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→Sensory processing: Rewritten lateralization of hearing to improve clarity on how hearing is actually primarily bilateral, and a more detailed explanation of the pathways involved. |
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In [[visual perception|vision]], [[retinal ganglion cell]]s undergo partial decussation at the [[optic chiasm]], where [[axon]]s from the nasal retinas cross to the opposite hemisphere, while axons from the temporal retinas remain on the [[Ipsilateral|ipsilateral side]].<ref>{{Cite web|url=https://theodora.com/anatomy/the_optic_nerve.html|title = The Optic Nerve - Human Anatomy | work = Photius Coutsoukis }}</ref><ref name=":0">{{Cite book |last=Bear |first=Mark F. |title=Neuroscience: exploring the brain |last2=Connors |first2=Barry W. |last3=Paradiso |first3=Michael A. |date=2016 |publisher=Wolters Kluwer |isbn=978-0-7817-7817-6 |edition=4th |___location=Philadelphia}}</ref> As a result, visual input from the left visual hemifield is processed by the right hemisphere's [[visual cortex]], while input from the right visual hemifield is processed by the left hemisphere's visual cortex.<ref name=":0" />
In [[hearing]], [[spiral ganglion]] neurons in the [[vestibulocochlear nerve]] project to the ipsilateral [[Cochlear nucleus|cochlear nuclei]] in the [[Medulla oblongata|medulla]].<ref name=":0" /><ref name=":1">{{Cite book |title=From neuron to brain |date=2012 |publisher=Sinauer Associates, Inc |isbn=978-0-87893-609-0 |editor-last=Nicholls |editor-first=John G. |edition=5th |___location=Sunderland, Mass}}</ref> However, second-order axons from the [[ventral cochlear nucleus]] branch to both the ipsilateral and contralateral [[Superior olivary complex|superior olivary complexes]].<ref name=":0" /><ref name=":1" /> Consequently, hearing is strongly lateralized only at the ipsilateral cochlear nuclei, while further processing in the [[Inferior colliculus|inferior colliculi]], the [[medial geniculate nucleus]] of the [[thalamus]], and the [[auditory cortex]] occurs bilaterally.<ref name=":0" /><ref name=":1" /> This lateralization explains why damage to one cochlear nucleus causes [[deafness]] in the ipsilateral ear, whereas damage above the cochlear nucleus typically results in only slight hearing loss.<ref name=":0" />
In the [[sense of touch]], most of the neurons from the skin cross to project to the [[somatosensory cortex]] of the opposite hemisphere.
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