NP1 - What is Neuropsychology? Flashcards
What is Neuropsychology?
Neuropsychilogy studies the relationship between (physical) brain functions and behavior (in specific behaviour, emotions and cognition)
What is one unique characteristic about neuropsychology as a science?
- research can be carried over individuals (and not on a randomized sample)
- verify whether improvements are because of treatment with test-retest method
What is the difference between Neurology and Psychiatry?
Neurology studes organic deficits of the brain
Psychiatry observes common symptoms but without necessarily an organic deficit
What are the two orientations of neuropsychological research?
- Fundamental Neuropsychological Research
~ focuses on the understanding of underlying cognitive disorders/processes and related brain structures using experimental paradigms - Clinically oriented Neuropsychological Reseach
~ focuses on (improving) the assessment and treatment of brain disorders
When to consult a Neuropsychologist?
- you have brain damage and want to know what are the consequences on behavior, emotion or cognition
- you have a brain disorder and want help to deal with consequences in behavior, cognition and emotion
- (e.g.) your grandfather has memory loss (etc.) and you want to know if it is due to depression or dementia
What are some characteristics of the job of a neuropsychologist?
- very varied work (e.g. diagnostic, guidance and treatment)
- both in children and adults
- it is multidisciplinary (works together with a lot of other medical disciplines
Neuro-myths
- misconception about scientifically-based facts on brain research
- come from misunderstanding, misquoting or misreading of scientific facts
- originates from overgeneralizations of empirical research
- reinforced/propagated by media, movies, series, …
- e.g. we use only 10% of our brain-> False!
- e.g. individuals learn better when they receive information in their preferred learning style-> False!
how can brain functions be measured?
- through methods that measure the change in activity of areas
- some areas have high metabolism even when at rest (not active)
- subtraction method
- functional imaging
Subtraction Method
- Franciscus Cornelis Donders
- 1818-1889
- Mental Chronometry:
- Reaction time paradigm
> the use of reaction times to evaluate cognitive processes - Pure Insertions
> a single cognitive processs can be inserted into a task without affecting the duration of other processes)
- Reaction time paradigm
How can you measure brain areas through subtraction method?
- by Donders
- three tasks:
*simple detection task
*go/no-go reaction time task
*discrimination reaction task
> subtraction of time for simple detection t. from discrimination r.t.= time to discriminate stimuli
> subtraction of time for go/no-go r.t. from discrimintion r.t.= time to make a response - often used in neuroimaging research (subtraction of activation scores in different parts of brain)
What are some criticism with the subtraction method?
- difference score (between complex and simple condition) not very reliable
> if disproportionate difference between conditions-> reevaluate complex condition - “fallacies of pure insertion”
= potential other mental processes involved in tasks
> factorial design used to solve this problem
How can the subtraction method be applied to brainimaging research and neuropsychological tests?
- Brainimaging research: scan the brain while completing two different tasks and subtracting the areas of the brain that are working in both occasions to see the difference
- Neuropsychological tests: Stroop Task (colors and words of different colors)
What is some criticism for the Stroop task? + How to solve it
- it has limited ecological validity (gap between test and everyday behavior)
> add questionnaires and observations
> virtual/augmented reality can help standardize the environment
(hard to say colour of word without reading word)
What is the emotional Stroop test?
- well known test in depression research
- naming of emotionally loaded and neutral words or pictures
- comparing reaction time
Dissociation + types
- introduced by Teuber
- to identify the neural substrate of a particular brain function and/or its localization
- using case studies, neuroimaging and/or neuropsychological testing
- selective loss of function (cognitive functioning is intact except for a specific part)
- ps. not general deterioration!
1. single dissociation
2. double dissociation
Single Dissociation
Difference between tasks due to brain lesion which should be associated with the aspect of behavior studied
- task A: healthy and injured patients have same performance
- task B: healthy patient has good performance and injured patient has lower performance
= part of the brain that was lesioned might be linked to type of task B
Double Dissociation
- demonstrates that two independent cognitive processes rely on different brain regions or mechanisms
- a single neural network model can also show patterns of double dissociation (a pattern of double dissociation in two patients does not necessarily indicate independent modules)
What is the most important factor when inferring a double dissociation?
- statistical measures have to be applied
- the values have to be statistically significantly over or below the normal range
What are two things to consider when interpreting a dissociation?
