Cognitive Methods & Techniques Flashcards
The 7 Ideal Properties of the Perfect Neuroscience Technique
High spatial resolution, high temporal resolution, large spacial coverage, taps into cognitive processes, is non-invasive, provides information about the brain, and can be used on the healthy human population.
The 3 Cognitive Methods
Eye-tracking, Computer-Modeling, and Behavioral Responses (psychophysics)
The 4 Intervention Methods
Stimulation/feedback, Surgical lesions (only in animals), Genetic Manipulations (only in animals), and Transcranial Magnetic Stimulation (TMS)
•Goal: Establish causal role
–Correlation techniques (e.g. imaging) = “This
region is associated with this task”
–Causation techniques = “If we alter this region,
does that alter performance on the task?”
What 3 things can we measure with Behavioral Techniques?
Reaction Time, Accuracy, Pattern of Errors
How can we use RT to study mental processing?
Mental chronometry is the use of response time in perceptual-motor tasks to infer the content, duration, and temporal sequencing of cognitive operations. Mental chronometry is one of the core paradigms of experimental and cognitive psychology, and has found application in various disciplines including cognitive psychophysiology, cognitive neuroscience, and behavioral neuroscience to elucidate mechanisms underlying cognitive processing.
Mental chronometry is studied using the measurements of reaction time (RT). Reaction time is the elapsed time between the presentation of a sensory stimulus and the subsequent behavioral response.
In psychometric psychology, RT it is considered to be an index of speed of processing. That is, it indicates how fast the thinker can execute the mental operations needed by the task at hand. Speed of processing is considered an index of processing efficiency. The behavioral response is typically a button press but can also be an eye movement, a vocal response, or some other observable behavior.
Behavioral Techniques: Chronometrics
?… The capitalized and lower-case consonants and vowels game. RT & Mental Processing.
Tasks are composed of set of mental operations; each step takes time.
Physical identity~Phonetic identity~Category
Steps: Encode, Compare, Decide, Respond.
Behavioral Techniques: Stroop Task
?…. the words BLUE flashed in green writing causes a delayed response when subjects are told to say the color. This is because seeing the word blue prompts us to say blue, not green.
Stimuli activate 2 representations:
–Physical color of text (task relevant)
–Color concept / meaning (irrelevant to task)
We are worse at task when word and color are mismatched= Interference
Conceptual representation is automatically activated.
Behavioral Techniques: Uses of Eye-Tracking
Where are they looking?
–How frequently do they make saccades?
–Do they return to previously fixated locations?
–Fixation monitoring (if you don’t want them to
wander)
–Gaze-dependent stimulus presentation
What 4 things can Behavioral Techniques tell us?
~How much Time does it take to perform different
tasks?
~Is there Interference?
~What is Memory Capacity under different Conditions?
~How Many different things can people pay Attention to?
Saccade
A saccade is a fast movement of an eye, head or other part of the body or of a device. A rapid movement of the eye between fixation points.
Goals of Computer Modeling
- Can we program a computer to do this cognitive task?
- Can we program it to do it in a biologically plausible way?
- Can we get it to mimic how the brain actually does it?
- Can we use it to make testable prediction?
Simulation of Computer Modeling
Idea: Computer as metaphor for brain (or mind)
–Computers represent and transform info
–Good model for studying human cognition
Simulation (imitation of behavior):
– Artificial intelligence: mimic behavior & cognitive processes supporting behavior
– Give computer input; must perform internal operations to create a behavior. How well does behavior of model match real behavior?
–Create different models for different theories of cognition. Which perform best?
Pros/Cons of Computer Modeling
• Pros:
– Can simulate complex behaviors
(using neuronlike units too).
–Can vary in level of explanation (Systems level, Molecular level, etc.)
–Can ‘lesion’ network and even retrain it! (testable predictions).
•Cons:
–Oversimplification of nervous system
–Not really biological
–Small in scale, narrow
Neuropsychology
Think Brain-damage Patients, Neurological damage, Cognitive deficits, Broca and Wernicke, “Nature’s experiments,” etc.
