| 1. |
- Bengtsson, Johan, et al.
(författare)
-
Autonomic modulation networks in schizophrenia : The relationship between heart rate variability and functional and structural connectivity in the brain
- 2020
-
Ingår i: Psychiatry Research. - : Elsevier BV. - 0925-4927 .- 1872-7506. ; 300
-
Tidskriftsartikel (refereegranskat)abstract
- Heart rate variability (HRV), a measurement of autonomic nervous system (ANS) activity, has been found reduced in schizophrenia. The anterior cingulate cortex (ACC), which is important in regulating the ANS, is structurally and functionally affected in schizophrenia. We investigate the relationship between HRV and functional and structural connectivity of the ACC in patients with schizophrenia and healthy controls. Ten patients with a diagnosis of schizophrenia and ten healthy controls were recruited. Heart rate was monitored in a naturalistic out-of-clinic setting. Magnetic resonance imaging (MRI) was performed, including resting-state functional MRI and diffusion tensor imaging. Patients with schizophrenia had significantly lower HRV compared to controls. A positive correlation between ACC connectivity with the bilateral cerebellum and HRV was found in the patients. HRV was also positively correlated with amplitude of low frequency fluctuations (ALFF) in the cerebellum, and with axial diffusivity in the middle cerebellar peduncle, in the patients. There was a significant negative relationship between antipsychotic medication dosage, HRV and all neuroimaging measures related to HRV. We conclude that ACC connectivity seems to be affected in schizophrenia, both structurally and functionally, and that the ACC-cerebellum connectivity, as well as cerebellar function, is associated with ANS regulation in patients with schizophrenia.
|
|
| 2. |
- Persson, Jonas, 1983-, et al.
(författare)
-
Inhibitory and excitatory neurotransmitter systems in depressed and healthy : A positron emission tomography and magnetic resonance spectroscopy study
- 2021
-
Ingår i: Psychiatry Research. - : Elsevier. - 0925-4927 .- 1872-7506. ; 315
-
Tidskriftsartikel (refereegranskat)abstract
- The Gamma-aminobutyric acid (GABA) and glutamate (Glu) neurotransmitter systems are implicated in depression. While previous studies found reduced GABA levels, and a tendency towards reduced Glu, using proton (H-1) magnetic resonance spectroscopy (H-1-MRS), little is known about GABA(A) receptor availability in depression. Here, the aim was to characterize GABA and Glu-levels in dorsal anterior cingulate cortex (dACC), whole-brain GABA(A) availability, and their relationship in patients with depression compared to healthy controls. Forty-two patients and 45 controls underwent H-1-MRS using a MEGA-PRESS sequence to quantify dACC GABA+ and Glu (contrasted against creatine [Cr]). Immediately preceding the H-1-MRS, a subsample of 28 patients and 15 controls underwent positron emission tomography (PET) with [C-11]Flumazenil to assess whole-brain GABA(A) receptor availability. There were no differences in dACC GABA+/Cr or Glu/Cr ratios between patients and controls. The same was true for whole-brain GABA(A) receptor availability. However, there was a significant negative relationship between GABA+/Cr ratio and receptor availability in ACC, in a whole-brain voxel-wise analysis across patients and controls, controlling for group or depressive symptoms. This relatively large study did not support the GABA-deficit hypothesis in depression, but shed light on GABA-system functioning, suggesting a balance between neurotransmitter concentration and receptor availability in dACC.
|
|
| 3. |
- Persson, Jonas, 1983-, et al.
(författare)
-
Intermittent theta burst stimulation over the dorsomedial prefrontal cortex modulates resting-state connectivity in depressive patients : A sham-controlled study
- 2020
-
Ingår i: Behavioural Brain Research. - : Elsevier BV. - 0166-4328 .- 1872-7549. ; 394
-
Tidskriftsartikel (refereegranskat)abstract
- The mechanisms underlying repetitive transcranial magnetic stimulation (rTMS) treatment are largely unknown. Although there is a general lack of sham controlled studies, findings show altered functional connectivity to the stimulated region following treatment. When targeting the dorsolateral prefrontal cortex (dlPFC), connectivity with the subgenual anterior cingulate cortex (sgACC) is predictive of response, but less is known about the effects on functional connectivity of targeting the dorsomedial PFC (dmPFC). Here, 30 patients with an ongoing depressive episode were recruited and randomized to 20 sessions at target intensity of either active or sham intermittent theta burst stimulation (iTBS) over dmPFC. Those receiving sham were offered active treatment in a subsequent open phase. A seven minute resting-state scan and depressive symptom assessment was performed before and after treatment. After exclusions due to attrition and excessive head movements 23 patients remained for analysis. Seed-based resting-state connectivity was calculated using two seeds for the dmPFC target as well as the sgACC. A symptom related increase in dmPFC connectivity after active treatment, compared to sham treatment, was found. The effect was observed in a region overlapping the precuneus and the posterior cingulate cortex (PCC), suggesting an increase in the connectivity between the targeted salience network and the default mode network mediating improvement in depressive symptoms. Connectivity between the precuneus and both the sgACC and the treatment target was predictive of symptom improvement following active treatment. The findings have implications for understanding the mechanisms behind iTBS and may inform future efforts to individualize the treatment.
