AGE-RELATED REDUCTIONS IN HUMAN RECOGNITION MEMORY DUE TO IMPAIRED ENCODING

The participation of the medial temporal cortex and other cerebral str uctures in the memory impairment that accompanies aging was examined b y means of positron emission tomography. Cerebral blood flow (rCBF) wa s measured during encoding and recognition of faces. Young people show ed increased rCBF in the right hippocampus and the left prefrontal and temporal cortices during encoding and in the right prefrontal and par ietal cortex during recognition. Old people showed no significant acti vation in areas activated during encoding in young people but did show right prefrontal activation during recognition. Age-related impairmen ts of memory may be due to a failure to encode the stimuli adequately, which is reflected in the lack of cortical and hippocampal activation during encoding.