Lecture 2 Flashcards
Discuss one of the first approaches of researching brain anatomy
Phrenology was one of the first approaches. It related your skull anatomy to behaviour. It did this by compartmentalising areas of the skull based on the bumps. However, nowadays we relate the brain anatomy to behaviour, not skull anatomy.
Describe a CT or CAT scan
Give a disadvantage
You put your head in a cylinder, one side is an x-ray source the other is an x-ray detector. This cylinder rotates around your head and all the pictures are combined into one. In a CAT scan, sometimes dye is injected to increase image contrast. However, this method can be unhealthy as you’re being exposed to radiation.
List the current methods of exploring brain anatomy
CT/CAT scan
MRI scan
List the current methods of recording brain activity
PET scan EEG ERP MEG fMRI Microelectrode recordings
Discuss a PET scan
Give some disadvantages
It records the emission of radioactivity from injected chemicals. The chemical accumulates in particular areas of the brain and detectors pick up on where it’s accumulating. You can do this before and after a stimulus to see which areas of the brain respond to particular stimuli.
Disadvantages: Radioactive substances are being used, it’s expensive and it has low temporal resolution.
Discuss MRI scans
Give 2 disadvantages
It uses a powerful magnetic field which makes use of the magnetic probabilities of hydrogen in your body. The magnet flips the hydrogen atoms and when they return to their original state a signal is emitted. Different tissues emit the signal at different rates to produce an image.
Disadvantage: The person must lie motionless and you have to be in an enclosed space. However, this can be solved with sedatives.
Discuss EEGs
Electrodes placed on the scalp record the electrical activity of many neurons. They record the spontaneous activity. Up to 264 electrodes are used.
Discuss ERPs
Give 2 disadvantages
These are measured via EEGs. An ERP (event related potential) is when you record the brain’s response to a stimulus or event. This can reveal information that self reports can’t as it follows information on a millisecond scale. This is repeated many times to get an average and is then compared to a control.
Disadvantages: Its spatial resolution is poor and it’s hard to see where in the brain the electrical activity occurred.
Describe Costa’s study
It involved males and females self reporting arousal in response to nudes of the opposite sex. Males reported arousal and females reported neutral. However, they both had strong ERPs suggesting they were both aroused.
Discuss MEGs
Give disadvantages
It works in the same way as an EEG, however, they’re recorded via extremely sensitive devices in a helmet. This method has excellent temporal resolution and better spatial resolution due to no interference of the skull.
Disadvantages: It’s more expensive than the EEG, it’s sensitive to movement, the signal needs to be shielded from other magnetic sources like the earth, cars etc.
Discuss fMRI
Give disadvantages
It works the same as MRI except it’s based on haemoglobin. After neurons increase their activity in brain regions, the amount of haemoglobin with oxygen increases. This means that the hydrogen atoms emit a stronger signal. This can then be used to compare two conditions. This is a very powerful method.
Disadvantages: It’s hard to find a good condition for comparison.
Give examples of when fMRI scans are used
To determine which half of the brain is dominant for language, to determine what type of surgery and how much brain tissue should be removed for epileptic patients, investigating visual spatial processing, to learn how specific brain functions develop.
What is cognitive subtraction?
It’s an approach where you find two conditions that differ only in the aspect you’re looking at. So if the brain area lights up, it’s in response to the stimuli. However, you need to consider that multiple areas might be necessary for the process.
Discuss microelectrode recordings
Give a disadvantage
A thin electrode is inserted into the brain. If it’s for research then it can only be used on animals. It can only be used on humans for neurological surgeries. It can study the electrical activity within one neuron, the electrical activity outside of a neuron or the activity of many nearby neurons. It has good spatial and temporal resolution.
Disadvantage: It’s an invasive technique.
Studying the effects of brain damage can tell us how the brain correlates with behaviour/function. Give examples of this
Studying people who have suffered a stroke and see what behavioural impairments they get. However, there is a lack of control and more than one area might b damaged by the stroke.
You can find links between brain area and function. This can be found via double dissociation.
You can create lesions in lab animals or ablations (removing part of the brain) to see its effect. The types of lesions are: aspiration lesions, RF lesions, knife cuts and cryogenic blockades.
