The Plasticity of Brain Gray Matter and White Matter following Lower Limb Amputation.

Guangyao Jiang,Xuntao Yin,Jixiang Wu,Tianzi Jiang,Jian Wang,Lei Li,Alan C Evans,Chuanming Li,Lu Zhao

doi:10.1155/2015/823185

Abstract

Accumulating evidence has indicated that amputation induces functional reorganization in the sensory and motor cortices. However, the extent of structural changes after lower limb amputation in patients without phantom pain remains uncertain. We studied 17 adult patients with right lower limb amputation and 18 healthy control subjects using T1-weighted magnetic resonance imaging and diffusion tensor imaging. Cortical thickness and fractional anisotropy (FA) of white matter (WM) were investigated. In amputees, a thinning trend was seen in the left premotor cortex (PMC). Smaller clusters were also noted in the visual-to-motor regions. In addition, the amputees also exhibited a decreased FA in the right superior corona radiata and WM regions underlying the right temporal lobe and left PMC. Fiber tractography from these WM regions showed microstructural changes in the commissural fibers connecting the bilateral premotor cortices, compatible with the hypothesis that amputation can lead to a change in interhemispheric interactions. Finally, the lower limb amputees also displayed significant FA reduction in the right inferior frontooccipital fasciculus, which is negatively correlated with the time since amputation. In conclusion, our findings indicate that the amputation of lower limb could induce changes in the cortical representation of the missing limb and the underlying WM connections.

Highlights

Human brain plasticity or neuroplasticity refers to the capacity of the nervous system to modify the organization of the brain structure and function in response to experience
Previous studies suggested that both short-term [2, 3] and long-term training [4,5,6] can modulate brain structural changes involved with both the gray matter (GM) and white matter (WM)
There were no significant differences in sex ratio, age, education, and Mini-Mental Status Examination (MMSE) scores between the amputees and controls

Summary

Introduction

Human brain plasticity or neuroplasticity refers to the capacity of the nervous system to modify the organization of the brain structure and function in response to experience. While some authors have argued that cortical reorganization following amputation is triggered by the loss of sensory input [16, 17], others have proposed that the mechanisms should be attributed to the persistent experience of pain [18]. These discrepancies in the literature raise the fundamental question of whether brain reorganization occurs in amputees without PLP.

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