posterior parietal cortex

Examples of posterior parietal cortex in the following topics:

• Motor Areas

  • The motor areas of the brain are located in both hemispheres of the cortex.
  • Premotor cortex: Located anterior to the primary motor cortex and responsible for some aspects of motor control.
  • Posterior parietal cortex – Guides planned movements, spatial reasoning, and attention.
  • Various experiments examining the motor cortex map showed that each point in motor cortex influences a range of muscles and joints, indicating significant overlapping in the map.
  • $$Topography of the human motor cortex, including the premotor cortex, SMA, primary motor cortex, primary somatosensory cortex, and posterior parietal cortex.

• Association Areas

  • Associative areas of the cortex integrate current states with past states to predict proper responses based on sets of stimuli.
  • The parietal, temporal, and occipital lobes, all located in the posterior part of the cortex, organize sensory information into a coherent perceptual model of our environment centered on our body image.
  • The association areas are organized as distributed networks, and each network connects areas distributed across widely spaced regions of the cortex.
  • For example, a patient with a lesion in the parietal-temporal-occipital association area has an agraphia, which means he is unable to write although he has no deficits in motor skills.

• Cerebral Lobes

  • The cortex is divided into four main lobes: frontal, parietal, occipital, temporal.
  • The precentral gyrus, forming the posterior border of the frontal lobe, contains the primary motor cortex, which controls voluntary movements of specific body parts.
  • The parietal lobe is a part of the brain positioned above (superior to) the occipital lobe and behind (posterior to) the frontal lobe.
  • This enables regions of the parietal cortex to map objects perceived visually into body coordinate positions.
  • Distinguish between the frontal, temporal, parietal, and occipital lobes of the cerebral cortex

• Cerebral Hemispheres and Lobes of the Brain

  • Cells on the posterior side of the occipital lobe are arranged as a spatial map of the retinal field.
  • The visual cortex receives raw sensory information through sensors in the retina of the eyes, which is then conveyed through the optic tracts to the visual cortex.
  • Damage to the primary visual cortex (located on the surface of the posterior occipital lobe) can cause blindness, due to the holes in the visual map on the surface of the cortex caused by the lesions.
  • The parietal lobe is associated with sensory skills.
  • The parietal lobe is comprised of the somatosensory cortex and part of the visual system.

• Human Language and the Brain

  • Wernicke's area, located in the cerebral cortex, is the part of the brain involved in understanding written and spoken language.
  • The primary auditory cortex, located in the temporal lobe and connected to the auditory system, is organized so that it responds to neighboring frequencies in the other cells of the cortex.
  • The angular gyrus, located in the parietal lobe of the brain, is responsible for several language processes, including number processing, spatial recognition and attention.
  • The areas of the brain necessary for processing language: Broca's area, Wernicke's area, the primary motor cortex, the posterior middle temporal gyrus, and the middle and posterior superior temporal gyrus.

• Parts of the Cerebellum

  • The surface of the cerebellum is covered with finely spaced parallel grooves, in striking contrast to the broad irregular convolutions of the cerebral cortex.
  • Like the cerebral cortex, the cerebellum is divided into two hemispheres.
  • Based on surface appearance, three lobes can be distinguished in the cerebellum: the flocculonodular lobe, anterior lobe (above the primary fissure), and the posterior lobe (below the primary fissure).
  • The medial zone of the anterior and posterior lobes constitutes the spinocerebellum, also known as the paleocerebellum.
  • It receives input exclusively from the cerebral cortex (especially the parietal lobe) via the pontine nuclei (forming corticopontocerebellar pathways), and sends output mainly to the ventrolateral thalamus (in turn connected to motor areas of the premotor cortex and primary motor area of the cerebral cortex) and to the red nucleus.

• Somatic Sensory Pathways

  • In the case of touch and certain types of pain, the third neuron has its cell body in the ventral posterior nucleus of the thalamus and ends in the postcentral gyrus of the parietal lobe.
  • One major target within the brain is the postcentral gyrus in the cerebral cortex.
  • The primary somatosensory area in the human cortex is located in the postcentral gyrus of the parietal lobe.
  • For example, there is a large area of cortex devoted to sensation in the hands, while the back has a much smaller area.
  • This is a pictorial representation of the anatomical divisions of the primary motor cortex and the primary somatosensory cortex; namely, the portion of the human brain directly responsible for the movement and exchange of sensory and motor information of the body.

• Brain: Cerebral Cortex and Brain Lobes

  • The cerebral cortex of the brain is divided into four lobes responsible for distinct functions: frontal, parietal, temporal, and occipital.
  • Each hemisphere of the mammalian cerebral cortex can be broken down into four functionally- and spatially-defined lobes: frontal, parietal, temporal, and occipital .
  • The parietal lobe is located at the top of the brain.
  • The parietal lobe contains a somatosensory map of the body similar to the motor cortex.
  • The human cerebral cortex includes the frontal, parietal, temporal, and occipital lobes, each of which is involved in a different higher function.

• Cerebral Cortex

  • The cerebral cortex is considered the ultimate control and information-processing center in the brain.
  • The cortex is divided into four different lobes (the parietal, occipital, temporal, and frontal lobes), each with a different specific function.
  • The cortex is wrinkly in appearance.
  • One notable sulcus is the central sulcus, or the wrinkle dividing the parietal lobe from the frontal lobe.
  • Counterclockwise from bottom: It contains the parietal lobe (green), the occipital lobe (red), the temporal lobe (yellow), and the frontal lobe (blue).

• Fontanels

  • The cranium of a newborn consists of five main bones: two frontal bones, two parietal bones, and one occipital bone.
  • At birth, the skull features a small posterior fontanelle (an open area covered by a tough membrane) where the two parietal bones adjoin the occipital bone (at the lambda).
  • The much larger, diamond-shaped anterior fontanelle—where the two frontal and two parietal bones join—generally remains open until a child is about two years old.
  • The more anterior one is the sphenoidal (between the sphenoid, parietal, temporal, and frontal bones), while the more posterior one is the mastoid (between the temporal, occipital, and parietal bones) .
  • This image shows the location of the anterior (frontal) and posterior fontanelles.