Methods to Measure the Brain

Question 1

computed tomography (CT)

Answer 1

• Like x-ray but from all possible directions
• Measures radiation absorption rates (bones absorbs a lot, blood absorbs very little)
• Making a gray scale with the absorption rates to match value to color to reconstruct the
  image
• There’s a pulse and a detector on the other side, so you get a pulse and then a signal and
  by that you know how much to measure back with the detector

Question 2

benefits of CT

Answer 2

assesses where damage is (high spatial resolution), not invasive

Question 3

cons of CT

Answer 3

low temporal resolution

Question 4

Magnetic Resonance Imaging (MRI)

Answer 4

Magnet measures relaxation of tissues back to the alignment with the scanner
- Different tissues have different relaxation rates (gray scale)

Question 5

pros of MRI

Answer 5

good spatial resolution, can do it over and over again, non-invasive

Question 6

cons of MRI

Answer 6

no temporal resolution

Question 7

Single Dissociation

Answer 7

one part of the brain leads to a impairment in one function (limited)
- Have damage in a region so patient cannot perform task X but can still perform
task Y
Ex: patient can’t recognize faces, but can recognize objects so do a test with patients who
have the same damage and a control group

Question 8

double dissociation

Answer 8

• solves for specificity of complex problems
• Two regions and you show how each area affects the other and vice versa
• Allows you to infer that a specific part of the brain is engaged in a specific part of
  cognitive processing
• Two different areas working in tandem with each other

Question 9

Transcranial Magnetic Stimulation (TMS) – Induced Lesion Method

Answer 9

• The coil is held to the head and releases a small magnetic field to the brain—> that is
  higher than normal—> which interferes with the functioning of the neurons by preventing
  them from firing action potentials
• Creates a short-lived, reversible legion
  Ex: delivering pulse with different timings of showing a letter: shows that the brain
  processes information differently based on timing

Question 10

TMS pros

Answer 10

Reversible legion; high temporal resolution

Question 11

TMS cons

Answer 11

superficial surface of the brain; have to keep relatively simple tasks

Question 12

Event-Related Potential (ERP) and EEG

Answer 12

-Functional Imaging
-Measures average electrical response
ex: generate a sounds and then take
the electrical activity in response to that sounds,
and do it again and again until left with an
average ERP–> Average gets rid of random fluctuations

Question 13

EEG pros

Answer 13

High temporal resolution

Question 14

EEG cons

Answer 14

Inverse problem, poor spatial resolution

Question 15

inverse problem

Answer 15

trying to solve back but not knowing exactly where the signal came
from –> poor spatial resolution

Question 16

Magnetoencephalography (MEG)

Answer 16

• Same as ERP but instead of picking up electrical activity, it picks up magnetic energy
• Also has a more accurate solution to inverse problem

Question 17

fMRI (functional Magnetic Resonance Imaging)

Answer 17

• Measure blood oxygenation level dependent (BOLD) signal
• Not a direct measure of neural activity → measuring oxygen of blood
• As neural activity increases → blood oxygen increases → the fMRI signal increases

Question 18

BOLD

Answer 18

(blood oxygenation level dependent) → Amount of oxygenation in the tissue (change of oxygen in the brain)

Question 19

fMRI Baseline

Answer 19

no baseline because neurons are always firing

Question 20

Assumption of pure insertion (subtracting logic)

Answer 20

you can insert a component process into a task
without disrupting the other components
- T1: view intact objects
- T2: view scrambled objects
- T2-T1 = “object” areas

Question 21

fMRI pros

Answer 21

very good spatial resolution

Question 22

fMRI con

Answer 22

poor temporal resolution

Question 23

single cell recording

Answer 23

Measures baseline activity of cell, changes to experimental manipulation, and what
increases/decreases firing

Question 24

single cell recording pro

Answer 24

high spatial and temporal resolution

Question 25

single cell recording con

Answer 25

only one cell, very time consuming