FUNCTIONAL ORGANIZATION OF THE VENTRAL STREAM IN NORMALLY DEVELOPING CHILDREN

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 本研究探讨了成人大脑腹侧流区(包括后额叶和枕叶腹外侧区)的视觉客体类别依赖活动是否存在于发育过程中，以及这种组织是否受到发育障碍的干扰。检查的疾病是威廉姆斯综合征(WS)，这是一种罕见的遗传缺陷，其特征是认知特征不均衡。WS患者具有完整的人脸识别能力，尽管在视觉空间任务(如积木构建)上存在严重损害。这种视觉能力的模式导致了一种假设，即WS的遗传缺陷不会改变腹侧流中支持物体识别的视觉表征，但确实会对背侧流所支持的视觉空间表征造成广泛的损害。这些研究的目的是通过详细检查WS的腹流功能来评估这一说法。我们将比较患有WS的青少年和年轻人与正常发育人群的fMRI激活模式。将使用两个正常发育的对照组，青少年和青壮年在年龄上匹配(CA匹配)，儿童在心理年龄匹配(MA匹配)。目前，关于腹侧流发育的证据很少，所以我们将首先检查儿童是否表现出与以前在成人中发现的类似的腹侧流组织，然后WS患者是否类似于CA或MA匹配。这一证据将解决目前正在进行的一场辩论，即具有严重后果的遗传缺陷是否会导致新的策略和神经重组而不是发育(Karmiloff-Smith，1998)。 为了验证这一点，提出了两个功能磁共振实验。其中一项任务将使用被动观看人脸、房屋、猫和鞋子来测试腹侧流功能。第二个任务将使用具有相同对象的工作记忆范例。通过使用各种物体作为刺激，我们可以调查在WS中发现的多余的人脸识别能力是否意味着完全功能的腹侧流、梭形脸区(FFA)的一小部分保留功能，或者是另一种系统。被动观看提供了任务要求较低的任务，从而最大限度地减少了与任务难度相关的混淆。成熟的记忆范式也有明显的好处；除了产生强大的腹侧流活动外，它还使我们能够检查前额叶激活，并评估激活与工作记忆任务表现之间的关系。在行为学研究中，WS患者在某些对象类别上表现出记忆障碍，这种缺陷可能反映了前额叶区域的异常激活。这些成像研究，以及在我们实验室完成的广泛的行为研究，将提供关于威廉姆斯综合征患者和正常发育儿童的腹侧流和前额叶皮质所支持的视觉功能的关键、详细的信息。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The present studies examine whether the visual object category-dependent activity found among adults in ventral stream areas, including posterior temporal and ventrolateral occipital cortices, exists during development and whether this organization is disrupted by a developmental disorder. The disorder examined is Williams syndrome (WS), a rare genetic deficit characterized by an uneven cognitive profile. People with WS have intact face recognition capacities in spite of severe impairments on visual spatial tasks such as block construction. This pattern of visual abilities has led to the proposal that the genetic defect in WS does not alter the visual representations underlying object recognition in the ventral stream but does cause extensive damage to the visual spatial representations subserved by the dorsal stream. The purpose of these studies is to evaluate this claim by examining in detail ventral stream function in WS. We will compare the pattern of fMRI activation in adolescents and young adults with WS to normally developing populations. Two normally developing control groups will be used, adolescents and young adults matched on chronological age (CA matches) and children matched in mental age (MA matches). Currently, little evidence exists on the development of the ventral stream, so we will first examine whether children display similar ventral steam organization to that found previously in adults, and then whether people with WS resemble either CA or MA matches. This evidence will address an ongoing debate on whether genetic deficits with severe consequences lead to novel strategies and neural reorganization over development (Karmiloff-Smith, 1998). To examine this, two functional MRI experiments are proposed. One task will use passive viewing of human faces, houses, cats, and shoes to test ventral stream function. The second task will use a working memory paradigm with the same objects. By utilizing a variety of object kinds as stimuli, we can investigate whether the spared face recognition abilities found in WS indicate a fully functioning ventral stream, a small area of preserved function in the Fusiform Face Area (FFA), or an alternative system. Passive viewing provides a task with low task demands, thus minimizing confounds related to task difficulty. The well-established memory paradigm also has distinct benefits; in addition to producing robust ventral stream activity, it enables us to examine prefrontal activation and assess the relationship between activation and performance on the working memory task. In behavioral studies, people with WS display memory impairments with some object categories, a deficit that may reflect abnormal activation in prefrontal areas. These imaging studies, together with the extensive behavioral studies done in our laboratory, will provide crucial, detailed information on the visual functions subserved by the ventral stream and prefrontal cortex in people with Williams syndrome and normally developing children.