Penfield's study
- Localisation of function is an area of investigation that was of huge interest to the Canadian neurosurgeon, Wilder Penfield (1891-1976)
- During his time as a neurosurgeon Penfield treated people with epilepsy that involved tonic-clonic seizures
- Penfield developed what became known as the ‘Montreal procedure’, a technique that targeted specific neurons using electrical stimulation to destroy them (which would, in turn, reduce epileptic seizures)
- The following is a description of Penfield’s (1959) study:
- The sample consisted of individual patients with epilepsy, over the course of 30 years of investigation i.e. the research comprised a collection of more than 1000 case studies
- Each patient lay down and after having local anaesthetic Penfield stimulated different areas of their brain and recorded their responses
- When the somatosensory area was stimulated patients felt a tingling sensation or that they were moving (even though they remained lying down)
- When the visual area was stimulated patients said that they could see various objects, shapes and colours
- When the temporal lobe was stimulated patients reported feeling a range of emotions e.g. fear and also a sense of deja-vu
- Stimulation of the temporal lobe also produced memories which the patients reported as if the events were happening in the present (although they remained aware of where they were and of what was happening)
- In short, the patients appeared to be experiencing a range of hallucinations
- Penfield concluded that the temporal lobe is linked to memory storage and that the emotions/meaning of specific memories are stored differently in the brain i.e. the temporal lobe plays a role in interpreting emotion and memory
- In short, the temporal lobe acts as the interpretive cortex
Exam Tip
Penfield’s study is a NAMED STUDY on the AQA specification which means that you could be asked to answer specific questions on it.
You might want to consider the ethics of conducting research such as Penfield’s (this was the 1950s when ethics committees were not as stringent as they are now). Who knows what additional damage Penfield’s research could have inflicted on his patients? You don’t have to supply an answer to this question but it’s worth posing the question as part of your AO3 response.
Evaluation of Penfield’s study of the interpretive cortex
Strengths
- Penfield’s research has good reliability as he used precise, objective, clinical methods which were replicable
- Penfield contributed a huge amount of knowledge to the understanding of localisation of brain function
Weaknesses
- The findings are not generalisable to people who do not have epilepsy:
- The brains of epileptic patients may be different to non-epileptic brains due to the potential damage caused by epilepsy
- The use of an objective, clinical procedure means that the results lack validity as they cannot show the everyday functioning of a brain without electrical stimulation
Worked example
Here is an example of a question you might be asked on this topic - for AO2.
AO2: You need to apply your knowledge and understanding, usually referring to the ‘stem’ in order to do so (the stem is the example given before the question)
After each featured question there is a ‘model’ answer i.e. one which would achieve top marks in the exam.
Dr Seenit has replicated Penfield’s study of the interpretive cortex. She used 60 patients, 42 of whom reported that they experienced deja-vu during the procedure.
Question: What percentage of the 60 participants reported deja-vu?
Show your workings. [2]
Model answer:
- 70% of the patients reported deja-vu.
- 42 x 100 = 4200 ÷ 60 = 70.
