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reductionist approach
scientific strategy to break a system down into increasingly smaller parts to understand it
observe & manipulate
What are the 2 categories of experiment?
methods of observational studies
humans: questionnaires, life history, postmortem tissue, brain scans, EEG
animals: neurotransmitter levels, physiological properties of neurons
methods of manipulative experiments
humans: FDA-approved drugs, treatments
animals: somatic manipulations, behavioral interventions, test non-FDA approved drugs
operant learning
used to study food consumption/obesity, liquid consumption, drug addiction, learning
Rats show consistent self-administration of cocaine. When cocaine became unavailable, they stopped pressing the button as often, but it never reached 0. After cocaine was available again, they pressed the button even more times.
Describe the rat operant learning experiment.
Neurocircuitry
aims to find what circuits are controlling behavior and how they are connected
TTX & Lidocaine
both of these chemicals block voltage-gated Na+ channels
stereotaxic atlas
map of the brain; relies on two landmarks: Lambda & bregma; brain areas are located by their coordinates
anterograde labeling
uses molecules taken up by the cell and then transported to the axon tips; uses anterogradely transported AAVs (viruses)
cell body —> axon (forward)
retrograde labeling
uses molecules taken up in the axon terminals and transported to the cell bodies; Cholera Toxin b (Cub), retrogradely transported AAVs
axon —> cell body (backward)
microdialysis
Uses stereotaxic surgery to implant cannulae (hollow metal tube) in a brain region of interest
Descend probe and perfuse artificial CSF across a membrane that allows diffusion of neurotransmitter
used in experimental animals and humans w/ seizure disorders
immunohistochemistry
A brain section is covered w/ antibody-containing solution
Antibodies attach to target cell
Unattached bodies are washed off
Labeled cells are visible
western blotting
Gel electrophoresis
Transfer proteins in samples to a “membrane”
Detect only protein of interest using antibodies against it
Visualize w/ detection kit
knock-out animals
eliminate one gene from the genotype and look for phenotypic differences; typically mice
Will knocking out X protein change Y behavior?
Viral over-expression
insert a target gene into viral DNA so that the target gene is overexpressed instead of a pathogenic gene
gene silencing techniques
uses RNAi via siRNA to interfere w/ transcription of genes w/ complementary sequence; can design and synthesize siRNA for target proteins
optogenetics
uses viral vectors to overexpress ion channels that can then influence membrane potential
ChR2
artificial light gated cation (+ ion) channel; blue light —> depolarization
HR
artificial light-gated Cl- channel; yellow light —> hyperpolarization
electrophysiology (“ephys”)
detect electrical activity which is amplified and interpreted by computer
Live animal: microelectrode placed out neuron to detect activity OR multi-electrode recording
Brian slice: patch-clamp OR intacellular; can manipulate receptors
macrolectrode recordings
detect PSPs from a population of neurons immediately below the skull; EEG
seizure
instead of activity being desynchronized across regions, there is too many action potentials, so there is a synchronization of electrical activity; “spike-and-wave” pattern
event-related potentials (ERP)
large potential shifts caused by discrete stimuli; sensory-evoked and auditory-evoked
CAT or CT scan
uses X-rays to map tissue density to show brain structure
MRI
uses magnets to produce images of brain structure
fMRI
Blood Oxygen Level-Dependent (BOLD) signal indicates metabolic activity; active brain regions require more oxygen
DTI
movement of water molecules in bundles of axons will be parallel to the the axon that make up the bundles; rainbow image
MEG
measures tiny magnetic fields given off by active neurons
high spatial resolution
provide a lot of structural detail
low temporal resolution
inability to track dynamic changes in brain activity well
transcranial magnetic stimulation
briefly stimulates discrete cortical regions w/ magnets
possible treatment for substance abuse; current treatment for anxiety/depression
behavioral pharmacology
involves the administration of drugs and observing behavior
animals: systemic and intracranial
humans: objective behavioral changes, self-reported systems, changes in brain activity
in situ hybridization
requires the use of a probe with a fluorescent label that will ONLY GLOW if the probe has binded to the target DNA (hybridization); requires the use of a flurorescent microscope
qPCR
done in tissue from a brain region, in a tube; similar to in situ hybridization