Psychology BLOA: Localisation of Function, HM Study

Psychology BLOA:
Localisation of Function
HM Study
Henry Molaison

Henry Molaison, commonly known by psychologists as 'HM', fell off his bike when he was 7 years old, and injured his head

When HM was 10 years old he began experiencing epileptic seizures

By the age of 27, HM was having so many seizures that he could not live a normal life
Background Information
The case study of HM
This case study is important because it provided evidence that there are different memory systems of the brain
Scoville & Milner (1957)
Scoville performed experimental surgery on HM to stop the seizures

The seizures did stop, but HM experienced both retrograde and anterograde amnesia for the rest of his life

This was a result of a little too much temporal lobe, hippocampus and surrounding areas being removed



Corkin et al. (1997)
Corkin et al. did a MRI scan of HM's brain to get a precise image of the brain damage

They discovered that parts of the temporal lobe, including the hippocampus and the amygdala, were missing, but also that the damage was not as extensive as previously believed

These areas tend to be pathways for memory


HM's Memory
Now, HM could not transfer new episodic or semantic memories (explicit memories) to his LTM

However, HM could form new long term procedural memories (implicit memories)

HM could also carry on normal conversation (working memory) but would forget it almost immediately
What can be learned
about localisation of function of the brain in relation to memory from the case study of HM?
Hippocampus and surrounding areas are vital in converting memories from STM to LTM

Hippocampus is a temporary rather than permanent memory store, as HM could retain memories of before surgery

Procedural memories are not stored via the hippocampus

The brain has several memory systems

Memory processes are much more
complex than originally believed

Evaluation of the case study of HM
Strengths
HM participated in research for more than 50 years

This longitudinal case study has contributed enormously to the knowledge of how memory processes are related to specific brain areas

For example:



Medial temporal lobes
Important for the forming, organisation, consolidation, and retrieval of memories
Cortical areas
Important for LTM, for facts and events (semantic or episodic memories), and the use of that information in daily life
Hippocampus
Procedural memories are NOT processed by the hippocampus
Limitations
HM was not able to remember all the time he participated in the research and therefore it could be argued unethical

(however, the findings of this study are very important and this justifies it)

It could be difficult to generalise a case study to a larger population

(however, findings from similar case studies suggest the same outcome)