Department of Psychiatry and Mental Health, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa.
Behav Brain Funct. 2010 Jul 8;6:39. doi: 10.1186/1744-9081-6-39.
It has been suggested that perceived mental effort reflects changes in arousal during tasks of attention. Such changes in arousal may be tonic or phasic, and may be mediated by the locus-coeruleus norepinephrine (LC-NE) system. We hypothesized that perceived mental effort during attentional tasks would correlate with tonic changes in cortical arousal, as assessed by relative electroencephalogram (EEG) band power and theta/beta ratio, and not with phasic changes in cortical arousal, assessed by P300 amplitude and latency.
Forty-six healthy individuals completed tasks that engage the anterior and posterior attention networks (continuous performance task, go/no-go task, and cued target detection task). During completion of the three attentional tasks a continuous record of tonic and phasic arousal was taken. Cortical measures of arousal included frequency band power, theta/beta ratios over frontal and parietal cortices, and P300 amplitude and latency over parietal cortices. Peripheral measures of arousal included skin conductance responses, heart rate and heart rate variance. Participants reported their perceived mental effort during each of the three attentional tasks.
First, changes in arousal were seen from rest to completion of the three attentional tasks and between the attentional tasks. Changes seen between the attentional tasks being related to the task design and the attentional network activated. Second, perceived mental effort increased when demands of the task increased and correlated with left parietal beta band power during the three tasks of attention. Third, increased mental effort during the go/no-go task and the cued target detection task was inversely related to theta/beta ratios.
These results indicate that perceived mental effort reflects tonic rather than phasic changes in arousal during tasks of attention. We suggest that perceived mental effort may reflect in part tonic activity of the LC-NE system in healthy individuals.
有人认为感知到的心理努力反映了注意力任务中警觉性的变化。这种警觉性的变化可能是紧张的或阶段性的，可能由蓝斑去甲肾上腺素（LC-NE）系统介导。我们假设在注意力任务中感知到的心理努力与皮层警觉性的紧张变化相关，通过相对脑电图（EEG）频带功率和θ/β比来评估，而不是与皮层警觉性的阶段性变化相关，通过 P300 幅度和潜伏期来评估。
46 名健康个体完成了参与前注意网络和后注意网络的任务（连续作业任务、go/no-go 任务和提示目标检测任务）。在完成三个注意力任务的过程中，对紧张和阶段性警觉进行了连续记录。警觉的皮层测量包括额部和顶叶皮质的频带功率、θ/β比，以及顶叶皮质的 P300 幅度和潜伏期。警觉的外周测量包括皮肤电反应、心率和心率变异性。参与者报告了他们在三个注意力任务中的感知心理努力。
首先，从休息到完成三个注意力任务以及在注意力任务之间都观察到了警觉性的变化。在注意力任务之间观察到的变化与任务设计和激活的注意力网络有关。其次，当任务需求增加时，警觉性增加，与三个注意力任务中的左顶叶β频带功率相关。第三，在 go/no-go 任务和提示目标检测任务中，增加的心理努力与θ/β比呈负相关。
这些结果表明，在注意力任务中，感知到的心理努力反映了警觉性的紧张变化，而不是阶段性变化。我们认为，感知到的心理努力可能部分反映了健康个体中 LC-NE 系统的紧张活动。
