Participants and study design
Psychiatric disorders, Psychiatric
DISORDERS
The data used in this study were collected as part of a bigger randomized, double-blind, placebo-controlled, cross-over study (SFB779/A06) that examined the immediate and delayed effects of a single S-Ketamine infusion. Thirty-five healthy male subjects (mean age ± standard deviation (SD) = 25.08 ± 4.18 years) were recruited via campus-wide and web-based advertisements. Medical examinations (physical examination, electrocardiogram, and blood and urine analyses) were carried out by study physicians. Psychiatric disorders were screened according to DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition; American Psychiatric AssociationThe study consisted of an initial measurement and two treatment arms with two consecutive measurement days. The first AMSR task was performed on the initial day (AMSR baseline session). The infusions were held on the second and fourth measurement days. Participants were randomly assigned to receive a placebo or ketamine infusion first. The time period between the two infusions was 3 weeks on average, with a minimum of 18 days to avoid carry-over effects. The infusion was administered as an initial bolus of S-Ketamine (0.11 mg/kg body weight) or saline over 8 min and a maintenance dose (0.22 mg/kg body weight S-Ketamine or 0.9% saline) over 40 min with a 2-min break between the bolus and maintenance infusions (Injectomat® MC Agilia; Fresenius Kabi GmbH, Bad Homburg, Germany). Vital signs were monitored during infusion (NONIN Pulse Oxymeter 8600-FO). The resting-state functional magnetic resonance imaging (rs-fMRI) at 7 T was measured directly before infusions (rsFC pre-placebo and pre-ketamine sessions) and during infusion on the second and fourth days as well as 24 h after infusions (rsFC post-placebo and post-ketamine sessions) on the third and fifth measurement days, which was followed by AMSR tasks outside the scanner (AMSR post-placebo and post-ketamine sessions) (sFig. 