paleocortical

Paleocortical, or paleocortex, refers to a portion of the cerebral cortex that is evolutionarily older than the neocortex. It has a simpler laminar structure, commonly described as three cortical layers, in contrast to the six-layered neocortex. This simpler organization reflects an earlier stage in cortical evolution and is associated with specific functional and regional specializations.

Anatomy and components: The best-known part of the paleocortex is the piriform cortex, which forms the primary olfactory cortex. The paleocortex also includes neighboring olfactory-related cortical areas along the ventral and medial temporal lobe, collectively involved in processing smell and its affective associations. It lies on the inferior and medial aspects of the temporal lobe and surrounding limbic regions, bordering the archicortex and neocortex.

Function: Paleocortical areas participate in initial olfactory perception and odor memory, transmitting olfactory information to limbic circuits that contribute to emotional responses and memory integration. Its connections help link smell with memory and affective states.

Development and evolution: Paleocortex is considered a primitive cortex preserved across mammals with functional olfactory systems. In humans, it is relatively reduced compared with the neocortex but remains a distinct cortical tier involved in olfactory processing.

Clinical relevance: Lesions or disease affecting paleocortical olfactory regions can impair smell and odor identification. Olfactory dysfunction can be an early feature of certain neurodegenerative disorders and may provide diagnostic value in some contexts.