Age-Related Reduced Somatosensory Gating Is Associated with Altered Alpha Frequency Desynchronization.

Chia-Hsiung Cheng,Sylvain Baillet,Pei-Ying S Chan,Yung-Yang Lin

doi:10.1155/2015/302878

Abstract

Sensory gating (SG), referring to an attenuated neural response to the second identical stimulus, is considered as preattentive processing in the central nervous system to filter redundant sensory inputs. Insufficient somatosensory SG has been found in the aged adults, particularly in the secondary somatosensory cortex (SII). However, it remains unclear which variables leading to the age-related somatosensory SG decline. There has been evidence showing a relationship between brain oscillations and cortical evoked excitability. Thus, this study used whole-head magnetoencephalography to record responses to paired-pulse electrical stimulation to the left median nerve in healthy young and elderly participants to test whether insufficient stimulus 1- (S1-) induced event-related desynchronization (ERD) contributes to a less-suppressed stimulus 2- (S2-) evoked response. Our analysis revealed that the minimum norm estimates showed age-related reduction of SG in the bilateral SII regions. Spectral power analysis showed that the elderly demonstrated significantly reduced alpha ERD in the contralateral SII (SIIc). Moreover, it was striking to note that lower S1-induced alpha ERD was associated with higher S2-evoked amplitudes in the SIIc among the aged adults. Conclusively, our findings suggest that age-related decline of somatosensory SG is partially attributed to the altered S1-induced oscillatory activity.

Highlights

Despite the continuous attention to the age-related changes in the higher hierarchical cognitive function, recent imaging studies have shown that the early-phase perceptual process, for example, cortical inhibition or sensory gating (SG), is modulated by aging [1,2,3,4,5,6,7]
Due to the longer peak latency of ERS (∼≧0.7 s) [23, 25] and our design of 0.5 s interstimulus interval (ISI), this study focused on the stimulus 1- (S1-)induced event-related desynchronization (ERD) responses
To obtain insight into the age-related alterations of cortical inhibition in the human somatosensory system, we applied paired-pulse electrical stimulation to the left median nerve, and our results revealed several important findings

Summary

Introduction

Despite the continuous attention to the age-related changes in the higher hierarchical cognitive function, recent imaging studies have shown that the early-phase perceptual process, for example, cortical inhibition or sensory gating (SG), is modulated by aging [1,2,3,4,5,6,7]. Most importantly, this cortical disinhibition has been linked to the aberrant neuropsychological or behavioral performance [5, 8, 9]. Our magnetoencephalographic (MEG) study by applying equivalent current dipole (ECD) modeling has demonstrated that the neurophysiological responses of the SII are vulnerable to aging in terms of cortical SG [2]

Results

Discussion

Conclusion