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skatergirl69420 t1_j8x9nhc wrote

im assuming by “types of folds” you’re referring to the gyri and sulci (in simple terms, a gyrus (gyri plural) would be the outward-appearing lumps/bumps, and a sulcus (sulci plural) would be the deeper grooves inward)

despite the brain being split in two hemispheres down the middle by the longitudinal fissure, hemispheres are only symmetrical to an extent. structural asymmetry varies between individuals, brain regions, etc. so the short answer to your question is no

however, it of course follows the same structure on both sides. the superior frontal gyrus is gonna be in approximately the same spot on either side, the uncus gyrus in approximately the same spot, the pre&post central gyri in approximately the same spot on either side of the central sulcus.

then, there can be differences in an individual due to disorders like pachygyria or microgyria (abnormally large or small gyri, respectively) which can span the entire cerebral cortex or be localized.

if some functions are processed more in one hemisphere than another, that would impact symmetry. interestingly, some studies have shown that a LACK of left hemisphere asymmetry is observed in individuals with dyslexia. some research also found that the asymmetry between hemispheres is not due to genetics, so its believed to be due to experiences

another factor that can affect the symmetry/asymmetry between hemispheres is if a portion of the brain that is typically for “xyz” function is also working for “abc” function. if a region has greater between-subject variability, its more likely to be asymmetrical to its respective location in the other hemisphere.

heres an article if u care to read more:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4947520/

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FredAbb t1_j90ki6y wrote

> however, it of course follows the same structure on both sides. the superior frontal gyrus is gonna be in approximately the same spot on either side, the uncus gyrus in approximately the same spot, the pre&post central gyri in approximately the same spot on either side of the central sulcus.

Could you compare it to the body being symmetrical because you have one hand on each side, but that doesn't mean your hands themselves are exactly symmetrical - e.g. fingers could have different lengths.

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Feline_is_kat t1_j90m129 wrote

Not really. Arms and legs have way too simple a function to be comparable and internal organs are completely asymmetrical.

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No-Wrap-9240 t1_j92t1fz wrote

Why do you say that? Are they always symmetrical? What about phantom limbs or the cannibalisation of certain areas?

How does limb dominance factor into that?

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dutchaggie96 t1_j903pej wrote

There's some decent hemispherical asymmetry in the temporal lobes. If i recall correctly (unlikely), the left side is specailized for language and the right side for music or other non language sounds. But they both do both still, its relative activation. The speech zones in the left temporal lobe were, in general, larger from what i can recall.

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