Temporal lobes critical to human memory
William Scoville, neurosurgeon obtained direct evidence for the role of temporal lobe in human memory. Scoville removed the medial temporal lobe and the hippocampus from an epileptic patient- called HM.
At age 9 he was struck by someone on a bicycle, he fell to the ground and suffered a head injury that led t o epilepsy.
By age 20 severely incapacitated
It was thought the epilepsy originated within the medial temporal lob
Surgery succeeded in relieving HM of seizures, but also left him with severe memory loss
Brenda Milner’s Studies of HM
- HM had good ST memory – ST memory involves the PFC, which hadn’t been removed
- Could carry on a normal conversation if it didn’t last too long or involve too many topics
- Good long-term memory for events that occurred before surgery – language skills good, IQ good, recollection of childhood events
- Could not convert new ST memory into new LT memory Examples: Less than 60 minutes after eating couldn’t remember eating, after 30 years of interaction with Brenda Milner he still failed to recognize her each time she entered a room and greeted him, didn’t recognize himself in recent photos because he remembered himself only as he appeared prior to surgery.
“ He couldn’t acquire the slightest new piece of knowledge. He lives today chained to the past, in a sort of childlike world. You can say his personal history stopped with the operation.” Milner commenting on HM (Kandel, 2006, p. 128)