Association between the superior longitudinal fasciculus and perceptual organization and working memory: A diffusion tensor imaging study.

The superior longitudinal fasciculus (SLF) is a white matter structure that has long bidirectional projections among the prefrontal, temporal, occipital, and parietal cortices and extends over a wide area in a human brain. Recently, anatomical details of the SLF have been clarified using a diffusion tensor imaging (DTI) template of subjects from the Human Connectome Project. However, the neurobehavioral functions of the SLF have not been fully elucidated. It is speculated that the SLF contributes to a broad cognitive domain including visuospatial nonverbal cognitive ability and verbal memory ability because of its anatomical location; however, previous findings in imaging studies are inconsistent. Showing the contribution of the SLF to cognitive function may be important for improving our understanding of the functional role of white matter structures in the human brain. This study aimed to identify the relationship between DTI indices of the SLF and the Verbal Comprehension, Perceptual Organization, Working Memory and Processing Speed Indices of the Wechsler Adult Intelligence Scale-Third Edition using regression analysis, accounting for the effects of age, sex and scanner type in 583 healthy volunteers. We showed significant correlations between the fractional anisotropy of the left SLF and the Perceptual Organization Index (ß = 0.21, p =  4.5×10-4) and Working Memory Index (ß = 0.19, p =  4.0×10-4). These findings may have implications for the rehabilitation of cognitive function in patients with neurological disorders.