Ondek Katelynn, Pevzner Aleksandr, Tercovich Kayleen, Schedlbauer Amber M, Izadi Ali, Ekstrom Arne D, Cowen Stephen L, Shahlaie Kiarash, Gurkoff Gene G
Department of Neurological Surgery, University of California, Davis, Davis, CA, United States.
Center for Neuroscience, University of California, Davis, Davis, CA, United States.
Front Neurol. 2020 Dec 4;11:600171. doi: 10.3389/fneur.2020.600171. eCollection 2020.
Whether from a fall, sports concussion, or even combat injury, there is a critical need to identify when an individual is able to return to play or work following traumatic brain injury (TBI). Electroencephalogram (EEG) and local field potentials (LFP) represent potential tools to monitor circuit-level abnormalities related to learning and memory: specifically, theta oscillations can be readily observed and play a critical role in cognition. Following moderate traumatic brain injury in the rat, lasting changes in theta oscillations coincide with deficits in spatial learning. We hypothesized, therefore, that theta oscillations can be used as an objective biomarker of recovery, with a return of oscillatory activity corresponding with improved spatial learning. In the current study, LFP were recorded from dorsal hippocampus and anterior cingulate in awake, behaving adult Sprague Dawley rats in both a novel environment on post-injury days 3 and 7, and Barnes maze spatial navigation on post-injury days 8-11. Theta oscillations, as measured by power, theta-delta ratio, peak theta frequency, and phase coherence, were significantly altered on day 3, but had largely recovered by day 7 post-injury. Injured rats had a mild behavioral phenotype and were not different from shams on the Barnes maze, as measured by escape latency. Injured rats did use suboptimal search strategies. Combined with our previous findings that demonstrated a correlation between persistent alterations in theta oscillations and spatial learning deficits, these new data suggest that neural oscillations, and particularly theta oscillations, have potential as a biomarker to monitor recovery of brain function following TBI. Specifically, we now demonstrate that oscillations are depressed following injury, but as oscillations recover, so does behavior.
无论是因跌倒、运动性脑震荡，甚至是战斗损伤导致的创伤性脑损伤（TBI），关键都在于确定个体在脑损伤后何时能够恢复运动或工作。脑电图（EEG）和局部场电位（LFP）是监测与学习和记忆相关的电路水平异常的潜在工具：具体而言，θ振荡易于观察到，且在认知中起关键作用。大鼠中度创伤性脑损伤后，θ振荡的持续变化与空间学习缺陷同时出现。因此，我们推测θ振荡可作为恢复的客观生物标志物，振荡活动的恢复与空间学习能力的改善相对应。在本研究中，在清醒、活动的成年Sprague Dawley大鼠的背侧海马体和前扣带回记录LFP，记录时间分别为损伤后第3天和第7天在新环境中的情况，以及损伤后第8 - 11天在巴恩斯迷宫中的空间导航情况。通过功率、θ-δ比率、θ峰值频率和相位相干性测量的θ振荡在第3天有显著改变，但在损伤后第7天基本恢复。受伤大鼠有轻微的行为表型，在巴恩斯迷宫中的逃避潜伏期与假手术组无异。受伤大鼠确实使用了次优搜索策略。结合我们之前的研究结果，即θ振荡的持续改变与空间学习缺陷之间存在相关性，这些新数据表明神经振荡，特别是θ振荡，有潜力作为监测TBI后脑功能恢复的生物标志物。具体而言，我们现在证明损伤后振荡会受到抑制，但随着振荡恢复，行为也会恢复。
