neuro: methods of studying the NS Flashcards
what are the 5 non invasive methods?
CT scans MRI PET fMRI EEG
describe CT scans in key words
X rays structure contrast agent absorbed rotate to produce series of X-rays reveal structural abnormalities (lesions + vascular damage indicate location of tumours)
describe MRI scans using key words
structure
strong magnetic field
high resolution images produced
form radio frequency waves that H+ ions emit when they align with magnetic field
protons release magnetic resonance energy
describe fMRI using key words
O2 increase in the blood to active areas of the brain
more oxygenated blood
functional activity
signal = BOLD signal (blood oxygen level dependent)
describe PET using key words
functional
positron emission tomography
radioactive dye injected into carotid artery
similar to glucose but doesn’t get metabolised
taken up by active cells
builds up in neurons
shows areas of brain activity from levels of radioactivity
colour coded
describe EEG
net of electrodes placed on scalp
records electrical activity
current of ions flowing across cell provides potential current
shows activity of APs, postsynaptic potentials etc = the sum of all the electrical events
what are ERPs?
event related potentials
EEG waves that accompany certain physiological events
what are the advantages of MRIs?
provides clearer images of brain than CT
higher spatial resolution (where)
no ionising exposure of X-rays
provides horizontal, sagittal and frontal planes
what are the disadvantages of MRIs?
expensive
no metal allowed
noisier
what are the 4 advantages that fMRI has over PET?
fMRI = O2 levels/bold signal
PET = injected dye like glucose
nothing has to be injected into person
provides structural and functional info in same image
better spatial resolution (where)
produces 3D images of activity over entire brain
what is a disadvantage of fMRI?
poor temporal resolution (when) → timing of neural events
what are the pros and cons of EEGs?
high temporal resolution (when) but poor spatial resolution (where) → can’t localise as recordings made on the scalp
less expensive than fMRI
direct reflection of neuronal activity
what is the difference between spatial and temporal resolution?
spatial = where temporal = when
what are the different invasive methods of studying NS function in animals?
intracellular recordings (electrophysiological technique)
extracellular recordings (electrophysiological technique)
electrical stimulation
optogenetic stimulation
micro dialysis (neuropharmacological technique)
immunohistochemistry (neuropharmalogical technique)
chemical lesions (disruptive technique)
records individual neurons as they fire, measures the changes in the membrane potential of a neuron over time, microelectrode positioned directly into neuron.
what method is this and is it invasive or non invasive?
intracellular recording
invasive
records near neurons as they fire action potentials, microelectrode positioned near neutron.
what method is this and is it invasive or non invasive?
extracellular recording
invasive
in extracellular recording, spikes indicate an action potential from a nearby neuron.
spikes of the _________ are assumed to come from the ____ neuron
same amplitude
same neuron
what is the difference between EEG and electrophysiology?
EEG = mass numbers of cells being recorded (not localised) electrophysiology = recording of individual cells
how does the electrical stimulating technique work?
examines neuronal circuits and the cause of bursts of APs
electrical stimulation = artificially activating nervous tissue
stimulating electrode → stuck in brain → switched on → activates tissue
can work out how parts of the brain relay info to each other via circuits
what is ontogenetic stimulation technique?
uses opsin (photoreceptors) that are extracted from bacteria/algae and inserted into genome of neurons using a virus neurons are then artificially responsive to light due to artificial proteins being inserted into their membrane
proteins then produce either excitation or inhibition of neurons when light is on
explain how ontogenetic stimulation is used in rats
opsin is inserted into genome of rats neurons in brain
laser light probe comes on → activates tissue in brain area linked to locomotion → activates light sensitive neurons → forces rat to run
used to measure neurotransmitters and chemicals secreted by the neuron during synaptic transmission
what technique is this?
microdialysis
how does microdialysis work?
small semi-permeable membrane is inserted into specific brain site of animal
solution circulates through the tube
chemicals in the extracellular fluid diffuse across membrane and are collected
samples then analysed using chomatography methods
key words to describe/recognise the immunohistochemistry technique
antibodies used to identify enzymes
enzymes produce specific neurotransmitters in specific cells
reveals chemical identity of cells
inject antigens
radio active labelling of antibodies that attach to enzymes
black or fluorescent
brain tissue → removed → sliced → reveals locations where labels have accumulated
method of disrupting neuronal function =
chemical lesions
how do chemical lesions work?
selectively lesioning = taking away bits of the brain
see what happens when disrupt function → remove chemicals, block circuits, remove tissue
give an example of a chemical lesion used to model a neurodegenerative disease
6-hydroxydopamine = neurotoxin that selectively destroys dopaminergic + noradrenergic neurons in the area of injected brain site
kills neurons locally
this models Parkinsons disease in order to pick apart what goes wrong in this specific disorder
give examples of species common behaviours
grooming, swimming, nest building, mating, fighting, eating, drinking
how does an open field test study species common behaviours?
animal placed in large, empty chamber
activity levels and number of boluses (excretion) recorded
low activity scores + high bolus content = indicator of fearfulness
(rats are usually fearful when first placed in field but declines with repeated exposure to same field)
if a fearful rat is highly THIGMOTAXIC what does its behaviour show?
rarely venture away from the walls of the test chamber and rarely engage in grooming and rearing activities
explain the colony-intruder paradigm
study looking at social defeat male rats are territorial measure and observe introducing a smaller male intruder into the habitat of a larger dominant male dominant male → aggressive behaviour intruder → defensive behaviour
why do learning paradigms play a major role in bio psychological research?
learning is a phenomenon of primary interest,
effective for producing and controlling animal behaviour so animals behave to goals of experiment,
can infer about sensory, motor, motivational, cognitive states of animals
describe classical conditioning
bell (CS) → no salivation over time and training: bell (CS) + meat powder (UCS) → salivation (UCR) conditioning established: bell (CS) → salivation (CR)
describe a study that tests the classical conditioning paradigm
place preference study testing drug addiction
day 1: assess rats natural preference for white or black compartment
day 2-4: am → give saline and place in black room
→ give drug and place in white room
day 5: assess conditioned compartment preference
results showed rats spent longer in white compartment
describe operant conditioning
specific behaviour → reinforcement (reward) → increased voluntary response
specific behaviour → punishment → decreased voluntary reward
describe a study that tests operant conditioning
self stimulation paradigm
animal pressers leaver → delivers electrical stimulation to pleasure centre → reward → increases response to pressing leaver
also tested with self supplying food (chunking)
what are the 4 semi natural animal learning paradigms
conditioned taste aversion
radical maze
morris water maze
conditioned defensive burying
why are semi natural learning paradigms studied in animals?
because they mimic situations that an animal might encounter in their natural environment
what type of field observations are observed in animals?
social dominance, aggression, courtship display, sex
