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The parietal lobe is a lobe in the brain
Brain

The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as cnidarian and echinoderm have a decentralized nervous system without a brain, while sponges lack any nervous system at all....
. It is positioned above (superior to) the occipital lobe
Occipital lobe

The occipital lobe is the Visual perception of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area, commonly called V1 ....
 and behind (posterior to) the frontal lobe
Frontal lobe

The frontal lobe is an area in the brain of mammals. It is located at the front of each cerebral hemisphere and positioned anterior to the parietal lobes and above and anterior to the temporal lobes....
.

The parietal lobe integrates sensory
Sensory

Sensory may refer to:In biology:* Sensory system, part of the nervous system of organisms* Sensory neuron, nerve cell responsible for transmitting information about external stimuli...
 information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the dorsal stream
Dorsal stream

The dorsal stream is a pathway for visual information that flows through the visual cortex, the part of the brain which provides visual processing....
 of the visual system
Visual system

The visual system is the part of the central nervous system which allows organisms to visual perception.It interprets the information from visible light to build a representation of the world surrounding the body....
. This enables regions of the parietal cortex to map objects perceived visually into body coordinate positions.

parietal lobe is defined by four anatomical boundaries: the central sulcus
Central sulcus

The central Sulcus is a fold in the cerebral cortex of brains in vertebrates. Also called the central fissure, it was originally called the fissure of Rolando or the Rolandic fissure, after Luigi Rolando....
 separates the parietal lobe from the frontal lobe
Frontal lobe

The frontal lobe is an area in the brain of mammals. It is located at the front of each cerebral hemisphere and positioned anterior to the parietal lobes and above and anterior to the temporal lobes....
; the parieto-occipital sulcus separates the parietal and occipital lobe
Occipital lobe

The occipital lobe is the Visual perception of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area, commonly called V1 ....
s; the lateral sulcus
Lateral sulcus

The lateral sulcus is one of the most prominent structures of the human brain....
 (sylvian fissure) is the most lateral boundary separating it from the temporal lobe
Temporal lobe

The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both the left and right hemispheres of the brain....
; and the medial longitudinal fissure
Medial longitudinal fissure

The great longitudinal fissure is the deep groove which separates the two cerebral hemisphere of the vertebrate brain.The falx cerebri, a dura mater meninges, lies within the medial longitudinal fissure....
 divides the two hemispheres.

Immediately posterior to the central sulcus, and the most anterior part of the parietal lobe, is the postcentral gyrus
Postcentral gyrus

The lateral postcentral gyrus is a prominent structure in the parietal lobe of the human brain and an important landmark. It was initially defined from surface stimulation studies of Penfield, and parallel surface potential studies of Bard, Woolsey, and Marshall....
 (Brodmann area
Brodmann area

A Brodmann area is a region of the cerebral cortex defined based on its cytoarchitecture, or organization of cells.Brodmann areas were originally defined and numbered by Korbinian Brodmann based on the organization of neurons he observed in the cortex using the Franz Nissl staining....
 3), the primary somatosensory cortical area.






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Encyclopedia


The parietal lobe is a lobe in the brain
Brain

The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as cnidarian and echinoderm have a decentralized nervous system without a brain, while sponges lack any nervous system at all....
. It is positioned above (superior to) the occipital lobe
Occipital lobe

The occipital lobe is the Visual perception of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area, commonly called V1 ....
 and behind (posterior to) the frontal lobe
Frontal lobe

The frontal lobe is an area in the brain of mammals. It is located at the front of each cerebral hemisphere and positioned anterior to the parietal lobes and above and anterior to the temporal lobes....
.

The parietal lobe integrates sensory
Sensory

Sensory may refer to:In biology:* Sensory system, part of the nervous system of organisms* Sensory neuron, nerve cell responsible for transmitting information about external stimuli...
 information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the dorsal stream
Dorsal stream

The dorsal stream is a pathway for visual information that flows through the visual cortex, the part of the brain which provides visual processing....
 of the visual system
Visual system

The visual system is the part of the central nervous system which allows organisms to visual perception.It interprets the information from visible light to build a representation of the world surrounding the body....
. This enables regions of the parietal cortex to map objects perceived visually into body coordinate positions.

