Someday it will be conclusively proven that the THC in marijuana blocks neural pathways. The negative effects of this neural blockage are well-documented; I’d like to share observations, based on personal experience, which I believe may redeem marijuana as a useful tool in brain development (or, as will be seen, re-development and corrective psychiatry).
As you grow and your brain develops, the neurons in your brain coordinate themselves into groups, developing electrical pathways which determine the brain’s output to a given external stimulus. Normally these pathways are determined by which neural connections and reactions to the external stimulus produces a reward sensation; the most successful connection remain and determine future interactions with and reactions to the world. Unsuccessful neural responses and connections are re-wired or die out.
Sometimes, however, a neural connection will arise which may work in the short term, but in the long term will be unhealthy and even harmful. For example, a young person may have a bad social experience and decide to withdraw; this fulfills his short-term goal of pain avoidance but shuts him out from a full experience of life and the world. His neural connections are wired in such a way as to react to social stimulus with a fear response; his brain reminds him how going out of his shell worked out in the past and advises him to avoid social interaction. As this pattern of behavior continues, the neural connection is reinforced until it is practically a destiny. People spend their entire lives locked in this fear-trap and other similarly frustrating neural knots.
THC, by temporarily blocking off neural pathways, forces the brain to develop new connections it may never otherwise have established. At the same time, it suppresses identity and ego while sharpening focus, facilitating honest and relatively objective reflection upon one’s own self and behavior (effects vary between strains of the plant, individual people, and innumerable other factors. I’m describing ideal but not uncommon effects of the plant). Under these conditions, behaviors learned and reinforced over an entire lifetime can be objectively examined and overcome. Assistance from an understanding and helpful teacher of life would facilitate the process.
Of course this process can only take place in a setting which encourages the development of neural connections. Smoking weed and then watching TV or playing video games is unlikely to be helpful. Walk through the woods, actively listen to a song or admire a work of art, talk with people. Break your routine. I envision a new school of psychiatry which simply encourages people to confront themselves, and if they wish, to redefine themselves.