Department of Neurological Surgery, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States of America.
Department of Neurology, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, United States of America.
J Neural Eng. 2022 Jul 22;19(4). doi: 10.1088/1741-2552/ac7fb9.
This study aimed to characterize hippocampal neural signatures of uncertainty by measuring beta band power in the period prior to movement cue.. Participants with epilepsy were implanted with hippocampal depth electrodes for stereo electroencephalographic (SEEG) monitoring. Hippocampal beta (13-30 Hz) power changes have been observed during motor tasks such as the direct reach (DR) and Go/No-Go (GNG) tasks. The primary difference between the tasks is the presence of uncertainty about whether movement should be executed. Previous research on cortical responses to uncertainty has found that baseline beta power changes with uncertainty. SEEG data were sampled throughout phases of the DR and GNG tasks. Beta-band power during the fixation phase was compared between the DR and GNG task using a Wilcoxon rank sum test. This unpaired test was also used to analyze response times from cue to task completion between tasks.Eight patients who performed both reaching tasks were analyzed in this study. Movement response times in the GNG task were on average 210 milliseconds slower than in the DR task. All patients exhibited a significantly increased response latency in the GNG task compared to the DR task (Wilcoxon rank-sum p-value < 0.001). Six out of eight patients demonstrated statistically significant differences in beta power in single hippocampal contacts between the fixation phases of the GNG and DR tasks. At the group level, baseline beta power was significantly lower in the GNG task than in the DR task (Wilcoxon rank-sum p-value < 0.001).. This novel study found that, in the presence of task uncertainty, baseline beta power in the hippocampus is lower than in its absence. This finding implicates movement uncertainty as an important factor in baseline hippocampal beta power during movement preparation.
本研究旨在通过测量运动线索前的β波段功率来描述海马体神经不确定性的特征。患有癫痫的参与者被植入海马体深部电极进行立体脑电图 (SEEG) 监测。在直接到达 (DR) 和 Go/No-Go (GNG) 任务等运动任务中，已经观察到海马体β（13-30 Hz）功率变化。任务之间的主要区别在于运动是否应该执行存在不确定性。以前关于皮质对不确定性反应的研究发现，基线β功率随不确定性而变化。在 DR 和 GNG 任务的各个阶段都采集了 SEEG 数据。使用 Wilcoxon 秩和检验比较 DR 和 GNG 任务的固定相期间的β带功率。该非配对检验还用于分析任务之间从线索到任务完成的反应时间。本研究分析了 8 名同时执行两种到达任务的患者。GNG 任务中的运动反应时间平均比 DR 任务慢 210 毫秒。与 DR 任务相比，所有患者在 GNG 任务中的反应潜伏期明显延长（Wilcoxon 秩和 p 值<0.001）。在 GNG 和 DR 任务的固定阶段，8 名患者中有 6 名患者的单个海马体接触的β功率存在统计学差异。在组水平上，GNG 任务中的基线β功率明显低于 DR 任务（Wilcoxon 秩和 p 值<0.001）。这项新研究发现，在存在任务不确定性的情况下，海马体的基线β功率低于不存在任务不确定性的情况。这一发现表明运动不确定性是运动准备期间海马体基线β功率的一个重要因素。