Anatomy

The parietal lobe is defined by four anatomical boundaries: the central sulcus
Central sulcus

The central Sulcus is a fold in the cerebral cortex of brains in vertebrates. Also called the central fissure, it was originally called the fissure of Rolando or the Rolandic fissure, after Luigi Rolando....
 separates the parietal lobe from the frontal lobe
Frontal lobe

The frontal lobe is an area in the brain of mammals. It is located at the front of each cerebral hemisphere and positioned anterior to the parietal lobes and above and anterior to the temporal lobes....
; the parieto-occipital sulcus separates the parietal and occipital lobe
Occipital lobe

The occipital lobe is the Visual perception of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area, commonly called V1 ....
s; the lateral sulcus
Lateral sulcus

The lateral sulcus is one of the most prominent structures of the human brain....
 (sylvian fissure) is the most lateral boundary separating it from the temporal lobe
Temporal lobe

The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both the left and right hemispheres of the brain....
; and the medial longitudinal fissure
Medial longitudinal fissure

The great longitudinal fissure is the deep groove which separates the two cerebral hemisphere of the vertebrate brain.The falx cerebri, a dura mater meninges, lies within the medial longitudinal fissure....
 divides the two hemispheres.

Immediately posterior to the central sulcus, and the most anterior part of the parietal lobe, is the postcentral gyrus
Postcentral gyrus

The lateral postcentral gyrus is a prominent structure in the parietal lobe of the human brain and an important landmark. It was initially defined from surface stimulation studies of Penfield, and parallel surface potential studies of Bard, Woolsey, and Marshall....
 (Brodmann area
Brodmann area

A Brodmann area is a region of the cerebral cortex defined based on its cytoarchitecture, or organization of cells.Brodmann areas were originally defined and numbered by Korbinian Brodmann based on the organization of neurons he observed in the cortex using the Franz Nissl staining....
 3), the primary somatosensory cortical area. Dividing this and the posterior parietal cortex
Posterior parietal cortex

The posterior parietal cortex is a portion of the parietal lobe which manipulates mental images, and integrates sensory and motor portions of the brain....
 is the postcentral sulcus
Postcentral sulcus

The postcentral sulcus of the parietal lobe lies parallel to, and behind, the central sulcus in the human brain. The postcentral sulcus divides the postcentral gyrus from the remainder of the parietal lobe....
.

The posterior parietal cortex can be subdivided into the superior parietal lobule
Superior parietal lobule

The superior parietal lobule is bounded in front by the upper part of the postcentral sulcus, but is usually connected with the posterior central gyrus above the end of the sulcus....
 (Brodmann areas 5
Brodmann area 5

Brodmann area 5 is one of Brodmann's cytologically defined regions of the brain. It is involved in somatosensory processing....
 + 7
Brodmann area 7

Brodmann area 7 is one of Brodmann's cytologically defined regions of the brain. It is involved in locating objects in space. It serves as a point of convergence between Visual perception and proprioception to determine where objects are in relation to parts of the body....
) and the inferior parietal lobule
Inferior parietal lobule

The inferior parietal lobule lies below the horizontal portion of the intraparietal sulcus, and behind the lower part of the postcentral sulcus....
 (39
Brodmann area 39

Brodmann area 39, or BA39, is part of the parietal lobecerebral cortex in the human brain. BA39 encompasses the angular gyrus, lying near to the junction of temporal lobe, occipital lobe and parietal lobes....
 + 40
Brodmann area 40

Brodmann area 40, or BA40, is part of the parietal lobecerebral cortex in the human brain. The inferior part of BA40 is in the area of the supramarginal gyrus, which lies at the posterior end of the lateral fissure, in the inferior lateral part of the parietal lobe....
), separated by the intraparietal sulcus
Intraparietal sulcus

