Coull J T, Nobre A C, Frith C D
Wellcome Department of Cognitive Neurology, Institute of Neurology, 12 Queen Square, London WC1N 3BG, UK.
Cereb Cortex. 2001 Jan;11(1):73-84. doi: 10.1093/cercor/11.1.73.
We examined whether the known noradrenergic attenuation of the alerting effect (the beneficial effect of a warning cue) results from an underlying effect of noradrenaline on temporal orienting (orienting toward a particular moment in time). Following a within-subjects, counterbalanced design, 10 healthy human volunteers received placebo, 200 microg clonidine or 1 mg guanfacine (alpha2 agonists) in three separate testing sessions. Subjects were scanned by fMRI while performing attentional orienting tasks containing spatially informative, temporally informative, non-informative or no cues. The alerting effect primarily activated left-lateralized prefrontal, premotor and parietal regions. Clonidine, but not guanfacine, impaired behavioural measures of the alerting effect while attenuating activity in the left temporo-parietal junction. Replicating previous results, the temporal orienting task activated left parietal and frontal cortex, while parietal cortex was activated bilaterally during spatial orienting. Of these networks, clonidine, but not guanfacine, attenuated left prefrontal cortex and insula activity during temporal orienting and attenuated right superior parietal cortex activity during spatial orienting,. To complement these neuroanatomical changes, clonidine produced selective behavioural effects on both temporal and spatial orienting. The anatomical dissociation between the effects of clonidine during temporal orienting versus alerting suggests that noradrenergic modulation of the alerting effect does not result only from an underlying effect on temporal orienting. Furthermore, we have demonstrated lateralized neuroanatomical substrates for the noradrenergic modulation of human attentional orienting in the spatial and temporal domains.
我们研究了已知的去甲肾上腺素能对警觉效应（警告线索的有益效应）的减弱是否源于去甲肾上腺素对时间定向（朝向特定时刻定向）的潜在影响。在一项被试内、平衡设计中，10名健康人类志愿者在三个单独的测试环节中分别接受了安慰剂、200微克可乐定或1毫克胍法辛（α2激动剂）。在执行包含空间信息、时间信息、非信息或无线索的注意力定向任务时，通过功能磁共振成像对受试者进行扫描。警觉效应主要激活了左侧前额叶、运动前区和顶叶区域。可乐定而非胍法辛削弱了警觉效应的行为测量指标，同时减弱了左侧颞顶联合区的活动。重复先前的结果，时间定向任务激活了左侧顶叶和额叶皮层，而在空间定向过程中双侧顶叶皮层被激活。在这些神经网络中，可乐定而非胍法辛在时间定向过程中减弱了左侧前额叶皮层和岛叶的活动，在空间定向过程中减弱了右侧顶上叶皮层的活动。为了补充这些神经解剖学变化，可乐定对时间和空间定向都产生了选择性行为影响。可乐定在时间定向与警觉效应上的影响之间的解剖学分离表明，去甲肾上腺素能对警觉效应的调节并非仅源于对时间定向的潜在影响。此外，我们已经证明了在空间和时间领域中，去甲肾上腺素能对人类注意力定向的调节存在偏侧化的神经解剖学基础。
