Biopsychology Methods Flashcards
What is spatial resolution?
How fine in space we can measure
What is temporal resolution?
When in time did the change occur
What is a neural stain?
Stain some tissue components but not others
Selective process
How do we prepare brain tissue?
Perfusion -remove blood Hardening Slicing Mounting
What is a Golgi stain?
Silver chromate strains neurons black but not all neurons pick up the strain
We can’t see intracellular details but we did get the first view of the synapse
What is a nissil stain?
Stain penetrates all cells
Stains ribosomes
First view of structures within the neuron
Uses cresyl violet to stain
Why do we trace neural pathways?
To identify pathways that connect structures
What is anterograde tracing?
Where do axons go?
Use autoradiography
What is autoradiography?
Amino acids with radioactive hydrogen isotopes are taken into cell bodies and incorporated into proteins
What is retrograde tracing?
Where do axons come from?
HRP is taken up by axon terminals and stains cell bodies black
What is in situ hybridization?
Peptides and proteins located by mRNA
Complementary sequence binds to mRNA creating hybrid RNA
Hybrid RNA is labelled to locate mRNA
How are small-molecule neurotransmitted located?
Probing for enzymes that synthesize
What is immunocytochemistry?
Antibodies specific to the protein of interest
Antibodies attach to proteins of interest and are labelled with radioactivity, substrate colour change, or dye
Analyze under a microscope
What is X-ray computed tomography (CT)
Computer-assisted X-ray
3D view of the brain
Composed of 8-9 horizontal cross-sections
Low-resolution image
Used to visualize structural abnormalities
How does PET imaging work?
Inject carotid artery with a positron-emitting radionuclide
Positrons interact with electrons to produce photons (gamma rays)
Scanner detected photons and maps how many gamma rays are coming from a particular region
What is Positron emission tomography (PET)?
Indirectly measures activity and distribution of other neurochemicals and proteins
Indicates areas of activity during a task
No structural information
What is magnetic resonance imaging (MRI)?
High spatial resolution
Horizontal, coronal, and sagittal planes
Expensive
How do MRIs work?
A strong magnetic field passed through the brain
What is functional MRI (fMRI)?
Uses MRI methods -functional -structural -non-invasive -3D images of activity over brain High spatial resolution Poor temporal resolution
What is the bold response?
Pictures do not reflect changes in activity but rather changes in BOLD signal
How does fMRI work?
Changes in Blood Oxygen Level Dependent (BOLD) signal
Correlates with neural activity and is not a direct measure of neural activity
What is diffusion tensor imaging (DTI)?
Identify white matter tracts in the brain
Use MRI
Water molecules move in the same direction in white matter, outside of white matter they move randomly
What is transcranial magnetic stimulation (TMS)?
Disrupts neural activity by placing magnetic field over the skull
Noninvasive
What is electroencephalography (EEG)?
Measures the voltage output of the averaged activity of a large number of cortical neurons
Detects the post-synaptic potentials
The signal is the difference in electrical potential between two large scalp electrodes as a function of time
What is a caveat of EEG?
Limited spatial resolution
Signal decays from the source over space and time
What can EEG measure?
Reflects the sum total of all electrical events
- EPSP
- IPSP
- eye movements
- scalp muscle movements
- skin
- blood flow
How do waveforms differ between states of consciousness?
Aroused state = low amplitude and fast EEG activity
Relaxed and awake state = high amplitude and slow EEG activity
Deep sleep state = high amplitude and slow EEG activity
What is signal averaging?
Disruptions in signal due to mind wandering or distractions
Repeat same stimuli several times and average signal
What is magnetoencephalography (MEG)?
Noninvasive
Measures magnetic fields generated from the scalp from neural activity
Measures ongoing activity of neurons parallel to brain surface
Good temporal and spatial resolution
What is stereotaxic surgery?
Invasive Directly manipulate brain Requires atlas and stereotaxic instrument Direction to brain regions in 3D Bregma reference point
What is a lesion method?
Remove or destroy specific brain areas or tracts to test for behaviour and cognition deficits
What is aspiration?
Remove cortical tissue and leave white matter underlying intact
What is an electrolytic lesion?
High radiofrequency current
Tissue is destroyed by heat
What is lesion by knife cuts?
Sever tracts
Specifically, destroy tracts and not overlying tissue
What are some reversible lesions?
Lidocaine anesthesia
Cryogenic blockade
Which are more mild, bilateral or unilateral lesions?
Unilateral
What are some caveats to interpreting brain lesions?
Can be misleading
Impossible to completely destroy only one region or interest
Affect other neural tissues that may be important
What is 6-hydroxydopamine?
A neurotoxin that selectively kills DA and NE neurons in the vicinity
What is kainic/ibotenic acid?
Destroys neuronal cell bodies at the injection site
Leaves axons passing through site intact
What are the applications of electrical stimulation?
Identify pathways
Immediate effects on patients
What are gene replacement techniques?
Involves replacement of one gene for another
Transgenic animals
What is optogenetics?
Study neural circuits without lesions
Opsins are activated by different wavelengths of light and implanted into the brain
What are 4 invasive electrophysiological recordings?
Intracellular unit recording
Extracellular unit recording
Multiple unit recording
Intracranial EEG recording
What is intracellular unit recording?
Measure changes in membrane potential over time
Microelectrode inside of a single neuron
What is extracellular unit recording?
Microelectrode places near outside of a neuron and freely moves
The signal is a series of spikes
No information on membrane potential
What is multiple unit recording?
Indicates the rate of firing in the vicinity of an electrode tip
Electrode tips are larger than a microelectrode
Picks up APs from many nearby neurons
Signal integrates
What is intracranial EEG recording?
Implanted electrodes used to record EEG in lab animals
High spatial and temporal resolution
What is in vivo cerebral microdialysis?
Measure extracellular small molecules in behaving animals
Tube with semipermeable membrane into the brain that has artificial CSF perfused through the tube
Small molecules then diffuse into the tube and are collected for measurement
How do we study anxiety in rodents?
Elevated plus maze
Open-field testing
We are measuring the degree of activity, thigmotaxis, defecation
What is the forced swim task?
5 minutes in water that cannot be escaped so rodents learn helplessness
Measure immobility and climbing
What is the social intervention test for rodents?
Novel strangers vs friends Number of interactions Time spent near vs far Number of transitions between chambers Tests social behaviours
What is the land maze?
Radial arm maze
-for spatial navigation
-mimics foraging behaviour
Rat learns to go to the arms baited with food
What is the water maze?
A swim task
Study a rat’s spatial ability
Rats swim to find an invisible escape platform
Study search strategies when we remove the platform
