Somatotopic Organization of Gentle Touch Processing in the Posterior Insular Cortex
Somatotopic Organization of Gentle Touch Processing in the Posterior Insular Cortex
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DOI：
10.1523/jneurosci.0400-09.2009
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发表时间：
2009-07-22
影响因子：
5.3
通讯作者：
Wessberg, Johan
中科院分区：
文献类型：
--
作者：
Bjornsdotter, Malin;Loken, Line;Wessberg, Johan
细小的(C和A三角)传入神经网络传递与身体生理状况有关的各种信号，包括轻柔的触觉、疼痛和温度变化。这种传入投射到岛叶皮质，在那里最近观察到对伤害性和冷刺激做出反应的躯体组织。为了探索与通过C触觉(CT)纤维介导的轻柔触摸相关的相应身体地图地形图的可能性，我们在功能磁共振成像(FMRI)中对一名Aβ传入缺失的患者(GL)和6名健康受试者的右前臂和大腿进行软刷刺激。为了改进功能磁共振成像分析，我们使用了高度敏感的多变量体素聚类法。包括GL在内的所有受试者均显示左侧(对侧)后岛叶皮质的体位组织，前臂突出于大腿刺激的前方。此外，尽管GL否认在日常生活中有任何触觉，但在强迫选择范式中，GL正确地将97%的刺激定位在前臂或大腿上。GL和健康受试者的激活模式的一致性表明，所识别的组织反映了CT纤维的中央投射。此外，目前观察到的岛叶激活与有害和冷却刺激的描述有很大的相似之处，这巩固了CT系统作为薄传入稳态网络的一部分，在维持身体健康方面的感觉-情感作用假说。
A network of thin (C and A delta) afferents relays various signals related to the physiological condition of the body, including sensations of gentle touch, pain, and temperature changes. Such afferents project to the insular cortex, where a somatotopic organization of responses to noxious and cooling stimuli was recently observed. To explore the possibility of a corresponding body-map topography in relation to gentle touch mediated through C tactile (CT) fibers, we applied soft brush stimuli to the right forearm and thigh of a patient (GL) lacking A beta afferents, and six healthy subjects during functional magnetic resonance imaging (fMRI). For improved fMRI analysis, we used a highly sensitive multivariate voxel clustering approach. A somatotopic organization of the left (contralateral) posterior insular cortex was consistently demonstrated in all subjects, including GL, with forearm projecting anterior to thigh stimulation. Also, despite denying any sense of touch in daily life, GL correctly localized 97% of the stimuli to the forearm or thigh in a forced-choice paradigm. The consistency in activation patterns across GL and the healthy subjects suggests that the identified organization reflects the central projection of CT fibers. Moreover, substantial similarities of the presently observed insular activation with that described for noxious and cooling stimuli solidify the hypothesized sensory-affective role of the CT system in the maintenance of physical well-being as part of a thin-afferent homeostatic network.