Turrini Sonia, Bevacqua Naomi, Cataneo Antonio, Chiappini Emilio, Fiori Francesca, Candidi Matteo, Avenanti Alessio
Centro Studi e Ricerche in Neuroscienze Cognitive, Dipartimento di Psicologia, Alma Mater Studiorum Università di Bologna, Cesena, Italy.
Precision Neuroscience and Neuromodulation Program, Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States.
Front Aging Neurosci. 2023 Feb 16;15:1119508. doi: 10.3389/fnagi.2023.1119508. eCollection 2023.
Transcranial magnetic stimulation (TMS) methods such as cortico-cortical paired associative stimulation (ccPAS) can increase the strength of functional connectivity between ventral premotor cortex (PMv) and primary motor cortex (M1) spike timing-dependent plasticity (STDP), leading to enhanced motor functions in young adults. However, whether this STDP-inducing protocol is effective in the aging brain remains unclear. In two groups of young and elderly healthy adults, we evaluated manual dexterity with the 9-hole peg task before and after ccPAS of the left PMv-M1 circuit. We observed that ccPAS enhanced dexterity in young adults, and this effect was anticipated by a progressive increase in motor-evoked potentials (MEPs) during ccPAS administration. No similar effects were observed in elderly individuals or in a control task. Across age groups, we observed that the magnitude of MEP changes predicted larger behavioral improvements. These findings demonstrate that left PMv-to-M1 ccPAS induces functionally specific improvements in young adults' manual dexterity and an increase in corticomotor excitability, but altered plasticity prevents the effectiveness of ccPAS in the elderly.
诸如皮质-皮质配对联想刺激（ccPAS）等经颅磁刺激（TMS）方法可以增强腹侧运动前皮层（PMv）与初级运动皮层（M1）之间基于峰时依赖可塑性（STDP）的功能连接强度，从而增强年轻人的运动功能。然而，这种诱导STDP的方案在衰老大脑中是否有效仍不清楚。在两组年轻和老年健康成年人中，我们在对左侧PMv-M1回路进行ccPAS前后，用9孔插钉试验评估了手部灵活性。我们观察到，ccPAS增强了年轻人的灵活性，并且在ccPAS实施过程中运动诱发电位（MEP）的逐渐增加预示了这种效果。在老年人或对照任务中未观察到类似效果。在所有年龄组中，我们观察到MEP变化的幅度预示着更大的行为改善。这些发现表明，左侧PMv至M1的ccPAS可诱导年轻人手部灵活性的功能特异性改善以及皮质运动兴奋性的增加，但可塑性的改变阻止了ccPAS在老年人中的有效性。
