Biological Approach: Techniques

Question 1

Computerized Axial Tomography (CAT/CT)

Answer 1

• Works on the principle of differential absorption of X-rays.
• Quick, non-invasive method of studying brain structure.
• CAT has an advantage over standard X-rays because it simultaneously records images of hard and soft tissues and blood vessels.
• CAT scans can be made for people who have implanted medical devices.
• Limitation: involves some level of radiation exposure.

Question 2

Magnetic Resonance Imaging (MRI)

Answer 2

• Produce a high-resolution 3D image of the brain structure, but do not involve X-rays.
• Atomic nuclei (mostly hydrogen) can emit energy when placed in an external magnetic field.
• The relative distribution of atoms in the brain can be detected when the energy pulses are detected.
• Hydrogen atoms exist naturally in the body, but their concentration in different tissue types differs.
• Advantages: non-exposure to radiation, better resolution, and can detect abnormalities in the soft tissue.
• Disadvantages: expensive, issues for claustrophobic people, and people with metal items cannot undergo the procedure.

Question 3

Functional Magnetic Resonance Imaging (fMRI)

Answer 3

• Shows ongoing brain processes/activity.
• The subject is required to carry out some task in which periods of activity are alternated with rest periods.
• The signal that is analyzed by the fMRI scanner to reconstruct brain activity is
  known as the BOLD signal (blood-oxygen-level dependent).
• Spatial Resolution
• Temporal Resolution
• Advantages: excellent spatial resolution (1-2 mm) and ability to see brain processes.
• Disadvantages: poor temporal resolution and claustrophobia.

Question 4

Temporal Resolution

Answer 4

Shortest time in which changes in brain activity can be registered.

Question 4

Spatial Resolution

Answer 4

• It discriminates between nearby locations when zooming in.
• Measured in VOXEL, the minor brain particle seen through a scanner (1-5 mm).

Question 5

Positron Emission Tomography (PET)

Answer 5

• Uses blood flow as an indicator.
• Injecting radioactive glucose into the blood and measuring brain activity.
• Older technique
• PET scans have a decent spatial resolution of about 4 mm throughout the brain. However, its temporal resolution is only 30-40 seconds, so quick processes are not easily detected.
• Darker Color = Less Activity
• Advantages: good spatial resolution (4 mm), detects tumors, in conjunction with MRI/CT, diagnoses causes of dementia, and small scanners.
• Disadvantages include unclear images, slow temporal resolution, use complexity, tracer injection discomfort, and a lengthy procedure (1-2 hours).

Question 6

Electroencephalography (EEG)

Answer 6

• Measures electric potentials generated by neural circuits.
• Tracks cortical activity.
• When large groups of neurons fire synchronously, electric potentials generated by these impulses become detectable at the head surface.
• Electrodes are attached to the scalp at predetermined points and pick up the changes in the electric potential of the scalp areas.
• Used for sleep studies, epilepsy, and after a stroke or seizure.
• Advantages: perfect temporal resolution, low-cost, measures directly, mobile service, and non-invasive.
• Disadvantages: It requires experience to interpret it and is unsuitable for detecting activity in subcortical areas.

Question 7

Draganski et al. (2004)

Answer 7

• MRI
• Determine changes in brain structure in response to learning a simple juggling routine for three months.

Question 8

Freed et al. (2001)

Answer 8

• PET scans
• Study dopamine-producing cells in the brains of Parkinson’s disease patients.

Question 9

Fisher, Aron, and Brown (2005)

Answer 9

• fMRI
• Study brain processes in response to looking at the picture of a loved one.