ORCID Profile
0000-0002-9946-3704
Current Organisations
University of Bergen
,
UiT Norges arktiske universitet
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Publisher: Informa UK Limited
Date: 04-05-2023
Publisher: Center for Open Science
Date: 03-04-2018
Abstract: Understanding the association between autonomic nervous system [ANS] function and brain morphology across the lifespan provides important insights into neurovisceral mechanisms underlying health and disease. Resting state ANS activity, indexed by measures of heart rate [HR] and its variability [HRV] has been associated with brain morphology, particularly cortical thickness [CT]. While findings have been mixed regarding the anatomical distribution and direction of the associations, these inconsistencies may be due to sex and age differences in HR/HRV and CT. Previous studies have been limited by small s le sizes, which impede the assessment of sex differences and aging effects on the association between ANS function and CT. To overcome these limitations, 20 groups worldwide contributed data collected under similar protocols of CT assessment and HR/HRV recording to be pooled in a mega-analysis (N = 1,218 (50.5% female), mean age 36.7 years (range: 12-87)). Findings suggest that the decline in HRV with increasing age is related to a decline in prefrontal CT, particularly in the orbitofrontal cortex. These effects were independent of sex and specific to HRV with no significant association between CT and HR. Greater CT across the adult lifespan may be vital for the maintenance of healthy cardiac regulation via the ANS. Nonetheless, in the absence of longitudinal data, alternative explanations need to be considered. Findings reveal an important association between cortical thickness and cardiac parasympathetic activity with implications for healthy aging and longevity.
Publisher: Informa UK Limited
Date: 27-06-2021
Publisher: Wiley
Date: 03-02-2015
DOI: 10.1002/HBM.22753
Publisher: MDPI AG
Date: 12-10-2022
Abstract: Background: Transcranial direct current stimulation (tDCS) is used as treatment for auditory verbal hallucinations (AVH). The theory behind the treatment is that tDCS increases activity in prefrontal cognitive control areas, which are assumed to be hypoactive, and simultaneously decreases activity in temporal speech perception areas, which are assumed to be hyperactive during AVH. We tested this hypofrontal/hypertemporal reversal theory by investigating anatomical, neurotransmitter, brain activity, and network connectivity changes over the course of tDCS treatment. Methods: A double-blind, randomized controlled trial was conducted with 21 patients receiving either sham or real tDCS treatment (2 mA) twice daily for 5 days. The anode was placed over the left dorsolateral prefrontal cortex (DLPFC) and the cathode over the left temporo-parietal cortex (TPC). Multimodal neuroimaging as well as clinical and neurocognitive functioning assessment were performed before, immediately after, and three months after treatment. Results: We found a small reduction in AVH severity in the real tDCS group, but no corresponding neuroimaging changes in either DLPFCD or TPC. Limitations: The study has a small s le size. Conclusion: The results suggest that the currently leading theory behind tDCS treatment of AVH may need to be revised, if confirmed by studies with larger N. Tentative findings point to the involvement of Broca’s area as a critical structure for tDCS treatment.
Publisher: Wiley
Date: 27-04-2015
DOI: 10.1111/PSYP.12445
Abstract: Mismatch negativity (MMN), an ERP elicited by a deviant stimulus in a train of standard stimuli, has been suggested to be associated to glutamatergic neurotransmission, mediated by glutamatergic NMDA receptors. In this study, we examined the relationship between interin idual variation of (1)H-MRS-measured glutamate+glutamine (Glx) in the superior temporal gyrus and MMN for duration and frequency deviants in 19 healthy young adults (9 male). We found a significant relationship between the peak latency of the duration-MMN peak and creatine-scaled Glx (p = .0003, η(2) = .43), with increased Glx level being associated to earlier peak of the duration-MMN (r = -.63). In contrast, the litude of the duration-MMN was not related to Glx. There was no significant relationship between Glx and the frequency-MMN. The present study is the first to demonstrate that interin idual variation in the glutamatergic neurotransmission affects the MMN response in healthy in iduals.
Publisher: Wiley
Date: 25-08-2020
DOI: 10.1111/EJN.14932
No related grants have been discovered for Karsten Specht.