Dissociated active and passive tactile shape recognition: a case study of pure tactile apraxia
Dissociated active and passive tactile shape recognition: a case study of pure tactile apraxia
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DOI：
10.1093/brain/124.11.2287
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发表时间：
2001-11-01
期刊：
影响因子：
14.5
通讯作者：
Schnider, A
中科院分区：
文献类型：
--
作者：
Valenza, N;Ptak, R;Schnider, A
触觉物体识别(TOR)障碍可能源于初级运动或感觉障碍，或触觉形状表征或语义记忆的较高认知障碍。对健康参与者的研究表明，探索性运动程序的存在与提取物体的特定属性直接相关。在脑损伤患者中，从来没有描述过这些程序的纯粹缺陷，而没有伴随的认识障碍。在这里，我们介绍了一位右半球脑梗塞患者，尽管感觉运动功能完好，但左手的TOR受损。在自发探索的条件下，对2D形状和物体的识别严重不足。对形状的触觉探索是杂乱无章的，探索程序，如轮廓跟踪策略，是识别对象精确形状所必需的，受到严重干扰。然而，在人工或口头引导的探索下对2D形状的识别以及对皮肤上描绘的形状的识别都是完整的，这表明形状识别在主动和被动触摸之间存在分离。左手感觉刺激时的功能磁共振成像显示，保留激活的右侧大脑半球初级感觉皮质。我们将患者的缺陷解释为没有触觉失认的纯触觉失用症，即特定的不能使用触觉反馈来产生触觉形状识别所需的探索性程序。
Disorders of tactile object recognition (TOR) may result from primary motor or sensory deficits or higher cognitive impairment of tactile shape representations or semantic memory. Studies with healthy participants suggest the existence of exploratory motor procedures directly linked to the extraction of specific properties of objects. A pure deficit of these procedures without concomitant gnostic disorders has never been described in a brain-damaged patient. Here, we present a patient with a right hemispheric infarction who, in spite of intact sensorimotor functions, had impaired TOR with the left hand. Recognition of 2D shapes and objects was severely deficient under the condition of spontaneous exploration. Tactile exploration of shapes was disorganized and exploratory procedures, such as the contour-following strategy, which is necessary to identify the precise shape of an object, were severely disturbed. However, recognition of 2D shapes under manually or verbally guided exploration and the recognition of shapes traced on the skin were intact, indicating a dissociation in shape recognition between active and passive touch. Functional MRI during sensory stimulation of the left hand showed preserved activation of the spared primary sensory cortex in the right hemisphere. We interpret the deficit of our patient as a pure tactile apraxia without tactile agnosia, i.e. a specific inability to use tactile feedback to generate the exploratory procedures necessary for tactile shape recognition.