Park S B, Coull J T, McShane R H, Young A H, Sahakian B J, Robbins T W, Cowen P J
MRC Psychopharmacology Unit, University of Oxford, Littlemore Hospital, U.K.
Neuropharmacology. 1994 Mar-Apr;33(3-4):575-88. doi: 10.1016/0028-3908(94)90089-2.
The amino-acid L-tryptophan is essential in the synthesis of brain serotonin, and its depletion can lead to a widespread reduction in central serotonergic activity. A placebo-controlled cross-over within-subjects design (n = 12) examined the effects of tryptophan depletion on human cognitive performance. A low-tryptophan (low-TRP) drink successfully reduced the levels of plasma and total free tryptophan. Computerized tests of memory, learning and executive function revealed selective and non-sedative impairments on cognitive performance following the active drink. Specifically, low-TRP impaired learning as seen in tests of visual discrimination and paired associates. Furthermore, low-TRP lengthened thinking times during the Tower of London planning task, but only in subjects already familiar with the task, suggesting a retrieval deficit. No evidence was found for an effect of the low-TRP drink on measures sensitive to frontal lobe dysfunction, supporting instead a specific role for the serotonergic system in the processes of memory and learning not directly implicated in frontal lobe function.
氨基酸L-色氨酸在大脑血清素的合成中至关重要，其消耗会导致中枢血清素能活性广泛降低。一项安慰剂对照的受试者内交叉设计（n = 12）研究了色氨酸消耗对人类认知表现的影响。一种低色氨酸（low-TRP）饮料成功降低了血浆和总游离色氨酸水平。计算机化的记忆、学习和执行功能测试显示，饮用活性饮料后认知表现出现了选择性且非镇静性的损害。具体而言，低色氨酸损害了视觉辨别和配对联想测试中的学习能力。此外，低色氨酸延长了伦敦塔计划任务中的思考时间，但仅在已经熟悉该任务的受试者中出现，这表明存在检索缺陷。未发现低色氨酸饮料对额叶功能障碍敏感指标有影响的证据，相反，这支持了血清素能系统在记忆和学习过程中具有特定作用，而这些过程与额叶功能并无直接关联。
