HM

HM

1. 1953

2. Due to severe seizures, had large parts of brain removed to stop the seizures.

   • Removed most of HM's anterior temporal lobe, included the hippocampus (the brain's memory centre from both sides of his brain).

3. He could now converse normally with someone he had just met, but upon that person leaving the room and returning it was as if HM had never met them before.

   • Completely forgetting the conversation they had just had moments earlier.

4. The seizures stopped

5. Could still recall memories from before operation: 1929 stock market crash, WWII and his family. But could no longer form new memories.

6. Became clear that a person can lose their ability to form new memories yet still retain their intellect, personality and carry on with normal life.

7. Solidified the notion that memory was a discreet brain function independent of language, movement and perception.

   • As he didn't have perceptual language or psychiatric defects.

8. Fact that he could retain info for several mins meant he had a proper working memory.

   • Long term memory also still intact, due to him being able to recall events prior to the operation.

9. Fact that he retained both short and long-term memories but could not form NEW long-term memories indicated that the hippocampus was crucial in converting working memory ruminations into long life recollections.