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Neuroimaging studies of normal aging. • The effects of normal aging on cognition • Neuroimaging as a scientific tool • The physiological basis of cognitive changes in normal aging . Visuospatial skills. Attention. Executive function. Language. Memory.
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Neuroimaging studies of normal aging • The effects of normal aging on cognition • Neuroimaging as a scientific tool • The physiological basis of cognitive changes in normal aging
Visuospatial skills Attention Executive function Language Memory
Working Memoryis the ability to maintain and manipulate information over short periods of time necessary to guide behavior
4371506 -----> 4371506 MAINTAIN 4371506 -----> 6051734 MAINTAIN and MANIPULATE
Where’s the flag? Should I kick it? Is this supposed to be fun?
1000 800 20s-30s 50s-60s Mean Reaction Time (msec) 600 70s-80s 400 200 ALONE COUNTING DIGIT SPAN Task Condition
STRUCTURAL FUNCTIONAL Magnetic Resonance Imaging Positron Emission Tomography
Structural brain changes with aging changes in brain volume young old
OTHER BRAIN REGIONS FRONTAL
STRUCTURAL FUNCTIONAL Magnetic Resonance Imaging Positron Emission Tomography
YOUNG OLD
SPATIAL RESOLUTION Primary visual cortex (V1) Ocular dominance columns red = right eye blue = left eye
CUE DELAY RESPONSE + + +
YOUNG ELDERLY UNDERRECRUITMENT NON-SELECTIVE RECRUITMENT OVER RECRUITMENT YOUNG OLD
800 600 400 Reaction Time (msec) 200 0 2 Letters 6 Letters
FASTEST SLOWEST YOUNG
Neural recruitment LESS ---------------------> MORE FAST ---------------------> SLOW Information processing speed
1500 1250 1000 750 500 Old Young Reaction Time (msec) 2 6 2 6 Memory Load
FASTEST SLOWEST YOUNG OLD
Neural recruitment LESS ------------------------------------------------> MORE FAST ---------------------> SLOW YOUNG OLD SLOW ---------------------> FAST Information processing speed
Summary • Age-related decline in selective cognitive processes • Functional MRI is a powerful method with excellent spatial and temporal resolution to study the physiological basis of cognitive decline in normal aging • Evidence for selective prefrontal cortical dysfunction (I.e. under-recruitment) with normal aging • Possible neural as well as behavioral compensation
Working memory task Functional MRI EVXRC e time