Stand der Ursachen - Mitteldeutsche Psychiatrietage 2011

Poster | Affektive Störungen
P26
Effects of acute ketamine infusion on resting state functional connectivity of anterior
cingulate cortex are related to its histoarchitectonics and drug induced changes
measured by MRS
M. Walter, M. Scheidegger, C. Metzger, A. Fuchs, H. Boecker, E. Seifritz, P. Boesiger, S. Grimm, A.
Henning, Magdeburg
Introduction: The four region model of the cingulate cortex, based on histoarchitectonical divisions was
recently shown to predict region specific functional connectivity at rest (Yu 2010) interconnecting
cingulated subregions with distinct components of the striatum, amygdale and thalamus. Given the specific
configuration of these cortical seed regions in terms of variable NMDA receptor profiles (Palomero-
Galagher 2008), we were interested, if effects of acute NMDA blockade would follow a systematic
distribution that is predicted by receptor densities as well as preferential connectivities of the cigulate
subregions. Further we were interested if these functional changes were correlated with acute changes of
metabolite concentrations within the glutamatergic system.
Methods: Nine healthy subjects with no history of neurological or psychiatric illness completed two
separate scan sessions on a Philips 3T MRI scanner. Fifteen minutes prior to the measurement, S-ketamine
or saline was administered as an intravenous bolus of 0.12 mg/kg, followed by a continuous infusion (0.25
mg/kg/h over 60 minutes).
Resting State fMRI (eyes closed) was acquired with a whole brain SENSE-sshEPI Sequence (R=2.0) for the
duration of 10 minutes using the following acquisition parameters: TE 35 ms, TR = 3s, 2.75 x 2.75mm
resolution of 32 axial slices (4mm). Funtional connectivity of three ACC seed regions was analysed using
DPARSF (Yan&Zang 2010) including global mean regression. Within subjects effects were tested using
SPM8’s paired t-test on subjects FC maps. Proton Magnetic Resonance Spectroscopy (1H-MRS) was
acquired from a volume of interest in the pregenual anterior cingulate cortex. Quantification of separable
concentrations of Glutamine, Glutamate and GABA was ascertained using a 2D-JPRESS sequence and
ProFit (Schulte et al 2006).
Results: In general connectivity of all anterior cingulate subregions (sACC-BA25, PACC-Ba24, aMCC-
Ba24’) to middle (MFS) and superior frontal (SFS) sulci were decreased under ketamine (Fig 1a).
Specifically, MFS was connected less strong to both PACC and aMCC. FC with SFS was reduced only for
PACC and MPFC showed smaller connectivity to aMCC (p