Hippocampus
Core of H.M.’s medial temporal resection story.
The anatomical lesson of Milner’s era is medial temporal: hippocampus and neighbouring cortex for declarative encoding — not the whole brain as a single memory store.
Later imaging refined which subregions matter; the original dissociation still anchors teaching maps.
Structures
Entorhinal / perirhinal cortex
Neighbour cortices also implicated in declarative memory.
Amygdala (partial in H.M.)
Resected tissue included amygdala; affective lessons are nuanced.
Frontal lobes
Milner’s wider programme on strategy and memory control.
Basal ganglia (skill learning)
Systems supporting procedural gains H.M. could show.
Neocortical remote stores
Where consolidated remote memories can survive MTL loss.
Pathways
Perforant / trisynaptic circuit
Classic hippocampal loop for encoding.
MTL–neocortical consolidation paths
Framework for why remote memories can remain.
Frontostriatal skill loops
Support procedural learning dissociated from episodes.
Fornix / diencephalic memory routes
Other amnesia anatomies that refine the MTL story.
Landmarks
Scoville resection diagrams
Historical surgical maps of H.M.’s lesion.
Mirror-tracing task
Iconic demonstration of intact skill learning.
Delayed recall batteries
Quantify anterograde declarative loss.
Post-mortem / MRI re-evaluations
Later anatomy refined what was actually removed.
Open atlas neighbours: hippocampus, entorhinal, amygdala, frontal.
Sources & research
- Loss of recent memory after bilateral hippocampal lesionsLandmark H.M. memory loss report.DOI
- The legacy of patient H.M. for neuroscienceLegacy review of patient H.M.DOI
- Cognitive neuroscience and the study of memoryCognitive neuroscience of memory synthesis.DOI
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