The Brain Observatory was selected to examine of the most important brain in neuroscience history, H.M’s.

The results and data from the our study, augmented by historical information on the life and science of patient HM, are now available at

Henry G. Molaison was a young man who, in the summer of 1953, became profoundly amnesic after an experimental surgery against his severe epileptic seizures. The surgery was directed at the Medial Temporal Lobes (MTL) of Henry’s brain with the goal of removing the hippocampus and neighboring structures. That is when Henry became Patient H.M. who would, for the rest of his life, take part in scientific experiments that fundamentally advanced our understanding of how memory works.

Henry G. Molaison (left) and Dr. Scoville (right)

Henry G. Molaison (left) and Dr. Scoville (right)

Patient H.M. died December 2nd, 2008. Dr. Annese and his research team at The Brain Observatory were selected and awarded a grant from the National Science Foundation to examine his brain postmortem. Using a novel procedure developed at The Brain Observatory that combined physical dissection and 3D imaging researchers created a microscopic model of the whole brain and discovered that a significant portion of the hippocampus was preserved in both hemispheres and still working after the 1953 surgery. These results countered decades of speculations that this structure had been completely destroyed or atrophic. The study also revealed a small, previously unreported, lesion in the left frontal cortex.

The results and data from the original study, augmented by historical information on the life and science of patient HM, are available for research and education at

We published the results of our study in the journal Nature Communications in January 2014. In this article we demonstrated that in fact, half of H.M.’s hippocampus had survived the 1953 surgery. We used the 3D virtual model of the brain to reconstruct the dynamics of the surgery and established that the brain damage above the left orbit was plausibly created by Dr. Scoville when he lifted the frontal lobe with his spatula, in order to reach into the medial temporal lobes.

The article also describes the general neuropathological state of the brain via multiple imaging moralities. H.M. was 82 when he died, naturally the brain had aged considerably and it shows several pathologic features, some severe, that contributed to his cognitive decline.