RESEARCH METHODS (2)

Question 1

What is the main goal of brain stimulation and lesioning techniques in neuroscience?

Answer 1

To establish causal relationships between brain activity and behavior—unlike imaging methods (like fMRI or EEG) that show correlation.

A method that changes brain activity directly to see if a specific brain area is needed for a behavior, unlike fMRI or EEG which only show correlations.

Question 2

How does transcranial magnetic stimulation (TMS) work, and what is it used for?

Answer 2

Uses rapidly changing magnetic fields to create small electric currents in specific brain areas, temporarily disrupting or enhancing their activity.

It shows cause-and-effect between brain regions and behavior and is also used to treat depression and study movement, perception, and language.

Question 3

What are the advantages and limitations of TMS?

Answer 3

✅ Advantages: Non-invasive, temporary, reversible, precise cortical targeting, and helps identify causal brain-behavior links.
⚠️ Limitations: Only affects superficial cortical areas, not deep brain structures; may cause discomfort or headaches; results depend on coil position and intensity.

Question 4

What is transcranial electrical stimulation (tES) and how does it differ from TMS?

Answer 4

tES applies weak electrical currents through scalp electrodes to modulate neuronal excitability, rather than trigger action potentials like TMS. Variants include tDCS (direct current) and tACS (alternating current). It’s cheaper, quieter, and can be used repeatedly for cognitive enhancement and clinical rehabilitation.

Question 5

What are the pros and cons of tES?

Answer 5

✅ Advantages: Portable, safe, affordable, easy to apply, modulates brain excitability and plasticity over time.
⚠️ Limitations: Effects are subtle and variable, poor spatial precision, and less predictable than TMS. Results can depend on electrode placement and individual differences.

Question 6

Describe transcranial ultrasound stimulation (tUS) and its unique benefits.

Answer 6

tUS uses focused ultrasound waves to stimulate deep brain areas non-invasively. It can reach subcortical regions (unlike TMS or tES) with high spatial precision and minimal side effects. It’s experimental but promising for modulating activity in regions related to mood, motor control, and sensory processing.

Question 7

What are the key advantages and drawbacks of tUS?

Answer 7

✅ Advantages: Can reach deep brain regions safely, very precise, non-invasive, silent.
⚠️ Drawbacks: Still new and less understood; equipment is expensive; mechanism of how ultrasound affects neurons isn’t fully known.

Question 8

What is focused ultrasound (fUS) imaging and how is it different from tUS?

Answer 8

fUS imaging measures blood flow changes using high-frequency sound waves to create high-resolution images of brain activity. Unlike tUS (which stimulates), fUS visualizes functional activity, even in animals or infants, and can be used when fMRI isn’t feasible.

Question 9

What are lesion studies and what do they reveal about brain function?

Answer 9

Lesion studies involve damaging or removing specific brain areas (surgically or naturally) to observe resulting behavioral changes. They reveal which regions are essential for specific tasks—linking structure to function. Modern lesioning can be done with lasers, radiofrequency, or ultrasound for precise targeting.

Question 10

What are the limitations of lesion studies in humans?

Answer 10

They are irreversible and cannot ethically be induced; rely on naturally occurring injuries or clinical cases; brain damage may spread beyond the target area; and results can vary depending on individual differences and brain plasticity.

Question 11

How do stimulation and lesion methods complement each other?

Answer 11

Lesion methods show what happens when a region is removed or deactivated (necessity), while stimulation shows what happens when it’s activated or modulated (sufficiency). Together, they provide strong evidence for causal brain-behavior relationships.

Question 13

What are psychophysiological recording methods, and what do they measure?

Answer 13

They record body activity from the surface to study how it connects to the mind.

Six main types:
Brain activity: EEG, MEG
Body movement: muscle tension, eye movement
Autonomic activity: skin conductance, heart and blood pressure.

Question 14

What does EEG (electroencephalography) do?

Answer 14

It records the brain’s electrical activity using small electrodes on the scalp. It picks up signals from neurons, but also from skin, eyes, and muscles.

