Neuroscience of Early Development (NED), 90 Avenue Vincent-D'indy, Montreal, QC, H2V 2S9, Canada.
Research Center of the CHU Sainte-Justine Mother and Child University Hospital Center, 3175 Chemin Côte Ste-Catherine, Montreal, QC, H3T 1C5, Canada.
J Neurodev Disord. 2018 Jan 29;10(1):4. doi: 10.1186/s11689-018-9223-3.
Fragile X syndrome (FXS) is a neurodevelopmental genetic disorder causing cognitive and behavioural deficits. Repetition suppression (RS), a learning phenomenon in which stimulus repetitions result in diminished brain activity, has been found to be impaired in FXS. Alterations in RS have been associated with behavioural problems in FXS; however, relations between RS and intellectual functioning have not yet been elucidated.
EEG was recorded in 14 FXS participants and 25 neurotypical controls during an auditory habituation paradigm using repeatedly presented pseudowords. Non-phased locked signal energy was compared across presentations and between groups using linear mixed models (LMMs) in order to investigate RS effects across repetitions and brain areas and a possible relation to non-verbal IQ (NVIQ) in FXS. In addition, we explored group differences according to NVIQ and we probed the feasibility of training a support vector machine to predict cognitive functioning levels across FXS participants based on single-trial RS features.
LMM analyses showed that repetition effects differ between groups (FXS vs. controls) as well as with respect to NVIQ in FXS. When exploring group differences in RS patterns, we found that neurotypical controls revealed the expected pattern of RS between the first and second presentations of a pseudoword. More importantly, while FXS participants in the ≤ 42 NVIQ group showed no RS, the > 42 NVIQ group showed a delayed RS response after several presentations. Concordantly, single-trial estimates of repetition effects over the first four repetitions provided the highest decoding accuracies in the classification between the FXS participant groups.
Electrophysiological measures of repetition effects provide a non-invasive and unbiased measure of brain responses sensitive to cognitive functioning levels, which may be useful for clinical trials in FXS.
脆性 X 综合征（FXS）是一种神经发育遗传疾病，可导致认知和行为缺陷。重复抑制（RS）是一种学习现象，即刺激重复会导致大脑活动减少，研究发现 FXS 中存在 RS 受损。RS 的改变与 FXS 中的行为问题有关；然而，RS 与智力功能之间的关系尚未阐明。
在使用反复呈现的伪词的听觉习惯化范式中，对 14 名 FXS 参与者和 25 名神经典型对照者进行了 EEG 记录。使用线性混合模型（LMM）比较了跨呈现和组之间的非相位锁定信号能量，以研究跨重复和脑区的 RS 效应，以及与 FXS 中的非言语智商（NVIQ）的可能关系。此外，我们根据 NVIQ 探索了组间差异，并探讨了基于单试 RS 特征训练支持向量机来预测 FXS 参与者认知功能水平的可行性。
LMM 分析表明，重复效应在组间（FXS 与对照组）以及 FXS 中的 NVIQ 方面存在差异。在探索 RS 模式的组间差异时，我们发现神经典型对照组在伪词的第一和第二呈现之间显示出预期的 RS 模式。更重要的是，虽然 NVIQ≤42 的 FXS 参与者没有显示 RS，但 NVIQ>42 的组在几次呈现后显示出延迟的 RS 反应。一致地，在前四个重复中重复效应的单试估计在 FXS 参与者组之间的分类中提供了最高的解码准确性。
重复效应的电生理测量提供了一种非侵入性和无偏的大脑反应测量方法，对 FXS 中的认知功能水平敏感，可能对 FXS 的临床试验有用。
