Module 4: Research Methods

What is the difference between a lesion and an ablation?

A lesion is damage to a structure. An ablation is removal of the structure.

Comparing MRI and fMRI, which one(s) measure the responses of brain chemicals to a magnetic field? Which one(s) show which brain areas are most active at the moment?

Both measure responses of brain chemicals to a magnetic field. Only fMRI shows which brain areas are most active at the moment.

What are the similarities and differences between MRI and fMRI?

Both methods measure the responses of brain chemicals to a magnetic field. MRI shows the anatomy of the brain. The fMRI method shows which brain areas are most active at the moment.

Suppose you are interested in determining if the volume of the hippocampus is associated with the amount of stress a person was experiencing. Which method would be the best choice?

CAT

Evoked potentials in the brain are most likely to be detected by a(n) __________.

EEG

In which regard, if either, do human brains exceed those of all other species?

Humans do not exceed all other species in either regard

What does fMRI measure?

It detects an increase in blood flow to a brain area immediately after an increase in brain activity, and it also detects a slightly slower increase in the percentage of hemoglobin lacking oxygen

In which way do men and women differ most — intellectual performance, total gray matter, or total white matter?

Men have more white matter, and therefore larger brains. However, men and women are equal in intellectual performance and nearly equal in gray matter.

Most studies using modern methods show a moderate positive correlation between brain size and IQ scores. Nevertheless, interpreting these results is problematic. Why?

On average, men have larger brains than women, but equal IQ scores.

What determines whether optogenetic stimulation excites a neuron or inhibits it?

Optogenetic stimulation activates a light-sensitive protein. If that protein opens a sodium channel in the membrane, the result is excitation of the neuron. If it opens a chloride channel, the result is inhibition.

Which method is dependent upon injecting a radioactive chemical into the blood to measure blood flow?

PET

Why do recent studies show a stronger relationship between brain size and IQ than older studies did?

The use of MRI greatly improves the measurement of brain size, in comparison to measurements based on the skull.

Which of these methods measures brain anatomy but NOT brain activity?

a. EEG b. PET c. MRI d. fMRI (c)

Which of these is the first step for positron-emission tomography (PET)?

a. Inject a radioactive chemical into the blood b. Insert an electrode into the brain c. Subject the brain to a strong magnetic field d. Attach light-sensitive proteins to a virus (a)

Which of these is the first step in using the optogenetic technique?

a. Inject a radioactive chemical into the blood b. Insert an electrode into the brain c. Subject the brain to a strong magnetic field d. Attach light-sensitive proteins to a virus (d)

Which of the following is a method to inactivate a brain area temporarily?

a. Stereotaxic instrument b. Transcranial magnetic stimulation c. Lesion d. Ablation (b)

Suppose someone demonstrates that a particular brain area becomes active when people listen to music. What would be a good way to test whether this brain area is really specialized for music perception?

a. Test whether the fMRI recordings are stronger in people who enjoy music more than others do b. Test whether the brain area becomes silent when someone is not listening to music c. Examine the size of this brain area in nonhuman animals d. Test whether we can use fMRI recordings to guess what kind of music someone is hearing (d)

What is one advantage of fMRI over PET scans?

a. The fMRI technique measures activity on a millisecond-by-millisecond basis b. The fMRI technique does not require inserting an electrode into the head c. The fMRI technique does not expose the brain to radioactivity d. The fMRI technique identifies which brain areas are most active at a given moment (c)

Removal of a brain area, generally with a surgical knife is known as an __________.

ablation

Thus far, it appears that the brain feature most strongly correlated with IQ in humans is the __________.

amount of gray matter

How does the method of transcranial magnetic stimulation of brain areas differ from magnetic inactivation?

brain activation results from mild, brief magnetic stimulation

Which technique is dependent upon the release of oxygen from hemoglobin molecules?

fMRI

Which method would be best suited to answer questions about which specific brain areas in humans are activated while performing a mental task?

functional magnetic resonance imaging (fMRI)

Applies a powerful magnetic field to align all the axes of rotation, and then tilts them with a brief radio frequency field

magnetic resonance imaging (MRI)

Measures faint magnetic fields generated by brain activity

magnetoencephalograph (MEG)

A stereotaxic instrument would most likely be used for __________.

placing an electrode in the brain

An electroencephalograph measures __________.

the average activity of the cells in a given region of the brain

Optogenetics

using light to control a limited population of neurons

Computerized axial tomography creates an image from __________.

x-rays