pallium

Pallium is a term with multiple uses in biology, deriving from the Latin pallium, meaning cloak or mantle. In neuroanatomy, it denotes the dorsal part of the telencephalon and is closely associated with the cerebral cortex and related structures in mammals.

In vertebrate brain development, the pallium arises as the dorsal portion of the telencephalon. In mammals it differentiates into several major regions: the neocortex (the six-layered, highly associative cortex), the archicortex (principally the hippocampal formation and neighboring areas), and the paleocortex (olfactory and related regions). The subpallium, a ventral counterpart, gives rise to structures such as the basal ganglia and related nuclei. The pallium thus underlies many aspects of higher cognitive function, memory, and sensory processing, with organizational differences across vertebrate lineages.

Across species, the pallium can show varying degrees of lamination and specialization. In mammals, the neocortex is a defining pallial structure, while other vertebrates possess pallial regions that perform similar functional roles but with different cellular architecture. The general concept emphasizes a dorsal, cortical-like region distinct from the ventrally derived subpallial structures.

In other contexts, pallium also appears in invertebrate anatomy. In mollusks, for example, the term can refer to the mantle, the outer body covering that secretes the shell. This use is separate from the neuroanatomical meaning, though it shares the same etymology.

Overall, pallium is a foundational term in comparative neuroanatomy and anatomy, marking the dorsal, cortical-type tissues or coverings in diverse organisms.