Research Methods

Question 1

Advantages of fMRI

Answer 1

(1) Nothing has to be injected into the volunteer;
(2) MRI provides both structural and functional information;
(3) spatial resolution is great;
(4) it can be used to produce three-dimensional images of activity over the entire brain.

Question 2

Disadvantages of fMRI

Answer 2

(1) fMRI are images of the Blood-Oxygen-Level-Dependent (BOLD) signal, and the relation between the BOLD signal and neural activity is complex (see Hillman, 2014).
(2) Furthermore, fMRI technology has poor temporal resolution, much slower than neural responses (e.g., action potential) which occurs in milliseconds.

Question 3

Interim summary

Answer 3

• When neurons fire or increase their firing rate, they draw on oxygen and various nutrients.
• The circulatory system of the brain reacts by sending the region that just fired more highly-oxygenated blood than is needed.
• This results in an increased blood oxygen level in the activated region. As a result of the magnetic characteristics of hemoglobin, oxygenated blood has a different magnetic signature than de-oxygenated blood.
• Therefore, with the right pulse sequence, an MRI scanner is able to detect this difference in blood oxygen level.

Question 4

Relational task

Answer 4

Alternating blocks of judgments about relations among features versus feature matching (planning/reasoning)
Anterior Prefrontal Cortex

Question 5

Gambling task

Answer 5

Gambling decision making task

Striatum; Ventral Medial Prefrontal; Insula; Orbitofrontal

Question 6

Social task

Answer 6

Animations of social and random interactions

Medial Prefrontal Cortex; Temporal Parietal Junction; Inferior and Superior Temporal Sulcus

Question 7

Emotion processing

Answer 7

Valence Judgments (negative and neutral pictures) 
Amygdala; Hippocampus; Insula; Medial Prefrontal

Question 8

Signal analysis

Answer 8

Biopotentials are a subset of biomedical signals that can be measured electrically using an electrode pair.
Electrodes are sensors or transducers that convert electrical signals into a format amenable to analysis.
These electrical signals may occur spontaneously, such as when we measure brain states using EEG.

Question 9

Biopotentials

Answer 9

Biopotentials, a type of electrical potential, represent the flow of current in biological tissue (e.g., nervous tissue).
-Scalp (EEG)
-Skin (Skin Conductance)
-Brain (Stimulation and animal behaviour)
The first, and many ways the most device, piece of kit is, however, the first in the chain: the connection (or “coupler”) to the biological process we are measuring.
For EEG/ECG this connection is an electrode, a small electrical conductor connecting to a non-metallic part of a biological circuit. The golden rule is:
Low output impedance – high input impedance

Question 10

Electroencephalography (EEG)

Answer 10

-EEG is a widely used technique that can study brain activity, at a millisecond resolution
-EEG is a marker of neuronal activity and it is non- invasive.
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-A limitation of EEG is its poor spatial resolution (i.e., we record signals on the scalp, not inside the brain).
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-Consequently, we record mainly cortical activity

Question 11

Transcranial Magnetic Stimulation

Answer 11

-Single or repetitive magnetic pulse (>20 Hz) can turn ‘on’ or ‘off’ brain regions

Question 12

Focused ultrasound

Answer 12

• Target very specific areas
• Can do surgery, stimulation and drug delivery
• Doesn’t ‘burn’ cortex like a laser surgery
• But very very new and few machines exists

Question 13

Skin conductance

Answer 13

It measures electrical conductance of the skin

• It is an autonomic response
• Increased skin conductance from emotional response and stress (which was covered in detail two weeks ago)
• Commonly known as ‘lie detector’ test

Question 14

Heart Rate Variability: Part 1

Answer 14

-We must be conscious that HRV analyses the intervals between consecutive heart beats, & not the beats per se

• Beat-to-beat variability manifests physiological rhythms coming from extrinsic processes, largely the autonomic nervous system.
• In our rest state, the parasympathetic system dominates and largely determines our inter-beat intervals.

Question 15

Heart Rate Variability: Part 2

Answer 15

-Low HRV is a strong marker for pathology.

-Lower levels of HRV are found in patients with most types of psychological disorders.
Thayer (2005; 2006) draws an analogy with the inhibitory control of the heart and the inhibitory control of what he calls “sympathoexcitatory subcortical threat circuits”.