Cognitive Connie
Förstå patient h.m. och hippocampus
Henry Molaison — känd under decennier i den vetenskapliga litteraturen enbart som H.M. — genomgick en bilateral medial temporallobsresektion 1953 vid 27 års ålder, utförd av neurokirurgen William Beecher Scoville på Hartford Hospital. Operationen avsåg att lindra svår, behandlingsresistent epilepsi. Den lyckades i hög grad med detta syfte, men de kognitiva konsekvenserna var förödande och vetenskapligt omvälvande: Henry lämnades med en djupgående, permanent anterograd amnesi — en nästan fullständig oförmåga att bilda nya långtidsminnen av deklarativ art.
Nyckelpersoner
William Beecher Scoville
1906–1984Neurosurgeon who performed H.M.'s bilateral medial temporal lobe resection in 1953. Recognising the cognitive consequences of the procedure, Scoville collaborated with Milner to document and publish the findings, providing the neuroscience community with an unprecedented case study.
Brenda Milner
1918–presentNeuropsychologist at the Montreal Neurological Institute who conducted the defining studies of H.M., establishing the hippocampus's role in declarative memory consolidation and discovering the preservation of procedural learning in anterograde amnesia. Now in her second century and still active, she is widely considered one of the founders of cognitive neuroscience.
Henry Molaison (H.M.)
1926–2008Unknowingly became the most studied individual in the history of neuroscience after his 1953 surgery left him with profound anterograde amnesia. His cooperation with researchers over five decades enabled the scientific community to map the hippocampus's role in memory consolidation and to discover the multiplicity of memory systems.
Suzanne Corkin
1937–2016MIT neuroscientist who studied H.M. from the 1960s until his death in 2008, conducting the later decades of research and coordinating the post-mortem brain analysis. Her 2013 book Permanent Present Tense provided the definitive popular account of H.M.'s life and what it taught neuroscience about memory.
Nyckelbegrepp
Anterograde amnesia↗
The inability to form new long-term memories after brain injury, while pre-injury memories remain largely intact. H.M.'s anterograde amnesia was nearly total for declarative (explicit) memories: he could not remember new facts, events, or people he had encountered since his 1953 surgery. His case defined the hippocampus as necessary for the consolidation of new declarative memories.
Retrograde amnesia
Loss of memories formed before brain injury. H.M. showed a temporally graded retrograde amnesia: memories from the years just before his surgery were more affected than memories from earlier in his life. This temporal gradient — sometimes called Ribot's Law — is consistent with the idea that memories become less hippocampus-dependent over time as they are consolidated into cortical networks.
Memory consolidation↗
The process by which newly encoded memories are stabilised into long-term storage. H.M.'s case demonstrated that the hippocampus plays a critical role in consolidation — the transfer of information from a labile, temporary form into a durable long-term representation — but is not the ultimate storage site for remote memories, which appear to be distributed across neocortical regions.
Declarative (explicit) vs procedural (implicit) memory
H.M.'s most theoretically important finding was the dissociation between declarative and procedural memory. Despite his profound anterograde amnesia for declarative memories (facts and episodes), he showed normal learning and retention of motor skills (like the mirror-drawing task) across sessions — even though he had no conscious recollection of having practised. This demonstrated that skill learning relies on different neural structures (striatum, cerebellum) rather than the hippocampus.
Episodic vs semantic memory
Episodic memory is memory for personally experienced events situated in time and place; semantic memory is general factual knowledge divorced from personal experience. H.M. had severely impaired episodic memory acquisition — he could not place himself in remembered events. Some semantic learning was preserved. The distinction between episodic and semantic memory systems, and their different hippocampal dependencies, was sharpened by H.M.'s case and subsequent neuropsychological research.
Short-term vs long-term memory↗
H.M. showed essentially normal short-term (working) memory — he could hold information in mind for seconds or minutes as long as he rehearsed it. The moment his attention shifted, however, the information vanished. This demonstrated that short-term memory does not require the hippocampus, and that the process converting short-term to long-term memories (consolidation) is the specifically hippocampus-dependent step.
Brenda Milner's contributions
Canadian-British neuropsychologist Brenda Milner conducted the definitive neuropsychological studies of H.M. over five decades, beginning in 1955. Her 1957 paper with Scoville established the hippocampus's role in memory consolidation and is one of the most cited neuroscience publications in history. Her 1962 discovery of H.M.'s intact procedural learning was equally foundational — it inaugurated the study of implicit memory systems and transformed the conceptual landscape of memory research.
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Vanliga frågor
Vem var Patient H.M. och varför är han berömd?+
Patient H.M. var Henry Molaison (1926–2008), en amerikansk man som genomgick hjärnoperation 1953 för att behandla svår epilepsi. Operationen tog bort större delen av hippocampus och omgivande mediala temporallobsstrukturer, vilket lämnade honom med en djupgående och permanent anterograd amnesi — han kunde inte längre bilda nya långtidsminnen av deklarativ art. Han blev den mest studerade individen i neuroscience-historiken eftersom hans fall visade, för första gången, att hippocampus är avgörande för att omvandla korttidsminnen till långtidsminnen.
Vad är skillnaden mellan anterograd och retrograd amnesi?+
Anterograd amnesi är oförmågan att bilda nya minnen efter en hjärnskada — du kan inte minnas vad som hände efter skadan. Retrograd amnesi är förlusten av minnen från före skadan. H.M. hade svår anterograd amnesi (han kunde inte minnas något som hände efter hans 1953-operation) och en mildare temporalt graderad retrograd amnesi (nyliga pre-operationsminnen var mer påverkade än äldre).
Vad avslöjade H.M:s fall om minnet?+
H.M:s fall producerade tre grundläggande insikter: (1) Hippocampus är nödvändig för konsolidering av nya deklarativa minnen (fakta och episoder) till långtidslagring. (2) Korttidsminne och långtidsminne är distinkta system — H.M. kunde hålla information i minnet i sekunder men kunde inte överföra det till långtidslagring. (3) Minnet är inte ett enda system — H.M. visade normal inlärning av motoriska färdigheter trots att han inte hade något medvetet minne av träningspassen, vilket avslöjar att implicit (procedurellt) minne förlitar sig på olika neurala strukturer.
Källor
Senast granskad juli 2025- 1.
Scoville W.B. & Milner B. (1957). Loss of recent memory after bilateral hippocampal lesions. Journal of Neurology, Neurosurgery and Psychiatry, 20(1), 11–21.
+Om den här källan
Original case report of patient H.M., establishing the hippocampus as critical for forming new declarative memories.
- 2.
Corkin S. (2002). What's new with the amnesic patient H.M.? Nature Reviews Neuroscience, 3(2), 153–160.
+Om den här källan
Comprehensive update on H.M.'s cognitive profile, summarising decades of testing with the world's most studied amnesic patient.