Khodaie Babak, Edelmann Elke, Leßmann Volkmar
Institut für Physiologie, Otto-von-Guericke-Universität (OVGU), Medizinische Fakultät, 39120 Magdeburg, Germany.
OVGU International ESF-funded Graduate School ABINEP, 39104 Magdeburg, Germany.
iScience. 2024 Feb 22;27(3):109320. doi: 10.1016/j.isci.2024.109320. eCollection 2024 Mar 15.
Synaptic plasticity in the hippocampus underlies episodic memory formation, with dorsal hippocampus being instrumental for spatial memory whereas ventral hippocampus is crucial for emotional learning. Here, we studied how GABAergic inhibition regulates physiologically relevant low repeat spike timing-dependent LTP (t-LTP) at Schaffer collateral-CA1 synapses along the dorsoventral hippocampal axis. We used two t-LTP protocols relying on only 6 repeats of paired spike-firing in pre- and postsynaptic cells within 10 s that differ in postsynaptic firing patterns. GABA receptor mechanisms played a greater role in blocking 6× 1:1 t-LTP that recruits single postsynaptic action potentials. 6× 1:4 t-LTP that depends on postsynaptic burst-firing unexpectedly required intact GABA receptor signaling. The magnitude of both t-LTP-forms decreased along the dorsoventral axis, despite increasing excitability and basal synaptic strength in this direction. This suggests that GABAergic inhibition contributes to the distinct roles of dorsal and ventral hippocampus in memory formation.
海马体中的突触可塑性是情景记忆形成的基础，背侧海马体对空间记忆起重要作用，而腹侧海马体对情绪学习至关重要。在此，我们研究了γ-氨基丁酸能抑制如何在背腹海马轴沿线的谢弗侧支-海马体CA1突触处调节生理相关的低重复尖峰时间依赖性长时程增强（t-LTP）。我们使用了两种t-LTP方案，仅依赖于在10秒内突触前和突触后细胞中6次重复的配对尖峰放电，这两种方案在突触后放电模式上有所不同。γ-氨基丁酸受体机制在阻断募集单个突触后动作电位的6×1:1 t-LTP中发挥了更大作用。依赖于突触后爆发式放电的6×1:4 t-LTP出乎意料地需要完整的γ-氨基丁酸受体信号传导。尽管在这个方向上兴奋性和基础突触强度增加，但两种t-LTP形式的幅度都沿背腹轴降低。这表明γ-氨基丁酸能抑制有助于背侧和腹侧海马体在记忆形成中的不同作用。
