Single-dose levodopa administration and aging independently disrupt time production
Single-dose levodopa administration and aging independently disrupt time production
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DOI：
10.1162/089892906775990615
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发表时间：
2006-03-01
影响因子：
3.2
通讯作者：
Stern, Y
中科院分区：
文献类型：
--
作者：
Rakitin, BC;Scarmeas, N;Stern, Y
我们检验了与年龄相关的时间生产缺陷是由多巴胺介导的假设。实验采用双盲方法，随机将32名健康的老年人和32名健康的年轻人分为无效安慰剂组和200毫克左旋多巴组。该程序包括训练参与者在不同的区块中产生两个目标时间间隔（6秒和17秒），药物/安慰剂给药，1小时延迟，然后延迟自由回忆时间生产无反馈重新测试。参与者还执行了快速选择反应时间（RT）任务，作为多巴胺能和衰老对注意力和精神运动速度的潜在影响的控制。结果表明，在重测过程中，老年被试表现出的时间依赖误差大于年轻被试。左旋多巴使两种目标间隔的生产时间延长。衰老和左旋多巴效应没有相互作用。此外，衰老减缓了RT，增加了RT的变异性，但左旋多巴对RT没有影响。这些结果表明，在这种剂量下，在这些特定条件下，时间是多巴胺介导的，而衰老对时间产生的影响不是。此外，左旋多巴的计时效应不能归因于多巴胺能功能对精神运动速度的影响。
We tested the hypothesis that age-related time production deficits are dopamine-mediated. The experiment was conducted double-blind, and with random assignment of 32 healthy aged and 32 healthy young participants to either inert placebo or levodopa (200 mg) groups. The procedure included training participants to produce two target time intervals (6 and 17 sec) in separate blocks, drug/placebo administration, a 1-hr delay, and then delayed free-recall time production retesting without feedback. Participants also performed a speeded choice reaction time (RT) task, as a control for potential dopaminergic and aging effects on attention and psychomotor speed. Results indicate that during retesting, aged participants show duration-dependent timing errors that are larger than those shown by the young participants. Levodopa administration yielded lengthened time production of both target intervals. The aging and levodopa effects did not interact. Also, aging slowed RT and increased RT variability, but levodopa had no effect on the RT. These results suggest that at this dosage and under these specific conditions, timing is dopamine-mediated but the effect of aging on time production is not. Moreover, the levodopa timing effect cannot be attributed to the effects of dopaminergic function on psychomotor speed.