Analysis and evaluation of somatotopic mapping and rs-fMRI parcellation for healthy aging and alzheimer’s disease

Task-based functional Magnetic Resonance Imaging (fMRI) has exhibited a thriving potential in the extraction of somatotopic maps of the human sensorimotor cortex representing the correspondence of cortex regions with the sensorimotor functions. Several studies have explored the correspondence of cortex divisions in the absence of motor functions utilizing resting-state fMRI (rs-fMRI) with the somatotopic maps using successive task and rest sessions. In this paper, it is shown that the mentioned similarity between the somatotopic divisions (task fMRI) and the clusters due to rsfMRI parcellation holds for the independent task and rest experimentations as well. Also, it is found that the motor cortices of BA3 and BA4 exhibit no significant change in the somatotopic divisions for both healthy aging and Alzheimer Disease (AD) cases, though AD has been shown to affect the voxel activities in BA3 and BA4. Then, the clusters of sensorimotor cortices are shown to remain unchanged in the AD compared with the healthy aging. There exist a close association with the somatotopic maps of the young for both the AD and healthy aging as well.