Inhibition, Oscillations and Information Processing in Schizophrenia

描述(申请人提供)：该中心的中心假设假设，GABA神经元亚群中的一种独特的分子变化模式会引起皮层网络振荡的干扰，这是精神分裂症信息处理缺陷的基础。皮质GABA神经传递标记物的紊乱在精神分裂症中很常见，最突出的是两种类型的GABA神经元：小白蛋白阳性(PV)快峰神经元和生长抑素阳性(SST)低阈值尖峰神经元。PV和SST细胞各自与同一类型的神经元形成网络，这些神经元被认为分别在伽马(30-80赫兹)和西塔(4-7赫兹)振荡的产生中发挥中心作用，这两种振荡在精神分裂症受试者中都受到干扰。网络振荡至少部分取决于3个生理特性：1)由突触前和突触后因素决定的GABA神经传递的强度[即抑制性突触后电流(IPSC)幅度]；2)GABA神经传递的动力学(即IPSC持续时间)，主要由突触后GABA-A受体的亚单位组成决定；以及3)当GABA-A受体被激活时，由此产生的抑制(即分流或超极化)的性质。这些生理特征中的每一个反过来又依赖于特定的基因产物集的表达。因此，我们假设精神分裂症患者伽马和西塔振荡的变化反映了基因产物中细胞类型的特定干扰，这些干扰影响了GABA介导的抑制的强度、动力学或性质。将以背外侧前额叶皮质(DLPFC)作为精神分裂症患者受影响的皮质区域的身体研究，将确定1)精神分裂症中GABA神经传递的突触前强度是否由于PV和SST神经元中可用于合成GABA的GAD67蛋白数量的缺乏而受损；2)A1和A2 GABA-A受体亚单位的表达是否因细胞类型的改变而扰乱精神分裂症中GABA神经传递的动力学；以及3)精神分裂症中氯转运体的表达是否中断了对GABA神经元的分流抑制输入和/或向锥体细胞的强健振荡所需的超极化抑制输入。拟议的研究在方法和概念上都是创新的，这些调查依赖于该中心其他项目中提出的研究，并为其提供信息。因此，拟议的研究结果可能对精神分裂症振荡和信息处理缺陷的潜在疾病机制以及在确定治疗这些缺陷的新分子靶点方面都具有很高的信息量。

DESCRIPTION (provided by applicant): The central hypothesis of this Center posits that a distinctive pattern of molecular alterations in subsets of GABA neurons gives rise to disturbances in cortical network oscillations that underlie the information processing deficits of schizophrenia. Disturbances in markers of cortical GABA neurotransmission are common in schizophrenia and are most prominent in two types of GABA neurons: parvalbumin-positive (PV), fast-spiking neurons and somatostatin-positive (SST), low-threshold spiking neurons. PV and SST cells each form networks with neurons of the same type that are thought to play central roles in the generation of gamma (30-80 Hz) and theta (4-7 Hz) oscillations, respectively, both of which are disturbed in subjects with schizophrenia. Network oscillations depend, at least in part, on 3 physiological properties: 1) the strength [i.e., inhibitory post-synaptic current (IPSC) amplitude] of GABA neurotransmission as determined by both pre- and post-synaptic factors; 2) the kinetics (i.e., IPSC duration) of GABA neurotransmission as determined principally by the subunit composition of post-synaptic GABA-A receptors; and 3) the nature of the resulting inhibition (i.e., shunting or hyperpolarizing) as determined by chloride ion flow when GABA-A receptors are activated. Each of these physiological features is, in turn, dependent upon the expression of particular sets of gene products. Consequently, we hypothesize that the alterations in gamma and theta oscillations in schizophrenia reflect cell type-specific disturbances in the gene products that influence the strength, kinetics or nature of GABA-mediated inhibition. Studies in postmortem human brain, using the dorsolateral prefrontal cortex (DLPFC) as a prototypic cortical region affected in schizophrenia, will be conducted to determine if 1) the presynaptic strength of GABA neurotransmission in schizophrenia is impaired due to deficits in the amount of GAD67 protein available to synthesize GABA in PV and SST neurons; 2) if cell type-specific alterations in the expression of a1 and a2 GABA-A receptor subunits disrupt the kinetics of GABA neurotransmission in schizophrenia; and 3) if shifts in the expression of chloride transporters in schizophrenia disrupt the shunting inhibitory input to GABA neurons and/or the hyperpolarizing inhibitory input to pyramidal cells required for robust oscillations. The proposed studies are both methodologically and conceptually innovative, and these investigations depend upon and inform the studies proposed in other projects in this Center. Thus, the outcomes of the proposed studies are likely to be highly informative regarding both the disease mechanisms underlying oscillatory and information processing deficits in schizophrenia and in identifying novel molecular targets for treating these deficits.