This has been proved. Supporters of marijuana worth considering. I understand that it will soon have in some states in the US to make a choice, but now it is proved.
The substance contained in cannabis - delta-9-tetrahydrocannabinol (THC) - causes the destruction of neural circuits in the cerebral cortex. It is found out by scientists from Osaka University, who studied the mechanisms of formation of networks of nerve cells in the brain. On their findings they told in an article published in the Journal of Neuroscience.
Developmental Switch in Spike Timing-Dependent Plasticity and Cannabinoid-Dependent Reorganization of the Thalamocortical Projection in the Barrel Cortex - http://www.jneurosci.org/content/36/26/7039