Question 15

Why is EEG useful, and what are alpha waves?

Answer 15

EEG helps find links between brain waves and mental states. Alpha waves (8–12 Hz) appear when a person is awake but relaxed. EEG is used for studying sleep, epilepsy, and brain activity.

Question 16

What are event-related potentials (ERPs) and sensory evoked potentials (SEPs)?

Answer 16

ERPs: Brain waves that happen right after a certain event or stimulus. SEPs: A type of ERP caused by a quick sound or flash, showing how the brain reacts to it.

Question 17

How do scientists remove background noise in EEG signals?

Answer 17

They use signal averaging — record the same event many times and average them. This cancels random noise and shows the true brain response to the event.

Question 18

What is the P300 wave, and what are far-field potentials?

Answer 18

P300 wave: A positive wave seen about 300 ms after something important or meaningful appears. Far-field potentials: Small, fast waves that come from deep in the brainstem right after a stimulus.

Question 19

What does MEG (magnetoencephalography) measure, and how is it different from EEG?

Answer 19

MEG measures tiny magnetic fields made by brain activity. It shows clearer location details than EEG and can detect deeper brain activity, but it’s expensive, large, and people must stay very still.

Question 20

What’s the difference between EEG and MEG?

Answer 20

• EEG measures the brain’s electrical activity, while MEG measures the magnetic fields produced by that activity.
• MEG gives clearer, more detailed images and can detect some deeper brain areas, but it is very expensive and requires large lab equipment.
• EEG is cheaper, more portable, and mainly records activity from the surface of the brain.

Question 21

What are the two main psychophysiological measures of somatic nervous system activity?

Answer 21

Muscle Tension — measured by Electromyography (EMG)
Eye Movement — measured by Electrooculography (EOG)

These help researchers study bodily responses linked to emotions, stress, and attention.

Question 22

What does Electromyography (EMG) measure?

Answer 22

EMG measures muscle tension by detecting electrical activity from muscle fibers.

Each muscle fiber contracts in an all-or-none way when activated by a motor neuron. Even when “resting,” a few fibers are always slightly contracted to maintain muscle tone.

Question 23

Why is muscle tension important to measure?

Answer 23

Anxiety and stress increase muscle tension.
EMG helps psychologists track psychological arousal or emotional states.

For example, anxious individuals often show high resting EMG levels even without moving.

Question 24

How is EMG recorded?

Answer 24

Two surface electrodes are taped onto the skin over the target muscle (like the forehead or forearm).
These electrodes pick up the electrical signals from contracting muscle fibers.
The signal strength reflects how many fibers are active at that moment.

Question 25

What does an increase in EMG amplitude show?

Answer 25

A higher amplitude means more muscle fibers are contracting. It indicates greater muscle activity or tension. ## Footnote This can occur during stress, focus, or physical movement.

Question 26

What is an “integrated” EMG signal and why is it used?

Answer 26

The raw EMG signal is spiky and irregular. A computer processes it to calculate total EMG activity per short time interval (like every 0.1 seconds). This creates a smooth curve showing overall muscle tension levels — easier to interpret for analysis.

Question 27

What does Electrooculography (EOG) measure?

Answer 27

EOG measures eye movement by detecting electrical potential differences between parts of the eye. ## Footnote The front of the eye (cornea) is positive, and the back (retina) is negative. When your eyes move, the electrical field shifts, which can be recorded.

Question 28

How is EOG recorded?

Answer 28

Horizontal movement: electrodes on each side of the eye. Vertical movement: electrodes above and below the eye. These electrodes detect changes in voltage as the eyes move in different directions.

Question 29

What is the output of EOG called and what does it show?

Answer 29

The output is an electrooculogram (EOG). It shows how the eyes move over time, helping measure visual attention, sleep stages, or reading patterns.

Question 30

Why do psychologists use EMG and EOG?

Answer 30

EMG: to measure muscle activity and tension, often linked to stress, emotion, or fatigue. EOG: to track eye movements, revealing attention focus, alertness, or visual processing.