- scores on one task should significantly fall above or below the average of the normative group
AND - the differences between the performances on task A and B differ significantly from each other
Imaging vs Image processing
Imaging= acquisition of data
Image processing= processing of the data
What can neuroimaging look for? + names of tehniques
- Structural Imaging
= visualization and analysis of anatomical properties of the brain
> CT, MRI, DTI, VBM, MRS - Functional Imaging
= identification of brain activity and brain functioning
> fMRI, PET, EEG, ERP, MEG
Spatial Resolution
+ best neuroimaging technique
- Sharpness of the image
- fMRI
Temporal Resolution
+ best neuroimaging technique
Speed of Recording
- EEG (/MEG)
What is CT?
- Computed Tomography
- Sagittal, Transverse or Coronal view
- uses multiple X-rays taken at different angles to produce cross-sectional images
- it has relatively high resolution
- able to identify abnormalities in the brain (e.g. haemorrhage, lesion or tumor)
How does CT work?
- series of photos taken, but position of x-rays and camera is constantly changing -> images are then combined using a mathematical algorithm
- possible to see every part of the head in details as a series of thin slices
- possible to create a three-dimensional image of the brain by superimposing cross-sectional scans
- great distinction between bones, ventricles and brain tissue
- often used to ascertain whether there is a haemorrhage or a space-occupying lesion
- also used in clinical practice
- only options for patients with claustrophobia, obesity and metal implants
What are some advantages and disadvantages of CT?
Advantages:
- less expensive than MRI
- very quick (~5 min)
- produces general image of an area such as internal organs, fractures or head trauma
Disadvantages:
- harmful for unborn babies
- very small dose of radiation
- (potential reaction to the use of dyes)
What is MRI?
- Magnetic Resonance Imaging
- uses powerful magnetic fields and radiofrequency to produce detailed images
- high resolution
- Clearer images of soft tissue: able to distinguish between grey and white brain areas
- shows white matter abnormalities
- able to identify abnormalities in the brain ( (e.g. haemorrhage, lesion or tumor)
How does MRI work?
- tissue reacts in magnetic field
- hydrogen atoms align their axis of rotation with the magnetic field line
What is white matter in the brain?
myelinated axons that connect brain areas that are anatomocally far apart
What is grey matter in the brain?
nuclei of neurons and other cells that make up the cortex and deeper basal ganglia, thalamus and hippocampus
What are some advantages and disadvantages of MRI?
Advantages:
- no radiation
- excellent for detecting very slight differences in soft tissue, ligaments and organs
Disadvantages
- very expensive
- takes longer than CT (~15 min to 2 hours)
- claustrophobia, very loud noises, increase in body temperature, …
- possible reactions to metals due to magnets (pacemakers, artificial joints, …)
CT vs MRI
(which one is best & when)
CT - rapid assessment in acute phase when patient is admitted to hospital
CT - used to detect cerebral haemorrage or contusion
MRI - preferred for scientific anatomical research into the development of the brain
How does neuropsychology dive into clinical matter?
- research into characteristics of patients with certain symptoms
*e.g. whether there is a difference in memory complaints in people with traumatic brain injury compared with those with a cerebral infarction - research into characteristics of neuropsychological tests
*e.g. whether the scores for a verbal memory tests are different to those for a non-verbal memory test
What are some issues that a clinical neuropsychologist can expect to deal with?
- differential diagnosis
*e.g. what disorders could underlie the complaints, symptoms and impairments - evaluation of treatments
- recommending a treatment term
- giving advice to people directly involved with the patient (…)
How is the diagnostic assessment carried out?
What is the first step?
- according to the empirical cycle
1. collection of data
*thorough analysis of the complaints
*observing and analysing the patient’s behavior
*structured questionnaires
*psychometric tests (e.g. relating to memory, attention and perception)
2. …
What are some limitations of psychological tests?
- the value of conclusions largely depends on the quality of tests and questionnaires used
*psychometric properties are not always accurately studied
*normative data is often limited - the way in which test results are interpreted can be ambiguous
*e.g. a loss in cognitive function on an attention task may be the result of damage to different locations of the brain
*this validity problem can be tackled with experimental research paradigms - test batteries can contain only limited number of tests
*matter of balancing which combination of tests for which construct - missing values (sometimes patients don’t complete everything)
how do neuropsychologists study the nature of disorders?
(Fundamental Research)
- through experimental paradigms
(a model of research that is copied by many researchers who all tend to use the same variables, start from the same assumptions, and use similar procedures) - e.g. study of spatial orientation by Posner (replying as quickly as possible to a stimulus)
What are the “experiments of nature”? What did they lead to?