•Link cognitive processes to neural structures.
•Logic: “If a behavior depends on processing
within a certain brain structure, then damage
to this structure should disrupt the behavior.”
Neuropsychology: 5 Types of Acquired Brain
•Vascular disorder strokes (or
cerebro-vascular accident; CVA), aneurysm.
–Blood flow disrupted, brain cells die
•Tumors
– Abnormal cells destroy or displace healthy cells.
•Degenerative & Infectious disorders – Alzheimer’s,
Parkinson’s, Huntington’s, MS, AIDS dementia,
Korsakoff’s
- Traumatic head injuries – most common in under 40 year-old males
- Neurosurgery – severe epilepsy (HM, split-brain)
Caveat
a warning or proviso of specific stipulations, conditions, or limitations.
synonyms: warning, caution, admonition.
Caveats & Considerations, Pros & Cons of Neuropsychology:
–Necessary vs Sufficient
–Plasticity / Reorganization
–Diffuse vs Focal Lesions
–Need proper controls (Control tasks, Control populations, etc.)
–Pro: Powerful test of whether a brain region is
critically involved and necessary for behavior
–Pro: Testable predictions for other techniques
–Con: No control over location, size, extent
–Con: Small sample sizes
–Con: Individual differences (pre-existing conditions and the nature of brain damage)
Control Tasks & Populations:
Single vs. Double Dissociations
?….. double is better, tripole dissociation is best
refers to a logical progression of scientific assumptions in localizing functional areas in the brain. For example, if symptom A appears with lesions in brain str ucture X, but not with those in Y, and symptom B appears with lesions of Y, but not of X, then those specific areas of the brain each have a specific function.
In brain damage, when function A is present and function B is absent in one person, and function A is absent and function B is present in another. Presence of a double dissociation means that the two functions involve different mechanisms and operate independently of one another.
Moreover, Double dissociation is the finding that some individuals usually brain damaged perform normally on task A and poorly on task B, whereas others show the opposite pattern.
Neurophysiology
Think Animal Research.
Research with animals: –Why? More invasive, more control = be_er experiments –Considerations: •Good model for humans? •Ethical concerns –Recording vs Lesioning
Neurophysiology: Single-cell Recording
Singlecell recording:
•Invasive (direct recording from brain)
•Thin electrode inserted into cortex
•Measure electrical activity from nearby neurons
–Extracellular (more common): action potentials (“spikes”)
–Intracellular (very difficult): graded membrane potentials
•Single-cell recording: “firing rate”
•Baseline activity: Neurons are constantly active
–Measure changes to experimental manipulation
–What increases or decreases firing rate?
•Awake behavior vs anesthetized
•Find a neuron: Does it respond to
visual stimuli?
•Characterize its response properties
–Neurons have preferences and receptive fields.
What’s involved in Single-cell recording?
–Train monkey to do task (can’t just give instructions) –MRI scan to localize recording site –Surgery –Recording sessions –Train on new task –Recording sessions –Etc
Baseline Activity of Neurons
The baseline activity of neurons in the cerebellar nuclei, studied during exposure to external factors, can be used as a measure of changes in cell activity.
Receptive Field
Location in space for which neuron is responsive.
Pros & Cons of Single-cell Recording
•Pros:
–Excellent spatial AND temporal resolution (“gold
standard”)
•Cons: –Poor spatial coverage –Is single neuron(s) representative of whole region? –Not humans –Not causal
Types of Functional Neuroimaging
–Scalp EEG / ERPs
–Intracranial electrodes (ECoG)
–FMRI
–MEG, PET, DTI, NIRS
Electrical & Magnetic Types of Functional Neuroimaging
- EEG = Electroencephalography = electrodes on scalp
- ERP = event-related potential = a type of EEG analysis
- ECoG=ElectrocorEcography= intracranial electrodes (invasive)
- MEG =magnetoencephalography= magnetic detectors on scalp
