Biological Overview

Question 1

What is Computerised axial tomography (CAT) or Computed tomography (CT)

Answer 1

Many x-rays used to be used on the brain. It wasn’t until the 70’s until x-rays were done multiple times to view the brain. a physician injects a dye into blood and then places a persons head into CT scanner. X-rays are then passes through the head and recorded by devices on the other side. From this, a computer constructs images of the brain.

Question 2

What is Magnetic Resonance Imaging (MRI)

Answer 2

It applies a powerful magnetic field (25,000 times the earths) which aligns/flips all the axons. When this field is turned off, the atoms release electromagnetic energy as they relax and return to their normal state. By measuring their energy, MRI forms an image of the brain. it can be sued to measure different tissues.

Question 3

What is a disadvantage of CAT?

Answer 3

There is exposure to radiation

Question 4

What is a disadvantage of MRI?

Answer 4

The person has to stay motionless in quite a scary piece of equipment. This can be hard to use on children.

Question 5

What is Electroencephalogram (EEG)?

Answer 5

This records the electrical activity of neurons. Electrodes are placed on the skull (can be a few, can be 100’s) and electrical activity in the brain is recorded. The electrodes measure cells activity underneath that electrode. This can record spontaneous behaviour or event related potential.

Question 6

What is Event Related Potential (ERP)?

Answer 6

This uses Electroencephalogram (EEG) but instead of recording spontaneous behaviour, it measures activity in response to a stimulus. It allows information to be processes on the millisecond scale.

Question 7

What is an example of the use of Electroencephalogram (EEG) and/or Event Related Potential (ERP)?

Answer 7

Costa et al. (2003). males and females were exposed to naked images of the opposite sex. Males reported they were aroused but women didn’t. However, brain activity suggested both sexes were aroused by the images.

Question 8

What is Magnetoencephalogram (MEG)?

Answer 8

This is similar to EEG. this record magnetic fields generated by electrical activity of neurons. Pt’s wear a helmet which is an extremely sensitive. Other electrical devices which give off magnetic waves or energy cannot be in the same room. Its less used because its more expensive and difficult to use.

Question 9

What are the advantages and disadvantages of Magnetoencephalogram (MEG)?

Answer 9

Spatial resolution as good as EEG, excellent temporal resolution
However, more expensive than EEG, sensitive to movement, small signal that needs to be shielded from other magnetic sources

Question 10

What is Positron-Emission Tomography (PET)?

Answer 10

his records the emission of radioactivity from injecting chemicals into the blood. The blood will go to areas of the brain which are being used. Detectors surrounding the head measure (radiation)the radioactivity emitted from each brain activity. Gamma radiation is detected. Can see what areas of the brain are activate.

Question 11

What are the disadvantages of Positron-Emission Tomography (PET)?

Answer 11

radioactive substances, low temporal resolution, expensive

Question 12

What is Functional Magnetic Resonance Imaging (FMRI)?

Answer 12

This is similar to MRI (magnetic field and radio frequency pulses) but doesn’t just measure tissue of brain but activity based on blood flow. The amount of haemoglobin with oxygen increases in active brain areas after the neurons have increased their activity. when a part of the brain become activated, first the blood vessels dilate to allow more blood flow and then as the brain area uses oxygen, the % of haemoglobin with oxygen decreases.

Question 13

What is cognitive subtraction?

Answer 13

The subtraction principle: Recording a brain whilst doing an activity (e.g. reading) and comparing it with the brain doing nothing wont measure a difference. There needs to be a task and a control that is similar. For example the task could be reading and the control could be looking at a piece of paper with gibberish that you cant read. Then subtracting the control from the task condition will show the difference.

Question 14

How does cognitive subtraction work with patients in a coma?

Answer 14

When patients are in a coma, some patients wake up and say they were awake the whole time but couldn’t move and were trapped in their body. To measure this, pt’s were asked to do two different tasks (cognitive) and measure their responses. Some patients were able to perform these cognitive tasks- showing they are still awake

Question 15

What happens when there is damage to Broca’s area?

Answer 15

Broca’s area is important in producing speech.Patients this with damage to their Broca’s area can understand speech but are unable to produce speech.

Question 16

What happens when there is damage to Wernicke’s area?

Answer 16

Wernicke’s area is responsible for speech processing and understanding language. patients with damage to this area of the brain can speak- however also at first it will sound normal, none of it will make sense. Patients cannot understand language.