Lecture 3 Flashcards
What is phrenology
The attempt to relate skull anatomy to behaviour
Give an example of phrenology
The skull is divided into compartments based on the bumps you can feel when touching a skull - compartments assigned to behaviours and characteristics
What does CAT stand for
Computerized Axial Tomography
What does CT stand for
Computed Tomographyh
What do CAT and CT scans do
Produce many x-ray photographs to create a scan of the brain. In CAT a dye is injected to increase image contrast
Name one disadvantage of CAT or CT scans
Exposure to radiation
What does PET stand for
Positron-Emission Tomography
How do PET scans work
Record the emission of radioactivity from injected chemicals. Chemical accumulates in certain brain regions. Detectors surrounding the head measure radioactivity emitted from each brain area. Images show which brain areas are active or inactive.
Name 3 disadvantages of PET scans
Radioactive substances. Low temporal resolution. Expensive
What does MRI stand for
Magnetic Resonance Imaging
Explain how MRI scans work
Makes use of the magnetic probabilities of the hydrogen in the body. Head is placed in magnet and hydrogen atoms align along the magnetic field. Radiofrequency pulse flips the hydrogen atoms and they return to original state and thereby emit a signal that is measured and used to form an image of the brain. Different tissues/substances emit energy with different speed and thus produce different images
Name one disadvantage of MRI scans
Person must lie as motionless as possible so it is therefore difficult for children and people who fear enclosed places
What does EEG stand for
Electroencephalogram
Explain what EEG’s do
Records electrical activity of neurons. Electrical activity recorded by electrodes placed on the scalp. Recording of spontaneous activity. Records activity from a large number of neurons - 32-264 electrodes are used.
Why do we record brain activity?
Allows us to follow information processing on the millisecond scale. Can reveal information that self-reports or overt responses can not.
What is a disadvantage of recording brain activity
Spatial resolution is poor so it is difficult to say where in the brain the measured activity actually comes from
What does MEG stand for
Magnetoencephalogram
How do MEG’s work
Similar to EEG. Records magnetic fields generated by electrical activity of neurons. Recorded by extremely sensitive devices mounted in a helmet. Spatial resolution is as good as EEG with excellent temporal resolution.
Name 3 disadvantages of MEG’s
More expensive than EEG. Sensitive to movement. Small signal that needs to be shielded from other magnetic sources.
What does fMRI stand for
Functional Magnetic Resonance Imaging
Explain how fMRI’s work
Same principle as MRI with magnetic field and RF pulses used to generate a signal. Based on haemoglobin - the amount of haemoglobin with oxygen increases in active brain regions a couple of seconds after the neurons have increased their activity. Stronger signals emitted from the hydrogen atoms in the brain areas with relatively more haemoglobin with oxygen. By comparing different conditions relative levels of brain activity can be measured and related to cognitive functions or behaviour
Name one use of fMRI
Determines which half of the brain is dominant for language
Name one application of recording brain activity
Relevance in epilepsy surgery: type of surgery, amount of brain tissue that is removed
Name one use of cognitive neuroscience
Investigation of the development of visual-spatial processing - can show how fMRI can be used together with behavioural test to learn more about the development of specific brain functions
