Stand der Ursachen - Mitteldeutsche Psychiatrietage 2011

Poster | Affektive Störungen
P23
Metabolism-BOLD-interaction in cortical regions of the task-positive, task-negative
and salience network and its alteration in Major Depression
C. Metzger, D. Horn, C. Seidenbecher, J. Steiner, J. Kaufmann, B. Bogerts, M. Walter, Magdeburg
Introduction: Metabolic aspects like Glutamate concentrations have been shown to influence BOLDresponses
under task conditions (Walter et al., 2009; Northoff et al. 2007). However, these studies focused
on one single region in the anterior cingulate cortex and were limited to tasks with specific main effect in
the investigated region. We wanted to show, whether Glutamate levels influence task-induced BOLD
responses in all brain regions equally and whether this is independent of any task-setting or specific for
certain tasks with main effects in those measured regions.
Methods: 20 healthy and 20 depressed volunteers were scanned in a 3T Siemens scanner. 4ml MRS voxels
were placed in 3 regions, predefined according to main-effects of task and network specificity in dorsal
anterior cingulate cortex (dACC), pregenual anterior cingulate cortex (pgACC) and anterior insula (AI). For
the MRS acquisition a 1D PRESS sequence (TE 80) was chosen. All subjects took part in an fMRI-salience
paradigm with conditions, which had been shown to reliably elicit task-induced BOLD-responses in the
predefined MRS regions of the task positive, task negative and salience-network (Metzger et al., 2010).
Data analysis was carried out using LCModel 6.1.0, SPM8 and SPSS 15. MRS-spectra were analysed as
ratios of Glx (including Glutamate and Glutamine) to Creatinine (Glx/Cr) for inter-subject reliability.
Results and Conclusion: In healthy controles Glx/Cr was directly correlated with task-induced BOLD
responses that show a main-effect of task in the respective region, but not with BOLD responses in
general. This effect was significantly altered in depressed subjects, where this relationship was not found.
Our study therefore emphasizes the importance of metabolic aspects underlying task induced BOLD
responses and could show that this metabolism-BOLD interaction is network-dependent and moreover
suggests directionality, which is altered in depressed patients. This stresses the importance of metabolic
changes in depression for network related brain dysfunction.
8. Mitteldeutsche Psychiatrietage | 85