PSYC 273 Lecture Notes - Lecture 15: Visual Cortex, White Matter, Disconnection
Chapter 15 Notes
*Important distinction:
• Left visual field=right hemisphere.
o Big piture, faial reogitio, spatial proessig.
• Right ute visual field=left hemisphere.
o Verbal and language, vocabulary/grammar, analytical.
The left and right brains are different. (Left brain v. right brained people is not supported by
science).
• Disconnection of the cerebral hemispheres reveals their individual processing
specializations.
o Lateralization: hemispheric specialization.
o Corpus Callosum: the main band of axons that connect the 2 cerebral
hemispheres.
▪ White matter: tells us automatically that this must be a bundle of axons,
and therefore be involved in transmitting neural signals (not much
processing/altering).
o Split Brain Individuals: an individual whose corpus callosum has been severed,
halting communication between the right and left hemispheres.
▪ Itetioall doe to people ith uotrollale epileps, so it ot
spread to the other side of the brain.
▪ Visual cortex works contralateral, but the information is not processed in
the opposite side.
• Ex: presents an item to the left side (of either eye), right visual
cortex sees it, and processes the information that allows them to
recognize the item by touch. Present it to the right visual cortex
(right side of either eye) and the person can recognize it verbally.
▪ For a itat orpus allosu it doest atter hih isual field sees the
key: the visual information will reach the left hemisphere eventually, and
necessary language processing occurs.
• Can read and report words when in right visual field (left brain).
When coming from left visual field (right brain), cannot report
that they see, but they can draw the item.
o Contralateral: pertaining to a location on the opposite side of the body.
▪ Sensory information on the left side of the body are processed in the
contralateral side of the brain.
▪ “plit rai idiiduals dot do this. The iforatio is trapped i the
same side of the brain, so if there is a reaction that side of the brain must
be responsible.
• Ex: Read and verbal words were easy when presented on the left
(projected in the left side of the brain instead of the right).
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o Showed that talking, analytics, vocabulary and grammar
are especially linked to the left hemisphere.
o Right hemisphere is important for spatial processing, face
recognition, emotional aspects of faces, and controlling
attention.
• The 2 hemispheres process information differently in the human brain. Most studies
focus on hearing and vision.
o The right ear advantage.
▪ Dichotic Presentation: the simultaneous delivery of different stimuli to
both the right and the left ears at the same time.
• Idetif pa faster.
• When this is done right handed people more accurately identify
verbal stimuli delivered to the right ear (processed in the left
hemisphere), while left handed people either show no difference
or preference to the left ear.
• Shows that language mechanisms are more prevalent in the left
hemisphere.
▪ Right Ear Advantage: people identify verbal stimuli delivered to the right
ear more easily.
• Its heard i the right ear, sed to the left of the rai hih is
right et to the Werikes area here it a e erall
processed more quickly.
o Visual perception of linguistic stimuli.
▪ Tachistoscope Test: a test in which stimuli are very briefly presented to
either the left or right visual half field. When the stimuli is presented for
less than 150 ms only one hemisphere gets the information because both
dot hae tie to shift their diretio.
• Confirms verbal (left)/spatial division.
• The detection of light, hue, or simple patterns are equivalent in
both hemispheres.
• Does the left hemisphere hear words and the right hemisphere hear music?
o Planum Temporale: an auditory region of the superior temporal cortex.
▪ Found to be larger in the left hemisphere than in the right.
• Even in infants= shows that we have an innate mechanism for
language.
• Same in monkeys, but they use left hemisphere for
communication rather than language.
▪ Iludes Werikes area iportat for laguage).
o Right hemisphere= music.
▪ Perfect pitch: being able to accurately name a musical note relies more
on the left
▪ Prosody: the perception of emotional tone of voice aspects of language.
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