屏状体，又名屏状核，位于大脑的外囊和极外囊之间的一块厚为1-2毫米的扁平形灰质。外囊分隔屏状体和豆状核（壳部分）。极外囊分隔屏状体和岛叶。虽然已知屏状体和大脑皮层有往复连接，但目前对屏状体的功能知之甚少。有些学者认为屏状体是豆状核的一部分，另一些学者认为屏状体应算作岛叶的一部分，更有一部分学者主张屏状体可分为豆状体部和岛叶部两部分。也有一些当代神经解剖学家认为屏状体和杏仁核一同属于基底核。

神经科学家佛朗西斯·克里克和克里斯托夫·科赫认为因为屏状体与大脑皮层多个区域有双向连接，所以可能在意识的产生中有重要作用。

The claustrum is a thin, irregular, sheet of neurons that is attached to the underside of the neocortex in the center of the brain. It is suspected to be present in the brains of all mammals.

The claustrum is a fraction of a millimetre to a few millimetres deep and is a vertical curved sheet of subcortical gray matter oriented sagittally between the white matter tracts of the external capsule and extreme capsule. The claustrum is lateral to the putamen and medial to the insular cortex and is considered by some sources to be part of the basal ganglia. There are lateral and medial tracts connecting the claustrum to many parts of the cortex and perhaps to the hippocampus, the amygdala, and the caudate nucleus (connections with subcortical centers are a matter of debate).