Methods Flashcards
Scientific Method
Observation –> hypothesis –> predictions –> experiements
Behavioral Approach
Measures of observable behavior and assumes that internal transformations or mental operations occur
i.e. Reaction times, task accuracy, task limittions, rating scales, time spent look at a stimulus, etc
Cognitive Psychology
the study of mental acitivity as an information-processing problem
Neuropsychological Approach
if a region of the brain is essential for some aspect of cognition, then damage to that region should affect performance on that aspect of cognition
The Damaged Brain
vascular disorders, tumors, degenerative disorders, traumatic brain injury, epilepsy
Vascular Disorders
angiography: a clinical imaging method used to evaluate the circulatory system
Cerebral Vascular Accidents: “stroke” occurs when blood flow to the brain is suddenly disrupted
Tumors
a mass of tissue that grow abnormally and has no physiological function
i.e. brain lesions (can be a result of a tumor)
H.M.
Degenerative Diseases
associated with both genetic aberrations and enviornmental agents
i.e. huntingtons disease, parkingson’s and alzheimers
Traumatic Brain Injury
can result from either closed or open head injury
Epilepsy
A condition characterized by excessive and abnormally patterned activity in the brain
H.M : had intractable epilapsy, had almost entire medial temporal lobe surgically removed
H.M
had intractable epilepsy and had almost his entire medial temporal lobe removed surgically
resulted in anterograde amnesia (unable to form new memories) suggesting MTL critical for long term memory
He could still acquire new skills even though he couldn’t remember
Difficulties working with Lesions
- often large
- dont stay within functionally-relevant boundaries
- there can be cortical plasticity/reorganization
- researchers are limited to a single “case study” because there may not be multiple individuals with similar lesions
Dissociation
neuropsychology
can it answer: is this brain area necessary for this process?
Single dissociation
A study in which two groups are each tested on two tasks, a between-group difference is apparent in only one task. The two groups are needed so that the participants performance can be compared with that of a control. Two tasks are necessary to examine whether a deficit is specific to a particular task or reflects a more general impairment.
Example of single dissociation
Testin H.M on famous faces vs skill learning (drawing star from reflection)
Disadvantages of single dissociation
limited in what it can truly tell us in terms of brain localization
Double Dissociation
stronger representation that identifies whether two cognitive functions are independent of each other, something at a single association cannot do.
Group 1 is impaired on task A not B, group 2 is impaired on B not A. Performances are compared with a control group that had not impairments
Example of double dissociation
parkinson’s patients - opposite results from H.M. and therfore form double dissociation
broca’s vs wernicke’s
Methods to perturb neural function
Pharmacological Studies
Transcranial Magnetic Stimulation (TMS)
Pharmacological Studies
may involve the administration of agonist drugs, those that have similar structure to a neurotransmitter and mimic its action, or antagonist drugs, those that bind to receptors and block or dempen neurotransmission.
Example of pharmacological study
administration of dopamine to study its effect on decision-making when a monetary reward was available
Drawbacks to pharmacological studies
lack of specificity due to injection into the bloodstream
TMS
Transcranial Magnetic Stimulation
A method to non-invasively producing focal stimulation of the human brain. Interupts firing
Advantages and disadvantages of TMS
Advantages: direct disruption of neural tissue and another good way to discern whether or not a brain region is necessary
Disadvantages: poor spatial resolution, small sample size and no way to interpret a null result
CAT
computed tomography
Important for structural imaging of neurological damage in patients
MRI
Magnetic Resonance Imaging
Provides high resolution images of soft tissue by exploiting the magnetic properties of atoms that make up organic tissue.
Radio waves cause atoms (mostly hydrogen) in the body to move out of their natural random positions and into line with the magnetic fields –> after the field pulse stops, atoms move back into normal positions and emit radio waves as they do so
DTI
diffusion tensor imaging
performed with an MRI scanner. Offers information about anatomical connectivity between regions
Methods for studying neural function
Event-related Potential (ERP)
Electroencephalography (EEG)
Positron Emission Tomograhy (PET)
Functional Magnetic Resonance Imaging (fMRI)
EEG
non-invasive electrodes that are placed on the scalp and measure electrical potentials produced by neurons
ERP
Tends to relect the brain’s global electrical activity
Measures EEG response –> amplified –> averaged (give average waveform over time)
Waveforms are traditionally plotted with positive peaks downward and negative peaks upward
Time-frequency Analysis in ERP
refers to the fact that amplitude of a wave in different frequency regions varies over the course of processing
components involved in ERP
Lantecy, direction, amplitude, topographical distribution, and polarity (N or P followed by a # depiciting latency in ms)
Latency
how long after the stimulus is presented
Direction
is the wave peak positive or negative?
amplitude
the strength of the voltage change
topographical distribution
fronal, parietal, occipital, temporal
advantages vs disadvantages of ERP
Advantages: excellent temporal resolution; direct measure of neural activity; event-related neural response
Disadvantages: poor spatial resolution
Positron Emission Tomography
(PET)
a small dose of a chemical (radionuclide) used to label glucose is injected into a patient –> the radionuclide emits positrons –> machine will rotate around a patients head to detect the positron emissions given off by the radionuclide
Used to examine brain function: brain regions will uptake more of the labeled glucose when active during a cognitive task; must be done in the block design
fMRI
Using radio waves the fMRI measures increases in blood flow in active parts of the brain. The detectors measure the ratio of ozygenated to deoxygenated hemoglobin (blood oxygen level-dependent/BOLD)
Uses subtractive logic – treats one activity as a baselind and subtracts it from the other, to get rid of all the activity the two conditions have in common
Block Design
fMRI
Must perform tasks in blocks of at least 30 sec, average across the trials in every block
Block Design disadvantages
Disadvantage: cannot sort by performance (i.e. words that are later remembered vs words that are later forgotton)
Pure insertion assumption
Pure Insertion Assumption
If a control task requires stage 1 and 2 of processing and experimental task requires stage 1, 2, and 3, we assume that the 3rd stage doesn’t alter the other stages
Event Related Design
measures blood flow response associated with individual trials rather than for a block of trials
Dm Effect: difference in response based on memory (what regions are more active during encoding of items later remembered than during encoding of items later forgotten)
Subsequent memory = remembered - forgotten
Advantages and Disadvantages of fMRI
Advantages: Measure magnetic properties of blood; temporal resolution = 2-3 secs; spatial resolution = 2-3mm; trials can be blocked/randomized
Disadvantages: poor temporal (time) resolution (seconds); results dependent on task and baseline (subtractive logic + pure-insertion problem); indirect measure of neural activity
Diffusion Tensor Imaging
a structural scar acquired with an MRI
Gives information about white matter tracts that for the connectivity between regions
Simulation
An imitation, a reproduction of behavior in an alternative medium (i.e. computers)
Dependent Variable
what you are measuring
Independent Variable
The variable that you are altering, with the expectation that it will have some effect on the dependent variable
Lesions Studies vs Neuroimaging
