The line of Gennari (also called the "band" or "stria" of Gennari) is a band of
myelinated
Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be l ...
axons
An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, th ...
that runs parallel to the surface of the
cerebral cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of ...
on the banks of the
calcarine fissure
The calcarine sulcus (or calcarine fissure) is an anatomical landmark located at the caudal end of the medial surface of the brain of humans and other primates. Its name comes from the Latin "calcar" meaning "spur". It is very deep, and known a ...
in the
occipital lobe
The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ''ob'', "behind", and ''caput'', "head".
The occipital lobe is the vi ...
. This formation is visible to the naked eye as a white strip running through the cortical
grey matter
Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. Grey matter is distingui ...
, and is the reason the
V1 in
primates
Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...
is also referred to as the "striate cortex." The line of Gennari is due to dense axonal input from the
thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
to layer IV of visual cortex. It is the name given to the enlarged external
band of Baillarger
Bands of Baillarger, in neuroanatomy, are two myeloarchitectural structures, the external band of Baillarger and the internal band of Baillarger. These are myelinated fibers that course in the internal granular layer (layer IV) and internal pyrami ...
. The structure is named for its discoverer,
Francesco Gennari
Francesco Gennari (born 4 October 1750 di Langhirano; died 4 December 1797) was an Italian anatomist. He is known for line of Gennari, a macroscopically white band seen in the cerebral cortex of the occipital lobe, which he observed on 2 Februar ...
, who first observed it in 1776 as a medical student at the
University of Parma
The University of Parma ( it, Università degli Studi di Parma, UNIPR) is a public university in Parma, Emilia-Romagna, Italy. It is organised in nine departments. As of 2016 the University of Parma has about 26,000 students.
History
During the ...
. He described it in a book which he published six years later. Although non-primate species have areas that are designated primary visual cortex, some (if not all) lack a stria of Gennari.
[Zilles and Wree. ''Isocortex'' in Paxinos (Ed.) ''The Rat Nervous System'', 1985.]
See also
*
Cerebral cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of ...
*
Brodmann area
A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells.
History
Brodmann areas were originally defined and numbered by the ...
*
Insular cortex
The insular cortex (also insula and insular lobe) is a portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal and frontal lobes) within each hemisphere of the mammalian bra ...
External links
Horizontal section of human brain showing line of Gennari from Polyak (1957)
References
Cerebral cortex
Occipital lobe
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