The claustrum is a thin sheet of grey matter deep in each hemisphere, between the insula on the outside and the putamen on the inside, separated from them by the extreme and external capsules. It is only a few tenths of a millimetre thick, yet spans more than 5 cm both front to back and top to bottom. [1]
The 3D brain needs JavaScript. The text below still says where the claustrum is and what it does.
The insula and putamen are lit together; the claustrum is not drawn on its own. The front (coronal) slice button cuts through them. Drag to turn, pinch or scroll to zoom, tap any part to name it; .
Not a separate shape in this atlas; lit: the part that holds it. Lit: the whole insula and putamen, on both sides. The claustrum lies against both of these lit parts, as a sheet between them: the insula on its outer side, across the extreme capsule, and the putamen on its inner side, across the external capsule. It is a few tenths of a millimetre thick and it has no shape of its own in the BodyParts3D model, so nothing is drawn at a guessed point. [1]
Lit here: the insula and the putamen, the parts the claustrum lies against — see each on its own page.
Where it is
Going outward from the putamen: the external capsule, then the claustrum, then the extreme capsule, then the insular cortex. [1][2]
Thin but wide: only a few tenths of a millimetre thick, yet more than 5 cm long both front to back and top to bottom, a curved sheet following the insula above it. [1]
A sheet that is not flat but curved, mainly under the region of the insula; in humans its volume is about a quarter of one percent of the cerebral cortex’s. [3]
It connects with the cerebral cortex and with deeper parts including the amygdala, hippocampus and thalamus; for its size it is considered the most densely connected structure in the brain. [1]
Its inputs are sorted by sense: prefrontal, visual, auditory and somatomotor areas each reach their own region of it, and its visual region is laid out as a map of the visual field, like the visual cortex. [1]
Leading ideas, not settled facts: it may combine sight, sound and touch into one experience, possibly supporting consciousness itself (Crick and Koch likened it to the conductor of an orchestra), or pick out the most relevant stimulus from background noise to direct attention. [1][3]
An honest limit: it is hard to study, because few people have damage confined to it and brain scans resolve so thin a sheet poorly. [1]
Connections
Reciprocal connections link it with the prefrontal, motor, somatosensory, auditory and visual cortex; most of its connections stay on the same side of the brain, though some cross. [1]
Little evidence links it directly with the brainstem or the spinal cord. [1]
The putamen on its inner side is connected with it, as well as with the substantia nigra, the globus pallidus and the thalamus. [2]
Inside it
Five cell types, most resembling the pyramidal neurons of the cortex, but not arranged in layers as the cortex is; local parvalbumin-expressing interneurons inhibit nearby projection neurons. [1]
Other names
Latin, meaning “to close” or “to shut”, or “hidden away”; it was first identified in 1672. [1][3]
Size
The model has no shape for the claustrum itself, so it is not measured here. The left insula that holds it measures about 52 mm front to back, 35 mm top to bottom and 19 mm side to side on this model (the box it fits in, not its volume). [4]
The model has no shape for the claustrum itself, so it is not measured here. The left putamen that holds it measures about 43 mm front to back, 26 mm top to bottom and 18 mm side to side on this model (the box it fits in, not its volume). [4]
Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.