Iglesias-Tejedor María, Díez Álvaro, Llorca-Bofí Vicent, Núñez Pablo, Castaño-Díaz Carolina, Bote Berta, Segarra Rafael, Sanz-Fuentenebro Javier, Molina Vicente
Clinical Neurophysiology Service, Clinical University Hospital of Valladolid, Valladolid, Spain.
Psychiatry Department, School of Medicine, University of Valladolid, Valladolid, Spain.
Prog Neuropsychopharmacol Biol Psychiatry. 2022 Jun 8;116:110541. doi: 10.1016/j.pnpbp.2022.110541. Epub 2022 Feb 23.
There is some consistency in previous EEG findings that patients with schizophrenia have increased resting-state cortical activity. Furthermore, in previous work, we have provided evidence that there is a deficit in the modulation of bioelectrical activity during the performance of a P300 task in schizophrenia. Our hypothesis here is that a basal hyperactivation would be related with altered ability to change or modulate cortical activity during a cognitive task. However, no study so far, to the best of our knowledge, has studied the association between resting-state activity and task-related modulation. With this aim, we used a dual EEG paradigm (resting state and oddball task for elicitation of the P300 evoked potential) in a sample of patients with schizophrenia (n = 100), which included a subgroup of patients with first episode psychosis (n = 30), as well as a group of healthy controls (n = 93). The study measures were absolute power for resting-state; and spectral entropy (SE) and connectivity strength (CS) for P300-task data, whose modulation had been previously found to be altered in schizophrenia. Following the literature on P300, we focused our study on the theta frequency band. As expected, our results showed an increase in resting state activity and altered task-related modulation. Moreover, we found an inverse relationship between the amount of resting-state activity and modulation of task-related activity. Our results confirm our hypothesis and support the idea that a greater amount of resting theta-band synchrony could hamper the modulation of signal regularity (quantified by SE) and activity density (measured by CS) during the P300 task performance. This association was found in both patients and controls, suggesting the existence of a common mechanism and a possible ceiling effect in schizophrenia patients in relation to a decreased inhibitory function that limits their cortical reactivity to the task.
先前的脑电图研究结果存在一定的一致性，即精神分裂症患者静息状态下的皮质活动增强。此外，在先前的研究中，我们已提供证据表明，精神分裂症患者在执行P300任务时生物电活动的调节存在缺陷。我们在此的假设是，基础激活增强与认知任务期间改变或调节皮质活动的能力改变有关。然而，据我们所知，迄今为止尚无研究探讨静息状态活动与任务相关调节之间的关联。为此，我们对100例精神分裂症患者（其中包括30例首发精神病患者亚组）以及93名健康对照者使用了双脑电图范式（静息状态和用于诱发P300诱发电位的Oddball任务）。研究测量指标包括静息状态下的绝对功率；以及P300任务数据的频谱熵（SE）和连接强度（CS），先前已发现精神分裂症患者这些指标的调节存在改变。根据关于P300的文献，我们将研究重点放在θ频段。正如预期的那样，我们的结果显示静息状态活动增加且任务相关调节改变。此外，我们发现静息状态活动量与任务相关活动调节之间存在负相关关系。我们的结果证实了我们的假设，并支持这样一种观点，即更大程度的静息θ频段同步可能会妨碍P300任务执行期间信号规律性（由SE量化）和活动密度（由CS测量）的调节。在患者和对照者中均发现了这种关联，这表明存在一种共同机制，并且精神分裂症患者可能存在一种上限效应，即抑制功能下降限制了他们对任务的皮质反应性。
