Méndez Juan Carlos, Rocchi Lorenzo, Jahanshahi Marjan, Rothwell John, Merchant Hugo
Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro, Mexico; Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom.
Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, United Kingdom; Dipartimento di Neurologia e Psichiatria, Università di Roma "Sapienza", Rome, Italy.
Neuroscience. 2017 Jul 25;356:167-175. doi: 10.1016/j.neuroscience.2017.05.023. Epub 2017 May 19.
Time perception in the millisecond and second ranges is thought to be processed by different neural mechanisms. However, whether there is a sharp boundary between these ranges and whether they are implemented in the same, overlapped or separate brain areas is still not certain. To probe the role of the right dorsolateral prefrontal cortex (dlPFC), the right supplementary motor area (SMA), and the cerebellum on time perception, we temporarily altered their activity on healthy volunteers on separate sessions using transcranial magnetic stimulation with the continuous Theta Burst Stimulation (cTBS) protocol. A control session was reserved for the stimulation of the primary somatosensory cortex (S1). Before and after stimulation, participants were tested on a temporal categorization task using intervals in the hundreds and thousands of milliseconds ranges, as well as on a pitch categorization task which was used as a further control. We then looked for changes in the Relative Threshold and the Constant Error, which, respectively, reflect participants' sensitivity to interval duration and their accuracy at setting an interval that acts as a boundary between categories. We found that after cTBS in all of the studied regions, the Relative Threshold, but not the Constant Error, was affected and only when hundreds of milliseconds intervals were being categorized. Categorization of thousands of milliseconds intervals and of pitch was not affected. These results suggest that the fronto-cerebellar circuit is particularly involved in the estimation of intervals in the hundreds of milliseconds range.
人们认为，毫秒和秒范围内的时间感知是由不同的神经机制处理的。然而，这些范围之间是否存在明显的界限，以及它们是在相同、重叠还是分开的脑区中实现，目前仍不确定。为了探究右侧背外侧前额叶皮层（dlPFC）、右侧辅助运动区（SMA）和小脑在时间感知中的作用，我们在不同的实验环节中，使用连续Theta爆发刺激（cTBS）方案的经颅磁刺激，暂时改变了健康志愿者这些脑区的活动。保留了一个对照实验环节用于刺激初级体感皮层（S1）。在刺激前后，参与者接受了一项时间分类任务的测试，该任务使用数百毫秒和数千毫秒范围内的时间间隔，以及一项音高分类任务，后者用作进一步的对照。然后，我们观察了相对阈值和恒定误差的变化，它们分别反映了参与者对时间间隔持续时间的敏感度以及他们设置作为类别边界的时间间隔的准确性。我们发现，在所有研究区域进行cTBS后，相对阈值受到了影响，但恒定误差未受影响，而且只有在对数百毫秒的时间间隔进行分类时才出现这种情况。对数千毫秒的时间间隔和音高的分类未受影响。这些结果表明，额小脑回路特别参与了数百毫秒范围内时间间隔的估计。
