Transcript PowerPoint Presentation - Dissecting working memory using

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
Attention
Visuospatial skills
Executive function
Language
Memory
Working Memory is the ability to maintain and
manipulate information over short periods of
time necessary to guide behavior
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MAINTAIN
MAINTAIN
and
MANIPULATE
Should I
kick it?
Where’s the
flag?
Is this supposed
to be fun?
Mean Reaction Time (msec)
1000
800
20s-30s
50s-60s
600
70s-80s
400
200
ALONE
COUNTING
DIGIT SPAN
Task Condition
STRUCTURAL
Magnetic Resonance Imaging
FUNCTIONAL
Positron Emission Tomography
Structural brain changes with aging
changes in brain volume
young
old
OTHER
BRAIN REGIONS
FRONTAL
STRUCTURAL
Magnetic Resonance Imaging
FUNCTIONAL
Positron Emission Tomography
YOUNG
OLD
SPATIAL RESOLUTION
Primary visual cortex (V1)
Ocular dominance columns
red = right eye
blue = left eye
TEMPORAL RESOLUTION
CUE
DELAY
RESPONSE
+
+
+
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YOUNG
UNDER
RECRUITMENT
YOUNG
OLD
ELDERLY
NON-SELECTIVE
RECRUITMENT
OVER
RECRUITMENT
Reaction Time (msec)
800
600
400
200
0
2 Letters
6 Letters
FASTEST
YOUNG
SLOWEST
Neural recruitment
LESS
FAST
--------------------->
--------------------->
MORE
SLOW
Information processing speed
Reaction Time (msec)
1500
1250
Old
Young
1000
750
500
2
6
2
Memory Load
6
FASTEST
YOUNG
OLD
SLOWEST
Neural recruitment
LESS
------------------------------------------------>
FAST ---------------------> SLOW
YOUNG
MORE
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
EVXRC
e
time
Functional MRI