> MRIs measured brain activity while the participants undertook seven tasks designed to test emotion, reward, motor function, working memory, language, relational or logical reasoning, and theory of mind or social information processing.
> The researchers found that both recent and heavy lifetime cannabis use was associated with a statistically significant reduction in brain activity only during the working memory task.
So, as far as emotion, reward, motor function, language, relational or logical reasoning, and theory of mind or social information processing go - no correlation between cannabis use and brain activity in those respects was found? Absence of evidence isn't evidence of absence of course, but it's interesting that significant effects were found with memory and only memory.