- very specific losses of a function following brain injury
- led to the methodology of single and double dissociation
What did Camillo Golgi discover?
the existance of individual neurons
What did Ramón y Cajal discover?
brain cells form independent units that communicate with eachother
What did Broadmann discover?
identified 52 areas of the brain and described strucutre of the cortex
How can you measure the volume of the brain?
- structural image of brain
- voxels: three-dimensional pixels with a resolution of 1 mm
- count the voxels and multiply them by their size in order to determine the volume
- computer software is able to divide white and grey matter when counting the voxels
how can the density of brain matter be measured?
- structural image of brain
- VBM (voxel-based morphometry)
- voxels standardized within average brain size so that density is comparable between individuals with different brain sizes
- abnormal thickness can indicate a problematic development or degenerative process
Cortical Thickness
- structural image of brain
- cortical thickness studies look at thickness locally
- provide information about number of cells in each column of the cortical surface
DTI
- structural image of brain
- diffusion tensor imaging
- utilises properties of water molecules
- information gained through the measurement of water to trace the measurements of axons in the white matter
- VBA (voxel-based analysis) can also be performed using DTI
MRS
- magnetic resonance spectroscopy
- information about concentration of certain molecules in the brain
- both functional and structural
- obtain info about local and specific part of brain
functional imaging
- to depict the function of brain areas
- different in spatial and temporal resolution
- high temporal resolution: necessary for rapid brain processes
- high spatial resolution: necessary for redefined localization of function
- communication between neurons in same area and communication between different areas in the brain
- EEG most commonly used for functional imaging
SPECT and PET
- SPECT: single-photon emission computed tomography
- PET: positron emission tomography
- they locate the radioactive particles and display them as an image
- depict functional processes in the brain
- circulation and energy consumption can also be visualised and provide information about the severity of the damage
PET
- functional imaging
- water is made radioactive and added to bloodstream
- extent to which water was absorbed by brain tissue is dependent on local oxygen consumption
- camera detected radioactive water: if concentrated in area-> area must be active
- good spatial resolution
MEG and EROS
MEG: magneto-encephalography (functional)
> uses magnetic fields that are produced during neural activity
EROS: event-related optical signal (functional)
> infrared light carried by optical fibres to measure brain activity
- ultrasound
> sound waves that can be used in prenatal brain research
MEG
- magnetoencephalography
- measures magnetic fields generated by neurons
- measures brain waves that are difficult to see using EEG (waves between neurons within an area)
- very expensive
- produces same type of information as EEG, but more complex calculations
- less accurate than EEG for deeper parts of the brain
EEG
- (functional imaging)
- Electro-encephalography
- electrodes are attached to the head and gel is used to make a connection to the skin
- best temporal resolution
- not good sensitivity
- high safety and low cost
What type of information can be acquired through EEG?
- information from the signal that the closest electrode picks up -> strength of fluctuation of signal is related to brain activity (signals averaged over many repetitions of stimulus)
- amplitude of different waves are calculated (e.g. proves extent of concentration)
- information from areas deep in the brain
ERP
- event-related potential or evoked-response potential
- average signal measured through EEG
- can provide information about the time lapse and strenght of neural connection
fMRI
- Functional magnetic resonance imaging
- uses MRI scanner
- temporal resolution limited (haemodynamic response is slower than neural response itself)
- not easy to distinguish between two neural responses to two identical stimuli that follow each other within less than 2-3 seconds
- great spatial resolution
- high safety and high cost
how does the fMRI work?
- series of scans of the brain taken
- scans are sensitive to blood properties
- brain areas that are active need more oxygen-> bigger blood supply
- register moments of activity of the magnetic protons in the body
- measures ration between oxygen-rich and oxygen-poor hemoglobin= BOLD
What is BOLD?
- blood oxygenation level dependent response
- ratio between oxygen-rich and oxygen-poor hemoglobin
The resting state method
- method used to look for correlations between signals from areas
- produces an image of functional networks
1. during relaxation the signal slowly increases and decreases (low-frequency flactuation); this pattern is the same for all areas
2. thoughts activate networks (e.g. sight of movement activates motor network)
:: strength of correlation= strength of connection
Mind Reading
- uses patterns of brain activation to work out what a person is seeing
- different stimuli are introduced (e.g. picture of a house)
- recognizing patterns allows researchers to know what the participant is seeing
