Johenning Friedrich W, Beed Prateep S, Trimbuch Thorsten, Bendels Michael H K, Winterer Jochen, Schmitz Dietmar
Neuroscience Research Center, Charité-Universitätsmedizin Berlin, Germany.
J Neurosci. 2009 Oct 28;29(43):13649-61. doi: 10.1523/JNEUROSCI.2672-09.2009.
The apical dendrite of layer 2/3 pyramidal cells in the piriform cortex receives two spatially distinct inputs: one projecting onto the distal apical dendrite in sensory layer 1a, the other targeting the proximal apical dendrite in layer 1b. We observe an expression gradient of A-type K(+) channels that weakens the backpropagating action potential-mediated depolarization in layer 1a compared with layer 1b. We find that the pairing of presynaptic and postsynaptic firing leads to significantly smaller Ca(2+) signals in the distal dendritic spines in layer 1a compared with the proximal spines in layer 1b. The consequence is a selective failure to induce long-term potentiation (LTP) in layer 1a, which can be rescued by pharmacological enhancement of action potential backpropagation. In contrast, LTP induction by pairing presynaptic and postsynaptic firing is possible in layer 1b but requires bursting of the postsynaptic cell. This output mode strongly depends on the balance of excitation and inhibition in the piriform cortex. We show, on the single-spine level, how the plasticity of functionally distinct synapses is gated by the intrinsic electrical properties of piriform cortex layer 2 pyramidal cell dendrites and the cellular output mode.
梨状皮层2/3层锥体细胞的顶端树突接收两种空间上不同的输入：一种投射到感觉1a层的远端顶端树突上，另一种靶向1b层的近端顶端树突。我们观察到A 型钾通道的表达梯度，与1b层相比，它减弱了1a层中由动作电位回传介导的去极化。我们发现，与1b层的近端棘突相比，1a层远端树突棘中突触前和突触后放电的配对导致显著更小的钙离子信号。结果是1a层选择性地无法诱导长时程增强（LTP），这可以通过药理增强动作电位回传来挽救。相比之下，在1b层中通过突触前和突触后放电配对诱导LTP是可能的，但需要突触后细胞爆发式放电。这种输出模式强烈依赖于梨状皮层中兴奋和抑制的平衡。我们在单棘突水平上展示了梨状皮层2层锥体细胞树突的内在电特性和细胞输出模式如何控制功能不同的突触的可塑性。
