ch. 1: clinical neuropsychology and assessment Flashcards
What is neuropsychology?
links behavior and mental processes to the brain
Neuropsychologist
study brain-behavior relationships (top-down)
Psychologist
Studies behavior.
Neurologist
MD diagnosing and treating nervous system disorders.
Neuropsychiatrist
MD focusing on organic aspects of mental disorders.
Neurosurgeon
MD specializing in nervous system surgery.
Neuroscientist
Researchers studying molecular composition and functioning of the nervous system (bottom-up).
What are key developments in modern neuropsychology that have occurred since the 70s?
- shift from laboratory to clinical settings
- formation of INS and NAN
- division 40 of the APA
- growth in scientific journals and memberships
What are unique aspects of neuropsychology?
- Science-based, data-driven, and objective.
- Emphasis on statistical measures (validity, reliability, standardization).
clinical neuropsychologist training
- doctoral level in clinical psychology with brain-behavior education
- 1 year internship
- 1-2 years postdoctoral fellowship
neuropsychologist responsibilities
- assessment/diagnosis
- treatment recommendations
- rehabilitation
- research
- teaching
what are assumptions about neuropsychological assessment?
- Behavior/cognition involves brain processes.
- Processes correspond to specific brain areas.
- Brain injury causes deficits, not new behaviors.
What are the theories on brain function?
- modularity/localization
- equipotentiality
- distributed processing
Modularity/Localizationist
brain has specialized modules
Equipotentiality
brain regions can substitute for each other
distributed processing
functions are networked across regions
association
two tasks affected similarly, suggesting a shared underlying ability or factor
dissociation
performance differs significantly between tasks, implying-task-specific sensitivities or difficulty
double dissociation
different tasks are independently affected in separate patient groups, proving they measure different functions
association and correlation
Association and dissociation suggest correlation but double dissociation concludes that there is no correlation
What are lesion methods?
studies how brain damage affects behavior and cognition
lesion approach: single case studies
- most helpful when dealing with very rare disorders; also allow us to identity exceptions for rules used for group studies
- allow us to refine the limits of theories
lesion approach: group case studies
- allows us to see the general/normal behavior for human beings
- We cannot take the averages and apply them to a single individual
Limitations of the lesion method
- no two lesions are identical
- lesions don’t respect structural boundaries
- heterogeneity of response to lesions
- deficits may reflect loss of function in damaged area, the adaptive response of areas adjacent to the damaged area, and disconnections of distant areas at the point of damage
What are the reversible lesions?
- WADA
- TMS/rTMS
WADA
involves injecting a barbiturate into the right or left internal carotid artery; temporarily anesthetizes one hemispheres (half of the brain is “asleep”)
What are the strengths and weaknesses of WADA?
- Strengths: Allows you to test the abilities of one hemisphere alone; used for patients that are considered for surgery for epilepsy
- weaknesses: highly invasive
TMS/rTMS
Magnetic pulses affect motor/cognitive functions
What are the strengths and weaknesses of TMS/rTMS?
- strengths: relatively noninvasive; no longer-term issues
- weaknesses: long-term effects are unclear
reversible vs. irreversible
- reversible: does not cause any long-term effects to the brain (WADA; rTMS/TMS)
- irreversible: cannot undo damage (lesion)
What are the electrophysiological methods?
- EEGs
- event-related potentials (ERPS)
electroencephalogram (EEG)
- uses electrodes placed on the scalp and reads the electrical activity generated by neurons
- Ongoing electrical activity in large groups of neurons firing synchrony
event-related potentials (ERPs)
A way of measuring potential changes in the brain from millisecond to millisecond
What are the advantages of electrophysiological methods?
- non-invasive, does not require behavioral responses
- passive viewing of stimuli, continuous EEG of normal interactions
- time blocking neural changes to external stimuli
What are the functional methods?
- positron emission tomography (PET scans)
- functional magnetic resonance imaging (fMRI)
positron emission tomography (PET scans)
- tracks radioactive glucose metabolism
- measures function but uses radiation
- Inject radioactive glucose into body and the person will do a task; the radioactive material will decay and sends out ions in polar opposite directions
- Active brain areas metabolize more glucose
What are the advantages and disadvantages of PET scans?
- advantages: measure function, can be used for any task
- disadvantages: radioactive (limit exposure), poor resolution, one task, expensive
fMRI
- uses radiofrequency pulses and a strong magnetic field to detect changes in blood flow
- Brain cells use more oxygen when they’re active, so areas that are more active appear brighter on an fMRI scan
What are the structural methods?
- magnetic resonance imaging (MRI)
- diffusion tensor imaging (DTI)
- CT scans
magnetic resonance imaging (MRI)
- magnetic fields create high-resolution images
- All hydrogen atoms in our brian spin in a random way; putting them in a magnetic field will cause them to align with the field → introducing a radio frequency pulse will “knock” out atoms of alignment
Atoms spin back to place → the spin back generates a measurable magnetic field; able to construct high/low density areas
what are the advantages/disadvantages of MRI?
- advantages: good spatial resolution, can see different tissues, no radiation = safe
- disadvantages: can’t have metal, can’t see calcium well, takes longer than CT
diffusion tensor imaging (DTI)
- Traces axon projections through fluid diffusion patterns.
- Looks at how water diffuses throughout the brain (how it crosses membranes and travels)
case of H.M.
Insights into memory function through hippocampal damage.
vegetative state
fMRI detects cognitive activity in patients misdiagnosed as vegetative.
