Department of Neurology, "Cannizzaro" Hospital, via Messina 829, 95126 Catania, Italy.
J Neural Transm (Vienna). 2010 Oct;117(10):1195-208. doi: 10.1007/s00702-010-0488-2. Epub 2010 Sep 16.
There is evidence that theta responses reflect cognitive performance: good performances are associated with a decrease in tonic theta power as well as an increase in phasic theta power. In the present study, both tonic and phasic theta activity were analysed in 22 patients with mild Alzheimer's disease (AD), and 16 healthy elderly controls. Single-trial theta power responses were evaluated by an active auditory oddball paradigm along an early poststimulus window (0-250 ms) and a late time window (250-500 ms), and then compared to prestimulus theta power during both target tone and standard tone processing. The main findings were: (1) in AD patients, there was an increased prestimulus theta power, as well as no significant poststimulus theta power increase upon both target and non-target stimulus processing; (2) in healthy aged controls, only during target tone processing, an enhancement of both early and late theta responses relative to the prestimulus baseline was found. Moreover, healthy controls had a frontal dominance of theta power. The results might indicate that, during target processing, theta response is not functionally sensitive in AD and cannot be involved in processing demands as efficiently as in healthy controls. From a psychophysiological point of view, this might suggest an impairment of attentional allocation resources. The psychological implications might be related to selective attention/working-memory impairment from the early stage of the disease. Our data confirm that both tonic and phasic theta are relevant indicators of cognitive performance: the lack of a phasic theta and an increase in tonic theta are congruous findings in cognitive decline. Another factor worth noting is that in AD patients theta response is not dominant at the frontal site (as observed in healthy controls), indicating a weaker frontal lobe network reactivity during stimulus processing.
有证据表明θ波反应反映了认知表现：良好的表现与紧张性θ功率降低以及相位性θ功率增加有关。在本研究中，分析了 22 例轻度阿尔茨海默病（AD）患者和 16 例健康老年对照者的紧张性和相位性θ活动。通过主动听觉Oddball 范式，在早期（0-250ms）和晚期（250-500ms）的刺激后窗口中评估了单个试次θ功率反应，然后将其与目标音和标准音处理过程中的刺激前θ功率进行比较。主要发现为：（1）AD 患者的刺激前θ功率增加，而对目标和非目标刺激的处理均无明显的后刺激θ功率增加；（2）在健康老年人对照者中，仅在目标音处理过程中，相对于刺激前基线，早期和晚期θ反应均增强。此外，健康对照者的θ功率具有额区优势。结果表明，在目标处理过程中，AD 患者的θ反应在功能上不敏感，并且不能像健康对照者那样有效地参与处理需求。从心理生理学的角度来看，这可能表明注意力分配资源受损。从心理学的角度来看，这可能与疾病早期的选择性注意力/工作记忆损伤有关。我们的数据证实，紧张性和相位性θ都是认知表现的相关指标：缺乏相位性θ和紧张性θ增加是认知衰退的一致发现。另一个值得注意的因素是，在 AD 患者中，θ反应在前额部位不占主导地位（如健康对照者所见），表明在刺激处理过程中额叶网络反应性较弱。
