Department of Neurology, University of Minnesota, Minneapolis, MN 55455, USA.
Proc Natl Acad Sci U S A. 2011 Aug 16;108(33):13818-22. doi: 10.1073/pnas.1104096108. Epub 2011 Aug 1.
The timing of events can be implicit or without awareness yet critical for task performance. However, the neural correlates of implicit timing are unknown. One system that has long been implicated in event timing is the olivocerebellar system, which originates exclusively from the inferior olive. By using event-related functional MRI in human subjects and a specially designed behavioral task, we examined the effect of the subjects' awareness of changes in stimulus timing on the olivocerebellar system response. Subjects were scanned while observing changes in stimulus timing that were presented near each subject's detection threshold such that subjects were aware of such changes in only approximately half the trials. The inferior olive and multiple areas within the cerebellar cortex showed a robust response to time changes regardless of whether the subjects were aware of these changes. Our findings provide support to the proposed role of the olivocerebellar system in encoding temporal information and further suggest that this system can operate independently of awareness and mediate implicit timing in a multitude of perceptual and motor operations, including classical conditioning and implicit learning.
事件的时间可以是隐含的或无意识的，但对任务表现至关重要。然而，隐含时间的神经相关性尚不清楚。一个长期以来一直被认为与事件时间有关的系统是橄榄小脑系统，它仅起源于下橄榄核。通过在人类受试者中使用与事件相关的功能磁共振成像和专门设计的行为任务，我们研究了受试者对刺激时间变化的意识对橄榄小脑系统反应的影响。在观察接近每个受试者检测阈值的刺激时间变化时对受试者进行扫描，以便只有大约一半的试验中受试者意识到这些变化。下橄榄核和小脑皮层内的多个区域对时间变化表现出强烈的反应，无论受试者是否意识到这些变化。我们的发现为橄榄小脑系统在编码时间信息方面的作用提供了支持，并进一步表明，该系统可以在无意识的情况下独立运作，并在多种感知和运动操作中介导隐含时间，包括经典条件反射和内隐学习。
