We recorded somatosensory evoked magnetic fields (SEFs) to right median nerve stimulation in healthy young and old subjects and assessed major SEF components. Then, we evaluated the phase-locking factor (PLF) for local field synchrony on neural oscillations and the weighted phase-lag index (wPLI) for cortico-cortical synchrony between SI and SII.
PLF was significantly increased in SI along with the increased amplitude of N20m in the old subjects. PLF was also increased in SII associated with a shortened peak latency of SEFs. wPLI analysis revealed the increased coherent activity between SI and SII.
Our results suggest that the functional coupling between SI and SII is influenced by the cortical disinhibition due to normal aging.
We provide the first electrophysiological evidence for age-related changes in oscillatory neural activities across the somatosensory areas.