Chapter 3 (Methods) Flashcards
What is cognitive psychology?
Study of mental activity as an information processing problem
Perceptions, thoughts and actions depend on internal transformations
Correlation vs Causation
Correlation - relationship between 2 variables
Causation - change in one variable causes a change in the other
What is chronometrics?
Reaction time is proportional to mental processing
Alzheimer’s disease
Amyloid plaques, analyzed post mortem
What is the Stroop effect?
Stroop effect - delay in reaction time due to multiple stimuli
Stroop test - say the color of the font each word is printed in
Worse at task when word and color are mismatched (interference)
- Physical color of text (task-relevant)
- Color concept/meaning (irrelevant to task)
Posner vowels/consonants experiment
Task - raise left hand for same (2 vowel, 2 consonant) raise right hand for different
Steps (encode, compare, decide, respond)
Basic uses of eye-tracking
Use eye movements/ gaze patterns to tap into mental processes.
Where are they looking, do they return to previous locations, how frequently do they make saccades (where we move our eyes)
Purpose of computer modeling
Use computers as a metaphor for the brain in order to study human cognition
Limitations of computer modeling
Simplification of nervous system
Not biological
Small in scale, narrow problems
Intracellular Recording
Tip of microelectrode is inserted inside cell, so membrane potential can be measured. Invasive. Thin electrode inserted into cortex.
- Graded membrane potentials
- Very difficult
Extracellular Recording
Allows investigator to record discharges of single neuron without impalement.
- action potentials (“spikes”)
- more common
Relevance of a neuron’s baseline activity
Neurons are constantly active
Need to use baseline activity as a control for stimulation
What is a receptive field
Location in space for which neuron is responsive
Limitations of single cell recording
Invasive, poor spatial coverage, a single neuron is not representative of the whole brain/region, not humans, not causal (unless lesion)
What are animal lesions used for?
Used to see how neural structure contributes to task - if a part of brain removed, is the performance on task impaired?
What techniques can be used for animal lesions?
Aspirate tissue: destroy brain structure via suction
Electrolytic lesion: similar, using electrical charge
Neurochemical Lesion: designed to damage specific cells types only.
Reversible lesion: Cooling, pharmacological
What is a single dissociation?
Damage to one particular area of the brain (area X) impairs the ability to do task A, but not task B (you are dissociating task B from area X)
What is a double dissociation?
Damage to area X impairs the ability to do task A but not task B. Damage to area Y impairs ability to do task B but not task A.
Can damage to a brain region tell you if it’s necessary and/or sufficient for a cognitive function?
No b/c of the HM model 1 was damaged but no impact on memory unless both were affected.
What are genetic manipulations in animals?
Goal: find genetic basis for brain disorders.
Approach: produce genetic alterations in animals
What does it mean to “knockout” rodents?
“knockout” mice where you replace gene and see how it affects their behavior - measure freezing behavior.
What is TMS?
“Virtual Lesions”
- same logic as neuropsychology
What is PET?
Measures local variations in cerebral blood flow (mostly replaced by fMRI)
Difference between fMRI and MRI
MRI studies brain anatomy while fMRI studies brain function
How does MRI work?
Applies a powerful magnetic field which makes protons parallel to field.
Then a radio frequency (RF) perturbs them and then they rebound to the MRI magnetic field.
What does MRI measure?
How long it takes protons to rebound (by detecting energy released)
How does fMRI work?
Focuses on oxygenated vs deoxygenated blood. More active brain area leads to more oxygen flowing through blood.
What does BOLD mean.
Blood Oxygenation Level Dependent signal indirect measure of neural activity. The greater the neural activity, the higher the blood flow, the greater the fMRI signal
What does fMRI measure?
Measures the time course of this process of oxygen absorption by looking at changes in BOLD overtime
fMRI advantages
High spatial resolution
Simultaneous coverage of whole brain
Non-invasive
fMRI limitations
Poor temporal resolution
Need lots of data
Purely correlational
What is a voxel?
a three-dimensional square or rectangular chunk of brain tissue called a volume element
What is an EEG?
electrodes on scalp record electrical signals
What is ERP?
A type of EEG analysis
Activity related to sensory, motor, cognitive events
EEG/ERP advantages
Great temporal resolution, inexpensive, accessible, non-invasive
EEG/ERP limitations
Poor spatial resolution, challenges in localizing source (inverse problem)
EEG vs MEG
MEG (magnetic) is a slightly different version of EEG (electrical) that solves the inverse problem and has better spatial localization
Limitations of MEG
more expensive, less accessible
What is ECoG?
Intracranial EEG (electrodes placed directly in/on brain)
ECoG advantages
Excelled temporal and spatial resolution, recording directly from brain in humans
ECoG limitations
Extremely invasive, no experimental control
What are the uses for TMS?
Functional localization/specialization, Timing and Combining with neuroimaging
What do DTI/DWI measure?
Use MRI to measure diffusion of water through axons
