FosGFP expression does not capture a sensory learning-related engram in superficial layers of mouse barrel cortex
FosGFP expression does not capture a sensory learning-related engram in superficial layers of mouse barrel cortex
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DOI：
10.1073/pnas.2112212118
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发表时间：
2021-12-28
影响因子：
11.1
通讯作者：
Barth, Alison L.
中科院分区：
文献类型：
--
作者：
Lee, Jiseok;Urban-Ciecko, Joanna;Barth, Alison L.
立即早期基因（IEG）表达已被用于识别与特定体验相关的小神经系综，其原理是激活的神经元的选择性子集将编码特定的记忆或行为反应。这些研究中的大多数都集中在高级大脑区域的“记忆痕迹”上，这些区域代表了更抽象或收敛的感觉信息，如海马体，前额叶皮层或杏仁核。在初级感觉皮层中，IEG表达可以标记对特定感觉刺激有反应的神经元，但由IEG表达标记的神经系综的经验依赖性成形尚未得到证实。在这里，我们使用fosGFP转基因小鼠纵向监测在体内表达的活性依赖基因c-fos在表层（L2/3）的初级躯体感觉皮层（S1）在胡须依赖的学习任务。我们发现，感觉联想训练不会改变L2/3神经元中的fosGFP表达。虽然训练广泛地增强了锥体神经元的丘脑皮质突触强度，但我们发现，到fosGFP+神经元上的突触并没有通过训练选择性地增加;相反，突触强化集中在fosGFP 2神经元上。总之，这些数据表明，IEG报告基因fosGFP的表达并不有利于识别在L2/3在桶皮质在胡须依赖的感觉联想学习的学习特异性印迹。
Immediate-early gene (IEG) expression has been used to identify small neural ensembles linked to a particular experience, based on the principle that a selective subset of activated neurons will encode specific memories or behavioral responses. The majority of these studies have focused on "engrams" in higher-order brain areas where more abstract or convergent sensory information is represented, such as the hippocampus, prefrontal cortex, or amygdala. In primary sensory cortex, IEG expression can label neurons that are responsive to specific sensory stimuli, but experience dependent shaping of neural ensembles marked by IEG expression has not been demonstrated. Here, we use a fosGFP transgenic mouse to longitudinally monitor in vivo expression of the activity dependent gene c-fos in superficial layers (L2/3) of primary somatosensory cortex (S1) during a whisker-dependent learning task. We find that sensory association training does not detectably alter fosGFP expression in L2/3 neurons. Although training broadly enhances thalamocortical synaptic strength in pyramidal neurons, we find that synapses onto fosGFP+ neurons are not selectively increased by training; rather, synaptic strengthening is concentrated in fosGFP2 neurons. Taken together, these data indicate that expression of the IEG reporter fosGFP does not facilitate identification of a learning-specific engram in L2/3 in barrel cortex during whisker-dependent sensory association learning.