|
|
| 4. |
- Struckmann, Wiebke, et al.
(författare)
-
Modulation of dorsolateral prefrontal cortex functional connectivity after intermittent theta-burst stimulation in depression : combining findings from fNIRS and fMRI
- 2022
-
Ingår i: NeuroImage. - : Elsevier. - 2213-1582. ; 34
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Resting-state functional magnetic resonance imaging (fMRI) can assess modulation of functional connectivity networks following repetitive transcranial magnetic stimulation (rTMS) in the treatment of depression. Functional near-infrared spectroscopy (fNIRS) is well suited for the concurrent application during rTMS treatment sessions to capture immediate blood oxygenation (oxy-Hb) effects, however limited in spatial resolution.Objective: To understand the network effects behind such a prefrontal fNIRS response during rTMS, and to test whether the fNIRS signal may be predictive of treatment response, we linked data from fNIRS and fMRI within a clinical intervention study.Methods: 42 patients with ongoing depression were recruited and randomized to receive active or sham intermittent theta-burst stimulation (iTBS) over the dorsomedial prefrontal cortex (dmPFC) twice daily for ten days at target intensity. Oxy-Hb was recorded with fNIRS during the first, fifth, and final day of iTBS, with the probe holders located laterally to the TMS coil over regions corresponding to the left and right dorsolateral prefrontal cortex (dlPFC). Resting-state fMRI scanning was performed before and after the whole iTBS treatment course. Functional connectivity analyses were then performed using dlPFC seeds from parcels of a brain atlas showing most overlap with the fNIRS probe locations during treatment.Results: After active iTBS, left dlPFC-connectivity to the right insula/operculum was reduced compared to sham. The left insula showed a connectivity reduction to the left dlPFC that correlated with an improvement in symptoms. In addition, the posterior parietal cortex showed a connectivity reduction to the left dlPFC that correlated with the fNIRS signal following active iTBS. Finally, the fNIRS oxy-Hb signal from the left dlPFC-seed during the first treatment day was predictive of dlPFC-connectivity change to precentral and temporal cortex regions.Conclusion: By linking findings from these two different methods, this study suggests that changes within both the salience network and the central executive network affect the fNIRS response to iTBS.
|
|
| 5. |
- Struckmann, Wiebke, et al.
(författare)
-
Modulation of the prefrontal blood oxygenation response to intermittent theta-burst stimulation in depression : A sham-controlled study with functional near-infrared spectroscopy
- 2021
-
Ingår i: World Journal of Biological Psychiatry. - : Informa UK Limited. - 1562-2975 .- 1814-1412. ; 22:4, s. 247-256
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To better understand the neural mechanisms behind the effect of intermittent theta-burst stimulation (iTBS), we investigated how the prefrontal blood oxygenation response measured by changes in oxygenated haemoglobin (oxy-Hb) was modulated during a sham-controlled iTBS treatment course, and whether this was related to depressive symptom change.METHODS: In this randomised, double-blind study, patients with ongoing treatment-resistant depression received either active (n = 18) or sham (n = 21) iTBS over the dorsomedial prefrontal cortex for ten to fifteen days with two sessions daily. Event-related functional near-infrared spectroscopy (fNIRS) was measured during each iTBS train, and resting-state oxy-Hb was compared before and after each iTBS session at the first, fifth, and last treatment day.RESULTS: Patients receiving active iTBS had an increase of the event-related oxy-Hb response compared to the sham group on the fifth (bilateral prefrontal cortices p < .001) and last (left prefrontal p = .007, right prefrontal p = .025) treatment day. Resting-state analysis showed suppressed oxy-Hb change in active iTBS compared to sham iTBS on the last treatment day (p = .024). Oxy-Hb change was unrelated to depressive symptom change (p = .474).CONCLUSIONS: This study describes a modulation of the blood oxygenation response over the prefrontal cortex that was built up during the course of active iTBS treatment in depression.
|
|
