Article

The effects of priming on frontal-temporal communication

Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Massachusetts Institute of Technology/Harvard Medical School, Boston, MA 02115, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 07/2008; 105(24):8405-9. DOI: 10.1073/pnas.0710674105
Source: PubMed

ABSTRACT

Repeated exposure to a stimulus facilitates its processing. This is reflected in faster and more accurate identification, reduced perceptual identification thresholds, and more efficient classifications for repeated compared with novel items. Here, we test a hypothesis that this experience-based behavioral facilitation is a result of enhanced communication between distinct cortical regions, which reduces local processing demands. A magnetoencephalographic investigation revealed that repeated object classification led to decreased neural responses in the prefrontal cortex and temporal cortex. Critically, this decrease in absolute activity was accompanied by greater neural synchrony (a measure of functional connectivity) between these regions with repetition. Additionally, the onset of the enhanced interregional synchrony predicted the degree of behavioral facilitation. These findings suggest that object repetition results in enhanced interactions between brain regions, which facilitates performance and reduces processing demands on the regions involved.

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    • "We suggest that this higher efficiency of processing is reflected by an increase in functional coupling between task-relevant brain regions: Brain regions significantly activated during the task were more strongly coupled with each other during CON than INC. Moreover, in line with the assumption that efficient processing entails lower levels of neural activity (Ghuman et al. 2008; Kujala et al. 2012), several brain regions showed less activation under CON relative to INC. "
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    ABSTRACT: Unconscious visuomotor priming defined as the advantage in reaction time (RT) or accuracy for target shapes mapped to the same (congruent condition) when compared with a different (incongruent condition) motor response as a preceding subliminally presented prime shape has been shown to modulate activity within a visuomotor network comprised of parietal and frontal motor areas in previous functional magnetic resonance imaging (fMRI) studies. The present fMRI study investigated whether, in addition to changes in brain activity, unconscious visuomotor priming results in a modulation of functional connectivity profiles. Activity associated with congruent compared with incongruent trials was lower in the bilateral inferior and medial superior frontal gyri, in the inferior parietal lobules, and in the right caudate nucleus and adjacent portions of the thalamus. Functional connectivity increased under congruent relative to incongruent conditions between ventral visual stream areas (e.g., calcarine, fusiform, and lingual gyri), the precentral gyrus, the supplementary motor area, posterior parietal areas, the inferior frontal gyrus, and the caudate nucleus. Our findings suggest that an increase in coupling between visuomotor regions, reflecting higher efficiency of processing, is an important neural mechanism underlying unconscious visuomotor priming, in addition to changes in the magnitude of activation. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
    Full-text · Article · Apr 2015 · Cerebral Cortex
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    • "Repeated object classification leads to decreased neural responses in the prefrontal cortex and temporal cortex. This decrease in absolute activity is accompanied by greater neural synchrony between these regions with repetition (Ghuman et al., 2008). Several researchers have suggested that this neural synchrony in the brain reflects structures in the stimulus environment (Friston, 2011; Brette, 2012). "
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    • "This hypothesis posits that behavioral facilitation is a consequence of an increase in synchronous activity, despite a decrease in the overall firing rate of neurons [Gotts, 2003]. In support of this hypothesis, MEG studies have found that repeated stimulus presentations increase local [Gilbert et al., 2010] and inter-regional coherence [Ghuman et al., 2008] in the alpha band. Our study does not include a behavior component, and thus does not speak directly to the repetition suppression/priming paradox. "
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