Krubitzer L A, Calford M B
Department of Physiology and Pharmacology, University of Queensland, Australia.
J Comp Neurol. 1992 Mar 1;317(1):1-30. doi: 10.1002/cne.903170102.
Five somatosensory fields were defined in the grey-headed flying fox by using microelectrode mapping procedures. These fields are: the primary somatosensory area, SI or area 3b; a field caudal to area 3b, area 1/2; the second somatosensory area, SII; the parietal ventral area, PV; and the ventral somatosensory area, VS. A large number of closely spaced electrode penetrations recording multiunit activity revealed that each of these fields had a complete somatotopic representation. Microelectrode maps of somatosensory fields were related to architecture in cortex that had been flattened, cut parallel to the cortical surface, and stained for myelin. Receptive field size and some neural properties of individual fields were directly compared. Area 3b was the largest field identified and its topography was similar to that described in many other mammals. Neurons in 3b were highly responsive to cutaneous stimulation of peripheral body parts and had relatively small receptive fields. The myeloarchitecture revealed patches of dense myelination surrounded by thin zones of lightly myelinated cortex. Microelectrode recordings showed that myelin-dense and sparse zones in 3b were related to neurons that responded consistently or habituated to repetitive stimulation respectively. In cortex caudal to 3b, and protruding into 3b, a complete representation of the body surface adjacent to much of the caudal boundary of 3b was defined. Neurons in this area habituated rapidly to repetitive stimulation. We termed this caudal field area 1/2 because it had properties of both area 1 and area 2 of primates. In cortex caudolateral to 3b and lateral to area 1/2 (cortex traditionally defined as SII) we describe three separate representations of the body surface coextensive with distinct myeloarchitectonic appearances. The second somatosensory area, SII, shared a congruent border with 3b at the representation of the nose. In SII, the overall orientation of the body representation was erect. The lips were represented rostrolaterally, the digits were represented laterally, and the toes were caudolateral to the digits. The trunk was represented caudally and the head was represented medially. A second complete representation, PV, had an inverted body representation with respect to SII and bordered SII at the representation of the distal limbs. The proximal body parts were represented rostrolaterally in PV. Finally, caudal to both SII and PV, an additional representation, VS, shared a congruent border with the distal hindlimb representation of both SII and PV. VS had a crude topography, and receptive fields of neurons in VS were relatively large. Many neurons in VS responded to both somatosensory and auditory stimulation.
通过微电极测绘程序，在灰头狐蝠中定义了五个躯体感觉区。这些区域分别是：初级躯体感觉区，即SI或3b区；3b区尾侧的一个区域，1/2区；第二躯体感觉区，SII；顶叶腹侧区，PV；以及腹侧躯体感觉区，VS。大量紧密间隔的电极穿刺记录多单位活动显示，这些区域中的每一个都有完整的躯体定位表征。躯体感觉区的微电极图谱与已被展平、平行于皮质表面切割并进行髓鞘染色的皮质结构相关。直接比较了各个区域的感受野大小和一些神经特性。3b区是已确定的最大区域，其地形与许多其他哺乳动物中描述的相似。3b区的神经元对周围身体部位的皮肤刺激反应强烈，且感受野相对较小。髓鞘结构显示，密集髓鞘化的斑块被轻度髓鞘化的皮质薄区包围。微电极记录表明，3b区中髓鞘密集和稀疏的区域分别与对重复刺激持续反应或产生习惯化的神经元有关。在3b区尾侧并延伸至3b区的皮质中，定义了与3b区大部分尾侧边界相邻的身体表面的完整表征。该区域的神经元对重复刺激迅速产生习惯化。我们将这个尾侧区域称为1/2区，因为它具有灵长类动物1区和2区的特性。在3b区的尾外侧和1/2区的外侧（传统上定义为SII的皮质），我们描述了与不同的髓鞘结构外观共存的三个独立的身体表面表征。第二躯体感觉区SII在鼻子的表征处与3b区有一致的边界。在SII中，身体表征的总体方向是直立的。嘴唇在 rostrolaterally 处表征，手指在外侧表征，脚趾在手指的尾外侧。躯干在尾侧表征，头部在内侧表征。第二个完整的表征PV相对于SII有一个倒置的身体表征，并在远端肢体的表征处与SII接壤。近端身体部位在PV中在rostrolaterally处表征。最后，在SII和PV的尾侧，另一个表征VS与SII和PV的远端后肢表征有一致的边界。VS的地形粗糙，VS中神经元的感受野相对较大。VS中的许多神经元对躯体感觉和听觉刺激都有反应。
