Indication that chronic marijuana and alcohol use may detrimentally influence the developing brain comes from neuroimaging studies showing a more distributed functional network and recruitment of alternate neural pathways (Jacobsen, Pugh, Constable, Westerveld, & Mencl, 2007; Schweinsburg, Nagel et al., 2008; Schweinsburg et al., 2005; Tapert et al., 2001; Tapert et al., 2004; Tapert et al., 2007); weaknesses in neurocognitive functioning especially attention, visuospatial functioning, and learning and retrieval of verbal and nonverbal information (Brown, Tapert, Granholm, & Delis, 2000; Medina et al., 2007; Tapert & Brown, 1999, 2000; Tapert, Granholm, Leedy, & Brown, 2002); morphological changes (Medina et al., 2008; Nagel et al., 2005); and anisotropic differences in WM (De Bellis et al., 2008; McQueeny et al., 2009). Vulnerability to marijuana use has been suggested in WM pathways within and connecting superior medial, and inferior frontal areas (Arnone et al., 2008; Bonekamp et al., 2007; Gruber & Yurgelun-Todd, 2005; Kanayama et al., 2004), temporal and parietal lobes (Ashtari, Cervellione, Cottone, Ardekani, & Kumra, 2009; Ashtari et al., 2007; Grant, Gonzalez, Carey, Natarajan, & Wolfson, 2003) and areas of the cerebellum including the tonsil (Ashtari et al., 2007; Chang, Yakupov, Cloak, & Ernst, 2006; Schweinsburg et al., 2006).
