Functional specialization within the medial frontal gyrus for perceptual go/no-go decisions based on "what,'' "when,'' and "where'' related information: An fMRI study
Functional specialization within the medial frontal gyrus for perceptual go/no-go decisions based on "what,'' "when,'' and "where'' related information: An fMRI study
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DOI：
10.1162/0898929054475226
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发表时间：
2005-07-01
影响因子：
3.2
通讯作者：
Hirsch, J
中科院分区：
文献类型：
--
作者：
Talati, A;Hirsch, J
参与执行和意志功能的皮质系统接收并整合来自多个系统的输入。然而，这些集成过程并没有得到很好的理解。特别是，我们还不知道这些输入通路在皮层信息处理的执行层面是收敛还是保持分离。如果单边信息流在服务于高级执行功能的结构中被保存，那么这些结构中的功能组织将可以预见地具有类似的组织。然而，如果单边输入信息流在任何与执行有关的结构中集成，那么活动模式将不一定反映较低的组织。在这项研究中，受试者在执行“知觉走/不走”任务时进行成像，该任务的指令是基于已知的单侧加工流的“空间走”（“在哪里”）、“何时”（“何时”）或对象（“什么”）刺激特征，并且在早期加工区域观察到预期的半球偏差。例如，在“做什么”和“什么时候”任务中，下枕回、中枕回和颞中回的活动倾向于左半球，而在“在哪里”任务中，活动倾向于右半球。我们在内侧额回中发现了类似的侧化，这是一个与高级执行功能和决策相关过程相关的区域。无论反应是被执行的还是想象的，都可以观察到这种侧化，并在多种感觉模式中得到证明。尽管在去/不去任务中活跃，扣带回没有表现出类似的侧化。这些发现进一步区分了内侧额叶和扣带执行区的组织和功能，并表明在内侧额叶回内运行的执行机制保留了输入处理流的基本方面。
Cortical systems engaged during executive and volitional functions receive and integrate input from multiple systems. However, these integration processes are not well understood. In particular, it is not known whether these input pathways converge or remain segregated at the executive levels of cortical information processing. If unilateral information streams are conserved within structures that serve high-level executive functions, then the functional organization within these structures would predictably be similarly organized. If, how- however, unilateral input information streams are integrated within ever, executive-related structures, then activity patterns will not necessarily reflect lower organizations. In this study, subjects were imaged during the performance of a "perceptual go/no-go'' task for which instructions were based on spatial go'' ("where''), temporal ("when''), or object ("what'') stimulus features known to engage unilateral processing streams, and the expected hemispheric biases were observed for early processing areas. For example, activity within the inferior and middle occipital gyri, and the middle temporal gyrus, during the what and when tasks, was biased toward the left hemisphere, and toward the right hemisphere during the "where'' task. We discover a similar lateralization within the medial frontal gyrus, a region associated with high-level executive functions and decision-related processes. This lateralization was observed regardless of whether the response was executed or imagined, and was demonstrated in multiple sensory modalities. Although active during the go/no-go task, the cingulate gyrus did not show a similar lateralization. These findings further differentiate the organizations and functions of the medial frontal and cingulate executive regions, and suggest that the executive mechanisms operative within the medial frontal gyrus preserve fundamental aspects of input processing streams.