Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
J Neurophysiol. 2010 Feb;103(2):827-43. doi: 10.1152/jn.00358.2009. Epub 2009 Dec 9.
Previously, we introduced a monkey model for human frontal midline theta oscillations as a possible neural correlate of attention. It was based on homologous theta oscillations found in the monkey's prefrontal and anterior cingulate cortices (areas 9 and 32) in a self-initiated hand-movement task. However, it has not been confirmed whether theta activity in the monkey model consistently appears in other situations demanding attention. Here, we examined the detailed properties of theta oscillations in four variations of forewarned reaction time tasks with warning (S1) and imperative (S2) stimuli. We characterized the theta oscillations generated exclusively in areas 9 and 32, as follows: 1) in the S1-S2 interval where movement preparation and reward expectation were presumably involved, the theta power was higher than in the pre-S1 period; 2) in the no-go trials of go/no-go tasks instructed by S1, the theta power in the S1-S2 interval was lower than in the pre-S1 period in an asymmetrical reward condition, whereas it was moderately higher in a symmetrical condition; 3) the theta power after reward delivery was higher than in the unrewarded trials; 4) the theta power in the pre-S1 period was higher than in the resting condition; and 5) when the monkey had to guess the S1-S2 duration internally without seeing S2, the theta power in the pre-S1 period was higher than in the original S1-S2 experiment. These findings suggest that attentional loads associated with different causes can induce the same theta activity, thereby supporting the consistency of attention-dependent theta oscillations in our model.
先前，我们介绍了一种人类额中线θ振荡的猴模型，作为注意的一种可能的神经相关物。它基于猴前额叶和前扣带回皮层（9 和 32 区）在自我启动手部运动任务中发现的同源θ振荡。然而，尚未证实猴模型中的θ活动是否始终出现在其他需要注意的情况下。在这里，我们检查了四种预警反应时任务的θ振荡的详细特性，这些任务具有预警（S1）和命令（S2）刺激。我们的特征如下：1）在运动准备和奖励预期所涉及的 S1-S2 间隔中，θ功率高于 S1 前间隔；2）在 S1 指导的 Go/No-Go 任务的非 Go 试验中，在不对称奖励条件下，S1-S2 间隔的θ功率低于 S1 前间隔，而在对称条件下则适度升高；3）奖励后θ功率高于无奖励试验；4）S1 前间隔的θ功率高于静息状态；5）当猴子必须在不看到 S2 的情况下内部猜测 S1-S2 持续时间时，S1 前间隔的θ功率高于原始 S1-S2 实验。这些发现表明，不同原因引起的注意力负荷可以诱导相同的θ活动，从而支持我们模型中注意力依赖的θ振荡的一致性。
