The Case of H.M. and the Neuroscience of Memory

Vocabulary and key concepts from the case study of Henry Molaison (H.M.), focusing on the neurobiology of memory and the roles of different brain regions.

Henry Molaison (H.M.)

The famous patient who provided amazing insights into how the brain works after his hippocampus was removed to treat severe seizures.

Dr. William Scoville

The renowned neurosurgeon who performed a risky surgery on Henry Molaison on September 1st, 1953, involving the removal of the hippocampus.

Hippocampus

A part of the limbic system associated with emotion that Brenda Milner's research showed is essential for memory consolidation.

Brenda Milner

The Ph.D student who studied H.M. and discovered that memory is not monolithic, identifying the distinction between short-term and long-term memory.

Short-term memory

The ability to retain information for a brief moment, such as H.M. repeating a number to himself for fifteen minutes.

Long-term memory

Permanent storage of information; H.M. was unable to form these new memories after his surgery.

Memory consolidation

The process where the hippocampus strengthens cortical synaptic connections and transfers memories back to the cortex for permanent storage.

Declarative memory

The type of memory involving conscious recall of names, dates, and facts, also referred to as "knowing that."

Procedural memory

The unconscious motor memory of skills like riding a bicycle or signing your name, also known as "knowing how."

Basal ganglia and cerebellum

The brain structures responsible for procedural memory that remained intact in H.M.'s brain.

Cortex

The part of the brain where immediate sensory data is temporarily transcribed and where the hippocampus eventually transfers memories for permanent storage.

Mirror star-tracing experiment

A famous test where H.M. improved his skill at tracing a star through a mirror over repeated trials despite having no conscious memory of previous attempts.

Digital map of H.M.'s brain

A map created after H.M.'s death by cutting his preserved brain into over 2000 individual slices to photograph individual neurons.