Alzheimer's disease. Light micrograph of a section through the brain of a patient suffering from Alzheimer's disease. The nerve cells (neurones) in the brains of Alzheimer's sufferers degenerate and die, leading to a deterioration in brain function. Characteristic changes in brain tissue include neurofibrillary tangles and senile plaques. Tangles are formed when protein fragments in neurones prevent them from transferring sensory information. Senile plaques are areas where material from dying nerve cells has accumulated around protein. This is the hippocampus, the part of the brain that generates emotion. Magnification unknown.