Lecture on H.M. and the Study of Memory

Introduction to H.M.

• Date: September 1st, 1953
• Key Figures:
  • William Scoville: Renowned neurosurgeon
  • Henry Molaison (H.M.): Patient
  • Brenda Milner: Ph.D. student who studied H.M.
• Procedure:
  • Scoville performed surgery on H.M., removing the hippocampus to reduce seizures.

The Case of H.M.

• Background:
  • H.M. suffered from seizures following a childhood accident.
  • Surgery was performed by Scoville to treat seizures based on localization theory of brain functions.
  • Hippocampus removal led to virtual elimination of seizures.
• Immediate Outcomes:
  • No change in personality
  • Improved IQ
  • Severe memory impairment
  • Loss of ability to form new memories
  • Retention of short-term memory for immediate tasks

Contributions to Memory Research

• Findings by Brenda Milner:
  • Differentiation between short-term and long-term memory.
  • Different brain regions are involved in different memory types.
• Memory Formation Process:
  • Initial sensory data transcription by neurons in the cortex.
  • Transfer to the hippocampus for synaptic strengthening.
  • Consolidation in the cortex for permanent storage.
• H.M.'s Condition:
  • Initial impressions formed but not consolidated into long-term memory.

Memory Distinction Experiments

• Mirror Drawing Task:
  • H.M.'s performance improved with practice despite no recollection of previous attempts.
  • Revealed differences between declarative and procedural memory.
• Declarative vs Procedural Memory:
  • Declarative: Facts, names, dates
  • Procedural: Skills like riding a bike
  • Different brain structures involved

Legacy of H.M.

• Life and Death:
  • Lived till age 82 in a peaceful nursing home environment.
  • Extensively studied by over 100 neuroscientists.
• Brain Preservation:
  • Preserved and scanned after death.
  • Sliced into over 2000 pieces for digital mapping.
  • Documentation broadcasted to a large audience.

Importance of H.M.'s Case

• Impact on Neuroscience:
  • Memory research foundations
  • Distinction in memory types
  • Long-term influence on understanding of brain function
• H.M.'s Enduring Legacy:
  • Though personally affected by memory loss, his case has contributed significantly to scientific knowledge.