The lab opened in 1966 when Dr. Alan Peters assumed the position of Waterhouse Professor and Chairman of the Department of Anatomy, as it was known then. The focus of the lab was electron microscopy, the goal, to characterize the fine structure of synapses and cell types, neurons and neuroglia, in the cerebral cortex.

Over the past several years we have examined the organization of neurons in cerebral cortex, with emphasis on the pyramidal cell modules. But more recently our focus has been on the effects of aging on primary cerebral cortex and white matter.

The pyramidal cell module By combining the results of careful cell counts, with antibody studies we have defined the pyramidal cell module, which we propose to be the smallest functional unit of cortex.(Figure A)

The cells in figure B and C are stained with an antibody to Calbindin. Photographed with Nomarsky optics, (figure B) bundles of axons are clearly visible as they cascade below the cell bodies. When visualized with a fluorescent marker and viewed in cross section on the confocal microscope (figure C) each bundle of axons appear as a brightly staining cluster.

With the addition of immunocytochemistry and confocal microscopy we have been able to modify the original diagram to include some of the inhibitory neurons in the modules (figure D).

We are now focusing on the effects of normal aging on the cerebral cortex and white matter. To carry out these studies we use electron microscopy, confocal microscopy, antibodies, and stereology, to try to determine which of the morphological changes that occur with age are responsible for the cognitive decline exhibited by aging primates.

This pair of electron micrographs illustrates some of the changes that occur in visual cortex with age. On the far left is an example of young, normal, myelinated axons. In an aging cortex, the myelin sheaths exhibit changes such as splits, ballooning, and dark cytoplasmic inclusions.