patient research Flashcards
issues of neuroimaging
cannot teach us about causality
can only provide us with correlational evidence
- do one thing and observe that activity
cannot show if stimulus is the cause of the activity
or whether observed activity causes a behaviour
atypical patients
used to investigate cognitive causality
atypical or injured brains offer unique opportunities to study causal links
link physiological differences to differences in behaviour and assume causal connection
single dissociation
loss or impairment of a brain function can be related to a single physical difference in the brain
eg lesion or result of a stroke
double dissociation
situation in which a single dissociation can be demonstrated in one person and the opposite type of single dissociation can be demonstrated for another
triple dissociation
situation in which a single dissociation of related brain processes can be demonstrated in 3 different individuals indicating independence of subprocesses
rare
brain lesions
insight into causal contribution of brain areas to cognitive function
- localisation
help us understand
- functional contribution of individual brain areas to the cognitive system
- functional connectivity of brain areas with one another
causes of brain lesion
categorised by cause
trauma (eg an accident)
stroke
surgical lesions (eg tumour removed)
stroke
result in sudden focal lesions combined with sudden loss of function
help us understand brain behaviour connections
types of stroke
ischemic
- blood clot blocks blood flow to an area of brain
- doesn’t get oxygen and cells die
hemorrhagic
- bleeding occurs inside or round brain tissue
hemispatial neglect
neuropsychological condition after a stroke to one hemisphere
affects motor an sensory cortex
deficit in attention and awareness to one side of field of vision
often contralateral to damaged hemisphere
affects attention, perception, memory and movement
symptoms of hemispatial neglect
inability to process and perceive stimuli on one side of the body or environment
not due to lack of sensation
eg bump into objects on neglected or only apply makeup to non-neglected
tumours
removal results in surgical lesions
compared to strokes, lesions grow slower
gives brain time to relocate functions due to plasticity
- still help understand brain behaviour connections but not as strong as stroke patients
lesioning technique
removing part of the brain surgically or using chemical injections to breakdown tissue
used to treat neurological dysfunctions in humans
similar to tumour removal
tests causal role of given brain areas in certain cognitive functions in animal studies
trauma
trauma to head can result in brain injury
different from stroke and tumour removal
injuries not usually focal but concern large brain areas
- hard to localise and quantify damage
primary impact = where brain was hit
secondary = internal damage from brain hitting skull due to primary
can also lead to secondary stroke due to internal bleeding (hemorrhagic)
Phineas Gage
first proof of localisation of function
brain damage from mental rod through head
seemed to recover
showed severe personality changes
due to areas of brain damaged
- most likely damaged left frontal cortex
neurodegeneration
progressive loss of structure or function of neurons
ultimately involves cell death
heterogenous group of disorders
characterised by progressive degeneration of central or peripheral nervous system
cannot be cured as we cannot regrow lost brain tissue
can only delay progression
alzheimers
caused by abnormal buildup of proteins in and around brain cells
results in loss of neurons and synapses
amyloid forms plaques around brain cells
tau forms tangles within brain cells
what parts of the brain does Alzheimers affect?
affects the cerebral cortex and certain subcortical structures
results in gross atrophy of temporal and parietal lobe
and parts of frontal cortex and cingulate gyrus
symptoms of Alzheimers
early = difficulty remembering recent events
forming new memories and storing them in LTM, often episodic
progresses = problems with language, disorientation, mood
advances = withdraw from family and society
bodily functions gradually lost until death
insight given by Alzheimers
insight into brain systems linked to:
memory - episodic
language - decay of mental lexicon
neural degeneration
forgetting
executive functions
Parkinson’s disease
death of dopaminergic neurons in the midbrain
results in dopamine deficiency impairing synaptic transmissions relying on dopamine
- produce less or no dopamine
cause of selective cell death unknown
symptoms of Parkinson’s
tremor, slow movement, difficulty walking
cognitive and behavioural problems
dementia in advanced stages
problems with sleep and sensory systems
insight given by Parkinson’s
insight into brain systems such as:
motor and sensory system interaction
action cognition
executive functions
- problems with abstract thinking
- slowed cognitive processing speed
atypical development disorders
heterogenous group of disorders
affect the development of the nervous system
lead to abnormal brain function which may affect aspects of cognition
eg autism
autism
affects information processing in the brain
and how nerve cells and their synapses connect and organise
affects social development
communication
face and emotion recognition
even if language abilities functional, often struggle with figurative language and inferences
insight of autism
causal relation of brain systems linked to:
social cognition
emotion perception
abstract and logical thinking
language
network connectivity and function
3 causes of brain lesions
stroke
tumour
trauma
3 neurodegenerative diseases
Alzheimer’s
dementia
Parkinson’s
3 atypical development disorders
autism
Down syndrome
dyslexia
