Department of Otolaryngology, Medical University of South Carolina, Charleston, South Carolina, USA.
Eur J Neurosci. 2022 Dec;56(12):6115-6140. doi: 10.1111/ejn.15847. Epub 2022 Nov 18.
There is great interest in developing non-invasive approaches for studying cortical plasticity in humans. High-frequency presentation of auditory and visual stimuli, or sensory tetanisation, can induce long-term-potentiation-like (LTP-like) changes in cortical activity. However, contrasting effects across studies suggest that sensory tetanisation may be unreliable. We review these contrasting effects, conduct our own study of auditory and visual tetanisation, and perform meta-analyses to determine the average effect of sensory tetanisation across studies. We measured auditory-evoked amplitude changes in a group of younger (18-29 years of age) and older (55-83 years of age) adults following tetanisation to 1 and 4 kHz tone bursts and following a slow-presentation control. We also measured visual-evoked amplitude changes following tetanisation to horizontal and vertical sign gradients. Auditory and visual response amplitudes decreased following tetanisation, consistent with some studies but contrasting with others finding amplitude increases (i.e. LTP-like changes). Older adults exhibited more modest auditory-evoked amplitude decreases, but visual-evoked amplitude decreases like those of younger adults. Changes in response amplitude were not specific to tetanised stimuli. Importantly, slow presentation of auditory tone bursts produced response amplitude changes approximating those observed following tetanisation in younger adults. Meta-analyses of visual and auditory tetanisation studies found that the overall effect of sensory tetanisation was not significant across studies or study sites. The results suggest that sensory tetanisation may not produce reliable changes in cortical responses and more work is needed to determine the validity of sensory tetanisation as a method for inducing human cortical plasticity in vivo.
人们对开发非侵入性方法来研究人类皮质可塑性非常感兴趣。高频呈现听觉和视觉刺激，或感觉强直刺激，可诱导皮质活动产生类似长时程增强（LTP 样）的变化。然而，不同研究之间的对比效果表明，感觉强直刺激可能不可靠。我们回顾了这些对比效果，进行了自己的听觉和视觉强直刺激研究，并进行荟萃分析，以确定不同研究中感觉强直刺激的平均效果。我们测量了一组年轻（18-29 岁）和老年（55-83 岁）成年人在 1 和 4 kHz 声爆发强直刺激以及缓慢呈现对照后听觉诱发电位幅度的变化。我们还测量了水平和垂直符号梯度强直刺激后视觉诱发电位幅度的变化。听觉和视觉反应幅度在强直刺激后下降，这与一些研究一致，但与其他研究发现的幅度增加（即 LTP 样变化）形成对比。老年成年人的听觉诱发电位幅度下降幅度较小，但视觉诱发电位幅度下降与年轻成年人相似。反应幅度的变化不是特定于强直刺激的。重要的是，听觉声爆发的缓慢呈现产生的反应幅度变化与年轻成年人强直刺激后观察到的变化近似。视觉和听觉强直刺激研究的荟萃分析发现，感觉强直刺激在不同研究或研究地点的总体效果不显著。结果表明，感觉强直刺激可能不会导致皮质反应的可靠变化，需要更多的工作来确定感觉强直刺激作为诱导体内人类皮质可塑性的方法的有效性。
