Tryptophan depletion effects on EEG and MEG responses suggest serotonergic modulation of auditory involuntary attention in humans
Tryptophan depletion effects on EEG and MEG responses suggest serotonergic modulation of auditory involuntary attention in humans
复制标题
DOI：
10.1006/nimg.2002.1142
复制
发表时间：
2002-08-01
期刊：
影响因子：
5.7
通讯作者：
Jääskeläinen, IP
中科院分区：
文献类型：
--
作者：
Ahveninen, J;Kähkönen, S;Jääskeläinen, IP
无意识的注意力转移，即，检测和定向到意外的刺激变化，可以在低脑血清素（5-羟色胺; 5-HT）水平下改变。这是在13名健康受试者（21-30岁; 6名女性）中通过使用饮食挑战，急性色氨酸耗竭（ATD），减少大脑中的5-HT合成进行的研究。摄入ATD或对照混合物（随机、双盲、交叉设计）5小时后，同时用64通道脑电图（EEG）和122通道脑磁图（MEG）测量指示不自主注意的脑反应。在测量过程中，受试者被指示通过快速按下两个按钮中的一个来区分等概率的200和400 ms音调。偶尔，音调的频率会改变（增加/减少10%），导致无意识的注意力转移。ATD显著降低血浆色氨酸浓度（总色氨酸降低75%，游离色氨酸降低35%）。与对照条件相比，ATD降低了异常音N2波的振幅，包括重叠失配负波（MMN）和N2 b子成分，这被认为反映了大脑中的变化检测。EEG结果伴随着MMN的磁对应物的峰潜伏期的显著增加。然而，没有ATD效应，观察到在P3任务无关的频率变化。对异常音调本身的反应时间（RT）没有受到显着影响，但在异常频率音调之后的试验中，ATD增加了RT，这表明对任务相关活动的重新定向受损。总之，结果表明，ATD后中枢5-HT功能水平下降可能会减少非自愿注意转移到任务无关的声音变化，从而调节资源分配到任务相关的活动。(C)2002 Elsevier Science（美国）。
Involuntary attention shifting, i.e., detecting and orienting to unexpected stimulus changes, may be altered at low brain serotonin (5-hydroxytryptamine; 5-HT) levels. This was studied in 13 healthy subjects (21-30 years old; 6 females) by using a dietary challenge, acute tryptophan depletion (ATD), which decreases 5-HT synthesis in the brain. Five hours after ingestion of either ATD or control mixture (randomized, double-blinded, crossover design), brain responses indexing involuntary attention were measured with simultaneous 64-channel electroencephalography (EEG) and 122-channel magnetoencephalography (MEG). During the measurement, the subjects were instructed to discriminate equiprobable 200- and 400-ms tones by pressing one of two buttons rapidly. Occasionally, the frequency of the tones changed (10% increase/decrease), causing involuntary attention shifting. ATD significantly lowered plasma tryptophan concentrations (total tryptophan decreased by 75%, free tryptophan decreased by 35%). As compared to the control condition, ATD reduced the amplitude of the deviant-tone N2 wave, including the overlapping mismatch negativity (MMN) and N2b subcomponents, which are suggested to reflect change detection in the brain. The EEG results were accompanied by a significant increase in the peak latency of the magnetic counterpart of MMN. However, no ATD effects were observed in P3 to task-irrelevant frequency change. Reaction time (RT) to deviants per se was not significantly affected, but RT in trials succeeding the deviant-frequency tones was increased by ATD, which suggested impaired reorienting to the task-relevant activity. In conclusion, the results suggest that decreased level of central 5-HT function after ATD may decrease involuntary attention shifting to task-irrelevant sound changes and thus modulate resource allocation to the task-relevant activity. (C) 2002 Elsevier Science (USA).