Kinesiology 1080A/B Lecture Notes - Lecture 4: Split-Brain, Roger Wolcott Sperry, Cerebral Cortex
11 Jun 2018
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Topic 2- Nervous System
After midterm 1
Cortical Reorganization
• M1 damage impairs voluntary behaviour; however with practice the activity can be reacquired
• Use single finger movement in fMRI- can test ideas like brain plasticity
• Participants were given a sequence to practice with fingers
• M1 is activated for the task that they practiced
• But when they are given a task that was not practiced, there was a lot less activation of M1.
• Shows specificity of plasticity
• One might be good at one task but not the other due to training plasticity.
Cerebral Asymmetries
1. Two hemispheres of the cerebral cortex are linked by the corpus callosum (makes two brains
functions as one)
2. Left and right cerebral hemispheres have specialized functions.
3. Left cerebral hemisphere- dominant for speech and language (very robust)
a. Movement praxis- allows you to sequence movements together, allows us to coordinate
different structures together
4. Right hemisphere- less important part in early 20th century
- Haptic information processing (touch information) - when you touch something
without looking at it and you know what it is.
- Highly specialized for visual spatial attention (a motor function specialized
within right cerebral hemispheres)
Split Brain Syndrome
• As a result of neurosurgical intervention
• By roger sperry- designed to treat people with epilepsy
• Prevent info from right to left
• It can reduce the effect of epilepsy
• Separated the corpus callosum
• Take home message- This shows that two hemispheres can full learn something, without
exposing that information to the opposite one, we can make one brain into two by messing up the
corpus callosum
Michael Gazzanaga
- Monkey received spilt brain surgery
- Performed task that pertains to just one hemisphere
- Was not able to repeat movement immediately once hemisphere was switched
- Two hemispheres can fully learn something without exposing that information to the opposite
hemisphere
- Joe was able to vocalize and identify objects that flashed on the right side of the screen only
(projected to the left hemisphere: dominant for speech and language)
- Individuals with split brain surgery do not fall into phase (inability to perform coordinated
movements with two limbs of the body)
o Would allow them to perform independent movements proficiently (e.g., be a good
drummer)
- Strong link between handedness and lateralization of the left hemisphere
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- Vast majority of population has speech and language lateralized to left cerebral hemisphere
Pierre Paul Broca
- Syphilis patient gradually lost his ability to produce speech (speech production deficit)
- Specific lesion in left hemisphere (Broca’a area)
- Broca’s aphasia- inability to produce speech
- Can understand, but unable to produce speech in response
- Have automated speech remaining (e.g., counting to 10, swear words)
- Melodic intonation therapy- having the individual speak in a song (musical abilities located in the
right hemisphere)
Karl Wernicke
- Speech perception (ability to understand and communicate with other people)
- Left temporal lobe lesion (Wernicke’s area)
- Lost rules associated with speech (“word salad”)
- Meaningless speech
Transcortical Sensory Aphasia
- Arcuate fasciculus= bundle of axons connecting Wernicke’s to Broca’s area
- Lesions to this area will develop conduction aphasia (disconnection syndrome)
- Communicates only a single word
- Ability to hear themselves and understand what they are saying is disconnected from production
Cerebral Asymmetries
- Speech and language is the most complicated thing the human brain does
- Neurons in the left speech region of our brain are more complex the homologous right brain
o Bigger
o More dendritic trees
o Referred to as magnopyramidal neurons (less myelinated)
- Homologous= opposite sides
Apraxia: a disorder of learned, skilled, purposeful movement not related to muscle paralysis or
comprehension deficits
o Ideational apraxia: inability to evoke the appropriate action representation from long-
term memory
▪ ask an individual to mime a task, and they will not be able to do it
▪ left parietal lesion
How numbers are represented in the brain
- Majority of the population represent numbers as a horizontal line, with the numbers ascending
from left to right (excluding those with creative/artist abilities)
- Lateralized to the left parietal lobe (those with a lesion to this area have d
- Spatial numerical association of response codes (SNARC effect)
o Mental number line
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o Using a computer monitor, individuals observe a fixation cross, then are presented with a
stimulus to que a pointing action in a particular direction (1 or 2 point left, 8 or 9 point
right)
o Stimulus is incompatible with mental number line
o Individuals have much shorter reaction times for the SNARC
o Reaction times increase significantly and are less accurate when not used
o When a number is associated consistently with a movement, we are able to plan and
perform a movement more efficiently
- Individuals with mathematical abilities generally possesses a stronger ability to respond to
SNARC effect
- Individuals native to English generally do not demonstrate a SNARC effect (robust for
individuals whose language does not move left to right)
Ideomotor Apraxia
• inability to translate the appropriate innervatory patterns into action
o They can explain you what they want to do but can’t physically do it
o Get frustrated
o Cannot translate the knowledge into actions
o Is it only naturalistic disorder aka is it only seen in clinics or day to day living as well
o Ideational apraxia is a kin to some aphasia and Ideomotor aphasia is kin to borco’s
aphasia
The Case of CK
• Somatosensory form of apraxia
• She was 21 years old when she had a large lesion in her right parietal lobe
• She didn’t have any speech or visuospatial difficulties in early stages
• But she had difficulties when she had to use fork, spoon to eat
• Anytime she holds a tool in her left or a right hand, she has difficulties→ shows a form of apraxia
• Her hand would move all over the place if she holds a tool in her hand
• Right hand is a little better than left hand
• Because her lesion involves parietal lobe→ she is getting too much information which causes her
to have a lot of movement when she has to use a tool to act on an object
• Not every lesion will result in the same problems- different brain, different deficit but same lesion
Developmental Dyspraxia
• Also referred to as DCD (developmental coordinative disorder)
• Its developmental – in kids
• It was thought it was a soft movement deficit
• A clumsy individual- hard time coordinating their limbs and other body parts
• Speech dyspraxia- you have to coordinate your lips and tongue together
o So somebody’s timing of the articulators have not developed
• Movement and speech therapy can help with dyspraxia
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Haptic information processing (touch information) - when you touch something without looking at it and you know what it is. Highly specialized for visual spatial attention (a motor function specialized within right cerebral hemispheres) It can reduce the effect of epilepsy exposing that information to the opposite one, we can make one brain into two by messing up the corpus callosum. Performed task that pertains to just one hemisphere. Was not able to repeat movement immediately once hemisphere was switched. Two hemispheres can fully learn something without exposing that information to the opposite hemisphere. Joe was able to vocalize and identify objects that flashed on the right side of the screen only (projected to the left hemisphere: dominant for speech and language) Individuals with split brain surgery do not fall into phase (inability to perform coordinated movements with two limbs of the body: would allow them to perform independent movements proficiently (e. g. , be a good drummer)
