Planum temporale

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Brain: Planum temporale
Approximate location of Wernicke's area highlighted in gray
NeuroNames ancil-432
Dorlands/Elsevier p_22/12644657

The planum temporale is the cortical area just posterior to the auditory cortex (Heschl's gyrus) within the Sylvian fissure.[1] It is a triangular region which forms the heart of Wernicke's area, one of the most important functional areas for language.[2]

The planum temporale shows a significant asymmetry. In 65% of all individuals the left planum temporale appears to be more developed, while the right planum temporale is more developed in only 10%. In some people’s brains, the planum temporale is more than five times larger on the left than on the right, making it the most asymmetrical structure in the brain.

This greater size of the left planum temporale compared with the right is already present in the foetus, where it can be observed starting from the 31st week of gestation. This observation strengthens the hypothesis of a genetic predisposition for brain asymmetry.[2] [3]

[edit] Functions

The planum temporale is a highly lateralized brain structure involved with language and with music. Although the planum temporale is found to have an asymmetry in the normal population, having a leftward bias in right-handed individuals, people who possess absolute pitch have an increased leftward asymmetry of the planum temporale. This is due to a smaller than average volume of the right planum temporale and not a larger than average volume of the left.[4] The planum temporale may also play an important role in auditory processing with recent research suggesting that the region is responsible for representsing the location of sounds in space.[5]

[edit] Other than Humans

Although this brain area was thought to be unique to humans, almost like the anatomic version of the linguistic "language organ" of Noam Chomsky, it was shown to be similarly leftward asymmetric in chimpanzees and other great apes but not other primates (Gannon et al., [2] ; as was a related, rightward asymmetric, brain region the planum parietale that is implicated with dyslexia in humans, Gannon et al., 2005. [3] Monkeys show cellular asymmetry but not gross anatomic asymmetry of the planum temporale. [4] Brain Research, 2008. The question still remains open; what are great apes or monkeys using this "non-human primate language area" for? [5][6] [7] [8]

[edit] References

  1. ^ Kolb & Whishaw: Fundamentals of Human Neuropsychology (2003), page 495
  2. ^ a b The Brain From Top To Bottom
  3. ^ Dorsaint-Pierre R et al. Asymmetries of the planum temporale and Heschl's gyrus: relationship to language lateralization. Brain. 2006 May;129(Pt 5):1164-76. Epub 2006 Mar 14.
  4. ^ Keenan JP, Thangeraj R, Halpern AR, Schlaug G, Absolute Pitch and Planum Temporale (2001), Neuroimage, 14(6), 1402-8
  5. ^ Science Daily. (22 September 2007). Brain Center For 'Sound Space' Identified. Retrieved 22 September 2007 from [1]
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