Experimental Investigation of Drug Effects (Ch2) Flashcards
Independent variable
Manipulated variable (drug dose), range from low to high to produce a DRC
Dependent variable
measure of behaviour of the subject (drug effect)
Within-subject design
Subject serves as their own control (eliminate individual difference variation). Use with stable behaviour, compare behaviour under drug to not under the drug. All individuals experience all experimental conditions. Fewer participants, longer to run, know effect in each individual.
Between-subject design
dependent mesure not stable across days or to compare different doses/drugs. Randomly assign rats to different hours, each group exposed to a different experimental condition and compare groups. Faster, need many more participants, compare average effects between group (don’t know what effect is on each individual)
Experimental control
control condition: eliminate method of administration as a source of behaviour change. Make a similar as possible to the drug condition, but no drug. Injection of saline, or sugar pill
Placebo effect
pharmacological inert compound administered to an individual. If a person believes they are getting a drug effect (side effect), they frequently report experiencing the effects. Expectation of an effect must be discriminated from the dug effect. Essential aspect of experimental design with humans.
Experimenter bias and how to solve issue
Experimenter may unknowingly influence the results if they know who has been given a placebo and who has been given a drug. Double-blind procedure: neither the subject nor the researchers know who has been given a drug and who has been given a placebo.
Non-experimental research
Correlation, not causation. Nonexperimental research measures 2 variables and uses statistics to see if there is a relationship between variance in one variable and variance in the other (correlation)
SMA (spontaneous motor activity)
place the animal in an open field box and count the number of line crossings within a fixer period of time. The alternative is to use a grid of IR beams.
Stereotopy
repetitive movements in a vertical dimension
Ambulatory movements
horizontal movements
Respondent (Classical/pavlovian) conditioning
The UCS causes a UCR. The CS and the UCS are paired and and UCR happens. Eventually, the CS causes the UCR(CR). The CR (heart rate, salivation, drug effect)
Operant behaviour
voluntary, emitted behaviour. Consequences influence the probability of occurrence of behaviour. Reinforcement strengthens and punishment weakens the behaviour.
Schedules of reinforcement
Different schedules produce different patterns of motivated behaviour.
Rate dependency
the effect of a drug behaviour depends on the rate of occurrence of the behaviour under baseline (no drug) conditions.
Test stimulus properties of drug
self-report paradigm: the animal indicates how it feels (levers - press one to inject drug and the other to inject saline. If presented with 2 drugs, can tell preference between them)
Tests of abuse potential (3)
1) Rate of responding
2) Progressive ratio
3) choice
Rate of responding
larger reinforcers produce higher rates of responding.
Complications with using rate of responding
the duration of action (short acting drugs self-administered at higher rates than long-acting), drugs interfere with the ability to make a response (pentobarbital puts you to sleep)
Progressive ratio
schedule of reinforcement where response requirement (# lever presses (price)) to obtain a reinforcer increases with each successive reinforcer. The breakpoint is the value that is above the drug.
Choice (2 tests)
The operant chamber with 2 levers, associate a drug to each and test for preference. The animal will show a preference for the drug that is more reinforcing.
Conditioned place preference/aversion - inject animal with drug in one context and saline in another context. Let the animal move freely between each, and if drug experience is positive, animal will spend more time in drug context (CPP)
Tests for antipsychotic effects (1)
1) escape-avoidance task
Escape-avoidance task
light on for 30s and then a 10s shock occurs. The animal can press the lever during the 30s to make shock not happen or press lever during the shock to stop it. Antipsychotics interfere with avoidance .
Tests for anxiolytic effects (2)
1) light-dark crossing test
2) elevated plus maze
Light-dark crossing test
2 compartment box, one side is brightly lit and the other is dark. The animal is placed in the bright side and the number of crossings is recorded. The time spent in the bright side and total motor activity are measured. Anxiolytics increase these measurements (rats freeze when anxious)
Elevated plus maze
cross shaped, 2 open and 2 closed arms. Elevated. If anxious, spend less time on open arms. Measure time on open arms, anxiolytics increase these measurements
Tests of analgesic effects (pain relief) (2)
1) tail flick test
2) hot plate test
Tail flick test
beam of light project onto an ink blackened spot on a rat’s tail (absorbs light more) measure interval between beam onset and removal of tail. Analgesic increases latency.
Hot plate test
metal plate at 50 degrees, initial response is to raise and lick hind paw. Measure interval to paw lick, kicking or attempt to escape apparatus. Analgesic increases latency.
Tests of learning and memory (2)
1) Mazes (radial arm maze)
2) delayed matching to sample
Mazes
Radial arm maze:
- multiple arms from a central point. Food at end of each. Error: visit an arm more than once. Different variations: bait 1/2 of arms, use cues within (intramaze) or without (extra maze) with a spatial relation to the baited arms.
delayed matching to sample
present a sample stimulus. Delay. Present 2 stimuli (one is the stimulus already seen). Matching to sample task: reinforcement if choose stimulus previously seen. Non-matching to sample task reinforcement if chooses stimulus not previously seen.
Testing in humans
subjective effect (introspection to generate a testable hypothesis), rating scales (profile of mood states).
Perception: absolute threshold and difference threshold
absolute threshold: lowest level of stimulation that can be reliable detected
difference threshold: smallest unit of difference in stimulation that can be reliably detected (JND, just noticeable difference).
difference threshold - critical frequency of fusion
CFF (critical frequency of fusion): frequency at which a flickering light appears to be constantly illuminated.
Tests of motor activity (3)
1) reaction time
2) body sway (Romberg Sway Test)
- test ability to stand still without swaying
3) pursuit rotor
- hold the end of a stylus on a point on a rotating disk (hand-eye coordination)
Test of attention and vigilance
Mackworth clock test: watch a circular dial with a moving clock hand. Hand occasionaly moves 2 steps rather than 1. Push button when this occurs
Tests of memory in humans (short and long)
Short term memory:
- N-back test: presented a series of characters on a screen and who target character occurs, must report a character that occurred N back form the target.
Long term memory (explicit and implicit)
- free recall: presented with a list of terms, recall
- cued recall (recognition): resented with a list, shown an array of items, identify those that were on the list.
