What are the effects of occasional marijuana use on a developing teenagers brain?

Risk mental illness: Research results seem to show that marijuana (pot, mj) can start a person's schizophrenia sooner than if he did not use mj. A teenager (with a brain, neurotransmitters, & receptors not fully developed), especially with a family history of schizophrenia or psychosis, should know his family history and avoid experimenting with mj or other illegal drugs that might have a similar effect on the brain.

It gets worse: A recent report in the british journal of psychiatry, nov '11, demonstrated a decrease in the size of the thalamus in marijuana users over time. Frequency of use did not mitigate the destruction of this important brain area. The thalamus functions as a way station relaying sensation, spatial ordering, & motor signaling to the cortex. More evidence showing the detrimental effects of mj!