the gray matter

基本解释

The cells of the gray matter...
灰质中的细胞……
and through the finest branches of the protoplasmic processes which become a part of the fine nerve fibre net of the gray matter.
而且也通过最终形成了灰质神经纤维一部分的原生质衍生物的精细侧枝连接。
He observed that the axons in his samples ended in the gray matter, and that their endings were consistent with the location of dendrites.
他发现，在他的标本中，轴突最终终止于灰质，并且它们的结合位点与树突的位置相一致。

It's called gray matter but that's just because it's out of the head.
叫做灰质,但那只是因为它离开了头颅
耶鲁公开课 - 心理学导论课程节选

Therefore, it should not be surprising that the zombie brain would look and function differently than the gray matter contained in your skull.
FORBES: Explaining the Neuroscience of the Zombie Epidemic
One experiment measured the brain structure of pathological liars, and compared it to normal controls — more specifically, the ratio of gray matter (the neural tissue that makes up the bulk of our brains) to white matter (the wiring that connects those brain cells).
FORBES: Do Liars Really Have Different Brains?
The pinlike electrodes, which protrude into the brain's gray matter, picked up signals from the neurons nearby.
FORBES: Technology