In the

anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...

animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

s, paleoencephalon refers to most regions in the

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...

that are not part of the

neocortex The neocortex, also called the neopallium, isocortex, or the six-layered cortex, is a set of layers of the mammalian cerebral cortex involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands, sp ...

or neoencephalon. The paleoencephalon is the

phylogenetically In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

oldest part of the animal brain. Paleoenchepheal areas of older species are larger in proportion to overall brain volume as compared to those of mammals. The Paleocortex is a type of thin, primitive cortical tissue that consists of three to five cortical laminae. In comparison, the neocortex has six layers and the archicortex has three or four layers.Purves et al.: Neuroscience 3rd Edition, 2004, page 617

References

Cerebrum Neuroanatomy {{neuroanatomy-stub