Day Psychology 8 Oct. 4 Disorders & Lateralization
Agenda:
Cortical Organization
Neural Disorders
Lateralization
Split Brain
Scan p. 109-116 Chp 4 Genetics
Record Clip 35
Exam in two wks Sat.
Video the undivided brain
- Each hemisphere controls the other side
- Corpus callosum
Prep Questions
- How are the cortical areas organized?
- What happens if these areas are damaged?
- Is there a separate consciousness in each hemisphere?
Post-synaptic has graded potentials, which travels down cell body
Torraine: energy stuff in energy drinks, does not work in same way as caffeine
- Similar to amino-acid
- First synthesized from oxon-bio, typically produced synthestically
- Has action on skeletal muscle fn
- Locks in gamma fn, typically in thalamus
- DOES NOT PROVIDE ENERGY
- We obtain energy only from caffeine or sugar
Neuron A and Neuron B synapse with Neuron C. You are measuring the electrical activity in
Neuron C. When Neuron A fires, an action potential is generated in Neuron C. But when both A
and B are stimulate, there is no action potential observed in C How can you explain this?
A. the neuro transmitter in b is Ach
B. Neuron A is disinhibited
C. Neuron B generates an IPSP
D. Neuron B depolarizes the post synaptic membrane
E. Measure error
Projection Areas
Three characteristics common to all
a) Topographic representation
Mortor Cortex responsible for motor mvmts
- moving laterally across the cortex
- there is a map-like quality
- start @ lower body parts, then goes up to top of body parts
b) Contralateral control
Right side of brain controls left side of body, vice versa
- opposite sides
Psychology Day 8 Oct. 4 Disorders & Lateralization
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Eg. If you have a stroke in right hemisphere, then your left side of body cant move
Only exception is your visual
o RHS goes to left hemisphere, left side visual, some goes to left
c) Functional assignment of space
o no equal representation on motor cortex of all bodily parts
o some parts has more important fn, has more cortex
eg. More cortex devoted to lips, facial movement than ankles
if there was equal representation, you wouldnt look like a human
How do we get this information?
1. Scan intact brain: scans were primitive, MRIs
- Can scan normal people
2. Evidence from brain damage
- Applies to clinical settings, ex. Phineas Gage
- Usually with patients
3. Direct stimulation of cortex
- Apply electrical current to surface of cortex and find your arm moves
Types of Scanning
Angiogram
- X-ray of head enhanced with dye
- Dont show soft tissue very well
- Used for finding blood vessels
- Used for finding where the stroke is
- Basic info abt where the blood is
- Doesnt provide much of brain structure
CAT scan
- Computeraized Axil Tomography
- X-Ray through 360 degree rotation
- Use computer enhancement, and put the slice of each angle togthr
- Can see tissue
- Good for diagnosis, not good enough for brain structure
- Terry Shaybil
o Baby taken off of life-support
o Ventricles: how you keep brain inflated, cerebral fluid
o But this baby has bigger ventricles because the brain tissues around it are dead
o
MRI (Magnetic resonance Imaging)
- Put patient in a strong magnetic field
- Has more detailed info than CAT
- Can tell brain structure much better
- For fMRI: can find function of brain
- MRI provides structural info of brain
- Cant have any metal on you
PET scan (Positron Emission Tomography)
Psychology Day 8 Oct. 4 Disorders & Lateralization
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Inject radioactive sugar glucose, radiated, mild form
Allows you to detect stuff as glucose travels in blood stream
Areas working more require more energy, thus you take up more sugar, therefore we can
see whats happening with your brain through the color scheme
Provides functional info of brain
o temporal lobe: Hearing words
o occipital lobe: seeing word
o frontal lobe, in motor cortex:
speaking
generating/think about seeing something
higher-order thought process
Association areas
- Somatosensory association area
- Motor association
- Visual Cortex: sends the input to Visual association
- Auditory association
o Are close to the primary projection area
o Integrate and interpret info
o Under normal circumstances
o May fall apart under neural disorders
Neural Disorders
Agnosia
- Inability to interpret sensory info
- Visual cortex is working well
- cant interpret info
Apraxia: inability to perform smooth motor actions
- E.g. not be able figure how to pass a paper to another person
- Cant string actions together
- But if you give instructions to the person on HOW to perform the passing of the paper,
then they are able to do it
Aphasia
- Speech
- Brocas >>>>>expressive
- Difficulty in stringing words together
- Telegraphic speech, use very few words
- Ex. may not be able to say can you get me a drink of water but they can say get water
- Is a form of apraxia
Wernickes>>>Receptive Aphasia
- Difficulty in understanding
- Ex. shown a set of keys, physician asks patient what is this
- that is an indication of mvmt of pieces of apparatus or intimating cost of apparatus in
various formspatients reply
- Is grammatically correct, but their reply is meaningless
Lateralization
Psychology Day 8 Oct. 4 Disorders & Lateralization
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Right hemisphere is not equal to left hemisphere in functions
Language z
Left hemisphere: verbal
- Right hemisphere: nonverbal
o Language
o Space
o Reading
o Form synthesis
o logical thought
o Emotion
Hemi-spatial neglect
- Results from damage (typically stroke) to right hemisphere
o Particular area: Parietal and temporal lobe
- Patient ignore contralateral special field
- Damage to right hemisphere, the patient ignores the left side of the reality
o Usually left visual problem
- Left side = nothingness, background stuff
o Ex. show a patient a pic of flower
Patient will draw only the right side of pic
o If asked to draw a clock
The individual will only draw the right side of the clock
o Or men will only shave half of their space, ex. the right
o Or eat only food on right side
o If the individual turns in the head and sees the stuff in their right visual field, then
it works
- Almost unheard of with damage to left
- Occurs more commonly with men than with women
- Is a disorder exclusively (only) in humans
- Lower animals dont show this disorder
o suggests that they have bilateral spatial representation
- As humans evolved, the language centres crowded out the spatial in the left hemisphere
o In doing-so, this gets rid of the bilateral spatial representation
Split Brain
- Individual suffering severe case of epilepsy
o Prevent the firing from spreading
o Operation on severing corpus callosum to prevent the spread from one
hemisphere into another hemisphere
Done while the patient is awake
The individual is almost undetectable after the operation
o Asks the patient if they are LH or RH
o Process: present info under 200 milliseconds
o Patients can still carry normal lives because they can adapt