Modulation of default-mode network activity by acute tryptophan depletion is associated with mood change: a resting state functional magnetic resonance imaging study.
ABSTRACT Recently, resting-state fMRI (R-fMRI) has attracted interest based on its ability to detect the default mode network. We examined the effect of acute tryptophan depletion (ATD) on the fractional amplitude of low-frequency fluctuation (fALFF) during the resting state, and the correlation between changes of mood and fALFF following ATD. We manipulated the central serotonergic levels of 21 right-handed healthy males (mean age=21.57±1.83 years) following ATD. A within-subjects, double-blind, placebo-controlled, and counter-balanced design was employed. Following ATD or sham depletion, subjects completed the Profile of Mood States (POMS) and underwent 5-min R-fMRI scans. Our findings show that the fALFF of the middle orbitofrontal cortex and precuneus was significantly decreased and the fALFF of the superior parietal lobule, paracentral lobule and precentral gyrus was significantly increased after ATD. The fALFF of the orbitofrontal cortex was negatively correlated with depressive mood. The fALFF of the superior parietal lobule was positively correlated with anger-hostility and the fALFF of the paracentral lobule was negatively correlated with vigor-activity. The middle orbitofrontal cortex plays a key role in serotonin depletion-induced brain changes and individual differences in depressive mood change. These results serve to further elucidate the mechanism of ATD-induced relapse in remitted MDD patients.
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ABSTRACT: Background. Fat affects gastric emptying (GE). 5-Hydroxythryptophan (5-HTP) is involved in central and peripheral satiety mechanisms. Influence of 5-HTP in addition to saturated or monounsaturated fatty acids (FA) on GE and hormone release was investigated. Subjects/Methods. 24 healthy individuals (12f : 12m, 22-29 years, BMI 19-25.7 kg/m²) were tested on 4 days with either 5-HTP + short-chain saturated FA (butter), placebo + butter, 5-HTP + monounsaturated FA (olive oil), or placebo + olive oil in double-blinded randomized order. Two hours after FA/5-HTP or placebo intake, a (13)C octanoid acid test was conducted. Cortisol, serotonin, cholecystokinin (CCK), and ghrelin were measured, as were mood and GE. Results. GE was delayed with butter and was normal with olive (P < 0.05) but not affected by 5-HTP. 5-HTP supplementation did not affect serotonin levels. Food intake increased plasma CCK (F = 6.136; P < 0.05) irrespective of the FA. Ghrelin levels significantly decreased with oil/5-HTP (F = 9.166; P < 0.001). The diurnal cortisol profile was unaffected by FA or 5-HTP, as were ratings of mood, hunger, and stool urgency. Conclusion. Diverse FAs have different effects on GE and secretion of orexigenic and anorexigenic hormones. Supplementation of 5-HTP had no effect on plasma serotonin and central functions. Further studies are needed to explain the complex interplay.Gastroenterology Research and Practice 01/2014; 2014:424503. · 1.50 Impact Factor
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ABSTRACT: Abnormal functional brain activity has been revealed in patients with Posttraumatic Stress Disorder (PTSD) in recent years, while the recovery neuromechanism of PTSD has not yet been elucidated. The aim of this study was to investigate the altered spontaneous brain activity in treatment-naïve chronic PTSD patients before and after 12 weeks׳ treatment with paroxetine. Twenty-one earthquake-related PTSD patients and seventeen traumatized controls underwent a resting functional magnetic resonance imaging (Rs-fMRI) scan at baseline. Amplitude of low-frequency fluctuation (ALFF) was calculated and compared between PTSD patients and controls. Then, the PTSD group completed 12 weeks of treatment with paroxetine, and Rs-fMRI was repeated to compare with the baseline. Lastly, correlation analyses of ALFF values within altered brain areas were conducted. Hyperactive function of visual cortex was observed in PTSD patients before and after treatment. After treatment, significantly increased ALFF values were observed in the left orbitofrontal cortex (OFC), while decreased ALFF values were found in the precuneus. Interestingly, a negative correlation between the mean ALFF values of OFC and those of precuneus and visual cortex was only observed in controls, but not in PTSD patients pre- or post-treatment. A corresponding control condition was absent in this study. The findings showed that manipulating regional spontaneous activity of precuneus and OFC could be a potential prognostic indicator of PTSD. However, hyperactive function of visual cortex and disrupted connections between OFC, precuneus and visual cortex did not reverse after treatment, which could be a potential target for further treatment. Copyright © 2014 Elsevier B.V. All rights reserved.Journal of Affective Disorders 12/2014; 174C:257-264. · 3.76 Impact Factor
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ABSTRACT: The (fractional) amplitudes of low-frequency fluctuations (f)ALFF are popular measures for the magnitude of low-frequency oscillations in resting-state fMRI (R-fMRI) data. Both measures can be directly derived from the spectral power of R-fMRI time courses. Numerous studies suggest that ALFF and fALFF might be used as biomarkers for a variety of diseases including schizophrenia, major depressive disorder, and obsessive-compulsive disorder. However, the temporal stability of (f)ALFF values, which is of great importance for the application of (f)ALFF both as a biomarker and scaling parameter, have not been studied in detail yet. Here, we quantify the temporal stability, robustness and reproducibility of both ALFF and fALFF maps obtained from R-fMRI data by performing statistical analyses over 55-minute resting-state scans which included a period of NaCl infusion. We also examine the differences of using either raw or standardised (f)ALFF maps. Our analyses show that no significant changes of (f)ALFF values over the 55minute period occur for both raw and standardised (f)ALFF maps. In addition, we demonstrate that raw (f)ALFF maps across subject are correlated with head motion as quantified via frame-wise displacement, whereas no such correlation is present in standardised (f)ALFF maps. In conclusion, the results of our study show that both ALFF and fALFF qualify as potential biomarkers due to their high temporal stability.NeuroImage 09/2014; · 6.13 Impact Factor