Author(s): OHARA, K., NAKAMOTO, A., MASE, A., NAKATA, H., ITO, K., SHIBASAKI, M., OHTAKA, C., Institution: NARA WOMEN'S UNIVERSITY, Country: JAPAN, Abstract-ID: 1060

INTRODUCTION:
Age-related declines in motor and gait function are associated with an increased risk of falls and reduced mobility in older adults. Lower-limb somatosensory input plays a critical role in gait regulation and postural control. Neuroimaging studies have further demonstrated that age-related impairment of plantar somatosensation is associated with increased prefrontal cortex activation during walking. However, the relationship between neurophysiological indices of somatosensory processing, such as somatosensory evoked potential (SEP), and gait function in older adults remain insufficiently understood. The purpose of this study was to examine the association between lower-limb SEP and gait function in older adults.
METHODS:
Fifty-one participants without dementia, of which 18 were men and 33 were women aged ≥65 years were recruited. SEP recordings were obtained following electrical stimulation of the tibial and peroneal nerves. Cortical SEP responses were recorded at the Cz electrode, and the latencies and amplitudes of the P37, N50, P60, and N70 components were analyzed. Motor and gait function were assessed during normal walking at a preferred speed, in addition to the Two-Step Test (2Step) as an index of gait capacity, the Timed Up and Go test (TUG) to evaluate functional mobility, and the Functional Reach (FR) test to assess dynamic balance performance. Correlation analyses were conducted to examine associations between SEP parameters and motor and gait outcomes using Pearson’s or Spearman’s correlation coefficients, as appropriate.
RESULTS:
Tibial nerve P37 latency and N50 amplitude were significantly correlated with 2Step values, indicating a relationship between early somatosensory cortical processing and gait. Peroneal nerve N70 latency was significantly associated with 2Step values, suggesting that later-stage somatosensory processing also contributes to gait performance. Peroneal nerve P60 amplitude was significantly correlated with TUG, while tibial nerve N70 amplitude showed a significant association with FR reach distance.
CONCLUSION:
These results suggest that age-related alterations in cortical somatosensory processing contribute to functional motor decline. Lower-limb SEP provides neurophysiological insight into sensory-motor integration underlying gait and balance in older adults. These findings demonstrate nerve-specific and component-specific relationships between SEP characteristics and different aspects of motor and gait function.