Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada.
Front Neural Circuits. 2022 Jul 7;16:895000. doi: 10.3389/fncir.2022.895000. eCollection 2022.
Abnormally high-amplitude hippocampal gamma activity (30-100 Hz) in behaving animals is seen after a hippocampal seizure, following injection of phencyclidine (PCP) or ketamine, and transiently in a delirium stage during induction of general anesthesia. High-amplitude hippocampal gamma activity in behaving rats is associated with hyperactive behavior and impairment in sensorimotor gating and sensory gating. The medial septum is necessary for the high-amplitude gamma activity and abnormal behaviors observed following a hippocampal seizure or injection of PCP/ketamine. Glutamatergic projection of the hippocampus to the nucleus accumbens (NAC) and dopaminergic transmission in NAC is necessary for abnormal behaviors. Large hippocampal gamma waves are suggested to contribute to seizure-induced automatism following temporal lobe seizures, and the schizophrenia-like symptoms induced by PCP/ketamine. Low-amplitude gamma activity is found during general anesthesia, associated with loss of consciousness in humans and loss of righting reflex in animals. Local inactivation or lesion of the medial septum, NAC, and brain areas connected to the septohippocampal-NAC system attenuates the increase in hippocampal gamma and associated behavioral disruptions induced by hippocampal seizure or PCP/ketamine. Inactivation or lesion of the septohippocampal-NAC system decreases the dose of anesthetic necessary for gamma decrease and loss of consciousness in animals. Thus, it is proposed that the septohippocampal-NAC system serves to control consciousness and the behavioral hyperactivity and neural dysfunctions during psychosis.
在行为动物中，海马体发作后、注射苯环利定 (PCP) 或氯胺酮后以及全身麻醉诱导的谵妄阶段，会出现异常高幅度的海马体γ 活动 (30-100 Hz)。行为大鼠中海马体的高幅度γ 活动与过度活跃的行为以及感觉门控和感觉门控受损有关。内侧隔室对于海马体发作或 PCP/氯胺酮注射后观察到的高幅度γ 活动和异常行为是必需的。海马体到伏隔核 (NAC) 的谷氨酸能投射和 NAC 中的多巴胺传递对于异常行为是必需的。大的海马体γ 波被认为有助于颞叶癫痫发作后的癫痫发作引起的自动症，以及 PCP/氯胺酮引起的精神分裂样症状。在全身麻醉期间发现低幅度γ 活动，与人类意识丧失和动物的定向反射丧失有关。内侧隔室、NAC 和与隔海马-NAC 系统相连的脑区的局部失活或损伤会减弱海马体 γ 的增加以及海马体发作或 PCP/氯胺酮引起的相关行为障碍。隔海马-NAC 系统的失活或损伤会降低动物中γ 降低和意识丧失所需的麻醉剂量。因此，有人提出，隔海马-NAC 系统有助于控制意识以及精神病期间的行为过度活跃和神经功能障碍。
