Medical School

A horizontal slice of the head of an adult man, from the Visible Human project. For this project, a cadaver was frozen and then sliced into thin sections, which were photographed at high resolution. This section shows the cerebral cortex and underlying white matter.

Mark West

Special Course Leader, Neurostereology
“Hippocampal Neurons”

Pyramidal neurons of the CA3 region of the hippocampus of a rat brain. The photo was taken at the Anatomical Institute, Aarhus University in 2004. Zeiss microscope. The section has been stained with the Golgi-Cox method which shows the details of the dendrites and axons of a small percentage of neurons in the region. It has been counterstained to show the location of the cell bodies of other pyramidal cells in the region, which appears as a blue layer.

(via dryeffects)

A variety of pyramidal neurons from different parts of the brain

Neuroimaging provides an excellent means of grossly examining the brain. It allows for volumetric measurements of individual structures and can be repeated over time as a coarse means of measuring disease progression. Neuroimaging also allows for exclusion of many reversible causes of dementia. Magnetic resonance imaging (MRI) is the preferred modality of imaging because it allows for excellent 3-dimensional visualization, especially of the hippocampus. The most common findings are cortical atrophy, dilated ventricles, and accentuated cortical sulci. On the T1-weighted MRI shown, extensive hippocampal atrophy has occurred on the right side (see arrow).

Alzheimer’s disease

The gross degenerative changes are the direct result of numerous microscopic changes. The neurofibrillary tangles and amyloid plaques (shown here) first described by Dr. Alzheimer are hallmarks of the disease, although they may also be found in several unrelated neurodegenerative disorders. A small number are even part of the normal aging process. These lesions are found at the microscopic level and are visible with special histologic stains. The combination of tangles plus plaques, as well as the distinctive laminar distribution, is necessary for a histopathologic determination of Alzheimer’s disease. Other pathologic findings include granulovacuolar degeneration and amyloid angiopathy.

Alzheimer’s disease

CT is not as useful as MRI in diagnosing or following the progression of Alzheimer’s disease, although it is commonly used as a first-line modality in patients who present with dementia. The principal findings are similar in both modalities and changes over time are useful; however, on a CT scan, the etiology of cerebral atrophy is more difficult to discriminate between Alzheimer’s disease and normal aging. The CT scan shown here demonstrates several areas of calcification within the basal ganglia, the result of extreme degeneration in a patient with Down’s syndrome and early Alzheimer’s disease.

Alzheimer’s disease

Positron emission tomography (PET) is a powerful tool that is actively being researched to assess the progression of dementia in patients with Alzheimer’s disease and also to differentiate between other forms of dementia. PET allows for noninvasive in vivo examinations of brain function using specially designed radioactive tracers that target specific molecules. A commonly implemented scan uses fluorodeoxyglucose (FDG), which is taken up by active mitochondria, to measure the metabolic activity of the brain. Patients with Alzheimer’s disease show evidence of near-global decreases in metabolic function, particularly in the temporoparietal regions.

Stroke is the third leading cause of death in the United States and a major cause of disability. The CT scan shown here demonstrates a large hemorrhagic stroke with midline shift.

Creutzfeldt-Jakob disease on MRI