neuroimaging studies of normal aging the effects of normal aging on cognition neuroimaging as a...
TRANSCRIPT
Neuroimaging studies of normal aging
• The effects of normal aging on cognition
• Neuroimaging as a scientific tool
• The physiological basis of cognitive changesin normal aging
Attention
Executive function
Visuospatial skills
Memory
Language
Working Memory is the ability to maintain and manipulate information over short periods of time necessary to guide behavior
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4371506 -----> 6051734 MAINTAIN and
MANIPULATE
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200
400
600
800
1000
Mea
n R
eact
ion
Tim
e (m
sec)
Task Condition
70s-80s
50s-60s
20s-30s
ALONE COUNTING DIGIT SPAN
STRUCTURAL FUNCTIONAL
Magnetic Resonance Imaging Positron Emission Tomography
Structural brain changes with agingchanges in brain volume
young old
FRONTAL
OTHER BRAIN REGIONS
STRUCTURAL FUNCTIONAL
Magnetic Resonance Imaging Positron Emission Tomography
OLD
YOUNG
red = right eyeblue = left eye
Ocular dominance columns
Primary visual cortex (V1)
SPATIAL RESOLUTION
TEMPORAL RESOLUTION
+ + +
CUE DELAY RESPONSE
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YOUNG ELDERLYUNDER
RECRUITMENTOVER
RECRUITMENT
YOUNG
OLD
NON-SELECTIVE RECRUITMENT
0
200
400
600
800
Rea
ctio
n T
ime
(mse
c)2 Letters 6 Letters
FASTEST SLOWEST
YOUNG
FAST ---------------------> SLOW
Neural recruitment
Information processing speed
LESS ---------------------> MORE
Memory Load2 6 2 6
500
750
1000
1250
1500
Young Old
Reaction Time (msec)
FASTEST SLOWEST
YOUNG
OLD
Neural recruitment
LESS ------------------------------------------------> MORE
FAST ---------------------> SLOW
Information processing speed
SLOW ---------------------> FASTYOUNG OLD
Summary
• Age-related decline in selective cognitive processes
• Functional MRI is a powerful method with excellent spatialand temporal resolution to study the physiological basis ofcognitive decline in normal aging
• Evidence for selective prefrontal cortical dysfunction(I.e. under-recruitment) with normal aging
• Possible neural as well as behavioral compensation
EVXRC e
time
Working memory task Functional MRI