Deterioration axonal architecture in the left hemisphere's white matter below the Middle Frontal Gyrus demonstrated by myelin staining (Gallyas silver impregnation method). These lesions are frequent in the deep and subcortical white matter in the brain of patient H.M. They are likely not a direct result of the original surgery but rather related to ageing and vascular disease. Widespread MRI hyper-intensities reflecting the underlying pathology are also evident in the radiologic images.

Nearest Nissl-Stained Section in the Atlas: 703


Detail of the lesion described above (20 x magnification). The loss of axons and demyelination compared to regions of intact white matter is evident. In addition, Individual axons show typical 'ballooning' that occurs as a result of degeneration.


Haematoxylin and Eosin Staining (H&E) staining showing severe white matter degeneration below the Middle Frontal Gyrus. It is very likely that the lesion has developed late in patient H.M.'s life due to hypertension. Tissue is missing altogether at the core of the lesion.

Nearest Nissl-Stained Section in the Atlas: 793


Anterior portion of the surgical lesion in the left temporal lobe. H&E staining. The lesion extends into the white matter as demonstrated by the pallor of the stain.

The cortex of the Inferior Temporal Gyrus shows normal layering. Dorsally, in the Planum Polare the supragranular layers of the cortex show degeneration.

Nearest Nissl-Stained Section in the Atlas: 883


The Inferior Temporal Lobe in the right hemisphere shows an atypical high concentration of amyloid plaques (also hallmark of Alzheimer's disease). According to the protocol, the tissue is impregnated with silver salts in solution. The salts 'attach' only to particular structures, or proteins, like the amyloid beta in the plaques. The sections are then treated with ammoniacal silver, and then 'developed' just like photographic plates (when photography was not digital) using a reducing solution to metallic silver that is visible in the tissue even at very low magnification. It is clear that patient H.M. did not develop Alzheimer pathology as he aged.

Nearest Nissl-Stained Section in the Atlas: 1207


Bielschowski staining did not reveal plaques or tangles in the hippocampus. This stain is used to confirm the clinical diagnosis of Alzheimer's disease. According to the protocol, the tissue is impregnated with silver salts in solution. The salts 'attach' only to particular structures, or proteins, like the amyloid beta in the plaques. The sections are then treated with ammoniacal silver, and then 'developed' just like photographic plates (when photography was not digital) using a reducing solution to metallic silver that is visible in the tissue even at very low magnification. It is clear that patient H.M. did not develop Alzheimer pathology as he aged.

Nearest Nissl-Stained Section in the Atlas: 1207