Article

Early onset of neural synchronization in the contextual associations network

Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA 02129, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 02/2011; 108(8):3389-94. DOI: 10.1073/pnas.1013760108
Source: PubMed

ABSTRACT

Objects are more easily recognized in their typical context. However, is contextual information activated early enough to facilitate the perception of individual objects, or is contextual facilitation caused by postperceptual mechanisms? To elucidate this issue, we first need to study the temporal dynamics and neural interactions associated with contextual processing. Studies have shown that the contextual network consists of the parahippocampal, retrosplenial, and medial prefrontal cortices. We used functional MRI, magnetoencephalography, and phase synchrony analyses to compare the neural response to stimuli with strong or weak contextual associations. The context network was activated in functional MRI and preferentially synchronized in magnetoencephalography (MEG) for stimuli with strong contextual associations. Phase synchrony increased early (150-250 ms) only when it involved the parahippocampal cortex, whereas retrosplenial-medial prefrontal cortices synchrony was enhanced later (300-400 ms). These results describe the neural dynamics of context processing and suggest that context is activated early during object perception.

Download full-text

Full-text

Available from: Maximilien Chaumon
  • Source
    • "Moshe Bar's " visual prediction theory " is consistent with perception–action coupling in the visual domain and points to specific cortical areas likely central to differentiating experts from novices. Specifically , Bar (Bar, 2009a,b; Cheung and Bar, 2012; Kveraga et al., 2011) notes the role of the orbitofrontal cortex (OFC) in multimodal associations and links this capability with heightened prediction capability in visual experts. He furthermore provides evidence that the OFC is part of a larger visual expertise network that includes the fusiform face area (FFA). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Given a decision that requires less than half a second for evaluating the characteristics of the incoming pitch and generating a motor response, hitting a baseball potentially requires unique perception-action coupling to achieve high performance. We designed a rapid perceptual decision making experiment modeled as a Go/No-Go task, yet tailored to reflect a real scenario confronted by a baseball hitter. For groups of experts (Division I baseball players) and novices (non-players) we recorded electroencephalography (EEG) while they performed the task. We analyzed evoked EEG single-trial variability, contingent negative variation (CNV), and pre-stimulus alpha power with respect to the expert vs. novice groups. We found strong evidence for differences in inhibitory processes between the two groups, specifically differential activity in supplementary motor areas (SMA), indicative of enhanced inhibitory control in the expert (baseball player) group. We also found selective activity in the fusiform gyrus (FG) and orbital gyrus in the expert group, suggesting an enhanced perception-action coupling in baseball players that differentiates them from matched controls. In sum, our results show that EEG correlates of decision formation can be used to identify neural markers of high-performance athletes. Copyright © 2015. Published by Elsevier Inc.
    Full-text · Article · Aug 2015 · NeuroImage
  • Source
    • "The functional architecture of the cerebral cortex includes regions and networks of regions that become active at different times. The temporal profiles range from brief activity during specific tasks, such as processing of individual visual percepts (Kveraga et al., 2011), to extended periods of resting state in the absence of external stimuli, when the brain is suspected to engage in activities such as memory encoding (Buckner et al., 2008). "
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper we construct an atlas that summarizes functional connectivity characteristics of a cognitive process from a population of individuals. The atlas encodes functional connectivity structure in a low-dimensional embedding space that is derived from a diffusion process on a graph that represents correlations of fMRI time courses. The functional atlas is decoupled from the anatomical space, and thus can represent functional networks with variable spatial distribution in a population. In practice the atlas is represented by a common prior distribution for the embedded fMRI signals of all subjects. We derive an algorithm for fitting this generative model to the observed data in a population. Our results in a language fMRI study demonstrate that the method identifies coherent and functionally equivalent regions across subjects. The method also successfully maps functional networks from a healthy population used as a training set to individuals whose language networks are affected by tumors.
    Preview · Article · Aug 2014 · NeuroImage
  • Source
    • "Tentatively, such sensorimotor integration could be enabled by oscillatory synchrony, i.e., rhythmic millisecond-range temporal correlations of neuronal activity (Womelsdorf et al., 2007; Singer, 2009). Previous MEG and EEG studies have revealed that the level of inter-areal phase synchrony within the alpha (8–14 Hz), beta (14–30 Hz) and gamma (30–80 Hz) frequency bands correlates with various perceptual, attention, and working memory task performances (Kujala et al., 2007; Palva et al., 2010; Hipp et al., 2011; Kveraga et al., 2011; Huang et al., 2014), therefore supporting the hypothesis that coordinated operation between task-relevant brain regions is reflected as strengthened oscillatory synchrony (for a review, see Palva and Palva, 2012). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The cortical dorsal auditory stream has been proposed to mediate mapping between auditory and articulatory-motor representations in speech processing. Whether this sensorimotor integration contributes to speech perception remains an open question. Here, magnetoencephalography was used to examine connectivity between auditory and motor areas while subjects were performing a sensorimotor task involving speech sound identification and overt repetition. Functional connectivity was estimated with inter-areal phase synchrony of electromagnetic oscillations. Structural equation modeling was applied to determine the direction of information flow. Compared to passive listening, engagement in the sensorimotor task enhanced connectivity within 200 ms after sound onset bilaterally between the temporoparietal junction (TPJ) and ventral premotor cortex (vPMC), with the left-hemisphere connection showing directionality from vPMC to TPJ. Passive listening to noisy speech elicited stronger connectivity than clear speech between left auditory cortex (AC) and vPMC at ~100 ms, and between left TPJ and dorsal premotor cortex (dPMC) at ~200 ms. Information flow was estimated from AC to vPMC and from dPMC to TPJ. Connectivity strength among the left AC, vPMC, and TPJ correlated positively with the identification of speech sounds within 150 ms after sound onset, with information flowing from AC to TPJ, from AC to vPMC, and from vPMC to TPJ. Taken together, these findings suggest that sensorimotor integration mediates the categorization of incoming speech sounds through reciprocal auditory-to-motor and motor-to-auditory projections.
    Full-text · Article · May 2014 · Frontiers in Psychology
Show more