lecture 5 - functions of the cortex Flashcards
(21 cards)
the cortex - a recap
Key points to remember:
1. Divided into 2 hemispheres.
2. Sulci and gyri – give the brain it’s textured look!
Sulci – think “sunken”
Gyri – bumps
3. Grey and white matter- grey = cell bodies, white = axons
diagram in notes
Key terms: a recap
- Anterior (rostral)
- Posterior (caudal)
- Dorsal (superior) - top
- Ventral (inferior) - bottom
- Medial - middle
- Lateral - side of brain
Why? Names of brain regions often refer to where they are (e.g. ventral tegmental area, dorsolateral prefrontal cortex)
diagram in notes
main subdivisions of the cortex
frontal lobe = planning, reasoning, imitation, attention
motor cortex = where Brin sends info to body telling you how to move
somatosensory cortex = to do with taste and touch
parietal lobe = speech
primary cortex = direct input from senses
association cortex = integrates information
occipital lobe = visual info
temporal lobe = hearing, smell, facial recognition
medial temporal lobe = learning and memory
diagram in notes
wilder and penfield 1891 - 1976
put electrodes onto brain to stimulate areas
patients awake so can report what experiencing
Penfiled and boldrey 1937
diagram in notes
areas labelled based on what patients reported or performed
primary motor cortex stimulated caused movement
somatosensory cortex to do with sensation
cortical map
motor and somatosensory maps - phantom limb syndrome
diagram in notes
when somatosensory Cortex for limb is still there so brain doesn’t know its gone
To summarise
- Frontal lobe – planning, reasoning, inhibition, attention, etc.
- Parietal lobe – speech, taste, reading etc.
- Temporal lobe – hearing, face recognition, memory etc.
- Occipital lobe – vision
- Primary cortex – receives direct input from senses
Association cortices – receives and integrates information from a range of other areas (then frontal association cortex plans appropriate behavioural response)
cognitive neuropsychology
- Brain damage. For example:
- Traumatic brain injury (TBI) – motorbike accident / car crash / American football “dings” / boxing
- Progressive brain injury – Huntington’s disease / dementia / Parkinson’s
- Stroke
- Surgery (e.g., lobotomy)
- Bacterial infection…
Huge global health issue, and cases increasing particularly of TBI.
Damage to different regions causes different symptoms…
Frontal lobe damage - odd behaviours
patient who manually evacuated her bowels - she couldn’t stop herself from doing it and did it in public
patient with difficulty with violent and aggressive behaviours and if got angry would take off her prosthetic leg and throw it at people - this aggressive and violent tendency results from frontal lobe damage and have issues suppressing it
frontal lobe dysfunction - Phineas gage
1948 - Damage to frontal lobe as metal pole went through his head and took out a portion of his temporal lobe : personality changes and loss of social inhibition - before was respectable and had christian morals and after was a womaniser and had lots of sexual inhibition
dementia - picks disease
Pick’s disease affects the frontal lobe
frontal part of brain shrinks
have less control over your behaviour - impairments in reasoning, memory and lacking social awareness and inhibition
frontal lobotomy
Severed the thalamocortical fibers (corona radiata) to disconnect emotional centers from the seat of intellect.
Reduced “problem behaviours” such as aggression. Blunted emotional reactivity, was used to treat anything from depression->schizophrenia
diagram of freeman-watts procedure
Frontal lobe and executive function
executive function = range of cog processes that help us to guide our behaviours
Executive function: top down regulation of behaviour/ cognition – including problem solving, response modulation
the troop effect - in notes
Incongruent trial performance - Stroop
- Patients with damage to different areas to frontal lobe.
- How does damage relate to performance when asked to red the colour?
- Damage to ACG = poor performance = anterior cingulate gyrus - diagram and table in notes
- Unable to inhibit reading the word
Poor executive function
BADS
- Behavioural Assessment of the Dysexecutive Syndrome - not the best test for BADS
- Designed to assess a range of executive functioning – planning, organising, initiating, monitoring, and adapting behaviour
- 6 tests, e.g.:
- Rule shift cards – Yes if red, no if black. Then rule change – yes if card same colour as previous, no if different - if struggle with executive functioning will struggle with rule shift - not a perfect tests as there are other reasons you could perform badly on it eg if have poor memory
Key search test - imagine a blank square is a field and that you lost your keys in the field and you need to find them, how would you go about doing that? if your systematic brain is fine as you have normal behaviours, if have brain injury would go all over the place
- Rule shift cards – Yes if red, no if black. Then rule change – yes if card same colour as previous, no if different - if struggle with executive functioning will struggle with rule shift - not a perfect tests as there are other reasons you could perform badly on it eg if have poor memory
Cortex and visual memory
info comes in through eyes and sent to back of brain to the primary visual cortex. as you move away from the primary visual cortex the brain gets more and more complex. brain starts processing info in V1 and V2 and then to V3 and V4 that adds colour and things like that. then we start to recognise faces and objects. the further its gets from C1 area the more complex it gets. this is the temporal pathway
diagrams in notes
damage to primary cortex/ temporal lobe can cause capgras syndrome
when patient recognises individual but thinks they are an imposter
they don’t have the normal emotional reaction to familiar stimuli - to do with the amygdala
diagram to explain in notes
damage to visual association cortex can cause Prosopagnosia
Impaired recognition of familiar faces
Ventral route relates to retrieval of memory - emotional and contextual information - about a face
can be caused by inability to associate face with emotional aspects
Posterior cortical atrophy - bensons syndrome
primary visual cortex also sends info to the parietal cortex and this is where the brain adds info about where in space that is - damage to this causes PCA
its a visual variant of Alzheimers - Alexia, depth perception and visual agnosia
have issues with depth perception and visual agnosia
reduced ability to judge aspects of space
stroke
common cause of damage to parietal lobe - blood supply cut off
hemorrhagic stroke = haemorrhage/ blood leaks into brain tissue
ischemic stroke = clot stops blood supply to an area of the brain = 85% of cases
middle cerebral artery (MCA) is the most common stroke
damage may cause visual neglect - eg can only do things in one visual field/ on one side
Summary
- Different parts of the cortex have different functions
- Damage to selective parts of the cortex will lead to deficits/impairments in certain functions
Brain damage have taught us a great deal about the functions of different brain areas
