Increased excitability of cortical neurons induced by associative learning: an ex vivo study
Increased excitability of cortical neurons induced by associative learning: an ex vivo study
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DOI：
10.1111/j.1460-9568.2010.07453.x
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发表时间：
2010-11-01
影响因子：
3.4
通讯作者：
Kossut, Malgorzata
中科院分区：
文献类型：
--
作者：
Bekisz, Marek;Garkun, Yury;Kossut, Malgorzata
在成年小鼠中，经典条件反射，其中胡须刺激与电击尾部配对，导致头部运动频率降低，诱导受刺激触须的皮质代表性扩张，并增强“训练”桶内的抑制性突触相互作用。我们研究了这种简单的联想学习模式是否也会引起神经元兴奋性的变化。使用全细胞记录从离体切片的桶皮层，我们发现，位于皮层代表的第四层兴奋性细胞的“训练”行触须有较高的频率记录在阈值电位的尖峰比神经元从“未经训练”的行，比细胞从控制动物。此外，兴奋性细胞内的“训练”桶的特征在于增加增益的输入-输出功能，较低的幅度的快速后超极化和降低的影响阻断BK通道的伊比利亚毒素。这些发现为IV层兴奋性神经元内在兴奋性增强的可能机制提供了新的见解。相反，在相同的桶中记录的快速尖峰抑制细胞在条件化程序后没有改变它们的内在兴奋性。“训练”桶内兴奋性神经元的兴奋性增加可能代表稳态可塑性的对应物，其与先前描述的增强的突触抑制平行。总之，这两种机制将有助于增加条件皮层网络内的输入选择性。
In adult mice, classical conditioning in which whisker stimulation is paired with an electric shock to the tail results in a decrease in the frequency of head movements, induces expansion of the cortical representation of stimulated vibrissae and enhances inhibitory synaptic interactions within the 'trained' barrels. We investigated whether such a simple associative learning paradigm also induced changes in neuronal excitability. Using whole-cell recordings from ex vivo slices of the barrel cortex we found that layer IV excitatory cells located in the cortical representation of the 'trained' row of vibrissae had a higher frequency of spikes recorded at threshold potential than neurons from the 'untrained' row and than cells from control animals. Additionally, excitatory cells within the 'trained' barrels were characterized by increased gain of the input-output function, lower amplitudes of fast after-hyperpolarization and decreased effect of blocking of BK channels by iberiotoxin. These findings provide new insight into the possible mechanism for enhanced intrinsic excitability of layer IV excitatory neurons. In contrast, the fast spiking inhibitory cells recorded in the same barrels did not change their intrinsic excitability after the conditioning procedure. The increased excitability of excitatory neurons within the 'trained' barrels may represent the counterpart of homeostatic plasticity, which parallels enhanced synaptic inhibition described previously. Together, the two mechanisms would contribute to increase the input selectivity within the conditioned cortical network.