for the 4 experimental tasks. (A) Mean proportion correct. (B) Mean threshold. (C) Mean reaction time. Error bars show standard error.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2665153&req=5

fig1: Behavior measures for the 4 experimental tasks. (A) Mean proportion correct. (B) Mean threshold. (C) Mean reaction time. Error bars show standard error.
Mentions: Measures of reaction time, accuracy, and threshold are summarized in Figure 1. We performed a 2 (modality) × 2 (experimental tasks) repeated measures analysis of variance on reaction time, accuracy, and threshold data from the day of scanning. For percent correct data (see Fig. 1A), all effects were statistically nonsignificant, indicating that task difficulty, as indicated by response accuracy, was equated across all experimental tasks. For threshold data (see Fig. 1A), the main effects of modality (F1,11 = 36.40, P < 0.001) and task (F1,11 = 41.59, P < 0.001) were significant. The main effect of modality indicates that auditory thresholds were generally lower than visual thresholds. The main effect of task indicates that comparison thresholds were generally higher than temporal sequencing thresholds. The interaction between modality and task also was significant (F1,11 = 9.27, P < 0.05), indicating that the difference between comparison and temporal sequencing thresholds was bigger for visual than for auditory tasks. For reaction time data (see Fig. 1A), the main effects of modality (F1,11 = 49.78, P < 0.001) and task (F1,11 = 12.13, P < 0.01) were significant. The main effect of modality indicates that auditory tasks were performed with longer reaction times than visual tasks. Finally, the main effect of task indicates that comparison tasks were associated with longer reaction times than sequencing tasks. The interaction term was nonsignificant.

Bottom Line: Emerging ideas of brain function emphasize the context-dependency of regional contributions to cognitive operations, where the function of a particular region is constrained by its pattern of functional connectivity.Analysis of right ventral PFC functional connectivity, however, suggested these activity patterns interact.These results underscore the interactive nature of brain processing, where modality-specific and process-specific networks interact for normal cognitive operations.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuropsychology, Toronto Western Hospital and Research Institute, Toronto, M5G 2M9 ON, Canada. protzner@uhnres.utoronto.ca

ABSTRACT
Emerging ideas of brain function emphasize the context-dependency of regional contributions to cognitive operations, where the function of a particular region is constrained by its pattern of functional connectivity. We used functional magnetic resonance imaging to examine how modality of input (auditory or visual) affects prefrontal cortex (PFC) functional connectivity for simple working memory tasks. The hypothesis was that PFC would show contextually dependent changes in functional connectivity in relation to the modality of input despite similar cognitive demands. Participants were presented with auditory or visual bandpass-filtered noise stimuli, and performed 2 simple short-term memory tasks. Brain activation patterns independently mapped onto modality and task demands. Analysis of right ventral PFC functional connectivity, however, suggested these activity patterns interact. One functional connectivity pattern showed task differences independent of stimulus modality and involved ventromedial and dorsolateral prefrontal and occipitoparietal cortices. A second pattern showed task differences that varied with modality, engaging superior temporal and occipital association regions. Importantly, these association regions showed nonzero functional connectivity in all conditions, rather than showing a zero connectivity in one modality and nonzero in the other. These results underscore the interactive nature of brain processing, where modality-specific and process-specific networks interact for normal cognitive operations.

Show MeSH