Chapter 3 Methods Flashcards
What is cognitive psychology?
The study of mental activity as an information-processing problem. The goal is to identify internal processing that underlies behavior.
What are the two concepts of cognitive psychology?
1) Information processing depends on mental representations
2) Mental representations undergo internal transformations (encoding, comparing, deciding, responding)
What is the word superiority effect?
People are most accurate in identifying a target when stimulus is a word, because we activate multiple representations
What is the stroop task and what does it show?
The task activates multiple representations simultaneously and shows that this ability isn’t always handy.
Stroop task = e.g. showing the word ‘red’ in the color blue
What are 6 causes of neurological dysfunction?
1) Vascular disorders
2) Tumors
3) Degenerative disorders
4) Infectious disorders
5) TBI (traumatic brain injury)
6) Epilepsy
What is: ischemia - aneurysm - artherosclerosis?
Ischemia = drop in blood pressure resulting from shock/blood loss
Aneurysm = sudden rise in blood pressure resulting in rupture in a blood vessel
Artherosclerosis = blockage of artery by fatty tissue (embolus)
What is the difference between malignant and benign tumors?
Malignant = tumor spreads, likely to recur after removal
Benign = tumor remains in place and unlikely to recur after removal
What are denegerative disorders? Name three examples
Disorder characterized by progressed loss of functions.
Cause is balance between genetic abberations and environment
Examples:
- Huntington: strong genetic connection
- Parkinson: less genetic
- Alzheimer: less genetic, atrophy cerebral cortex
Name two examples of infectious disorders and what these cause
- HIV: destroys axons, resulting in dementia
- MS (perhaps): infection of CNS, occurs most often in temperate climates
What can happen during a traumatic brain injury at anatomical level?
Brain shakes within the skull, what can result in
- Edema: swelling –> more pressure –> less blood flow –> ischemia + secondary lesions
- DAI: diffuse axonial injury = twisting of white matter, with disruption of cytoskeleton and axonal transport
What is epilepsy and how can it be treated?
Excessive/abnormal patterned brain activity
Treatment: removal of brain area that initiates epilepsy / callosotomy (not that common anymore)
What is the difference between single and double dissociation?
Single = Lesion to brain area impairs ability of doing A, but not B
–> A and B use different brain areas
Double = Lesion to X impairs A, but not B. Lesion to Y impairs B, but not A.
–> A and B are complementary (e.g. Wernicke and Broca area)
What is the difference between an agonist and antagonist? What is the downside of using these?
Agonist = drug that works like neurotransmitter
Antagonist = drug that blocks neurotransmission
Interference means changing signaling. The effect is very unspecific and affects the entire brain
How do genetic manipulations contribute to the study of the brain?
- Selective animal breeding
- Knockout procedure, where a gene is being manipulated so it doesn’t express itself
What is the difference between invasive and non-invasive stimulation methods?
Invasive: surgical intervention
What is deep brain stimulation (DBS) and for what can you use it?
Implanting electrodes in brain regions for a long period to modulate neuronal activity
Use it for treatment of Parkinson (implant in basal ganglia) or coma, OCD or PTSD
What is optogenetics?
Controlling neuronal activity with viral transduction. The genetic material responsible for a certain trait is inserted in a virus and then injected in the target brain area. It will infect targeted neurons, which makes them e.g. more reactive to light
What is TMS and how do you apply it? What is the difference between single pulse TMS and repetitive TMS?
Transcranial Magnetic Stimulation
1 Strong coil produces magnetic field
2 Magnetic field induces changing electrical field in underlying brain area
3 Causes neuronal (motor) activity. Strong pulse causes temporary lesions, weak pulse causes activation
Single pulse: one pulse per trial
Repetitive: temporarily changes area
What is tDCS and tACS?
tDCS: transcranial direct current stimulation
- Two electrodes on scalp that can selectively excite or inhibit neural areas
- Short term treatment for pain patients
tACS: transcranial alternating current stimulation
- oscillatory movement in current electrode. Different frequencies affect different cognitive functions
What is the downside of tDCS, tACS and TMS?
Poor spatial resolution, no strong inferences possible
What is CT and how does it work?
Computerized tomography uses X-rays to create 2D pictures of the body/brain. It’s a tool for structural analysis, but now it’s only used in medical imaging
What is MRI and how does it work?
