The following list of locations provide a walk through the brain of H.M. Select each panel to see the corresponding location.
In the hallmark 1952 surgery, Dr. Scoville used a spatula to lift the frontal lobes of the brain to gain access to the hippocampus. In the process, a small area of the frontal lobe was damaged.
Dr. Scoville removed much of the hippocampus bilaterally (on both sides of the brain), and in some cases all that remains is a cavity and a small bit of unhealthy tissue in the surrounding area.
The hippocampal lesion in the same tissue slice on the other side.
Regions of the hippocampus spared in the procedure. The example image shows the region of the dentate gyrus.
One advantage of tissue staining is that certain regions, such as the entorhinal cortex (difficult to identify on MRI), can be easily spotted by cell features which allows for a more extensive examination into the extent of the lesion.
Patient HM also presented with extensive damage in the deep white matter (regions of the brain that contain the pathways which connect nerve cells).
A main challenge of the examination of patient HM is distinguishing between the pathology present from HM's epilepsy (such as the lesion in the cerebellum pictured here) and that resulting from the surgery.
Radiology images (MRI, T1) are used as a standard tool in clinical neuroscience. They can be tailor-made to pickup tissue properties, are non-invasive, but have low resolution.