Jantzen K J, Steinberg F L, Kelso J A S
Center for Complex Systems and Brain Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431, USA.
Neuroimage. 2005 May 1;25(4):1031-42. doi: 10.1016/j.neuroimage.2004.12.029.
Growing evidence suggests that interval timing in humans is supported by distributed brain networks. Recently, we demonstrated that the specific network recruited for the performance of rhythmic timing is not static but is influenced by the coordination pattern employed during interval acquisition. Here we expand on this previous work to investigate the role of stimulus modality and coordination pattern in determining the brain areas recruited for performance of a self-paced rhythmic timing task. Subjects were paced with either a visual or an auditory metronome in either a synchronized (on the beat) or syncopated (off the beat) coordination pattern. The pacing stimulus was then removed and subjects continued to move based on the required interval. When compared with networks recruited for auditory pacing and continuation, the visual-specific activity was observed in the classic dorsal visual stream that included bilateral MT/V5, bilateral superior parietal lobe, and right ventral premotor cortex. Activity in these regions was present not only during pacing, when visual information is used to guide motor behavior, but also during continuation, when visual information specifying the temporal interval was no longer present. These results suggest a role for modality-specific areas in processing and representing temporal information. The cognitive demands imposed by syncopated coordination resulted in increased activity in a broad network that included supplementary motor area, lateral pre-motor cortex, bilateral insula, and cerebellum. This coordination-dependent activity persisted during the subsequent continuation period, when stimuli were removed and no coordination constraints were imposed. Taken together, the present results provide additional evidence that time and timing are served by a context-dependent distributed network rooted in basic sensorimotor processes.
越来越多的证据表明，人类的间隔计时由分布式脑网络支持。最近，我们证明，为有节奏的计时表现而招募的特定网络并非静态，而是受间隔习得过程中所采用的协调模式影响。在此，我们拓展此前的研究工作，以探究刺激模态和协调模式在确定为自定节奏的有节奏计时任务表现而招募的脑区中的作用。受试者以视觉或听觉节拍器为节奏，采用同步（合拍）或切分（不合拍）协调模式。然后移除节奏刺激，受试者根据所需间隔继续移动。与为听觉节奏和持续移动而招募的网络相比，在经典的背侧视觉流中观察到了视觉特异性活动，该视觉流包括双侧MT/V5、双侧顶上叶和右侧腹侧运动前皮质。这些区域的活动不仅在使用视觉信息来指导运动行为的节奏阶段出现，而且在不再存在指定时间间隔的视觉信息的持续阶段也出现。这些结果表明，特定模态区域在处理和表征时间信息方面发挥了作用。切分协调所带来的认知需求导致一个广泛网络的活动增加，该网络包括辅助运动区、外侧运动前皮质、双侧脑岛和小脑。这种依赖协调的活动在随后的持续阶段持续存在，此时刺激已移除，且没有施加协调限制。综上所述，目前的结果提供了更多证据，表明时间和计时由植根于基本感觉运动过程的依赖上下文的分布式网络提供支持。
