REALITY MONITORING AND DOPAMINE

The Role of Dopamine in Reality Memory

Reality-monitoring characterizes the ability to determine whether information was perceived in the environment or only imagined . Impaired reality-monitoring abilities have been associated with hallucinations in patients with schizophrenia and patients with Parkinson's disease.

The investigators hypothesize a link between dopaminergic (DA) transmission and reality-monitoring.

This hypothesis is based on several studies in the literature: 1) DA transmission anomalies are observed in both schizophrenia and Parkinson's disease; 2) DA agonists may induce hallucination; 3) DA antagonists reduce hallucinations and improve reality-monitoring abilities in patients with schizophrenia. In addition, also suggesting a link between mesocorticolimbic connectivity, subcortical DA transmission and reality-monitoring, The investigators have shown that fronto-temporal transcranial Direct Current Stimulation (tDCS) leads:

• on the one hand, to modulate reality-monitoring performance in healthy volunteers and patients;
• on the other hand, to induce subcortical DA release. However, to date, no study has yet explored the direct link between DA transmission and reality-monitoring.

Inclusion Criteria:

• Healthy volunteers who have given their written informed consent
• Men and women from 18 to 45 years old
• Normal or corrected vision
• Being fluent in French or French for native language
• Being affiliated with health insurance

Exclusion Criteria:

• Healthy volunteers who have given their written informed consent
• Men and women from 18 to 45 years old
• Normal or corrected vision
• Being fluent in French or French for native language
• Being affiliated with health insurance
• Inadmissibility of the subject's consent or refusal
• Working-memory deficit (as controlled with MMSE score< 23)
• Any past or current psychiatric or somatic condition(as controlled with the Mini International Neuropsychiatric Interview, MINI)
• Any past or current neurological condition
• History of cranio-cerebral trauma, arterial hypotension or hypertension, cardiological or serious medical condition
• Abnormal potassium dosage (below 3.1 mmol/L or above 4.9 mmol/L)
• Anormal ECG
• History of schizophrenia or bipolar disorder in first-degree relatives
• Alcohol-drinking and caffeine intake at least during 24 hours before each session
• Drug therapy excepting contraceptives
• Cardiologic or severe medical conditio
• Pregnancy(checked with a pregnancy autotest), lactation, or insufficient contraceptive measure (precautionary measure)
• Consumption of recreational drugs during the last 6 months
• Known sensitivity to any of the study medication and their excipients
• Lactose intolerance
• Porphyria
• Hepatic insufficiency