Psychology Department, Otago University Dunedin, New Zealand.
Psychology Department, University of Canterbury, Christchurch, New Zealand.
J Psychopharmacol. 2023 Aug;37(8):809-821. doi: 10.1177/02698811231187339. Epub 2023 Jul 29.
Hippocampal phase precession, which depends on the precise spike timing of place cells relative to local theta oscillations, has been proposed to underlie sequential memory. N-methyl-D-asparate (NMDA) receptor antagonists such as ketamine disrupt memory and also reproduce several schizophrenia-like symptoms, including spatial memory impairments and disorganized cognition. It is possible that these impairments result from disruptions to phase precession.
AIMS/METHODS: We used an ABA design to test whether an acute, subanesthetic dose (7.5 mg/kg) of ketamine disrupted phase precession in CA1 of male rats as they navigated around a rectangular track for a food reward.
RESULTS/OUTCOMES: Ketamine did not affect the ability of CA1 place cells to precess despite changes to place cell firing rates, local field potential properties and locomotor speed. However, ketamine reduced the range of phase precession that occurred across a theta cycle.
Phase precession is largely robust to acute NMDA receptor antagonism by ketamine, but the reduced range of precession could have important implications for learning and memory.
海马体相位进动依赖于位置细胞相对于局部 theta 振荡的精确尖峰定时，被认为是序列记忆的基础。N-甲基-D-天冬氨酸（NMDA）受体拮抗剂，如氯胺酮，会破坏记忆，并且还会产生几种类似精神分裂症的症状，包括空间记忆障碍和认知紊乱。这些损伤可能是由于相位进动的破坏造成的。
目的/方法：我们使用 ABA 设计来测试急性、亚麻醉剂量（7.5mg/kg）氯胺酮是否会在雄性大鼠围绕矩形轨迹寻找食物奖励时，破坏 CA1 中海马体相位进动。
结果/结论：尽管 CA1 位置细胞的放电率、局部场电位特性和运动速度发生了变化，但氯胺酮并没有影响 CA1 位置细胞的进动能力。然而，氯胺酮降低了整个 theta 周期内相位进动的范围。
尽管急性 NMDA 受体拮抗剂氯胺酮对相位进动有很大的稳定性，但进动范围的缩小可能对学习和记忆有重要影响。
