Complex cognition such as inhibitory processing relies on the communication of prefrontal cortices, basal ganglia, and the thalamus to mediate input and selectively engage related circuits (Stevens et al., 2007). The current findings suggest that the integration of these processes may be significantly different in MJ+ALC users and may be a corollary of both positive and negative changes in white matter microstructure. Observed in three distinct regions, areas of increased FA in MJ+ALC users implicate possible signaling of alternate pathways as the result of aberrant fiber structure in dedicated areas. Within this context, increased FA in the arcuate portion of the SLF is particularly striking considering that this region shows reduced density in typically developing adolescents (Paus et al., 1999) and no age-dependent FA changes among male teens (Ashtari et al., 2007).
