Lunate sulcus

Source: Wikipedia, the free encyclopedia.
Lunate sulcus
Lateral surface of left cerebral hemisphere, viewed from the side.
Details
LocationOccipital lobe
FunctionSulcus
Identifiers
Latinsulcus lunatus
NeuroLex IDbirnlex_4017
TA98A14.1.09.134
TA25483
FMA83788
Anatomical terms of neuroanatomy

In brain anatomy, the lunate sulcus or simian sulcus, also known as the sulcus lunatus, is a fissure in the occipital lobe[1] variably found in humans and more often larger when present in apes and monkeys.[2] The lunate sulcus marks the transition between V1 and V2.[3]

The lunate sulcus lies further back in the human brain than in the chimpanzee's.[4] The evolutionary expansion in humans of the areas in front of the lunate sulcus would have caused a shift in the location of the fissure.[4][5] Evolutionary pressures may have resulted in the human brain undergoing internal reorganization to develop the capability of language.[6] It has been speculated that this reorganization is implemented during early maturity and is responsible for eidetic imagery in some adolescents.[6]

During early development, the neural connections in prefrontal cortex and posterior parietal lobe rapidly expand to allow capability for human language, while

pongid-like.[8]

History

Comparison of the Affenspalte homologue, renamed the lunate sulcus by Sir Grafton Elliot Smith, in the primary visual cortex of chimpanzee versus human brains.[9] The Affenspalte, or lunate sulcus, is marked by the red line.

The lunate sulcus was first identified during the early 1900s in the human brain as a

Homo sapiens was due to the evolutionary rapid overgrowth of the cerebral cortex that is unique to human neurodevelopment.[9]

Smith’s observation that the caudal shift of the lunate sulcus could also be used as a predictor for determining both the evolutionary posterolateral shift of the occipital lobes/V1 and the corresponding expansion of the neighboring parietotemporo-occipital visual association cortices was supported by recent research.[9][10] However, some neuroanatomists today disagree with Smith’s assertion that a lunate sulcus exists in humans, arguing that there is only an Affenspalte which is unique to apes. Specifically, in a high-resolution MRI study conducted by Allen et al. (2006), the researchers scanned and analyzed 220 human brains and found no sign of the lunate sulcus homologue. Based on this finding, they suggested that the claim asserting humans have a lunate sulcus homologue fails to account for and show appreciation of the extensive evolutionary reorganization of the visual cortex in humans.[1]

Evolution

Analyzing variability in the location of gross

hominoids.[12] Despite this, previous allometry studies have suggested that the lunate sulcus shifts from a lateral-anterior to a medial-posterior position as brain size increases.[13][14] Such shifts have been credited with predicting whether the lunate sulcus will occur or not based on an increase or reduction in V1 volume, thus providing an explanation for inconsistencies in its presence and position in the occipital lobes.[13][15] Moreover, a study conducted by de Sousa et al. (2010) compared the volumes of the V1 relative to the position of the lunate sulcus in three-dimensional reconstructed non-human hominoid brains to determine if an allometric relationship existed between V1 volume and lunate sulcus position. The researchers found that the position of the lunate sulcus does accurately predict V1 volume in apes, and that V1 volume in humans is smaller than would be expected based on our large brain size.[10] Furthermore, other research suggests a more posteriorly positioned lunate sulcus from the early hominin fossil record.[4][5]
Based on all these findings, de Sousa et al. (2010) concluded V1 reduction began during early hominin evolution, given the more lateral-anterior position of the lunate sulcus in human and other primate brains today.

References

  1. ^
    PMID 16835937
    .
  2. PMID 18516336
    .
  3. ^ Schmolesky, M. "The organization of the retina and visual system". {{cite journal}}: Cite journal requires |journal= (help)
  4. ^ a b c Rincon, Paul (2004). "Human brain began evolving early". BBC.
  5. ^ a b Bruner, E (2014). Human paleoneurology. Springer.
  6. ^
    doi:10.5539/ijb.v7n3p59
    .
  7. PMID 15148381
    .
  8. S2CID 4428635
    .
  9. ^
    PMID 24822043
    .
  10. ^
    PMID 20172590
    .
  11. doi:10.1002/ajpa.10249
    .
  12. S2CID 3359887
    .
  13. ^
    doi:10.1146/annurev.an.04.100175.000331
    .
  14. S2CID 142597701
    .
  15. PMID 12050080
    .
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