Centre for Rural and Remote Mental Health, University of Newcastle, Australia.
Int J Neuropsychopharmacol. 2009 Nov;12(10):1295-305. doi: 10.1017/S1461145709990551. Epub 2009 Sep 9.
Cholinergic neurotransmission has been implicated in memory and attention. We investigated the effect of the non-competitive nicotinic antagonist mecamylamine on three components of attention processes (i.e. alerting, orienting and executive control) in 12 healthy male subjects whilst performing the Attention Network Task (ANT) in a magnetic resonance imaging (MRI) scanner. Participants received 15 mg mecamylamine in a single blind and placebo- controlled randomized procedure 90 min prior to obtaining functional MRI data. Our results confirm previous reports of beneficial effects of cueing (alerting and orienting) and detrimental effects of conflict (executive control) on reaction times when performing the ANT. The functional MRI data confirmed distinct neural networks associated with each of the three attention components. Alerting was associated with increased left temporal lobe activation while orienting increased bilateral prefrontal, right precuneus and left caudate activation. Executive control activated anterior cingulate and precuneus. Mecamylamine slowed overall response time and down-regulated brain activation associated with orienting and to some extent brain activation associated with executive control when compared to placebo. These findings are consistent with nicotinic modulation of orienting attention by cueing and executive control when responding to conflicting information. The latter nicotine antagonist effect may be mediated via cholinergic modulation of dopamine neurotransmission in mesolimbic pathways.
胆碱能神经传递与记忆和注意力有关。我们在磁共振成像（MRI）扫描仪中研究了非竞争性烟碱拮抗剂美金刚胺对 12 名健康男性在执行注意网络任务（ANT）时的注意过程的三个成分（警觉、定向和执行控制）的影响。参与者在获得功能 MRI 数据之前 90 分钟，以单盲和安慰剂对照随机程序接受 15 毫克美金刚胺。我们的结果证实了先前关于提示（警觉和定向）对反应时间有益，以及冲突（执行控制）对反应时间有害的报告。功能 MRI 数据证实了与三个注意力成分中的每一个都相关的不同神经网络。警觉与左颞叶激活增加有关，而定向则增加双侧前额叶、右楔前叶和左尾状核的激活。执行控制激活前扣带和楔前叶。与安慰剂相比，美金刚胺会减慢整体反应时间，并下调与定向相关的大脑激活，以及在某种程度上与执行控制相关的大脑激活。这些发现与烟碱通过提示对定向注意力的调制以及对冲突信息的反应时的执行控制一致。后一种尼古丁拮抗剂效应可能是通过中脑边缘多巴胺神经递质的胆碱能调制介导的。
