Brodmann area 19, or BA 19, is part of 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 ...

cortex Cortex or cortical may refer to: Biology * Cortex (anatomy), the outermost layer of an organ ** Cerebral cortex, the outer layer of the vertebrate cerebrum, part of which is the ''forebrain'' *** Motor cortex, the regions of the cerebral cortex i ...

in the

human brain The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the ...

. Along with area 18, it comprises the extrastriate (or peristriate) cortex. In humans with normal sight,

extrastriate cortex The extrastriate cortex is the region of the occipital cortex of the mammalian brain located next to the primary visual cortex. Primary visual cortex (V1) is also named striate cortex because of its striped appearance in the microscope. The extra ...

is a visual association area, with feature-extracting, shape recognition, attentional, and multimodal integrating functions. This area is also known as peristriate area 19, and it refers to a subdivision of the cytoarchitecturally defined

occipital region The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...

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 ...

. In the human it is located in parts of the

lingual gyrus The lingual gyrus, also known as the ''medial'' occipitotemporal gyrus, is a brain structure that is linked to processing vision, especially related to letters. It is thought to also play a role in analysis of logical conditions (i.e., logical ord ...

, the

cuneus The cuneus (; plural cunei) is a smaller lobe in the occipital lobe of the brain. The cuneus is bounded anteriorly by the parieto-occipital sulcus and inferiorly by the calcarine sulcus. Function The cuneus (Brodmann area 17) receives visua ...

, the lateral occipital gyrus (H) and the superior occipital gyrus (H) of the

where it is bounded approximately by the

parieto-occipital sulcus In neuroanatomy, the parieto-occipital sulcus (also called the parieto-occipital fissure) is a deep sulcus in the cerebral cortex that marks the boundary between the cuneus and precuneus, and also between the parietal and occipital lobes. Only ...

. It is bounded on one side by the parastriate area 18, which it surrounds. It is bounded rostrally by the

angular area 39 Brodmann area 39, or BA39, is part of the parietal cortex in the human brain. BA39 encompasses the angular gyrus, lying near to the junction of temporal, occipital and parietal lobes. This area is also known as angular area 39 (H). It corresp ...

(H) and the occipitotemporal area 37 (H) (Brodmann-1909).

In animals

Brodmann area 19-1909 is a subdivision of the cerebral cortex of the

guenon The guenons (, ) are Old World monkeys of the genus ''Cercopithecus'' (). Not all members of this genus have the word "guenon" in their common names; also, because of changes in scientific classification, some monkeys in other genera may have co ...

defined on the basis of cytoarchitecture. It is cytoarchitecturally homologous to the peristriate area 19 of the human (Brodmann-1909). Distinctive features (Brodmann-1905): Compared to

Brodmann area 18 Human Brodmann area 18, or BA18, is part of the occipital cortex in the human brain. It accounts for the bulk of the volume of the occipital lobe. It is known as a "Visual Association Area" or V2 and is a first stage in processing or feature ext ...

-1909, the

pyramidal cell Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cor ...

s of sublayer 3b of the external

pyramidal layer A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilater ...

(III) are not as densely distributed, the layer is not as narrow, and its boundary with the internal granular layer (IV) is not as distinct; the cells in sublayer 3b are concentrated at its outer boundary leaving a narrow clear zone with no large pyramidal cells adjacent to layer IV; the

granule cell A granule is a large particle or grain. It can refer to: * Granule (cell biology), any of several submicroscopic structures, some with explicable origins, others noted only as cell type-specific features of unknown function ** Azurophilic granul ...

s of layer IV are less densely distributed and are intermixed with larger

polymorphic cell Polymorphism, polymorphic, polymorph, polymorphous, or polymorphy may refer to: Computing * Polymorphism (computer science), the ability in programming to present the same programming interface for differing underlying forms * Ad hoc polymorphism ...

s so that, while the layer is still quite dark and prominent, it is somewhat widened and not as self-contained; the internal pyramidal layer (V) is characterized by large pyramidal

ganglion cells {{stack, A ganglion cell is a cell found in a ganglion. Examples of ganglion cells include: * Retinal ganglion cell (RGC) found in the ganglion cell layer of the retina * Cells that reside in the adrenal medulla, where they are involved in the s ...

, most in small groups, a pattern not seen in area 18; the cells in the

multiform layer 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 ...

(VI) are clearly larger than in area 18; overall, area 19 is somewhat thicker and less densely populated than area 18.

Function

Area 19 is a

histological Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

ly delineated band anterolaterally abutting visual area 18. Single-cell electrophysiological recordings from area 19 in the

cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...

suggest sensitivity to motion-delineated forms; recordings from

primate 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 ...

s have yielded varying results, indicating that this area may be a heterogeneous collection of visual areas, with multiple incomplete representations of the visual scene. In humans, this band is reputed to contain regions of the visual areas designated V3, V4, V5 (also known as the

middle temporal area The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus and ...

, or MT), and V6 (also known as

dorsomedial area The visual cortex of the brain is the area of the cerebral cortex that processes visual perception, visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in ...

) in the primate.

Functional magnetic resonance imaging Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area o ...

shows the existence of various retinotopic maps within area 19. In general, the diverse fields that comprise area 19 have reciprocal connections with areas 17 and 18, as well as posterior parietal and inferior temporal association areas. Area 19 has been noted to receive inputs from the

retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

via the

superior colliculus In neuroanatomy, the superior colliculus () is a structure lying on the roof of the mammalian midbrain. In non-mammalian vertebrates, the homologous structure is known as the optic tectum, or optic lobe. The adjective form ''tectal'' is commonly ...

and pulvinar, and may contribute to the phenomenon of

blindsight Blindsight is the ability of people who are cortically blind to respond to visual stimuli that they do not consciously see due to lesions in the primary visual cortex, also known as the striate cortex or Brodmann Area 17. The term was coined by ...

. In patients blind from a young age, the area has been found to be activated by somatosensory stimuli. Because of these findings, it is thought that area 19 is the differentiation point of the two visual streams, of the 'what' and 'where' visual pathways. The dorsal region may contain motion-sensitive neurons, and ventral areas may be specialised for object recognition.

References

* Hyvarinen, J., Carlson, Y. and Hyvarinen, L. (1981) Early visual deprivation alters modality of neuronal responses in area 19 of monkey cortex, ''Neurosci. Lett.'' 26, 239–243 * Theories of visual cortex organization in primates: areas of the third level, ''Prog Brain Res.'' 1996;112:213-21

External links

* For Neuroanatomy of the peristriate area 19 visi
BrainInfo
* For Neuroanatomy of Brodmann area 19 visi
BrainInfo
{{Prosencephalon 19 Occipital lobe

In animals

Function

See also

References

External links