Pallium (neuroanatomy)

Pallium
Schematic cross-section of the forebrain of a basal chordate such as a shark.
Schematic illustration of differences in neuronal specification and migration patterns between the mammalian and avian pallium
Details
Part of	Telencephalon
Identifiers
Latin	pallium, or cortex cerebri
NeuroLex ID	birnlex_1494
TA98	A14.1.09.003
TA2	5527
TE	(neuroanatomy)_by_E5.14.3.4.3.1.30 E5.14.3.4.3.1.30
Anatomical terms of neuroanatomy [edit on Wikidata]

In neuroanatomy, pallium (pl.: pallia or palliums) refers to the layers of grey and white matter that cover the upper surface of the cerebrum in vertebrates. The non-pallial part of the telencephalon builds the subpallium. In basal vertebrates, the pallium is a relatively simple three-layered structure, encompassing 3–4 histogenetically distinct domains, plus the olfactory bulb.

It used to be thought that pallium equals cortex and subpallium equals telencephalic nuclei, but it has turned out, according to comparative evidence provided by molecular markers, that the pallium develops both cortical structures (allocortex and isocortex) and pallial nuclei (claustroamygdaloid complex), whereas the subpallium develops striatal, pallidal, diagonal-innominate and preoptic nuclei, plus the corticoid structure of the olfactory tuberculum.^[1]

In mammals, the cortical part of the pallium registers a definite evolutionary step-up in complexity, forming the cerebral cortex, most of which consists of a progressively expanded six-layered portion isocortex, with simpler three-layered cortical regions allocortex at the margins. The allocortex subdivides into hippocampal allocortex, medially, and olfactory allocortex, laterally (including rostrally the olfactory bulb and anterior olfactory areas).