Table 3. Main information about patients from Studies I, II Study I Study II Diagnosis schizotypal disorder F21 (N = 2) schizoaffective disorder, depressive type F25.1 (N = 7) schizoaffective disorder, mixed type F25.2 (N = 1) delusional disorder F22.0 (N = 1) History of antipsychotic treatment Medication at 4 weeks of follow-up Additional treatment neuroleptic naive (N = 2) neuroleptic free (N = 7; 1 for at least half a year, and 6 for at least 1 month) treated with other antipsychotics before the switch to olanzapine (N = 2; 1 patient with trifluoperazine 30 mg/d; 1 patient with haloperidol decanoate 50 mg) 42 schizotypal disorder F21.0 (N = 5) paranoid schizophrenia F20.0 (N = 4) neuroleptic naive patients 5-10 mg/d of olanzapine 2.5±1 mg/day of risperidone benzodiazepines (5 received clonazepam 2-4 mg/d, 3 – lorazepam 2-4 mg/d) citalopram (4 patients – 20 mg/d) trihexyphenidyl (3 patients – 4 mg/d) no additional therapy Before the EEG/MEG measurements, the subjective levels of anxiety, mood, and arousal were measured with the visual analogue scales (VAS). The VAS allows the quantification of small changes over time and there is a good subject/observer agreement for this method (Hornblow and Kidson 1976; Hotopf et al. 1999; Lundberg 1980). The VAS was presented in the form of a 10-cm line. The anchor statements were “not at all” and “very much so”. Two experimental sessions were separated by one week. Studies were performed at the Republican Vilnius Psychiatric Hospital (Vilnius, Lithuania) (Studies I, II) and at the BioMag Laboratory, at the Helsinki University Central Hospital (Helsinki, Finland) (Studies III, IV). The studies were approved by the Ethic Committees of the Hospitals. Subjects gave their written informed consent to participate in the study.
3.2. Study design and data acquisition Study design ERP recordings were performed at the baseline and at follow-up in Studies I, II. We used random, double-blind, cross-over design in Studies III, IV; VAS was employed immediately prior to the EEG/MEG measurements. The main study design is summarized in Table 4. Table 4. Design of the studies Study First recording Subsequent recording Study I baseline (before olanzapine treatment) at 2 and 4 weeks’ follow-up Study II baseline (before risperidone treatment) at 2 weeks’ follow-up Study III four hours after the administration of 30 mg of memantine or a placebo Study IV four hours after the administration of 40 mg of methylphenidate or a placebo Data acquisition Studies I, II 43 after 1 week after 1 week All data were acquired in an electrically shielded room. The recording sessions were always carried out between 9 a.m. and 2 p.m. The main recording parameters are presented in Table 5. The ERPs were recorded with a 32- channel EEG device (Galileo NT, by EBNeuro, Italy) (passband 0.01–30 Hz) from F3, Fz, F4, C3, Cz, C4, and Pz sites (according to the 10/20 International system) using Ag/AgCl electrodes. Ear electrodes served as a reference for all electrodes and the ground electrode was attached to the forehead. ERPs were acquired during active and passive auditory oddball paradigms. The signal-rejection threshold was set for an amplitude of more than 100 µV. The active