Magnetic Resonance Imaging: structural imaging
1 MRI creactes magnetic field
2 Radio fields pass through magnetized regions, protons absorb this energy
3 Radio field is turned off and protons release energy and align toward orientation of magnetic field
4 Detectors get the energy signals and construct image
What is DTI and how does it work?
Diffusion tensor imaging gives you an image of structural connectivity in the brain
MRI scanner measures density + flow of water in axons. With two pulses to the magnetic field, the MRI is sensitive to diffusion of water.
What are the 5 main categories of methods?
1) Stimulation methods (TMS/DBS)
2) Structural imaging methods (MRI/CT)
3) Functional imaging methods (fMRI/PET)
4) Measuring neural activity (EEG/MEG)
5) Neural disruptions and genetic manipulations (TBI, breeding)
What are the three ways of measuring neural activity?
1) Single-cell neurophysiology
2) Invasive neurophysiology
3) Non-invasive electrical recording of neural activity (EEG/MEG)
What uncertainty brings single-cell neurophysiology?
You always measure a set of neurons and not an individual neuron. There is always uncertainty about what you are actually measuring
What is electrocorticography (ECoG) and how does it work?
A grid of electrodes is placed directly on brain surface. Activity of populations of neurons is measured for long time to detect seizures (in epileptic patients).
It has good spatial and temporal resolution with no distortion
What are ERP’s and how does EEG (electroencephalography) measure those? Why is this useful?
ERP = event related potential = response from the brain triggered by stimulus/movement
- Useful for questions about time course of cognition
EEG records with a cap of electrodes, that measures changes in electrical potentials (ERP or oscillations). EEG can measure abnormalities in brain function
Name 3 disadvantages of EEG
1) No detection of deeper brain structures
2) Low spatial resolution
3) Inverse problem: pattern can be caused by infinite number of different brain regions
What is the difference between spatial and temporal resolution?
Spatial = accuracy of telling what area is active exactly
Temporal = accuracy of telling when the area was active exactly
What is MEG and what is the difference with EEG?
MEG = Magnetoencephalography
Measures magnetic field produced by the brain (ERF=event-related fields)
It has the same temporal resolution as EEG, but it has better spatial resolution. The skull doesn’t blur the magnetic signals. Disadvantage is the cost of such a study.
What are voxels?
Small cubes that the MRI scanner makes of the brain to see where changes in metabolic activity takes place
What is the hemodynamic response and why is it important for functional analysis?
More blood flows to a brain area that is active. An fMRI or PET can detect these differences in bloodflow
What is PET, how does it work and why is it not often used anymore?
1) Radioactive tracer in blood
2) Tracer distributes in brain according to physiological needs
3) Radioactivity measured with detectors
Not used that often, because of time-consuming process, costs and fear in participants. Only blocked designs possible (many conditions presented in one block)
How does fMRI work and why is this the preferred functional imaging method?
1) Blood with oxygen is different than blood with no oxygen
2) Active brain areas use more oxygen
3) BOLD (blood oxygenation level dependent) signals are detected by fMRI
Less expensive than PET, easy to maintain, better spatial resolution, complete statistical analysis possible
What is the difference between block designs and event-related designs?
Block design: blocks of tasks with rest in between. It can detect small effects
Event-related design: each task is presented for a short time, which allows more randomness. A larger range of experimental setups is possible
What is Multivoxel pattern analysis (MVPA)?
Researcher identifies patterns across voxels that can provide information about functional roles and networks of a brain area
What are connectivity maps and how are they made?
Visualizations of structural and functional connections in the brain
1) define network nodes / structure
2) measure correlation (DTI/fMRI)
3) generate association matrix
4) visualize correlations in map
What findings have been made with Rs-fMRI?
Data collection when subjects are at rest. It revealed how networks reconfigure when people learn a new skill.
Changes in connectivity between frontal lobe and ACC (anterior cingulate cortex) predict learning speed
What is the difference between convergence and divergence in neurons?
Convergence = neuron receives input from multiple other neurons
Divergence = one neuron projects to multiple other neurons
What are converging methods? Explain convergence, complementarity and meta-analysis
Methods that combine different approaches to get to the same result
Convergence = study concept with different methods. If all give same result, it’s strong evidence
Complementarity = Different methods provide different sorts of information and therefore complement each other
Meta-analysis = combining information from multiple studies
