Somatosensory area 3b is selectively unaffected in corticobasal syndrome: Combining MRI and histology

Abstract An increasing number of neuroimaging studies addressing patients with corticobasal syndrome (CBS) utilize macroscopic definitions of brain regions. As a closer link to functionally relevant units, we aimed at identifying MR-based atrophy patterns in regions defined by probability maps of cortical microstructure. For this purpose, three analyses were conducted: i.) Whole brain cortical thickness was compared between 36 CBS patients and 24 controls. A pattern of pericentral atrophy was found, covering primary motor area 4, premotor area 6 and primary somatosensory areas 1, 2 and 3a. Within the central region, only area 3b was without atrophy. ii.) In 18 patients, longitudinal measures with follow-ups of up to 59 months (mean 21.3±15.4) were analyzed. Areas 1, 2 and 6 showed significantly faster atrophy rates than primary somatosensory area 3b. iii.) In an individual autopsy case, longitudinal in-vivo morphometry and postmortem pathohistology were conducted. The rate of MR-based atrophy was significantly correlated with tufted-astrocyte load in those cytoarchitectonically defined regions also seen in the group study, with area 3b being selectively unaffected.