The intraparietal sulcus is located on the lateral surface of the parietal lobe, and consists of an oblique and a horizontal portion. The IPS contains a series of functionally distinct subregions that have been intensively investigated using both single cell neurophysiology in primates and human functional neuroimaging....
 (IP). The intraparietal sulcus and adjacent gyri
Gyrus

A gyrus is a ridge on the Cerebral cortex. It is generally surrounded by one or more sulcus ....
 are essential in guidance of limb and eye movement
Saccade

A saccade is a fast eye movements, head or other part of an animal's body or device. It can also be a fast shift in frequency of an emitted signal or other quick change....
, and based on cytoarchitectural and functional differences is further divided into medial (MIP), lateral (LIP), ventral (VIP), and anterior (AIP) areas.

Function

The parietal lobe plays important roles in integrating sensory information from various parts of the body, knowledge of numbers and their relations, and in the manipulation of objects. Portions of the parietal lobe are involved with visuospatial processing. Although multisensory in nature, the posterior parietal cortex is often referred to by vision scientists as the dorsal stream of vision (as opposed to the ventral stream in the temporal lobe
Temporal lobe

The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both the left and right hemispheres of the brain....
). This dorsal stream has been called both the 'where' stream (as in spatial vision) and the 'how' stream (as in vision for action).

Various studies in the 1990s found that different regions of the posterior parietal cortex in Macaque
Macaque

The macaques constitute a genus of Old World monkeys of the subfamily Cercopithecinae. Aside from humans , the macaques are the most widespread primate genus, ranging from northern Africa to Japan....
s represent different parts of space.

  • The lateral intraparietal (LIP) contains a map of neurons (retinotopically-coded when the eyes are fixed) representing the saliency of spatial locations, and attention to these spatial locations. It can be used by the oculomotor system for targeting eye movements, when appropriate.


  • The ventral intraparietal (VIP) area receives input from a number of senses (visual, somatosensory, auditory, and vestibular
    Vestibular system

    The vestibular system, which contributes to our balance and our sense of spatial orientation, is the sensory system that provides the dominant input about movement and equilibrioception....
    ). Neurons with tactile receptive fields represented space in a head-centered reference frame. The cells with visual receptive fields also fire with head-centered reference frames but possibly also with eye-centered coordinates


  • The medial intraparietal (MIP) area neurons encode the location of a reach target in eye-centered coordinates.


  • The anterior intraparietal (AIP) area contains neurons responsive to shape, size, and orientation of objects to be grasped as well as for manipulation of hands themselves, both to viewed and remembered stimuli.


More recent fMRI studies have shown that humans have similar functional regions in and around the intraparietal sulcus and parietal-occipital junction. The human 'parietal eye fields' and 'parietal reach region', equivalent to LIP and MIP in the monkey, also appear to be organized in gaze-centered coordinates so that their goal-related activity is 'remapped' when the eyes move.

Pathology


Gerstmann's syndrome is associated with lesion to the dominant (usually left) parietal lobe. Balint's syndrome
Balint's syndrome

Balint's syndrome, identified by the Austro-Hungarian neurologist Rezso B?lint in 1909, is a disjointed psychic paralysis of gaze with haphazard scanning....
 is associated with bilateral lesions. The syndrome of hemispatial neglect
Hemispatial neglect

Hemispatial neglect, also called hemiagnosia, hemineglect, unilateral neglect, spatial neglect or neglect syndrome is a neuropsychological condition in which, after damage to one hemisphere of the brain, a deficit in attention to and awareness of one side of space is observed....
 is usually associated with large deficits of attention of the non-dominant hemisphere. Optic ataxia is associated with difficulties reaching toward objects in the visual field opposite to the side of the parietal damage. Some aspects of optic ataxia have been explained in terms of the functional organization described above.

Additional images


See also


Lobes of the brain
Lobes of the brain

Brain lobes were originally a purely anatomical classification, but have been shown also to be related to different brain functions. The telencephalon, the largest portion of the human brain, is divided into lobes, but so is the cerebellum....