Dynamics of postsynaptic calcium involved in plasticity of visual cortex

突触后钙的动态参与视觉皮层的可塑性

• 批准号: 07458220
• 负责人: TSUMOTO Tadaharu
• 金额: $ 4.74万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07458220/
• 关键词: Synaptic plasticity; Visual cortex; Long-term potentiation; Long-term depression; Development; Rat; Calcium; Memory; 脳; 神経回路; カルシウムイメージング; ニューロン

In the developing visual cortex, repetitive stimulation of afferent pathways was reported to induce long-term potentiation (LTP) or long-term depression (LTD) of synaptic transmission in layr II/III of the cortex. It was not clearly known, however, what factors determine the direction of long-term changes in synaptic efficacy, i.e., LT or LTD.The present results were designed to address this question.Thin slices of the visual cortex were prepared from young rats (postnatal days 20-26). Under visual control, neurons in layr II/III were loaded with a fluorescent Ca^<2+> indicator, rhod 2, through glass micropipettes for patch-clamp recording. Changes in fluorescence intensity were recorded simultaneously with excitaory postsynaptic potentials (EPSPs) evoked by test stimulation of layr IV.Tetanic stimulation of layr IV which induced LTP of EPSPs led to a massive increase in fluorescence intensity at dendritic hot spots. On the other hand, tetanic stimulation which induced a moderate rise of fluorescence led to LTD of EPSPs. In sum, it is suggested that a rise of postsynaptic Ca^<2+> during synaptic inputs beyond a certain threshold induces LTP while a weak or moderate rise below the threshold induces LTD.

据报道，在发育中的视觉皮层中，传入通路的重复刺激会诱导皮层 II/III 层突触传递的长期增强 (LTP) 或长期抑制 (LTD)。然而，目前尚不清楚哪些因素决定了突触功效（即 LT 或 LTD）长期变化的方向。本研究结果旨在解决这个问题。从年轻大鼠身上制备视觉皮层薄片（产后第 20-26 天）。在视觉控制下，通过玻璃微量移液管将荧光Ca 2+ 指示剂rhod 2装载到第II/III层中的神经元以用于膜片钳记录。荧光强度的变化与 IV 层测试刺激引起的兴奋性突触后电位 (EPSP) 同时记录。IV 层的强直刺激诱导 EPSP 的 LTP，导致树突热点处的荧光强度大幅增加。另一方面，强直刺激诱导荧光适度上升，导致 EPSP 的 LTD 增加。总之，表明在突触输入期间突触后Ca 2+ 的升高超过特定阈值诱发LTP，而低于阈值的微弱或中等升高诱发LTD。

项目成果

Kimura, F.et al.: "Presynaptically silent synapses : Spontaneously active terminals without stimulus-evoked release demonstrated in cortical autapses." Journal of Neurophysiology. 77. 2805-2815 (1997)

Kimura, F.等人：“突触前沉默突触：在皮层自动突触中证明没有刺激诱发释放的自发活动末梢。”

Tamura,H.,Sato,H.,Katsuyama,N.,Hata,Y.,and Tsumoto,T.: "Less segregated processing of visual information in V2 than V1 of the monkey visual cortex." Europ.J.Neurosci.8. 300-309 (1996)

Tamura,H.、Sato,H.、Katsuyama,N.、Hata,Y. 和 Tsumoto,T.：“与猴子视觉皮层的 V1 相比，V2 中视觉信息的隔离处理更少。”

Sato,H.,Tamura,H.,Katksuyama,N.,Hata,Y.and Tsumoto,T.: "Mechanisms underlying direction selectivity of neurons in the primary visual cortex of the macaque." J.Neurophysiol.74. 1382-1394 (1995)

Sato, H.、Tamura, H.、Katksuyama, N.、Hata, Y. 和 Tsumoto, T.：“猕猴初级视觉皮层神经元方向选择性的机制。”

Yasuda,H.and Tsumoto,T.: "Long-term depression in visual cortex is associated with a lower rise of postsynaptic Ca2+ than LTP." Neurosci.Res.(in press). (1996)

Yasuda,H. 和 Tsumoto,T.：“与 LTP 相比，视觉皮层的长期抑制与突触后 Ca2 升高较低有关。”

Akaneya, Y.et al.: "Long-term depression blocked by brain derived neurotrophic factor in rat visual cortex." Journal of Neurophysiology. 76. 4198-4201 (1996)

Akaneya, Y. 等人：“大鼠视觉皮层中的脑源性神经营养因子可阻断长期抑郁。”