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COMPENSATION (Episodic memory (Episodic memory retrieval (Effects of age…
COMPENSATION
PASA
Posterior-anterior shift in aging
Age related decrease in occipital activity coupled with age-related increase in PFC.
Older Adults (OA) compensate for visual processing deficits recruiting higher cognitive processes
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HAROLD
Hemispheric asymmetry reduction in Older adults
-More bilateral pattern of PFC activity
-Compensatory mechanism
-correlate with successful cognitive performance
-it reflect a difficulty in engaging specialized neural mechanisms
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Visual perception
Age related reductions in activation of
-Visual cortex regions
-Anterior regions of the ventral pathway: parahippocampal gyrus, amygdala medial temporal lobe. It reflects extension of occipital desease or specific deficit in memory and emotion-related processes
Increases in more anterior brain regions:
-PFC
-ACC
-Insula
Attention
Attention shows a compensation in form of PASA or activation of deep gray matter regions (straiatum, thalamus, insula).
-When cueing selective attention: stronger PFC activation
-In other tasks (odd-ball) no diff. in frontal activity
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Working memory
Maintenance, manipulation, monitoring
-Reduction activity in PFC regions engaged by Y
-Greater activation in other PFC regions, such as controlateral
Verbal WM - reduced left, increased right PFC->HAROLD
Spatial WM - reduced right, increased left->HAROLD
Executive functions
Set of processes: inhibition, switching, updating.
PFC increases in these ex tasks.
It reflects greater cognitive demand.
Episodic memory
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Episodic memory encoding
Reduction in Left PFC activity
and increased right PFC, dorsolateral and orbitoprefrontal cortex
Decrease in posterior regions (parietal and visual)
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Frontal overactivation compensate structural and functional changes in MT regions associated with:
-hippocampal shrinkage
-decreased hippocampal e parahippocampal activations
Normal aging: frontal shrinkage along with increased frontal activation
Pathological aging: declining in hippocampal e entorhinal volume e activation
Moreover Y show activations that are specific; O show less neural specifity in FFA, parahippocampal place area and lateral occipital areas for letters.
Difficult suppression of the Default mode network
Failure to suppress is related to lower performance on some cognitive tasks.
increased frontal activity is due to a failure to shift from default network to active network