It has been hypothesized that this normal reduction in gray matter volume in the cerebellum is due to the pruning of the synaptic connections (Cohen-Cory, 2002). One possible reason for abnormal pruning could be the toxic effect of THC at a critical period of brain maturation. Endogenous cannabinoids have an important role in synaptic pruning due to their interaction with GB1 receptors controlling the release of glutamate and GABA (Bossong and Niesink, 2010). Exogenous cannabinoids might disturb this system by competing for the receptors, thus inhibiting the pruning particularly in receptor-rich areas like the cerebellum (Casu et al, 2005) or the prefrontal cortex (Bossong and Niesink, 2010).
