Further studies in our laboratory comparing verbal encoding abilities between adolescents reporting marijuana use and matched controls have found no differences on task performance. Yet, marijuana users evidence more frontal and less temporal activation compared to matched controls. Although both groups performed similarly on the fMRI task, adolescent marijuana users have shown poorer performance on sensitive measures administered as part of an extensive neuropsychological test battery (e.g., California Verbal Learning Test-II, Wechsler Memory Scale-III Story Memory), particularly on initial learning trials 30. Taken together, changes in brain activation in adolescent marijuana users on a verbal encoding task may be indicative of less allocation of attentional resources toward encoding the novel material.
