Ch4 Methods of Research Flashcards
behavioral measures for animal and advantages of animals
we want to understand neurochem basis of beh’r/drug induced change sin beh’r. So develop animal models of disorders and screen drugs preclinically
animals offer rigorous control, well known genetics, and allow unethical methods
Schedules of reinforcement and operant reward/punishments
Fixed Ratio = reinforcement given after fixed # responses
Fixed Interval = reinforcement given after amount of time
Positive = give something
Negative = take something away
Reinforcement = inc. beh’r
Punishment = dec. beh’r
Measures of analgesia
analgesia = reduction of perceived pain w/o losing consciousness
tail-flick test = response to heat on tail (longer delay = more reduced pain)
hot plate test = latency to mouse moving from hot plate
Testing Learning (3 mazes)
Radial arm maze = food at each arm, learn to visit each arm once. use external cues as guides
Morris Water maze = must find platform in water pool, use external cues
Barnes Maze = find hole in circular platform (more natural than morris), external cues.
ALL SENSITIVE TO HIPPOCAMPUS LESIONS
Testing Memory
novel obj. recog. = animal trained on two similar obj, test with replacement of a novel obj (more interested in it?)
Delayed Response Test = see if rember where food hidden, working memory (sensitive to PFC lesions)
Caveats for tests of learning/memory
Can’t determine if drug altered: att’n/motivation, the encoding/retireval/storing of memory, or the effects of the motor/sensory ability
Testing Anxiety
test with open boxes/light-dark box/elevated mazes
Simulates natural conflict situations as rodent exposed in unfamiliar enviro and wants to hide bc prey animal
Measure time spent in open/closed areas. Reduction anxiety = more time in open
Fear Conditioning
Conditioned Emotional Response = present signal that shock about to come
Contextual = return to same environment causes freezing
Cued = different enviro but play the signal and that causes freezing
OCD and aggression Tests
OCD = marble-burying, if bury more marbles, more OCD anxious,
Impulsive Aggression = Resident-Intruder Test, isolated mouse introduced to another mouse, lashes out at them,
Testing Depression (5 tests)
Forced swim test and tail suspension test for “behavioral despair” - time when they give up moving
Sucrose Preference Test = see if they like the sugar water more or no preference = anhedonia, relies on ability to taste sugar!
Chronic Mild Unpredictable Stress = better model of human depression, expose them to physically stressful events for several weeks. Results in cog impairments/anxiety/social withdrawl and anhedonia and requires chronic antidepressants to treat
Maternal Separation = young separated from moms for brief periods daily for first weeks of life. Tested as adults showed changes in corticotropin releasing factor (CRF, stress) that can predispose depression
Schizophrenia and ASD (3 tests)
Pre-pulse Inhibition = loud noise does a startle, pre-pulse to loud noise lets people attentuate their startle (ppi). Schizo and ASD have impaired PPI, measure with EMG. Impairments in sensorimotor gating - distinguishing between stimuli/filtering unneccesary. Fail to gait hallucination/sensory exp
Amphetamine-Induced Hyperkinesia = high doses amphet prodcues schizo symptoms (inc. stereotyped motor beh’r). Used to screen for antipsychotics, reduces locomotion with drugs
Crawley 3-chamber box = test sociability, ASD knockout mice spend equal times in empty chamber and chamber with other mice (normal spend more time with other mice).
Self Administration and Stimulation
Self Admin = used to study abuse potential. allow self admin of drug. Breaking Point = point where effort exceeds reward, higher point = higher abuse potential
Intracranial Self Stimulation (ICSS) = self admin electric current on brain reward center. Threshold = stimulation value where they just continually self-adminster. Need higher threshold as go on as drugs break reward centers
Conditioned Place Preference and Drug Discrimination Testing
CPP - condition association between drug effect and environment
Drug Discrim - animals learn to discriminate internal cues of drugs and press levers based on drug/saline
Optogenetics
insert genes that make the neurons light sensitive, freely behaving animals
Implanted Microelectrodes
single cell (intracellular)
or in fluid (extracellular)
In vivo microdialysis
measure NT released in brain region while actively doing a beh’r
Locating/Quantifying NT/receptors
Slice method - localization, uses intact tissues to see receptor distribution
Soup method - quantification, tissue sample isolated in test tube, study number and affinity of receptors
Positron Emission Tomography PET
maps radioactive substances, used to determine localization of drug uptake/activity
fMRI
tests BOLD signal, not a direct test of activation, indirect blood flow for activation
transgenic, knockout, knockin, knockdown
transgenic - human genes inserted into mice, model for neurodegen diseases
knockout - lack gene for a protein, constitutive (since fertiliation), site-specific (brain region at a time), inducible (can turn on/off)
knockin - point mutation of single substitution, may do gain/loss, allows specific mutation
knockdown - RNAinterference mice, assess the lower levels of gene products, more valid of the human condition since most just not one mutation
CRISPR
new mutations directly generated, eliminates time/resources, new mutations can be added to existing
may accidentally have off-target mutations, pathogenic consequences
Problems of genetic engineering
- beh’rs are controlled by multiple genes not just one
- other genes may compensate for the loss leaving no change in phenotype
- altered gene function occurs in all tissues at all devo stages
- environmental factors also affect genes, epigenetics
- inbred mice so genetically homogenous not good models for humans
