清醒小鼠初级和次级体感皮层的同侧刺激编码。
Ipsilateral Stimulus Encoding in Primary and Secondary Somatosensory Cortex of Awake Mice.
机构信息
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, 30332
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, 30332.
出版信息
J Neurosci. 2022 Mar 30;42(13):2701-2715. doi: 10.1523/JNEUROSCI.1417-21.2022. Epub 2022 Feb 8.
Lateralization is a hallmark of somatosensory processing in the mammalian brain. However, in addition to their contralateral representation, unilateral tactile stimuli also modulate neuronal activity in somatosensory cortices of the ipsilateral hemisphere. The cellular organization and functional role of these ipsilateral stimulus responses in awake somatosensory cortices, especially regarding stimulus coding, are unknown. Here, we targeted silicon probe recordings to the vibrissa region of primary (S1) and secondary (S2) somatosensory cortex of awake head-fixed mice of either sex while delivering ipsilateral and contralateral whisker stimuli. Ipsilateral stimuli drove larger and more reliable responses in S2 than in S1, and activated a larger fraction of stimulus-responsive neurons. Ipsilateral stimulus-responsive neurons were rare in layer 4 of S1, but were located in equal proportion across all layers in S2. Linear classifier analyses further revealed that decoding of the ipsilateral stimulus was more accurate in S2 than S1, whereas S1 decoded contralateral stimuli most accurately. These results reveal substantial encoding of ipsilateral stimuli in S1 and especially S2, consistent with the hypothesis that higher cortical areas may integrate tactile inputs across larger portions of space, spanning both sides of the body. Tactile information obtained by one side of the body is represented in the activity of neurons of the opposite brain hemisphere. However, unilateral tactile stimulation also modulates neuronal activity in the other, or ipsilateral, brain hemisphere. This ipsilateral activity may play an important role in the representation and processing of tactile information, in particular when the sense of touch involves both sides of the body. Our work in the whisker system of awake mice reveals that neocortical ipsilateral activity, in particular that of deep layer excitatory neurons of secondary somatosensory cortex (S2), contains information about the presence and the velocity of unilateral tactile stimuli, which supports a key role for S2 in integrating tactile information across both body sides.
偏侧化是哺乳动物大脑体感处理的一个标志。然而，除了对侧的代表外，单侧触觉刺激也会调节同侧半球体感皮层的神经元活动。这些同侧刺激反应在清醒体感皮层中的细胞组织和功能作用，特别是关于刺激编码，尚不清楚。在这里，我们在两性清醒固定头部的小鼠的初级（S1）和次级（S2）体感皮层的触须区域靶向硅探针记录，同时给予同侧和对侧触须刺激。同侧刺激在 S2 中产生的反应比 S1 更大、更可靠，并激活了更大比例的对刺激有反应的神经元。同侧刺激反应神经元在 S1 的第 4 层中很少见，但在 S2 的所有层中都以相等的比例存在。线性分类器分析进一步表明，S2 中对同侧刺激的解码比 S1 更准确，而 S1 对对侧刺激的解码最准确。这些结果表明，S1 和特别是 S2 中对同侧刺激的编码相当大，这与更高的皮质区域可能整合跨越身体两侧更大空间的触觉输入的假设一致。身体一侧获得的触觉信息在对侧大脑半球的神经元活动中得到表示。然而，单侧触觉刺激也会调节另一侧或同侧大脑半球的神经元活动。这种同侧活动可能在触觉信息的表示和处理中发挥重要作用，特别是当触觉涉及身体两侧时。我们在清醒小鼠的触须系统中的工作表明，新皮层的同侧活动，特别是次级体感皮层（S2）的深层兴奋性神经元的同侧活动，包含关于单侧触觉刺激的存在和速度的信息，这支持了 S2 在整合跨越身体两侧的触觉信息方面的关键作用。
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