Olfactory learning-induced long-lasting enhancement of descending and ascending synaptic transmission to the piriform cortex
Olfactory learning-induced long-lasting enhancement of descending and ascending synaptic transmission to the piriform cortex
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DOI：
10.1523/jneurosci.0178-08.2008
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发表时间：
2008-06-25
影响因子：
5.3
通讯作者：
Maroun, Mouna
中科院分区：
文献类型：
--
作者：
Cohen, Yaniv;Reuveni, Iris;Maroun, Mouna
学习一项特别困难的嗅觉辨别(OD)任务会导致规则学习的获得。这种学习能力的显著增强伴随着梨状皮质(PC)锥体神经元之间突触连接的长期增强。因为在OD任务中的成功表现需要整合关于身份和气味的奖赏价值的信息，很可能更高级别的大脑区域也参与规则学习的获得和维持。前PC(APC)从嗅球接受强烈的上行输入，携带与环境中的嗅觉线索有关的信息。它还接受来自眶前皮质(OFC)的大量下行输入，该皮质被认为在编码气味刺激的预测值方面发挥着重要作用。利用在体诱发场突触后电位的记录，我们研究了OFC向APC投射的生理特性，并检测了OD学习后梨状皮质下行和上行突触输入是否发生了改变。我们表明，学习能力的增强伴随着下行和上行输入的突触传递的长期增强。长期的突触增强并不伴随成对脉冲易化的改变，这表明这种改变可能是突触后的。长时程增强诱导的倾向受到先前学习的影响，令人惊讶的是，先前暴露在气味和训练设备中也会影响到这一倾向。这些数据表明，要学习OD规则，需要加强APC与其输入源之间的连通性。
Learning of a particularly difficult olfactory-discrimination (OD) task results in acquisition of rule learning. This remarkable enhancement in learning capability is accompanied by long-term enhancement of synaptic connectivity between piriform cortex (PC) pyramidal neurons. Because successful performance in the OD task requires integration of information about the identity and also about the reward value of odors, it is likely that a higher-order brain area would also be involved in rule learning acquisition and maintenance. The anterior PC (APC) receives a strong ascending input from the olfactory bulb, carrying information regarding olfactory cues in the environment. It also receives substantial descending input from the orbitofrontal cortex (OFC), which is thought to play an important role in encoding the predictive value of odor stimuli. Using in vivo recordings of evoked field postsynaptic potentials, we characterized the physiological properties of projections to APC from the OFC and examined whether descending and ascending synaptic inputs to the piriform cortex are modified after OD learning. We show that enhanced learning capability is accompanied by long-term enhancement of synaptic transmission in both the descending and ascending inputs. Long-term synaptic enhancement is not accompanied by modifications in paired-pulse facilitation, indicating that such modifications are likely postsynaptic. Predisposition for long-term potentiation induction was affected by previous learning, and surprisingly also by previous exposure to the odors and training apparatus. These data suggest that enhanced connectivity between the APC and its input sources is required for OD rule learning.