HM Technical

On December 2nd, 2009 we began slicing the brain of the amnesic patient H.M. into giant histological sections.

Postmortem MR imaging has revealed widespread deep White Matter pathology localized primarily in the frontal lobes. Histopathological staining will elucidate the nature of the abnormal WM signal revealed by MRI sequences; however, for the time being (in Phase 1), our main concern is histotechnical.

Section thickness determines the total number of slices and it is an extremely important parameter for subsequent histo-pathological staining and analysis.

We believe that the enormous attention that was devoted to patient H.M. when he was living and generously served as a keen research subject ought to be matched by a similarly involved study of his brain.

Once the collection of tissue slices from the brain of patient H.M. was safely archived cryo-genically, the work towards reconstructing a neurological picture of the case began.

Histological sections are going to be stored cryogenically in serial order. We have set the goal to acquire an image of the specimen’s blockface before each section is collected. To that effect, in order to eliminate the possibility of human error during the very long procedure, we have made image acquisition completely automatic.

The decision to cut the brain as one single block was taken on account of the fact that gross dissection of the sample into smaller blocks or thick slabs to be processed separately amounts to the inevitable loss of (considerable) tissue.

As the brain of Patient H.M. was cut, histological slices were being collected in serial order in 36-well compartment boxes containing 0.1 M phosphate buffer solution. The next step is to store all tissue slices long-term in the freezer in a solution that will preserve the morphology and molecular milieu of the tissue.

We have received many inquiries regarding our methods during and after the cutting of the brain of patient H.M. that occurred from December 2nd through December 4th. We have addressed the most frequently asked questions and we will continue explaining our protocols in the future.  We are very pleased and honored to be able to share our research efforts with the public as well as the scientific community.