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Neuroscience
Thursday, February 12, 2015

7:42 AM

• Lectures 1 & 2
• We need evidence: science changes so much over time that this lecture will probably be obsolete in 200 years
• LOCALISATION - the idea that different brain areas perform different tasks
○ Cognitive and motor things
• Cognitive Neuropsychology = see what a person with damage to the brain exactly can and cannot do, link it to the normal brain, and devise
models of the brain/mind, then use these models to make precise diagnoses
○ Helps to build up 'an architecture'
○ Brain deficits can be used to see how a normal brain operates
 This can also work the other way around, where normal brains help us understand lesioned brains
○ Grey matter= cortex= outer lining of brain = like the bark of a tree
○ Brain is asymmetric…much speculation as to whether or not it is advantageous (question from lecture)
• Lobes
○ Frontal (thinking and planning), occipital (vision), parietal (sensory), temporal (hearing, meaning)
 These all communicate via cells neurons
 Different sides of the lobes (in different hemispheres) do very different processes
□ So, the question "what does the temporal lobe do?" is meaningless is we do not know which hemisphere we are talking
about
• Neurons - cells that transmit nerve impulses…has a body and branches
○ Dendrites = branches that spread to different areas of the cortex…allows different areas to communicate
 Damage to these causes problems in the cortex (cognitive syndromes result from this)
 Thinning out (generally happens with old age) = problem with dendrites
□ Dementia, Alzheimer's
□ Progresses slowly, person can still walk/feel because their axons remain unimpaired
○ Axons = go down to the body (cross both hemispheres)
 Damage to these can cause motor deficits
 Left hemisphere controls right side of body; vice-versa
□ Lesion in right hemisphere will affect the left hemisphere
○ Communicate via synapses by releasing neurotransmitters
• "damage to the brain can mean a blow to the head, a disease that destroys half of the cells, or can be a disease that hampers the
manufacturing of the neurotransmitters"
• Anterior artery = supplies oxygen and glucose (blood) to the front of the brain
○ Destroy this and the frontal lobes will be impaired
• Middle artery = supplies oxygen and glucose to the middle of the brain
○ Destroy this and the parietal-temporal lobes will be impaired
• Posterior artery = supplies blood to the back to the brain
○ Destroy this and the occipital lobe will be impaired (stroke)
• Stroke = like a bomb that goes off in the brain; can destroy everything (axons and dendrites)
○ Hemorrhage = spills blood
○ There are several different types of dementia and strokes respectively
○ This is different to Alzheimer's which slowly kills the cells
○ How big a stroke is not nearly as important as where it is
○ Both motor and cognitive symptoms
• Dementia = mainly cortical, much less localised than strokes
○ Dendrites are damaged…person can walk and feel but cannot think properly, lose memory, have language problems
○ Progresses slowly over many years
○ Also subject to the law of localisation…however localisation is much less precise
• Homunculus = representation of the body in terms of how precise the motor/sensory system is in that area
○ So, statistically speaking, a stroke is much more likely to impair the hands than the back
 Many more fine movements in your hand
• Sides of the brain cross right at the end of the brain and beginning of the neck…so a tiny lesion there will have a large eff ect
• Main exception to the crossing-over = vision
○ Half of left eye produced by left brain and half by right brain…vice-versa
○ Left side of left eye and left side of right eye linked to right hemisphere…vice -versa
• No crossing over for the organs
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Lecture 3
Repetition = key to scientific experiment
The different hemispheres of the brain cross sides right before the neck (for motor reactions)
Brain Localisation and Architecture of the Mind
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• Brain Localisation and Architecture of the Mind
○ Phrenology = at the time, was a fantastic revolution
 Put the "mind" into the brain rather than the heart for the first time
 Started localisation of function
○ The modularity hypothesis = our mental life is made possible by the orchestrated activity of
multiple cognitive processors, or modules
 Every module has its own form of processing
• The concept of modularity
○ Same lesion can cause vastly different effects in different areas
○ Different networks work alone but also together
• **** Important question: How do we know there are modules? ****
○ Broca = found Broca's area, which is involved with speech production
 Came from a patient named Tantan, whose post-mortem examination found a small lesion
in a specific area
□ Tantan could understand most speech, but could not really produce it
○ Wernicke = had a patient who was almost continuously speaking but could barely understand
anything
 Found a lesion in a different area, which proves that there are many different modules for
"one" function, such as the production and comprehension of speech
• Cognitive models = hierarchal
○ Little mermaid had Agnosia -- which literally translates to "no" or "lack of" in Greek…because she
failed to speak and recognised objects for things that they were not
• Scenescence = the process of growing old…proceeds for a long period, thus for more than half the
average life span, the standards of normal functioning are in inclination or declination…what is normal
at one age can be abnormal at another
• Bicycle drawing activity-- shows some of process of a common neurological experiment
○ Collect norms (bicycles we drew) and run a task analysis
 Find out what normal people do that the patient does not
 Their performance must be out of the range of normality to be considered a deficit
• The Logic of Dissociation - central to the logic of relating normal functioning to the effects of brain injury
