Functional Adaptive Longitudinal Reorganization of Superior Parietal Lobule Networks in Amyotrophic Lateral Sclerosis: Evidence Suggesting Compensatory Mechanisms

To investigate longitudinal changes in resting-state functional connectivity (rs-FC) of the superior parietal lobule (SPL) in limb-onset amyotrophic lateral sclerosis (ALS). Resting-state fMRI was used to compare SPL connectivity between 14 ALS patients and 14 healthy controls (HCs) at baseline and during a 5-month follow-up (n=10 ALS patients). Imaging sequences were acquired using a 3-Tesla scanner equipped with a 64-channel head coil. The data were preprocessed and analyzed using CONN and SPM12, employing FDR correction (p<0.05) to identify significant resting-state functional connectivity (rs-FC) alterations. ALS patients showed significant FC alterations in both right and left SPL compared to HCs. At baseline, the right SPL exhibited increased FC with the right Lateral Visual Network, Medial Visual Network (MVN), right Occipital Fusiform Gyrus (OFG), and left Lingual Gyrus (LG). At follow-up, these increases persisted and expanded, notably to the Occipital Visual Network and left LVN. For several connections, including the right OFG and MVN, the corresponding beta values were descriptively larger at follow-up than at baseline. Conversely, at follow-up, the right SPL showed decreased FC with the left Salience Network (SN). The left SPL showed no baseline changes but, at follow-up, exhibited increased FC with visual networks and the Default Mode Network, alongside decreased FC with the SN. These findings may be suggestive of adaptive reorganization of SPL-related brain networks in response to neurodegeneration in ALS. • ALS patients show longitudinal SPL FC alterations over 5 months. • Increased right SPL FC with visual networks at baseline and follow-up. • Right SPL-visual network FC magnitude was greater at follow-up. • Left SPL showed increased FC with visual and DMNs only at follow-up. • Decreased SPL-salience FC at follow-up shows extra-motor disruption.