Article

Modulation of Brain Resting-State Networks by Sad Mood Induction

Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Victoria, Australia.
PLoS ONE (Impact Factor: 3.23). 02/2008; 3(3):e1794. DOI: 10.1371/journal.pone.0001794
Source: PubMed

ABSTRACT

There is growing interest in the nature of slow variations of the blood oxygen level-dependent (BOLD) signal observed in functional MRI resting-state studies. In humans, these slow BOLD variations are thought to reflect an underlying or intrinsic form of brain functional connectivity in discrete neuroanatomical systems. While these 'resting-state networks' may be relatively enduring phenomena, other evidence suggest that dynamic changes in their functional connectivity may also emerge depending on the brain state of subjects during scanning.
In this study, we examined healthy subjects (n = 24) with a mood induction paradigm during two continuous fMRI recordings to assess the effects of a change in self-generated mood state (neutral to sad) on the functional connectivity of these resting-state networks (n = 24). Using independent component analysis, we identified five networks that were common to both experimental states, each showing dominant signal fluctuations in the very low frequency domain (approximately 0.04 Hz). Between the two states, we observed apparent increases and decreases in the overall functional connectivity of these networks. Primary findings included increased connectivity strength of a paralimbic network involving the dorsal anterior cingulate and anterior insula cortices with subjects' increasing sadness and decreased functional connectivity of the 'default mode network'.
These findings support recent studies that suggest the functional connectivity of certain resting-state networks may, in part, reflect a dynamic image of the current brain state. In our study, this was linked to changes in subjective mood.

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    • "Similar to the majority of studies on BOLD signal, a low-pass filter was set at 0.1 Hz to eliminate frequencies generated by physiological mechanisms (Fox and Raichle, 2007). A high-pass filter was also set at 0.008 Hz to remove low-frequency drift, as carried out in other studies (e.g. Harrison et al., 2008). Finally, band-pass filtered volumes were smoothed with a 6 mm 3 full-width at half maximum gaussian kernel to account for any possible inter-subject differences remaining after normalization, and to improve signal-to-noise ratio. "
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    ABSTRACT: A cognitive-stimulation tool was created to regulate functional connectivity within the brain Default-Mode Network (DMN). Computerised exercises were designed based on the hypothesis that repeated task-dependent coactivation of multiple DMN regions would translate into regulation of resting-state network connectivity. Forty seniors (mean age: 65.90 years; SD: 8.53) were recruited and assigned either to an experimental group (n=21) who received one month of intensive cognitive stimulation, or to a control group (n=19) who maintained a regime of daily-life activities explicitly focused on activities based on social interactions. An MRI protocol and a battery of neuropsychological tests were administered at baseline and at the end of the study. Changes in the DMN (measured via functional connectivity of posterior-cingulate seeds), in brain volumes, and in cognitive performance were measured with mixed models assessing group-by-timepoint interactions. Moreover, regression models were run to test grey-matter correlates of the various stimulation tasks. Significant associations were found between task performance and grey-matter volume of multiple DMN core regions. Training-dependent up-regulation of functional connectivity was found in the posterior DMN subcomponent. This interaction was driven by a pattern of increased connectivity in the training group, while little or no up-regulation was seen in the control group. Minimal changes in brain volumes, but no change in cognitive performance were found. The training-dependent regulation of functional connectivity within the posterior DMN subcomponent suggests that this stimulation programme might exert a beneficial impact with regard to prevention and treatment of early AD neurodegeneration, in which this neurofunctional pathway is progressively affected by the disease.
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    • "Waites et al. demonstrated that FC maps, derived from a resting-state scan acquired directly after a language task, capture a combination of static and transient synchrony between brain states (Waites et al. 2005). Moreover, mood and cognitive state of a person are strongly modulated by external social as well as emotional stimuli (Harrison et al. 2008). The perception of a situation, and thus also the brain's dynamic response to it, however, depend not only on current mood and cognitive load but also on personal experiences from the past, which have shaped how individuals react to social-emotional stimuli (Davidson 1998). "

    Full-text · Dataset · Sep 2015
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    • "Waites et al. demonstrated that FC maps, derived from a resting-state scan acquired directly after a language task, capture a combination of static and transient synchrony between brain states (Waites et al. 2005). Moreover, mood and cognitive state of a person are strongly modulated by external social as well as emotional stimuli (Harrison et al. 2008). The perception of a situation, and thus also the brain's dynamic response to it, however, depend not only on current mood and cognitive load but also on personal experiences from the past, which have shaped how individuals react to social-emotional stimuli (Davidson 1998). "
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    ABSTRACT: Introduction: To understand the interplay between affective social information processing and its influence on mental states we investigated changes in functional connectivity (FC) patterns after audio exposure to emotional biographic narratives. Methods: While lying in the 7T MR scanner, 23 male participants listened to narratives of early childhood experiences of three persons, each having either a secure, dismissing, or preoccupied attachment representation. Directly after having listened to each of the prototypical narratives, participants underwent a 10-minute resting-state fMRI scan. To study changes in FC patterns between experimental conditions, three post-task conditions were compared to a baseline condition. Specific local alterations, as well as differences in connectivity patterns between distributed brain regions, were quantified using Network-based statistics (NBS) and graph metrics. Results: Using NBS, a nine-region subnetwork showing reduced FC after having listened to the dismissing narrative was identified. Of this subnetwork, only the left Supplementary Motor Area (SMA) exhibited a decrease in the nodal graph metrics degree and strength exclusively after listening to the dismissing narrative. No other region showed post-task changes in nodal metrics. A post hoc analysis of dynamic characteristics of FC of the left SMA showed a significant decrease in the dismissing condition when compared with the other conditions in the first three minutes of the scan, but faded away in the two subsequent intervals the differences. Conclusions: Nodal metrics and NBS converge on reduced connectivity measures exclusively in left SMA in the dismissing condition, which may specifically reflect ongoing network changes underlying prolonged emotional reactivity to attachment-related processing.
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