Posterior parietal cortex

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Brain: Posterior parietal cortex
Lobes of the brain NL.svg
Lobes of the brain. Parietal lobe is yellow, and the posterior portion is near the red region.
Gray726-Brodman.svg
Lateral surface of the brain with Brodmann's areas numbered. (#5 and #7 in upper right)
Latin Cortex parietalis posterior

The posterior parietal cortex (the portion of parietal neocortex posterior to the primary somatosensory cortex) plays an important role in producing planned movements. Before an effective movement can be initiated, the nervous system must know the original positions of the body parts that are to be moved, and the positions of any external objects with which the body is going to interact. The posterior parietal cortex receives input from the three sensory systems that play roles in the localization of the body and external objects in space: the visual system, the auditory system, and the somatosensory system. In turn, much of the output of the posterior parietal cortex goes to areas of frontal motor cortex: the dorsolateral prefrontal cortex, various areas of the secondary motor cortex, and the frontal eye field. fMRI studies in monkeys and TMS studies in humans indicate that the posterior parietal cortex comprises a mosaic of small areas, each specialized for guiding particular movements of eyes, head, arms or hands.

Damage to the posterior parietal cortex can produce a variety of sensorimotor deficits, including deficits in the perception and memory of spatial relationships, in accurate reaching and grasping, in the control of eye movement, and in attention. The two most striking consequences of PPC damage are apraxia and hemispatial neglect.[1]

Some sources say that the PPC consists of Brodmann area 5 and Brodmann area 7.[2] Other sources say it is only area 7.[3]

There is also evidence indicating that it plays a role in perception of pain.[4]

Recent findings have suggested that feelings of "free will" at least partially originate in this area.[5][6]

One study found that novice artists have increased blood flow in the right posterior parietal compared to expert artists when challenged with art-related tasks.[7]

During a study conducted by neuroscientists at New York University, published in 2012 in the journal Neuron, a significant amount of coherent patterns of firing of neurons in the brain's PPC were discovered. To reach this conclusion, the NYU researchers had examined the neurological activity of macaque monkeys while having them perform a variety of tasks that required them to either reach and to simultaneously employ rapid eye movements or to only use rapid eye movements, in which were known as saccades. The coherent pattern of the firing of neurons in the PPC were only seen when both the eyes and arms were required to move for the same task, but not for tasks that involved only saccades.[8]

In neuroimaging studies, this region, particularly the angular gyrus is active when individuals have strong recollections of episodic memory.

References[edit]

  1. ^ Pinel, John P.J. Biopsychology Seventh Edition. Pearson Education Inc., 2009
  2. ^ "THE BRAIN FROM TOP TO BOTTOM". 
  3. ^ Estomih Mtui; Gregory Gruener (2006). Clinical Neuroanatomy and Neuroscience: With STUDENT CONSULT Online Access. Philadelphia: Saunders. p. 32. ISBN 1-4160-3445-5. 
  4. ^ Witting N, Kupers RC, Svensson P, Arendt-Nielsen L, Gjedde A, Jensen TS (November 2001). "Experimental brush-evoked allodynia activates posterior parietal cortex". Neurology 57 (10): 1817–24. doi:10.1212/wnl.57.10.1817. PMID 11723270. 
  5. ^ Desmurget, M.; Reilly, K. T.; Richard, N.; Szathmari, A.; Mottolese, C.; Sirigu, A. (2009). "Movement Intention After Parietal Cortex Stimulation in Humans". Science 324 (5928): 811–813. doi:10.1126/science.1169896. PMID 19423830.  edit
  6. ^ Haggard, P. (2009). "The Sources of Human Volition". Science 324 (5928): 731–733. doi:10.1126/science.1173827. PMID 19423807.  edit
  7. ^ http://muse.jhu.edu/journals/leonardo/v034/34.1solso.html
  8. ^ Dean, H.; Hagan, M.; Pesaran, B. (2012). "Only Coherent Spiking in Posterior Parietal Cortex Coordinates Looking and Reaching". Neuron. doi:10.1016/j.neuron.2011.12.035. 

External links[edit]