In a series of studies, researchers tested patient H.M., who had his hippocampus and surrounding medial temporal lobe surgically removed to treat severe epilepsy. After surgery, H.M. could recall events from before the operation and could carry on a conversation, but he could not remember new acquaintances even after meeting them dozens of times. Surprisingly, he could learn new motor skills like mirror tracing, even though he had no memory of practicing them.
H.M.'s inability to form memories after surgery, while retaining pre-surgery memories, is best classified as:
- Acheck_circle
Anterograde amnesia
- B
Retrograde amnesia
- C
Infantile amnesia
- D
Source amnesia
Explanation
Anterograde amnesia is the inability to form new memories after a brain injury or surgery while older memories remain intact. Retrograde amnesia involves losing memories from before an event. Source and infantile amnesia describe different memory phenomena.