Effect of aluminum upon conditioned avoidance response acquisition in the absence of neurofibrillary degeneration

Aluminum induces neurofibrillary degeneration in cats but not rats. Cats develop a progressive encephalopathy in which an early manifestation is impaired learning-memory performance. At brain aluminum concentrations of 5 to 6 times that found in cat, rats demonstrate an initial transient weight loss and acquisition deficit immediately following intracranial injection. However, rats do not develop a progressive encephalopathy or a chronic learning deficit.