senile plaque

n.
  1. A spherical mass of amyloid fibrils surrounded by distorted interwoven neuronal processes, found in the cerebral cortex in Alzheimer's disease.neuritic plaque
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.