Current Biology 1999 9 1275-1278.

Recruitment of unique neural systems
supporting visual memory in normal aging

A R McIntosh, A B Sekuler, C Penpeci, M N Rajah
C L Grady, R Sekuler and P J Bennett

Rotman Research Institute of Baycrest Centre, Toronto, ON, Canada
Dept of Psychology, University of Toronto, Toronto, ON, Canada
Volen Center for Complex Systems, Brandeis University, Waltham MA

Abstract

Performance on many cognitive tasks change in normal aging [1-3]. However, recent behavioral work has identified some tasks that seem to be age-invariant [4]. To understand the brain mechanisms responsible for this, we combined psychophysical measures of visual short-term memory and positron emission tomography (PET) in young and old individuals.

Participants judged the difference between two visual stimuli, and the memory load was manipulated by interposing a delay between the two stimuli. Both age groups performed the task equally well, but the neural systems supporting performance differed between young and old individuals. While there was some overlap in the brain regions supporting performance (e.g., occipital, temporal and inferior prefrontal cortices, caudate), the functional interconnections among these common regions were much weaker in old participants. This suggests that the regions were not operating effectively as a network in old individuals.

However, old participants recruited unique areas, including medial temporal and dorsolateral prefrontal cortices. These unique areas were strongly interactive and related to performance only in old participants. Therefore, these areas may have acted to compensate for reduced interactions among the other brain areas.

References for abstract

[1] Craik, F.I.M. and Jennings, J.M., Human memory. In F.I.M. Craik and T.A. Salthouse (Eds.), Handbook of cognition and aging, Lawrence Erlbaum Associates, Hillsdale, NJ, 1992, pp. 51-110.

[2] Kosnik, W., Winslow, L., Kline, D., Rasinski, K. and Sekuler, R., Visual changes in daily life throughout adulthood, J Gerontol, 43 (1988) 63-70.

[3] Sekuler, R. and Sekuler, A.B., Visual perception and cognition. In J.G. Evans, Williams, T.F., J.-P. Michel, B.L. Beattie and G.K. Wilcock (Eds.), Oxford Textbook of Geriatric Medicine, 2nd Edition, Oxford University Press, Oxford, in press.

[4] Bennett, P.J. and Sekuler, A.B., Visual pattern analysis in elderly observers. University of Toronto, Dept of Psychology, Vision Research Lab, Toronto, 1992.

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