Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, 113-0033, Japan.
Institute of AI and Beyond, The University of Tokyo, Tokyo, 113-0033, Japan.
J Physiol. 2021 Jun;599(12):3151-3167. doi: 10.1113/JP281152. Epub 2021 May 29.
Neurons in the retrosplenial cortex (RSC), a cerebral region that connects synaptically with various brain regions, are known to increase neuronal activity in accordance with hippocampal sharp wave-ripples. Pyramidal cells in granular RSC (gRSC) layer 2/3, but not layer 5, exhibit slowly ramping depolarization and considerably delayed spikes in response to a step-pulse current injection. The latencies of delayed spikes in RSC layer 2/3 pyramidal neurons were shortened by a preceding current injection. This effect was mimicked by activation of axonal afferents from the subiculum, but not of neocortical afferents. The subiculum is likely to facilitate information processing and flow in the RSC.
The retrosplenial cortex (RSC), a cerebral region involved in diverse cognitive functions, is an anatomical hub that forms monosynaptic connections with various brain areas. Here, we report a unique form of short-term intrinsic plasticity in mouse granular RSC layer 2/3 pyramidal cells. These cells exhibited delayed spikes in response to somatic current injection, but the spike latencies were shortened by a preceding brief depolarization (priming). This priming-induced sensitization is distinct from desensitization, which is commonly observed in other cortical neurons. The facilitatory priming effect lasted for more than 3 s, providing a time window for increased sensitivity to RSC inputs. Based on in vitro and in vivo patch-clamp recordings following optogenetic stimulation of axonal fibres, we found that preactivation of subicular afferents replicated the facilitatory priming effect. The results suggest that subicular inputs to RSC layer 2/3 neurons may modulate subsequent information integration in the RSC layer 2/3 circuits.
已知与各种脑区突触连接的大脑后隔区（RSC）中的神经元会根据海马体的尖波-涟漪增加神经元活动。颗粒状 RSC（gRSC）第 2/3 层而非第 5 层的锥体神经元在受到阶跃脉冲电流注入时会表现出缓慢上升的去极化和明显延迟的尖峰。RSC 第 2/3 层锥体神经元的延迟尖峰潜伏期通过先前的电流注入而缩短。这种效应可以通过来自下托的轴突传入的激活来模拟，但不能通过新皮层传入的激活来模拟。下托可能有助于 RSC 中的信息处理和流动。
参与多种认知功能的大脑后隔区（RSC）是一个解剖学枢纽，与各种脑区形成单突触连接。在这里，我们报告了在小鼠颗粒状 RSC 第 2/3 层锥体细胞中存在一种独特的短期内在可塑性形式。这些细胞对体细胞电流注入表现出延迟尖峰，但通过先前的短暂去极化（引发）可以缩短尖峰潜伏期。这种引发诱导的敏感化与在其他皮质神经元中常见的脱敏不同。引发诱导的敏感化效应持续超过 3 s，为增加对 RSC 输入的敏感性提供了时间窗口。基于轴突纤维光遗传刺激后的离体和体内膜片钳记录，我们发现下托传入的预激活复制了促进引发的敏感化效应。结果表明，下托到 RSC 第 2/3 层神经元的输入可能调节 RSC 第 2/3 层电路中的后续信息整合。
