Ways of Studying the Brain

Define “temporal resolution”

The level of accuracy in identifying the exact location of brain activity in time (when activity happened)

Define “spatial resolution”

The level of accuracy in identifying the exact location of a brain structure or brain activity in space (where activity happened)

What are the 4 ways of studying the brain?

1) Post mortem dissection

2) FMRI (functional magnetic resonance imaging)

3) EEG (electroencephalogram)

4) ERP (event related potential)

How can we use post mortem dissections to study the brain?

Unusual brains are dissected such as brains that suffered trauma, or from individuals with mental illness. These brains are compared with neurotypical (healthy) brains

Broca’s area, responsible for language production was discovered using post mortem on a patient called Tan, who could only say “Tan” (expressive aphasia). Damage in an area of the frontal lobe was found after Tans post mortem dissection

Post mortem dissection - Evaluation

The high spatial resolution of a post mortem allows the study of microscopic brain structures down to the neuronal level

As post mortem’s aren’t conducted on the living brain, unusual behaviour in life and damage found is correlational (suggests a possible link but doesn’t prove cause and effect)

Post mortem techniques have been significant in the historical development of psychology’s understanding of brain functioning such as the discovery of language centres

How can we use FMRI’s to study the brain?

*Functional magnetic resonance imaging

FMRI detects blood flow in the brain. As more active areas of the brain need more blood (containing oxygenated hemoglobin with distinct magnetic properties), these active areas can be compared to low activation areas with lower blood supplies and displayed on an FMRI image

FMRI - Evaluation

An FMRI is a non-invasive and safe technique for experiments compared to options that use radiation like PET scanners

Poor temporal resolution as one image is taken every few seconds, this is ineffective as many brain processes are much faster than this

FMRI machines are expensive to build and operate. Also as the participants needs to be still, experiments with body movement are not possible

How we can use EEG’s to study the brain?

*Electroencephalogram

An EEG device is a collection of 22-34 electrodes that are attached to a cap and fitted to the scalp with conductive gel. The read out from each electrode is the sum total of activation in the brain cortex under the electrode. Displayed as a series of lines showing patterns called brain waves. Amplitude (size of waves) show brain wave intensity, frequency (distance between each wave) shows the speed of activation

EEG - Evaluation

Cheaper than alternatives such as FMRIs and are able to be used in experiments in which the participant moves

Very good temporal accuracy, measuring brain activation with a resolution measured in milliseconds

Poor spatial activity as the brain wave pattern is a sum of a large number of neurones in the cortex under the electrode. Also cannot detect activity deep within the brain

How can we use ERP’s to study the brain?

*Event related potential

ERP uses the same technique and equipment as EEGs, but presents a stimulus many times which creates a smooth curve of activation by combing the data in a process called statistical averaging. The brain waves peak and dip which shows exactly when cognitive processes in the brain happen after the stimulus is presented

ERP - Evaluation

ERP’s allow researchers to isolate and study how individual cognitive processes take place in the brain, while EEG’s record general brain activity

Like EEG’s, ERP’s have good temporal resolution with a millisecond sampling rate, but very poor spatial resolution

Some processes cannot be studied by ERP as they cannot be presented a large number of times with the same response