Lorenzon Paolo, Redolfi Nelly, Podolsky Michael J, Zamparo Ilaria, Franchi Sira Angela, Pietra Gianluca, Boccaccio Anna, Menini Anna, Murthy Venkatesh N, Lodovichi Claudia
Venetian Institute of Molecular Medicine (VIMM), 35129 Padua, Italy.
Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114.
J Neurosci. 2015 Jan 7;35(1):146-60. doi: 10.1523/JNEUROSCI.0613-14.2015.
The type of neuronal activity required for circuit development is a matter of significant debate. We addressed this issue by analyzing the topographic organization of the olfactory bulb in transgenic mice engineered to have very little afferent spontaneous activity due to the overexpression of the inwardly rectifying potassium channel Kir2.1 in the olfactory sensory neurons (Kir2.1 mice). In these conditions, the topography of the olfactory bulb was unrefined. Odor-evoked responses were readily recorded in glomeruli with reduced spontaneous afferent activity, although the functional maps were coarser than in controls and contributed to altered olfactory discrimination behavior. In addition, overexpression of Kir2.1 in adults induced a regression of the already refined connectivity to an immature (i.e., coarser) status. Our data suggest that spontaneous activity plays a critical role not only in the development but also in the maintenance of the topography of the olfactory bulb and in sensory information processing.
对于神经回路发育所需的神经元活动类型，存在着重大争议。我们通过分析转基因小鼠嗅球的拓扑结构来解决这个问题，这些转基因小鼠由于嗅感觉神经元内向整流钾通道Kir2.1的过表达而几乎没有传入性自发活动（Kir2.1小鼠）。在这些条件下，嗅球的拓扑结构未得到完善。在传入自发活动减少的肾小球中很容易记录到气味诱发反应，尽管功能图谱比对照组更粗糙，并且导致嗅觉辨别行为改变。此外，在成年小鼠中过表达Kir2.1会导致已经完善的连接性退化到不成熟（即更粗糙）状态。我们的数据表明，自发活动不仅在嗅球拓扑结构的发育中起关键作用，而且在其维持以及感觉信息处理中也起关键作用。
