F.M. Kirby Neurobiology Center, Boston Children's Hospital, Center for Life Science 12061, 3 Blackfan Circle, Boston, MA 02115, USA; Department of Neurology, Boston Children's Hospital and Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; Center for Brain Science, Harvard University, Cambridge, MA 02138, USA.
Department of Neurology, Boston Children's Hospital and Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA.
Cell Rep. 2017 Oct 24;21(4):1048-1062. doi: 10.1016/j.celrep.2017.09.095.
Intrinsically photosensitive retinal ganglion cells of the M1 type encode environmental irradiance for functions that include circadian and pupillary regulation. Their distinct role, morphology, and molecular markers indicate that they are stereotyped circuit elements, but their physiological uniformity has not been investigated in a systematic fashion. We have profiled the biophysical parameters of mouse M1s and found that extreme variation is their hallmark. Most parameters span 1-3 log units, and the full range is evident in M1s that innervate brain regions serving divergent functions. Biophysical profiles differ among cells possessing similar morphology and between neighboring M1s recorded simultaneously. Variation in each parameter is largely independent of that in others, allowing for flexible individualization. Accordingly, a common stimulus drives heterogeneous spike outputs across cells. By contrast, a population of directionally selective retinal ganglion cells appeared physiologically uniform under similar conditions. Thus, M1s lack biophysical constancy and send diverse signals downstream.
M1 型内在光敏感视网膜神经节细胞将环境辐照度编码用于包括昼夜节律和瞳孔调节等功能。它们独特的作用、形态和分子标记表明它们是定型的电路元件，但它们的生理一致性尚未以系统的方式进行研究。我们对小鼠 M1 的生物物理参数进行了分析，发现极端变化是它们的特点。大多数参数跨越 1-3 个对数单位，并且在支配不同功能的脑区的 M1 中可以明显看到全范围的变化。具有相似形态的细胞和同时记录的相邻 M1 之间的生物物理特征不同。每个参数的变化在很大程度上与其他参数的变化无关，允许灵活的个性化。因此，相同的刺激会在不同的细胞中产生异构的尖峰输出。相比之下，在类似条件下，一群方向选择性视网膜神经节细胞表现出生理均匀性。因此，M1 缺乏生物物理的恒定性，并向下游发送多样化的信号。
