Cerebral Lateralization
- Lateralization of function: differences in function between the right and left cerebral hemispheres
- language is the most lateralized of all cognitive abilities – often residing in the left hemisphere
- motor functions seem to be more strongly lateralized than sensory, emotional and cognitive
functions
→ speak production is more strongly lateralized than the understanding of speech
Visual connection to the brain
- light from the right half of the visual strikes the left half of each retina, and light from the left
visual field strikes the right half of each retina (crossed)
- the left half of each retina connects to the left hemisphere – therefore sees the right visual field
- the right half of each retina connects to the right hemisphere – which sees the left visual field
- at the optic chiasm axons from the left half of the retina cross to the left hemisphere
Right visual field → left half of each retina → left hemisphere
Left visual field → right half of each retina → right hemisphere
Split-Brain Patients:
- patients whose left and right hemispheres have been separated by commissurotomy
- corpus callosum: has the function of transferring learned information from one hemisphere to the
other
- when the corpus callosum is cut – each hemisphere can function independently – like two brains
→ each side with its own stream of consciousness, abilities, memory and emotions
- it was known that epileptic discharges often spread from one hemisphere to the other through the
corpus collossum → a split brain can reduce or even eliminate seizures
- a small amount of information can travel between the hemispheres through several smaller
commissures such as the anterior commissures and the hippocampal commissure
- each hemisphere of a split brain is a subject scotoma covering the entire ipsilateral visual field
→ which allows each split-brain hemisphere to have its own focus of attention to do two tasks at
once
- emotional reactions, but not visual information is readily passed from the right hemisphere to the
left hemisphere
, - a patients left hemisphere often reacts with the appropriate emotional verbal response to an image
that had been presented to the right hemisphere
→ even though it did not know what the image was like
- when a test objects presented to left hemisphere (right visual field)
→ split brain patients will say what it is and can reach out with their right hand and identify the
object
- when a test object is presented to the right hemisphere either visually (in the left visual field) or
tactually (in the left hand)
→ split brain patient will likely say nothing appeared – since the right hemisphere is aware but
cannot communicate it to the left (speaking) hemisphere
→ but patients left hand can identify objects even though the left hemisphere is unaware of its
identity
Cross-cueing:
- communication between the two cerebral hemispheres of a split-brain patient through an external
route (different from the indirect pathways of the brainstem)
→ Example: when split-brain patients are provided an image to the right hemisphere, they have
trouble verbally reporting what it is. When the right-hemisphere knows the answer, it
can signal (shaking head) that the left-brain's guess was wrong
Helping-hand phenomenon:
- occurs when the two hemispheres are presented with different information about the correct choice
and the are asked to reach out and pick up the correct object from a collection in full view
→ usually the right hand will reach out to pick out what the left hemisphere saw
→ but the right hemisphere seeing what it thinks is an error being made – then causes the left hand
to grab the right hand and pull it over to the other object
Cortical blindness:
- people do see an object they are just not aware of it
The left and the right cerebral hemisphere:
- are entirely separated
→ except for the cerebral commissures connecting them
- are similar in appearance
- the sides have major differences between them in function
- differences are always relative
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper macami. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €3,49. Je zit daarna nergens aan vast.