人脑Von Economo 神经元功能活动模式和调节机制的电生理学研究

Von Economo neurons (VENs) are large bipolar neurons located in the brains of large-brained social animals, including humans, which have been proposed to represent an adaptation to rapidly relay socially-relevant information over long distances across the brain. Indeed, a number of psychological and social behavior disorders are associated with the selective loss of VENs. However, due to the limited availability of live brain tissue from large-brained social animals with VENs, the electrophysiology properties of VENs remain unknown. We propose to utilize resected human tissue obtained as a by-product of neurosurgeries at our hospital in order to conduct whole cell patch clamp studies of human VENs. Under informed patient consent, surgical waste consisting of neocortical tissue will be obtained, sliced and incubated for investigation. Preliminary results have demonstrated the viability of the cortical slices for more than 24 hours of in vitro incubation. We propose to test four hypotheses of human VENs: ① The intrinsic property of them is singificantly different from that of pyrimedal cells.② The local connectivities of them are different from that of pyrimedal cells, they receive synaptic inputs from pyrimedal and internurons but do not make synaptic output to these cells. ③ They have different synaptic plasticity properties from pyramidal neurons. ④ Their intrinsic property and synaptic currents are modulated by dopamine and serotonin. Understanding the electrophysiological properties of VENs would enhance our understanding of the neuronal mechanisms underlying long distance coordination between multiple cortical areas. As these long distance connections may mediate higher order brain functions, these early studies may provide new insights into human cognition. Clinically, elucidating the properties of VENs may help to understand the selective loss of VENs in a number of neuropsychic disorders, and may provide new strategies of early intervention and treatment.

Von Economo 神经元（VEN）是人类和少数大脑量的群居物种特有的一种大型双极神经元，可能是大脑皮层少数锥体神经元为适应在复杂社会认知活动中的皮层远程投射功能特化形成。其病理意义惊人，与多种有社会认知和情感缺陷的神经精神疾病高度相关。因其分布物种的大脑活组织标本限制，VENs的电生理学研究至今空白。本项目拟应用脑外科肿瘤手术开窗切除的非病理皮层组织，在前期工作已建立人脑片培养方法的基础上，验证人脑VENs：①自身兴奋性有别于锥体神经元；②连接方式与锥体神经元不同,只接受锥体神经元和某种中间抑制性神经元的输入，但不向它们输出；③突触的可塑性与锥体神经元不同；④其功能活动受多巴胺和5-羟色胺神经递质动态调节。本项目揭示基础神经科学中与VENs有关的重要未知问题，有助于阐明人脑多脑区协同和完成高级社会功能的神经机制，为某些神经精神疾病中VENs的选择性受损提出合理解释和早期干预策略。

神经科学对人脑皮层神经元以及神经回路的认识主要依据对啮齿类大脑的研究。Von Economo 神经元（VENs）为人科灵长类（人和人猿）、鲸鱼和大象等具有大脑量的群居哺乳动物所特有，啮齿类没有。人脑中VENs 总数少，具有惊人的病理意义。VENs 在某些以社会技能、认知和情感缺陷为特征的神经精神疾病中选择性易损。由于VENs 分布物种的大脑活组织标本难以获得，其电生理学研究至今空白。我们搭建了双膜片钳系统，建立了人脑手术切除非病理皮层组织体外切片和培养技术，对23例人脑片FS中间神经元的内在电生理特征进行研究，发现人脑FS中间神经元与啮齿类动物存在电生理学差异。对3例含VENs的人脑标本研究发现，人脑VENs与锥体神经元的电生理学特征无明显差异，提示VENs可能是大脑量的哺乳动物为适应复杂的神经回路和社会认知功能由皮层少数锥体神经元（PYRs）特化形成，但有待扩大样本验证。.癫痫共患精神障碍近年来受到极大关注。许多研究提示其与边缘叶多巴胺（DA）系统活动增强有关，但具体机制不清。我们选用17-21d TH-GFP转基因型小鼠制备离体皮层-中脑腹侧被盖区（ventral tegmental area，VTA）脑片。应用细胞贴附式、全细胞式膜片钳技术记录VTA区DA神经元的电生理特征，应用无镁离子人工脑脊液（artificial cerebrospinal fluid，ACSF）孵育脑片诱导皮层癫痫样放电，制作离体癫痫模型（epileptic model，EP-model）。初步发现，在癫痫样状态下，VTA区DANs的内在兴奋性和自发放电频率明显增高，自发和诱发APs半宽明显变窄，sEPSC的频率明显增高，但sEPSC的幅度及sIPSC无变化。在癫痫状态下，谷氨酸受体阻滞剂CNQX和AP5可轻度减少DANs的自发放电频率。诱发PSCs的对脉冲频率（paired-pulse ratio, PPR; eEPSC2/eEPSC1 or eIPSC2/eIPSC1）无变化。结果提示，中脑VTA脑片的DANs神经元在癫痫状态下的自发放电增加，主要与其内在兴奋性和外在兴奋性传入增高有关。在外在兴奋性传入方面，谷氨酸能兴奋性突触传入可能起部分作用。这些变化可能促进癫痫性精神障碍疾病的发生。研究也探讨了新型抗癫痫药左乙拉西坦对癫痫VTA脑片DANs的电生理作用（数据在整理中）。.关键词