科学家发现新型脑细胞

In a mysterious addition to the brain’s family of cells, researchers have discovered a new kind of neuron—a dense, bushy bundle (above) that is present in people but seems to be missing in mice.

在大脑细胞家族中，又增加了神秘的一员，研究员们发现了一种新的神经元——一种致密而分支的神经簇（如上图所示），它们在人类中出现而在小鼠中却无法找到。

These “rosehip neurons,” were found in the uppermost layer of the cortex, which is home to many different types of neurons that inhibit the activity of other neurons.

这种“玫瑰果神经元”，发现于大脑皮质的最顶层，这里有很多不同类型的负责抑制其他神经元活动的神经元分布。

Scientists spotted the neurons in slices of human brain tissue as part of a larger effort to inventory human brain cells by combining microscopic study of brain anatomy and the genetic analysis of individual cells.

科学家们之所以在人类大脑组织切片中发现这种神经元，是作为另一个更大型项目的一部分，该项目试图列出人类脑细胞的清单，他们通过把大脑解剖学的显微镜研究和个体细胞的遗传学分析结合起来（来进行研究）。

The cells were small and compact, with a dense, bushy shape.

这种细胞小而致密，带有一种紧密，分支的形状。

At the points along their projections where they transmit signals to other cells—called axonal boutons—they had unusually large, bulbous structures, which inspired their name.

顺着它们的延伸方向在它们把信号传递给其他细胞的结点处—叫做轴突剑端—它们有着不同寻常的大而呈球形的结构，因此得名（玫瑰果神经元）。

To precisely classify these cells, the scientists then analyzed their gene expression.

为了将这种细胞进行准确分类，科学家们后来分析了它们的基因表达。

That’s when they realized that the set of genes expressed in these inhibitory rosehip neurons doesn’t closely match any previously identified cell in the mouse, suggesting they have no analog in the rodent often used as a model for humans, the authors report today in Nature Neuroscience.

这时他们才意识到这种抑制性的玫瑰果神经元所表达的一系列基因，跟之前在小鼠中被鉴定出的细胞完全不匹配，表明它们在鼠类中并没有类似物，而鼠类经常被作为人类的模型，作者们在今天的《自然神经科学》杂志上发表了报告。

The discovery also raises the question of whether these neurons are key to certain brain functions that separate us from mice.

这一发现也提出了一个问题，那就是这种神经元是否是可以把人类跟鼠类区分开来的某些大脑功能的关键所在。

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