is the concept of dissociations…a dissociation occurs when a patient performs very poorly on a task and
normally on or at a higher level on another task
...
to novel or meaningful stimuli presented to
the side opposite the brain lesion, when the failure cannot be attributed to either sensory or
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the side opposite the brain lesion, when the failure cannot be attributed to either sensory or
motor deficits
• Lecture 5
○ The problem of resource artefacts
○ Neglect
 Not that they don't see things, but rather that they don't attend to things
□ Ignore one side of the environment
 If asked to copy a photo, they will copy the side that they see (only right side of the
cat)
 Asked to find the stars, only found those stars on the right
○ Hemianopia - deficit in half of the visual system, opposite from neglect
○ Lesion in the optic tract…don't see half of environment (you don't see, rather than not
attending which is neglect)
○ Can turn their head to see something
○ Neglect happens most on the right side (left field visual neglect)
○ Deficit of attention
○ They have knowledge but cannot access it when they need it
○ Sometimes patients hear voices from both sides but only turn to the right
 However, others may completely ignore any sounds made from neglected field
○ President Wilson had a stroke in Versailles which led to neglect
○ Met with the Queen of Belgium, she was insulted because she stood on his bad side and he
ignored her
 US called Freud in for help diagnosing Wilson
□ Freud said it was due to the "emotional pressure"
○ Couldn't come up with the right image of a map even in his brain…had no mental left side
○ Cerebral-spinal fluid = feeds and protects brain
○ This is in the ventricles, which are in the middle of the brain
○ Scans show opposite image…stroke will be a darker color than rest of scan
○ Parietal lobe= severe neglect
 This patient had errors in reading and on all the tests…but could draw from memory
○ Study: Patients asked to imagine flying from New York to LA, name states they would fly over
○ Named states on right side, but 0 on left side
○ Then asked to imagine flying from LA to NY, got different states
 Have all the knowledge but cannot always access it when they need it
○ Can see strokes on scans because they are a different color…real scans will show the right side as
the left (flipped) and vice-versa
○ Italian study- imagine yourself in the square facing the cathedral, what do you see?
○ Said what they saw on the right side
○ Then asked them to turn around, shoulder to church…told about the shops that were on the
then right side
○ Have all info, but fail to access it due to neglect
○ Errors in reading = read disgrace as "grace"
○ Patient could still draw from memory
 This means that patients can have perceptual or memory (visual imagery) neglect; or
both
□ Shows our brain is made up of several different routes
 Each stroke produces a different symptom in neglect
• Lecture 6
○ Perceptual neglect- when people read/see wrongly
○ Memory neglect- people cannot build up a full visual imagery of the external states
○ Some people with neglect ignore their own figure (personal neglect)
○ Only shave one side of face, put makeup only on one eye
 However, these people may not show any other type of neglect
○ Perceptual, representational, personal
○ Each type of this can dissociate from the other
○ The mind does not work as a computer…memory is a representation of reality
○ If you do not encode/consolidate you do not learn
○ Each step can be damaged in its own way
○ Color constancy -> dress debate
○ Even if we wear a red coat in different lightings it stays the same shade in our mind
because that is what we know it to be
○ House on fire study
○ Patients with left visual field neglect cannot attend to the bit of the house on fire
However, when asked which house they would rather buy, they chose the one
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 However, when asked which house they would rather buy, they chose the one
not on fire and make up their own reasons for doing so
 Pick the right stimulus without knowing how they did so
Implicit Processing- the brain processes some stimuli without us being aware of it
○ Photos of things such as lamp/foot put together, but patients cannot see foot side
 When asked what relates to the image (of lamp-foot), they say a shoe, and
come up with strange reasons as to how they got to that conclusion
The brain does not work like a computer
○ Any metaphor of the brain being like a computer is untrue
 These exist because we use what we know to make sense of the universe
 Cerebro-spinal fluid protects and feeds the brain
Amnesia
○ Little dot in right hemisphere (MRI image)…stroke without blood…wherever in this
area there is a lesion, it will produce similar symptoms to other lesions in the same
ventrical network
 This patient came in complaining of memory problems
 No recollection of eating 3 times in one day at the same place
□ However, could repeat telephone number and recite old memories
 This is called anterograde amnesia, when someone cannot learn new things
□ Can tell you what the capitols of places are and how to do things but not
new things
Anterograde amnesia = cant learn new things
○ Medial temporal damage
○ Case HM-> had bad epilepsy…surgeon cut out bits of both hippocampi
 1950's
 Became immediately amnesic
 However, could still do things like riding a bike
Hippocampus (seahorse) = memory
○ One can see epilepsy on EEG, not MRI
○ Part of the memory circuit where when damaged, people become very much amnesic
 However, people still remember semantics and how to repeat a telephone
number immediatley
 May still process stimuli implicitly
The brain does not store all memories, we do forget
○ Every time we remember, our memory changes
○ Eyewitness testimony -> 2/3 of death row cases based solely on eyewitnesses were
later proved innocent by DNA testing
 The brain constructs what it wishes to see
Retrograde amnesia = before; anterograde amnesia = after
Long term memory vs short term memory

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