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Conscious recall of past events which have specific temporal and spatial contexts, termed episodic memory, is mediated by a system of interrelated brain regions. In Alzheimer's disease (AD) this system breaks down, resulting in an inability to recall events from the immediate past. Studies of normal human auditory-verbal short-term memory suggest that the brain system underlying these processes has distinct components, and the present study utilized the methods of functional brain mapping to determine the nature and extent of the breakdown that occurs in AD. Using subtraction techniques of PET-acquired images of regional cerebral blood flow we demonstrate that AD patients show a compensatory hyperactivation of various regions of cerebral cortex normally involved in these tasks, as well as activation of cortical areas not activated by normal elderly subjects. These results provide clear evidence of functional plasticity in the AD patient's brain even if those changes do not result in normal memory function.

Original publication




Conference paper

Publication Date





239 - 242


Alzheimer's Disease Research Center, Pittsburgh, Pennsylvania 15213, USA. JTBECKER@VMS.CIS.PITT.EDU


Brain, Neural Pathways, Humans, Alzheimer Disease, Tomography, Emission-Computed, Brain Mapping, Memory, Short-Term, Cerebrovascular Circulation, Reference Values, Phonetics, Aged, Female, Male