Movement Control & Neuroplasticity Research Group, Department Movement Sciences, Group Biomedical Sciences, KU Leuven, Leuven 3000, Belgium.
Leuven Brain Institute (LBI), KU Leuven, Leuven 3000, Belgium.
J Neurosci. 2022 Feb 9;42(6):1119-1130. doi: 10.1523/JNEUROSCI.1154-21.2021. Epub 2021 Dec 7.
Recent studies suggest an important role of the principal inhibitory neurotransmitter GABA for motor performance in the context of aging. Nonetheless, as previous magnetic resonance spectroscopy (MRS) studies primarily reported resting-state GABA levels, much less is known about transient changes in GABA levels during motor task performance and how these relate to behavior and brain activity patterns. Therefore, we investigated GABA+ levels of left primary sensorimotor cortex (SM1) acquired before, during, and after execution of a unimanual/bimanual action selection task in 30 (human) young adults (YA; age 24.5 ± 4.1, 15 male) and 30 older adults (OA; age 67.8 ± 4.9, 14 male). In addition to task-related MRS data, task-related functional magnetic resonance imaging (fMRI) data were acquired. Behavioral results indicated lower motor performance in OA as opposed to YA, particularly in complex task conditions. MRS results demonstrated lower GABA+ levels in OA as compared with YA. Furthermore, a transient task-related decrease of GABA+ levels was observed, regardless of age. Notably, this task-induced modulation of GABA+ levels was linked to task-related brain activity patterns in SM1 such that a more profound task-induced instantaneous lowering of GABA+ was related to higher SM1 activity. Additionally, higher brain activity was related to better performance in the bimanual conditions, despite some age-related differences. Finally, the modulatory capacity of GABA+ was positively related to motor performance in OA but not YA. Together, these results underscore the importance of transient dynamical changes in neurochemical content for brain function and behavior, particularly in the context of aging. Emerging evidence designates an important role to regional GABA levels in motor control, especially in the context of aging. However, it remains unclear whether changes in GABA levels emerge when executing a motor task and how these changes relate to brain activity patterns and performance. Here, we identified a transient decrease of sensorimotor GABA+ levels during performance of an action selection task across young adults (YA) and older adults (OA). Interestingly, whereas a more profound GABA+ modulation related to higher brain activity across age groups, its association with motor performance differed across age groups. Within OA, our results highlighted a functional merit of a task-related release from inhibitory tone, i.e. lowering regional GABA+ levels was associated with task-relevant brain activity.
最近的研究表明，主要抑制性神经递质 GABA 对于衰老背景下的运动表现起着重要作用。尽管如此，由于之前的磁共振波谱（MRS）研究主要报告了静息状态下的 GABA 水平，因此对于运动任务执行过程中 GABA 水平的瞬态变化以及这些变化与行为和大脑活动模式的关系知之甚少。因此，我们在 30 名（人类）年轻成年人（YA；年龄 24.5±4.1，15 名男性）和 30 名老年人（OA；年龄 67.8±4.9，14 名男性）执行单手/双手动作选择任务之前、期间和之后，分别检测了左侧初级感觉运动皮层（SM1）中的 GABA+水平。除了与任务相关的 MRS 数据外，还采集了与任务相关的功能磁共振成像（fMRI）数据。行为结果表明，OA 的运动表现低于 YA，尤其是在复杂任务条件下。MRS 结果表明，OA 中的 GABA+水平低于 YA。此外，无论年龄大小，都观察到 GABA+水平的瞬态任务相关下降。值得注意的是，这种任务诱导的 GABA+水平调节与 SM1 中的任务相关大脑活动模式有关，即 GABA+的瞬时降低与 SM1 更高的活动相关。此外，尽管存在一些与年龄相关的差异，但更高的大脑活动与双手条件下更好的表现相关。最后，GABA+的调节能力与 OA 中的运动表现呈正相关，但在 YA 中则不然。总的来说，这些结果强调了神经化学物质含量的瞬态动力学变化对大脑功能和行为的重要性，尤其是在衰老背景下。越来越多的证据表明，区域 GABA 水平在运动控制中起着重要作用，尤其是在衰老背景下。然而，目前尚不清楚在执行运动任务时是否会出现 GABA 水平的变化，以及这些变化与大脑活动模式和表现的关系。在这里，我们在年轻成年人（YA）和老年人（OA）中发现了在执行动作选择任务期间感觉运动 GABA+水平的短暂下降。有趣的是，尽管 GABA+的更显著调节与整个年龄组的更高大脑活动相关，但它与运动表现的关联在年龄组之间有所不同。在 OA 中，我们的结果强调了与任务相关的抑制性音调释放的功能优势，即降低区域 GABA+水平与与任务相关的大脑活动相关。
