Department of Psychology, University of Oslo, Oslo, Norway.
Department of Neurology, Oslo University Hospital, Oslo, Norway.
Eur J Neurosci. 2021 Feb;53(4):1072-1085. doi: 10.1111/ejn.14964. Epub 2020 Sep 21.
Stimulus response modulation (SRM) of sensory evoked potentials represents a promising method as a non-invasive index of long-term potentiation (LTP)-like synaptic plasticity in the human sensory cortices. As of today, however, no consensus exists regarding which experimental parameters elicit the most robust SRM response. The aim of the current study was twofold; firstly, we aimed to replicate former studies demonstrating visual SRM in healthy adults. Second, we integrated visual and auditory stimuli within the same SRM recording session to assay potential cross-modal associations. Such an association between modalities would strengthen the assumption that the SRM effect reflects common mechanisms underlying synaptic plasticity rather than reflecting modality-specific phenomena. A replication of previous findings showing robust potentiation of the visual evoked potential was evident, supporting the majority of previous work using similar paradigms, lending further support to the notion that high-frequent visual stimulation is a viable probe into LTP-like synaptic plasticity in the human visual cortex. The auditory evoked potentials (AEPs) did not, however, fully replicate previous work, though a significant increase of temporally later AEP components was found. In contrast to our hypothesis, there were no significant within-subject cross-modality correlations between the visual and auditory SRM. This lack of significant association might suggest that auditory and visual SRM depend on different mechanisms, and that further SRM studies on non-invasive LTP-like synaptic plasticity should focus on optimizing paradigms within the visual modality.
刺激反应调制 (SRM) 是一种有前途的方法，可作为人类感觉皮层中长时程增强 (LTP) 样突触可塑性的非侵入性指标。然而，到目前为止，关于哪些实验参数可以产生最强大的 SRM 反应，还没有达成共识。本研究的目的有两个；首先，我们旨在复制以前的研究，证明健康成年人的视觉 SRM。其次，我们在同一个 SRM 记录会话中整合视觉和听觉刺激，以检测潜在的跨模态关联。这种模态之间的关联将加强这样一种假设，即 SRM 效应反映了突触可塑性的共同机制，而不是反映了特定于模态的现象。对先前发现的强有力的视觉诱发电位增强的复制是显而易见的，这支持了使用类似范式的大多数先前工作，进一步支持了高频视觉刺激是研究人类视觉皮层中 LTP 样突触可塑性的可行探针的观点。然而，听觉诱发电位 (AEPs) 并没有完全复制以前的工作，尽管发现了时间上较晚的 AEP 成分的显著增加。与我们的假设相反，视觉和听觉 SRM 之间没有显著的受试者内跨模态相关性。这种缺乏显著关联可能表明听觉和视觉 SRM 依赖于不同的机制，并且进一步的非侵入性 LTP 样突触可塑性的 SRM 研究应该集中在优化视觉模态内的范式上。
