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


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.

Download full-text


Available from: David M Schnyer,
  • Source
    • "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. "
    [Show abstract] [Hide abstract]
    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:
    Cerebral Cortex 04/2015; DOI:10.1093/cercor/bhv070 · 8.67 Impact Factor
  • Source
    • "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. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In functional MRI studies, repetition suppression refers to the reduction of hemodynamic activation to repeated stimulus presentation. For example, the repeated presentation of a face reduces the hemodynamic response evoked by faces in the fusiform gyrus. The neural events that underlie repetition suppression are not well understood. Indeed, in contrast to the hemodynamic response, the face-specific N200 recorded from subdural electrodes on the ventral occipitotemporal cortex, primarily along the fusiform gyrus, has been reported to be insensitive to face-identity repetition. We have previously described a face-specific broadband gamma (30-100 Hz) response at ventral face-specific N200 sites that is functionally dissociable from the N200. In this study, we investigate whether gamma and other components of the electroencephalogram spectrum are affected by face-identity repetition independently of the N200. Participants viewed sequentially presented identical faces. At sites on and around the fusiform gyrus, we found that face repetition modulated alpha (8-12 Hz), low-gamma (30-60 Hz), and high-gamma (60-100 Hz) synchrony, but not the N200. These findings provide evidence of a spatially co-localized progression of face processing. Whereas the N200 reflects an initial obligatory response that is less sensitive to face-identity repetition, the subsequent spectral fluctuations reflect more elaborative face processing and are thus sensitive to face novelty. It is notable that the observed modulations were different for different frequency bands. We observed repetition suppression of broadband gamma, but repetition enhancement of alpha synchrony. This difference is discussed with regard to an existing model of repetition suppression and behavioral repetition priming. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
    Human Brain Mapping 08/2014; 35(8). DOI:10.1002/hbm.22467 · 5.97 Impact Factor
  • Source
    • ") that there is a temporal offset between our observed STS beta-band activity and related frontolimbic responses supports the existence of a possible feed-forward/feed-back mechanism within these pathways during visual emotion processing (Ledoux 1998; Karnath 2001), but a more complete understanding of this possibility will require further quantitative exploration, such as assessing inter-regional beta-band phase-locking (Fenske et al. 2006; Jensen and Colgin 2007; Ghuman et al. 2008; Penny et al. 2008; Hipp et al. 2011; Kveraga et al. 2011). Our results suggest a more distributed and tightly interwoven neuronal representation of human facial emotion expressions than previously appreciated; however, we cannot rule out the influence of a common driver effect on our observed correlations among STS and related frontolimbic beta-band signals. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The processing of social information in the human brain is widely distributed neuroanatomically and finely orchestrated over time. However, a detailed account of the spatiotemporal organization of these key neural underpinnings of human social cognition remains to be elucidated. Here, we applied functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) in the same participants to investigate spatial and temporal neural patterns evoked by viewing videos of facial muscle configurations. We show that observing the emergence of expressions elicits sustained blood oxygenation level-dependent responses in the superior temporal sulcus (STS), a region implicated in processing meaningful biological motion. We also found corresponding event-related changes in sustained MEG beta-band (14-30 Hz) oscillatory activity in the STS, consistent with the possible role of beta-band activity in visual perception. Dynamically evolving fearful and happy expressions elicited early (0-400 ms) transient beta-band activity in sensorimotor cortex that persisted beyond 400 ms, at which time it became accompanied by a frontolimbic spread (400-1000 ms). In addition, individual differences in sustained STS beta-band activity correlated with speed of emotion recognition, substantiating the behavioral relevance of these signals. This STS beta-band activity showed valence-specific coupling with the time courses of facial movements as they emerged into full-blown fearful and happy expressions (negative and positive coupling, respectively). These data offer new insights into the perceptual relevance and orchestrated function of the STS and interconnected pathways in social-emotion cognition.
    Cerebral Cortex 01/2014; 25(7). DOI:10.1093/cercor/bht427 · 8.67 Impact Factor
Show more