功能磁共振观察反应抑制功能老化

fMRI of response inhibition in normal aging

目的应用fMRI探讨反应抑制功能老化的神经功能特点。方法对正常青年组及老年组(各25名)行停止信号任务fMRI扫描,使用SPM 8软件处理数据,以组间差异脑激活区作为反应抑制功能老化相关脑区,对各区信号强度与行为学数据[停止信号反应时间(SSRT)]行相关性分析。结果 fMRI脑激活区(P<0.01,FDR校正)在青年组激活以额、顶叶为主,老年组激活区左侧化分布略明显;老年组较青年组在双侧前额中回、左侧额下回、右侧顶下小叶及尾状核头、前扣带回有强激活区。相关性分析显示,青年组右侧前额中回与SSRT呈正相关,左侧额中回、左侧额中/下回与SSRT呈负相关;老年组前扣带回、左侧额中回、左侧额中/下回与SSRT均呈正相关。结论老年人反应抑制功能老化,依赖更多脑区进行功能代偿,主要依赖左侧额中/下回进行补充代偿和前扣带回进行重建代偿。

Objective To investigate functional activation patterns of response inhibition in normal aging with fMRI. Methods Stop-signal task fMRI was performed in young and aged adult group （each n=25）, fMRI data were analyzed with SPM 8 to get fMRI activation mapps between groups as related regions of response inhibition aging. The response magnitudes were correlated with behavioral data （stop signal reaction time, SSRT）. Results fMRI activations （P〈0. 01, FDR corrected） in young adult group occurred predominantly in prefrontal and parietal regions, while in aged adult group showed left laterally extensive. There were more activations for aged adult group in bilateral anterior middle frontal gyri, left inferior frontal gyrus, right inferior parietal lobule, right caudate nucleus head and anterior cingulated cortex. In young adult group, there was positive correlation between SSRT and fMRI response magnitude in right anterior middle frontal gy- rus, and negative correlation in left middle and left middle/inferior frontal gyrus. Such positive correlation was found in the aged adult group in anterior cingulated cortex, left middle and left middle/inferior frontal gyrus. Conclusion Aged adults activate additional areas were consistent with compensatory interpretation during aging of response inhibition. Compensa- tion might include both recruitment （left middle/inferior frontal gyrus） and reorganization （anterior cingulated cortex）.