brain
Acronym: Br
The term brain refers to one of two parts of the central nervous system (CNS) as defined by dissection in vertebrates. It is the part of the CNS located in the cranial cavity; the other part is the spinal cord. (Some biologists use 'brain' in reference to the central ganglion of the nervous system of invertebrate species as well ( Wikipedia )).
     Neuroanatomists subdivide the brain in three different ways. Most textbooks and brain atlases are organized according to the Classica Model, which at the highest level divides the brain into forebrain, midbrain and hindbrain. Below that level structures are grouped by proximity as the brain is dissected to finer and finer levels.
     The definition of the brain in the second model, the Developmental CNS Model, differs from the Classical Model in that structures are grouped by the location of their precursors in the embryo; and it includes the retina, a structure which is located outside the cranial cavity of the mature animal but originates in the Encephalon (embryonic brain). (The retina is classically defined as part of the peripheral nervous system.) To avoid confusion, the standard NeuroNames terminology for structures defined by dissection of the mature brain are in English; standard names for subdivisions based on embryonic precursor are in Latin and capitalized. Thus, the highest level divisions of the Developmental CNS Model are the Telencephalon, Mesencephalon, and Rhombencephalon, which represent to a large extent, but with significant exceptions, to the forebrain, midbrain, and hindbrain of the Classical Model.
     In the third model, the Functional CNS Model, structures are grouped by a combination of criteria, including embryonic origin, internal structure, connectivity, and function. Division at the highest level is into four structures: the pallium, subcortical nuclei, cerebellum, and cerebrospinal trunk. (The pallium consists of the cerebral cortex and the cortical subplate nuclei.) In the Functional Model the retina is a component of the cerebrospinal trunk. The hierarchical organization of the Functional Model is derived almost entirely from Swanson-2004. The terminology of the Functional Model is English, using insofar as possible the same standard NeuroNames term for structures that are identical to structures in the Classical Model.
     Each of the three models is more useful than the others for certain purposes. The Classical Model is most useful for understanding the terminology of the neuroanatomical literature of the past century and for surgical applications, which involve dissection according to classical landmarks. The Developmental Model is more useful for analyzing the embryonic and genetic origins of brain structure. The Functional Model is most useful for addressing the fundamental challenge of neuroscience, namely to understand the relations between neural structure and function.
     In that context, the primary purpose of BrainInfo/NeuroNames is to clarify the relations between the structural concepts and the terminologies of these and other ways of looking at the central nervous system.

Also known as: suprasegmental structuresNeuroNames ID : 21


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