Browsing by Subject "DEFAULT-MODE NETWORK"

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  • Komulainen, Emma; Heikkila, Roope; Meskanen, Katarina; Raij, Tuukka T.; Nummenmaa, Lauri; Lahti, Jari; Jylhä, Pekka; Melartin, Tarja; Harmer, Catherine J.; Isometsa, Erkki; Ekelund, Jesper (2016)
    Increased self-focus is a core factor in the psychopathology of depression. Cortical midline structures (CMS) are implicated in the neurobiology of self, depression and antidepressant treatment response. Mirtazapine, an antidepressant that increases serotonin and norepinephrine release, enhances processing of positive and attenuates processing of negative emotional information in healthy volunteers after a single dose. These early changes, which are opposite to the negative information bias in depression, may be important for the therapeutic effect of mirtazapine. It nevertheless remains unresolved whether/how mirtazapine specifically influences processing of self-referential emotional information. Half of the healthy volunteers (n=15/30) received a single dose of mirtazapine, in an open-label design, two hours before functional magnetic resonance imaging (fMRI), and the other half was scanned as a control group without medication. During fMRI the participants categorized positive and negative self-referential adjectives. Mirtazapine attenuated responses to self-referential processing in the medial prefrontal cortex and the anterior cingulate cortex. Mirtazapine further decreased responses to positive self-referential processing in the posterior cingulate cortex and parietal cortex. These decreased responses of the CMS suggest that mirtazapine may rapidly improve the ability of the CMS to down-regulate self-referential processing. In depressed patients, this could lead to decreased self-focus and rumination, contributing to the antidepressant effect.
  • Komulainen, Emma; Heikkila, Roope; Meskanen, Katarina; Raij, Tuukka T.; Nummenmaa, Lauri; Lahti, Jari; Jylhä, Pekka; Melartin, Tarja; Harmer, Catherine J.; Isometsa, Erkki; Ekelund, Jesper (SAGE SCIENCE PRESS (UK), 2016)
    Increased self-focus is a core factor in the psychopathology of depression. Cortical midline structures (CMS) are implicated in the neurobiology of self, depression and antidepressant treatment response. Mirtazapine, an antidepressant that increases serotonin and norepinephrine release, enhances processing of positive and attenuates processing of negative emotional information in healthy volunteers after a single dose. These early changes, which are opposite to the negative information bias in depression, may be important for the therapeutic effect of mirtazapine. It nevertheless remains unresolved whether/how mirtazapine specifically influences processing of self-referential emotional information. Half of the healthy volunteers (n=15/30) received a single dose of mirtazapine, in an open-label design, two hours before functional magnetic resonance imaging (fMRI), and the other half was scanned as a control group without medication. During fMRI the participants categorized positive and negative self-referential adjectives. Mirtazapine attenuated responses to self-referential processing in the medial prefrontal cortex and the anterior cingulate cortex. Mirtazapine further decreased responses to positive self-referential processing in the posterior cingulate cortex and parietal cortex. These decreased responses of the CMS suggest that mirtazapine may rapidly improve the ability of the CMS to down-regulate self-referential processing. In depressed patients, this could lead to decreased self-focus and rumination, contributing to the antidepressant effect.
  • Kauttonen, Janne; Hlushchuk, Yevhen; Jaaskelainen, Iiro P.; Tikka, Pia (2018)
    How does the human brain recall and connect relevant memories with unfolding events? To study this, we presented 25 healthy subjects, during functional magnetic resonance imaging, the movie 'Memento' (director C. Nolan). In this movie, scenes are presented in chronologically reverse order with certain scenes briefly overlapping previously presented scenes. Such overlapping "key-frames" serve as effective memory cues for the viewers, prompting recall of relevant memories of the previously seen scene and connecting them with the concurrent scene. We hypothesized that these repeating key-frames serve as immediate recall cues and would facilitate reconstruction of the story piece-by-piece. The chronological version of Memento, shown in a separate experiment for another group of subjects, served as a control condition. Using multivariate event-related pattern analysis method and representational similarity analysis, focal fingerprint patterns of hemodynamic activity were found to emerge during presentation of key-frame scenes. This effect was present in higher-order cortical network with regions including precuneus, angular gyrus, cingulate gyrus, as well as lateral, superior, and middle frontal gyri within frontal poles. This network was right hemispheric dominant. These distributed patterns of brain activity appear to underlie ability to recall relevant memories and connect them with ongoing events, i.e., "what goes with what" in a complex story. Given the real-life likeness of cinematic experience, these results provide new insight into how the human brain recalls, given proper cues, relevant memories to facilitate understanding and prediction of everyday life events.
