THC and CBD have distinct symptomatic and behavioral effects. In healthy individuals, THC can induce psychotic symptoms and anxiety, and can impair memory. In contrast, CBD has anxiolytic and possibly antipsychotic properties, while not impairing memory and other cognitive functions. Instead, CBD has been shown to have significant neuroprotective effects. In humans, CBD values correlated positively with gray matter concentration in bilateral hippocampus. Recent data from experimental animals and in vitro studies suggest that these distinct effects might be caused by opposing effects on brain cannabinoid receptors.

Neuroimaging studies have consistently identified brain activity recorded at prefrontal and medial temporal regions as relevant for episodic memory. Additionally, the abundance of cannabinoid receptors in the hippocampus and the parahippocampal and entorhinal cortices suggests a potential impact of CBD in memory deficits typical in healthy aging. However, the evidence relating cannabinoids to these conditions is relatively recent and has been obtained from either biochemical or pharmacological studies. It might be hypothesized that CBDs could be useful to delay or even arrest the progression of functional and structural neuronal degeneration.

The investigators will use an episodic memory paradigm to test the effects of THC, CBD and placebo on memory encoding and retention and the underlying neuronal networks on healthy male subjects.

Inclusion Criteria:

• no acute or chronic disease

Exclusion Criteria:

• opioid intake
• medication or drug abuse
• kidney or liver dysfunction
• claustrophobia
• none removable metallic parts (e.g. hip replacement)