RESEARCH METHODS (4)

Question 1

What is electrical brain stimulation?

Answer 1

A technique that stimulates neurons electrically using a bipolar electrode (two insulated wires). Weak pulses make neurons near the tip fire more.

Question 2

Why is electrical stimulation important in research?

Answer 2

Helps identify the function of a brain area.

Usually produces behavioral effects opposite to lesions in the same area.

Can elicit behaviors like eating, drinking, attacking, mating, or sleeping.

Effects depend on location of electrode, current parameters, and environment.

Question 3

Who is usually tested with electrical brain stimulation?

Answer 3

Mostly nonhuman animals because it’s invasive.

Sometimes conscious humans for therapeutic purposes.

Question 4

What are the four invasive recording methods?

Answer 4

Intracellular unit recording – records graded changes in a single neuron’s membrane potential.

Extracellular unit recording – records firing of a neuron from outside the cell.

Multiple-unit recording – records combined activity from many neurons.

Invasive EEG – EEG recorded inside the brain using implanted electrodes.

Question 5

What is intracellular unit recording?

Answer 5

Records moment-by-moment changes in one neuron’s membrane potential.

Usually done in immobilized animals, but new tech allows freely moving animals.

Question 6

What is extracellular unit recording?

Answer 6

Electrode tip is in the fluid near a neuron.

Records neuron firing but not membrane potential.

Can now record up to ~1,000 neurons at once using multiple electrodes.

Question 7

What is multiple-unit recording?

Answer 7

Electrode tip is larger → picks up many neurons’ signals.

Signals are added together to show total firing per time unit.

Question 8

What is invasive EEG recording?

Answer 8

Electrodes are implanted in the brain rather than on the scalp.

Cortical EEG: often via skull screws.

Subcortical EEG: via implanted wire electrodes.

Question 9

How are drugs commonly administered in psychopharmacology experiments?

Answer 9

• Orally: fed to the subject.
• Intragastrically (IG): injected through a tube into the stomach
  Hypodermically:
• Intraperitoneally (IP): into the abdominal cavity.
• Intramuscularly (IM): into a large muscle.
• Subcutaneously (SC): under the skin.
• Intravenously (IV): into a vein.
• Direct brain administration: via a stereotaxically implanted cannula for drugs that cannot cross the blood-brain barrier.

Question 10

What are selective neurotoxic lesions and why are they used?

Answer 10

Target specific neurons rather than all neurons in an area.
Use neurotoxins that destroy certain cells while leaving others intact.

Examples:
Kainic acid or ibotenic acid: destroys cell bodies near the injection site; axons passing through remain.
6-hydroxydopamine (6-OHDA): destroys only neurons that release dopamine or norepinephrine; other neurons are unaffected.

Question 12

What is the 2-deoxyglucose (2-DG) technique?

Answer 12

Inject animal with radioactive 2-DG, which is like glucose. Active neurons absorb it but don’t metabolize it. Brain is removed, sliced, and processed with autoradiography. Active areas appear as dark spots, which can be color-coded to show activity.

Question 13

What is cerebral dialysis?

Answer 13

Measures extracellular neurochemicals in behaving animals. Implant a fine tube with a semipermeable section in a brain area. Chemicals diffuse into the tube for collection or analysis. Can be analyzed later or sent directly to a chromatograph.

Question 14

How does immunocytochemistry locate neurotransmitters/receptors?

Answer 14

Uses antibodies labeled with dye or radioactivity. Antibodies bind to neuroproteins or enzymes needed for neurotransmitter synthesis. Exposing brain slices to these labeled antibodies shows where proteins are located.

Question 15

How does in situ hybridization locate neurotransmitters/receptors?

Answer 15

In situ hybridization uses a labeled DNA or RNA probe that binds to specific mRNA, showing where certain neurotransmitters or receptors are being made in the brain.

Question 16

What are the three main genetic methods used in biopsychology?

Answer 16

Gene knockout – remove a specific gene.
Gene knockin – add or replace a gene.
Gene editing – precisely edit genes (e.g., CRISPR/Cas9).

Question 17

What is a gene knockout technique and an example?

Answer 17

Removes a gene to see its role in behavior.

Example: Melanopsin knockout mice – gene deleted → mice had impaired circadian rhythms, but other mechanisms also contributed.

Question 18

What is a gene knockin technique and an example?

Answer 18

Adds or replaces a gene in an organism.

Example: Transgenic mice with a human schizophrenia gene → showed brain abnormalities (smaller cortex, enlarged ventricles) and abnormal behaviors.

Question 19

What is gene editing and how is CRISPR/Cas9 used?

Answer 19

Edits genes at specific times during development.

CRISPR/Cas9 method: Cas9 protein + guide-RNA → targets specific DNA. Can be delivered via virus peripherally (whole organism) or intracranially (specific brain region). Cas9 can activate, inhibit, or reversibly control gene expression.

Question 20

What is Green Fluorescent Protein (GFP) and why is it useful in neuroscience?

Answer 20

GFP is a protein that glows green under blue light. It can be expressed in specific cells to visualize them. First used in C. elegans neurons to see touch receptor neurons. Allows tracing of neurons, labeling neurotransmitters, synaptic vesicles, and visualizing postsynaptic potentials.

Question 21

What is the Brainbow technique?

Answer 21

Modifies GFP to create multiple colors (cyan, yellow, blue). Each neuron gets a unique color, making it easier to trace neural pathways. Helps map the brain’s complex network of neurons.

Question 22

What are opsins and how are they used in neuroscience?

Answer 22

Opsins are light-sensitive ion channels from bacteria/algae. Light opens them → ions enter → neurons depolarize or hyperpolarize. Inserting opsin genes into neurons allows control of specific neuron activity with light.

Question 23

How does optogenetics work in living animals?

Answer 23

Virus carries opsin gene → targets specific neurons. Optical fiber implanted → light activates opsins. Can increase or suppress activity of targeted neurons. Wireless tech allows use in freely moving animals.

Question 24

What is the purpose of neuropsychological testing?

Answer 24

Assist in diagnosing neural disorders, especially when imaging/EEG is inconclusive.

Guide counseling and patient care.

Evaluate treatment effectiveness and side effects.

Question 25

What is the single-test approach?

Answer 25

Early method before the 1950s. Goal: Detect brain damage and distinguish structural vs. functional issues. Limitation: No single test could detect all complex symptoms.

Question 26

What is the standardized-test-battery approach?

Answer 26

Emerged by the 1960s, e.g., Halstead-Reitan Battery. Uses a set of tests rather than one test. Objective: Identify brain-damaged patients. Limitation: Good at distinguishing neurological vs. healthy, not neurological vs. psychiatric patients.

Question 27

What is the customized-test-battery approach (modern approach)?

Answer 27

Developed by Luria & Soviet neuropsychologists. Begins with a common battery for general symptoms. Followed by customized tests to explore specific deficits. Focus: Characterize the nature of deficits, not just detect damage. Advantages: Tests are aligned with modern theories (e.g., short-term vs. long-term memory). Evaluates cognitive strategies, not just scores. Requires skilled neuropsychologist for precise test selection.

Question 28

Why is the modern customized approach superior?

Answer 28

Detects subtle deficits in perception, emotion, motivation, cognition. Provides detailed profiles of patient abilities. Supports personalized interventions.