Coloured magnetic resonance imaging (MRI) scan showing brain areas (green) that show differential microstructure organisation in people that are exposed to tetrahydrocannabinol (THC), the principal psychoactive constituent of cannabis. At bottom centre is the ventromedial prefrontal cortex (vmPFC), above that are the left and right agranular anterior insular cortexes and above them are the left and right amygdala. Changes in the microstructures of these areas have been shown to impact memory performance, negative intrusive thinking, and paternal substance abuse.