  • Rikandi, Eva; Mantyla, Teemu; Lindgren, Maija; Kieseppa, Tuula; Suvisaari, Jaana; Raij, Tuukka T. (2018)
    Background: Functional connectivity is altered in psychotic disorders. Multiple findings concentrate on the default mode network, anchored on the precuneus-posterior cingulate cortex (PC-PCC). However, the nature of the alterations varies between studies and connectivity alterations have not been studied during an ecologically valid natural stimulus. In the present study, we investigated the functional and structural connectivity of a PC-PCC region, where functioning differentiated first-episode psychosis patients from control subjects during free viewing of a movie in our earlier study. Methods: 14 first-episode psychosis patients and 12 control subjects were imaged with GE 3T, and 29 patients and 19 control subjects were imaged with a Siemens Skyra 3T scanner while watching scenes from the movie Alice in Wonderland. Group differences in functional connectivity were analysed for both scanners separately and results were compared to identify any overlap. Diffusion tensor measures of 26 patients and 19 control subjects were compared for the related white matter tracts, identified by deterministic tractography. Results: Functional connectivity was increased in patients across scanners between the midline regions of the PC-PCC and the anterior cingulate cortex-medial prefrontal cortex (ACC-mPFC). We found no group differences in any of the diffusion tensor imaging measures. Conclusions: Already in the early stages of psychosis functional connectivity between the midline structures of the PC-PCC and the ACC-mPFC is consistently increased during naturalistic stimulus. (c) 2018 Elsevier B.V. All rights reserved.
  • Kullberg-Turtiainen, Marjo; Vuorela, Kaisa; Huttula, Lilli; Turtiainen, Petri; Koskinen, Sanna (2019)
    Few long-term studies report late outcomes after severe traumatic brain injury. New rehabilitation techniques are needed for this heterogenous patient group. We present a dance intervention six and half years after an extreme severe TBI including excessive diffuse axonal injury, which disconnects the brain networks. Given the fact, that efficient brain function depends on the integrated operation of large-scale brain networks like default mode network (DMN), we created an intervention with multisensory and multimodal approach and goal-directed behavior. The intervention lasted four months including weekly one-hour dance lessons with the help of a physiotherapist and dance teacher. The measures included functional independence measure (FIM), repeated electroencephalogram (EEG) analysis of three subnets of DMN and clinical evaluations and observations. The results showed clear improvement after the intervention, and FIM stayed in elevated level during several years after the intervention. We present suggestion for further studies using larger patient groups.
  • Komulainen, Emma; Heikkilä, Roope; Nummenmaa, Lauri; Raij, Tuukka T.; Harmer, Catherine J.; Isometsä, Erkki; Ekelund, Jesper (2018)
    Background: Increased self-focus and negative self-concept play an important role in depression. Antidepressants influence self-referential processing in healthy volunteers, but their function in self-processing of depressed patients remains unknown. Methods: Thirty-two depressed patients were randomly allocated to receive either escitalopram 10 mg or placebo for one week. After one week, neural responses to positive and negative self-referential adjectives and neutral control stimuli were assessed with functional magnetic resonance imaging. A group of matched healthy volunteers served as a control group. Results: Escitalopram decreased responses of medial fronto-parietal regions to self-referential words relative to non-emotional control stimuli, driven by increased responses to the control condition. Escitalopram also increased responses in the pre-defined region of the medial prefrontal cortex (MPFC) and the anterior cingulate cortex (ACC) to positive relative to negative words. Importantly, the changes in neural responses occurred before any effect on depressive symptoms, implying a direct effect of escitalopram. Furthermore, the placebo group had decreased responses of the MPFC and the ACC to positive self-referential processing relative to the matched healthy controls. However, neural responses of the escitalopram group and the healthy unmedicated controls were similar. Limitations: Differences between the groups in self-reported depression symptoms and personality traits may have influenced the results. Conclusion: One-week treatment with escitalopram normalized aberrant self-referential processing in depressed patients, shifting the focus from the self to the external environment and potentiating positive self-referential processing. This may be an important factor in mechanism of action of antidepressants.