Transient enhancement of stimulus-evoked activity in neocortex during sensory learning.

IF 1.8 4区 医学 Q4 NEUROSCIENCES
Learning & memory Pub Date : 2024-07-02 Print Date: 2024-06-01 DOI:10.1101/lm.053870.123
Mo Zhu, Sandra J Kuhlman, Alison L Barth
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引用次数: 0

Abstract

Synaptic potentiation has been linked to learning in sensory cortex, but the connection between this potentiation and increased sensory-evoked neural activity is not clear. Here, we used longitudinal in vivo Ca2+ imaging in the barrel cortex of awake mice to test the hypothesis that increased excitatory synaptic strength during the learning of a whisker-dependent sensory-association task would be correlated with enhanced stimulus-evoked firing. To isolate stimulus-evoked responses from dynamic, task-related activity, imaging was performed outside of the training context. Although prior studies indicate that multiwhisker stimuli drive robust subthreshold activity, we observed sparse activation of L2/3 pyramidal (Pyr) neurons in both control and trained mice. Despite evidence for excitatory synaptic strengthening at thalamocortical and intracortical synapses in this brain area at the onset of learning-indeed, under our imaging conditions thalamocortical axons were robustly activated-we observed that L2/3 Pyr neurons in somatosensory (barrel) cortex displayed only modest increases in stimulus-evoked activity that were concentrated at the onset of training. Activity renormalized over longer training periods. In contrast, when stimuli and rewards were uncoupled in a pseudotraining paradigm, stimulus-evoked activity in L2/3 Pyr neurons was significantly suppressed. These findings indicate that sensory-association training but not sensory stimulation without coupled rewards may briefly enhance sensory-evoked activity, a phenomenon that might help link sensory input to behavioral outcomes at the onset of learning.

感觉学习过程中新皮层刺激诱发活动的短暂增强
突触电位与感觉皮层的学习有关,但这种电位与感觉诱发的神经活动增加之间的联系尚不清楚。在这里,我们利用清醒小鼠桶状皮层的纵向活体 Ca2+ 成像来验证一个假设:在学习胡须依赖性感觉联想任务的过程中,兴奋性突触强度的增加会与刺激诱发的发射增强相关。为了将刺激诱发反应从动态的任务相关活动中分离出来,成像是在训练环境之外进行的。尽管之前的研究表明多鞭毛刺激会驱动强阈下活动,但我们在对照组和训练组小鼠中都观察到了 L2/3 锥体(Pyr)神经元的稀疏激活。尽管有证据表明在学习开始时这一脑区的丘皮质和皮质内突触的兴奋性突触加强--事实上,在我们的成像条件下,丘皮质轴突被强有力地激活--但我们观察到,体感(桶状)皮层中的 L2/3 Pyr 神经元只显示出刺激诱发活动的适度增加,而且集中在训练开始时。随着训练时间的延长,活动重新正常化。相反,在假训练范式中,当刺激和奖赏不耦合时,L2/3 Pyr 神经元的刺激诱发活动明显受到抑制。这些研究结果表明,感觉联想训练(而非无耦合奖励的感觉刺激)可能会短暂增强感觉诱发活动,这种现象可能有助于在学习开始时将感觉输入与行为结果联系起来。
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来源期刊
Learning & memory
Learning & memory 医学-神经科学
CiteScore
3.60
自引率
5.00%
发文量
45
审稿时长
6-12 weeks
期刊介绍: The neurobiology of learning and memory is entering a new interdisciplinary era. Advances in neuropsychology have identified regions of brain tissue that are critical for certain types of function. Electrophysiological techniques have revealed behavioral correlates of neuronal activity. Studies of synaptic plasticity suggest that some mechanisms of memory formation may resemble those of neural development. And molecular approaches have identified genes with patterns of expression that influence behavior. It is clear that future progress depends on interdisciplinary investigations. The current literature of learning and memory is large but fragmented. Until now, there has been no single journal devoted to this area of study and no dominant journal that demands attention by serious workers in the area, regardless of specialty. Learning & Memory provides a forum for these investigations in the form of research papers and review articles.
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