Knecht S, Kunesch E, Schnitzler A
Department of Neurology, University of Düsseldorf, Germany.
Neuropsychologia. 1996 Jul;34(7):669-87. doi: 10.1016/0028-3932(95)00148-4.
Recent animal studies have shown that there is an evolutionary shift within the order of primates from parallel to serial processing of haptic information. In an attempt to determine whether there is also evidence of serial processing in humans 10 patients with parietal cortical lesions, three patients with subcortical lesions and one patient after hemispherectomy, were examined. Case-by-case and across subject analysis of lesion type, sensorimotor profile and electrophysiological findings showed that in unihemispheric lesions: (a) there is little impairment of thermesthesia, nociception and vibration sense: (b) two-point discrimination and integrity of the N20 somatosensory component are highly correlated; (c) a loss of the N20 component is accompanied by a severe impairment of stereognosis; (d) conversely, in more posterior lesions astereognosis can occur with an intact N20 component; and (e) if the lesion is in the right hemisphere there is frequently impairment of graphesthesia in both hands. These data are taken to indicate serial processing from SI (as evidenced by an intact N20 component) to posterior parietal cortex allowing progressive spatial and temporal integration. In graphesthesia our data suggest an integrative function of the right parietal cortex for both sides of the body. Other sensory qualities like vibration nociception and thermesthesia are apparently processed in a non-serial, probably parallel way involving both hemispheres. The effects of cerebral lesions in our series suggest parallel as well as serial processing of somesthetic information in man underlying the perception of different haptic features.
近期的动物研究表明，灵长目动物在触觉信息处理方面存在从并行处理到串行处理的进化转变。为了确定人类是否也存在串行处理的证据，我们对10例顶叶皮质病变患者、3例皮质下病变患者和1例半球切除术后患者进行了检查。对病变类型、感觉运动特征和电生理结果进行逐例和跨受试者分析后发现，在单半球病变中：(a) 温度觉、痛觉和振动觉几乎没有受损；(b) 两点辨别能力与N20体感成分的完整性高度相关；(c) N20成分缺失伴随着实体觉严重受损；(d) 相反，在更靠后的病变中，N20成分完整时也可能出现实体觉缺失；(e) 如果病变位于右侧半球，双手常常会出现触觉失认症。这些数据表明存在从SI（由完整的N20成分证明）到顶叶后皮质的串行处理，从而实现渐进的空间和时间整合。在触觉失认症方面，我们的数据表明右侧顶叶皮质对身体两侧具有整合功能。其他感觉特性，如振动觉、痛觉和温度觉，显然是以非串行、可能是并行的方式进行处理的，涉及两个半球。我们系列研究中脑损伤的影响表明，人类在感知不同触觉特征时，躯体感觉信息存在并行和串行处理。
