Department of Psychology, Swansea University, Swansea, United Kingdom; Centre for Advanced Imaging, University of Queensland, Brisbane, Australia; ARC Centre of Excellence in Cognition and its Disorders, Macquarie University, Sydney, Australia.
Department of Psychology, Swansea University, Swansea, United Kingdom; Centre for Advanced Imaging, University of Queensland, Brisbane, Australia; ARC Science of Learning Research Centre, University of Queensland, Brisbane, Australia.
Neuropsychologia. 2020 Sep;146:107539. doi: 10.1016/j.neuropsychologia.2020.107539. Epub 2020 Jul 3.
Age-related decline in motor function is associated with over-activation of the sensorimotor circuitry. Using a multimodal MEG-fMRI paradigm, we investigated whether this neural over-recruitment in old age would be related to changes in movement-related beta desynchronization (MRBD), a correlate of the inhibitory neurotransmitter γ-aminobutyric acid (GABA), and whether it would characterize compensatory recruitment or a reduction in neural specialization (dedifferentiation). We used MEG to assess age-related changes in beta band oscillations in primary motor cortices, fMRI to localize age-related changes in brain activity, and the Finger Configuration Task to measure task performance during overt and covert motor processing: motor execution (ME) and motor imagery (MI). The results are threefold: first, showing age-related neuroplasticity during ME of older adults, compared to young adults, as evidenced by increased MRBD in motor cortices and over-recruitment of sensorimotor areas; second, showing similar age-related neuroplastic changes during MI; and finally, showing signs of dedifferentiation during ME in older adults whose performance negatively correlated with connectivity to bilateral primary motor cortex. Together, these findings demonstrate that elevated MRBD levels, reflecting greater GABAergic inhibitory activity, and over-activation of the sensorimotor network during ME may not be compensatory, but rather might reflect an age-related decline of the quality of the underlying neural signal.
年龄相关的运动功能下降与感觉运动回路的过度激活有关。我们使用多模态 MEG-fMRI 范式，研究这种老年时的神经过度募集是否与运动相关的β去同步化（MRBD）变化有关，MRBD 是抑制性神经递质γ-氨基丁酸（GABA）的相关指标，以及它是否会表征补偿性招募或神经专业化（去分化）的减少。我们使用 MEG 来评估初级运动皮层中β波段振荡的年龄相关性变化，使用 fMRI 来定位大脑活动的年龄相关性变化，并使用手指构型任务来测量在明显和隐蔽的运动处理期间的任务表现：运动执行（ME）和运动想象（MI）。结果有三个方面：首先，与年轻人相比，老年人在 ME 期间表现出与年龄相关的神经可塑性，这表现为运动皮层中的 MRBD 增加和感觉运动区域的过度募集；其次，在 MI 期间表现出相似的与年龄相关的神经可塑性变化；最后，在 ME 期间表现出去分化的迹象，在 ME 期间表现出去分化迹象的老年人的表现与双侧初级运动皮层的连通性呈负相关。总之，这些发现表明，MRBD 水平升高，反映了 GABA 能抑制活性增加，以及 ME 期间感觉运动网络的过度激活，可能不是补偿性的，而是可能反映了潜在神经信号质量的年龄相关下降。
