LEARNING-INDUCED AFTERHYPERPOLARIZATION REDUCTIONS IN HIPPOCAMPUS ARE SPECIFIC FOR CELL TYPE AND POTASSIUM CONDUCTANCE
LEARNING-INDUCED AFTERHYPERPOLARIZATION REDUCTIONS IN HIPPOCAMPUS ARE SPECIFIC FOR CELL TYPE AND POTASSIUM CONDUCTANCE
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DOI：
10.1007/bf00227987
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发表时间：
1990-01-01
影响因子：
2
通讯作者：
DISTERHOFT, JF
中科院分区：
文献类型：
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作者：
DEJONGE, MC;BLACK, J;DISTERHOFT, JF
海马切片从在跟踪眨眼条件反射任务中训练的兔子以及从幼稚和假条件反射对照中制备。从CA 1锥体细胞（N=49）和齿状回颗粒细胞（N=52）的细胞内记录中获得后爆发后超极化（AHP），动作电位和其他细胞特性的测量。在CA 1细胞中发现了AHP幅度的条件特异性降低，但在齿状颗粒细胞中没有。在AHP的这种减少是明显的，在50毫秒后结束的去极化电流脉冲，并保持至少650毫秒。其他测量的细胞特性（输入电阻，静息膜电位，动作电位的形状，向内整流，尖峰阈值）不受训练的影响，无论是在CA 1锥体细胞或齿状颗粒细胞。时间过程测量表明，中等的、不依赖于Ca 2+的层次分析法和缓慢的、依赖于Ca 2+的层次分析法都因调节而降低。慢AHP主要反映了钙依赖性K+电流，IAHPRising和下降斜率，峰值幅度和宽度的个人动作电位没有改变的学习。这与无脊椎动物的观察结果形成鲜明对比，其中报告了学习后的动作电位加宽。我们的结论是，减少AHP，以下campaillly依赖的联想学习发生在特定的海马细胞类型，而不是其他的，介导的变化，在一个Ca 2-独立的AHP和一个特定的Ca 2+依赖的K+电流，IAHP。
Hippocampal slices were prepared from rabbits trained in a trace eye-blink conditioning task and from naive and pseudoconditioned controls. Measurements of the post-burst afterhyperpolarization (AHP), action potential, and other cellular properties were obtained from intracellular recordings of CA1 pyramidal (N=49) and dentate gyrus granule cells (N=52). A conditioning-specific reduction in the amplitude of the AHP was found in CA1 cells but not in dentate granule cells. This reduction in the AHP was apparent at 50 ms after the end of a depolarizing current pulse, and was maintained for at least 650 ms. Other measured cell characteristics (input resistance, resting membrane potential, action potential shape, inward rectification, spike threshold) were not affected by training, in either CA1 pyramidal or dentate granule cells. Time-course measures indicate that both the medium, Ca2+-independent AHP and the slow, Ca2+-dependent AHP are reduced by conditioning. The slow AHP largely reflects the Ca2+-dependent K+current, IAHPRising and falling slopes, peak amplitude, and width of individual action potentials were not changed by learning. This contrasts with observations from invertebrates in which action potential broadening was reported following learning. We conclude that the reduction in AHP that follows hippocampally-dependent associative learning occurs in specific hippocampal cell types and not others, and is mediated by changes in a Ca2-independent AHP and a particular Ca2+-dependent K+current, IAHP.