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Flashcards in aging Deck (15)
1

cognitive decline and structural changes

Cognitive decline:
- perception.
- memory encoding and retrieval
- working memory and executive functions

Structural changes:
- cortical thinning
- white matter defects
- reduction in hippocampal activation

2

PFC and working memory

1. poor working memory in aged monkeys: delayed response and visual discrimination
2. volume reduction of the dlPFC and anterior cingulate Cx
3. changes in spines of layer 3 of dlPFC in rodents - 32% of spines loss on layer 3 pyramidal neurons loss with aging

3

compare mushroom spines and thin spines

Mushroom spines:
- High degree of stability
-Mediate strong synaptic currents via AMPA receptors

Thin spines:
-Less stable, i.e. can be stabilized or retract
-High degree of plasticity

4

DNMS acquisition in monkeys

vs synaptic density/ density of thin spines/ mean mushroom spine head volume: decrease?

vs mean thin spine head volume: increase?

5

age-related changes in firing of prefrontal neurons

check slide 15

6

hippocampus and aging - trisynaptic pathway

mossy fiber pathway
Schaffer collateral pathway
perforant fiber pathway

7

poorer spatial memory in aged rats

Morris water maze task

8

morphological changes in the hippocampus and MTL cortex

- No cell loss in H and MTL
- Alterations in synapses
- Reduction in synaptic contacts per axonal bouton
- Increase in non-synaptic boutons in the portion of the molecular layer that receives input from the entorhinal cortex
- Decline in neurogenesis in the DG?

9

no change in total number of hippocampal or MTL neurons in monkeys

granule cells
CA3/2, CA1
parahippocampal region

10

synaptic changes in the dentate gyrus

from young to aged:
SSB to NSB
MSB to SSB
MSB to MSB with less synaptic boutons

11

performance on the delayed nonmatching-to-sample task

slide 21

12

estradiol and dendritic arbor of layer 3 PFC neurons

effect of estrogen decline: estradiol vs Veh

13

take home message

1. The cognitive processes that are mediated by the dorsolateral prefrontal cortex (dlPFC) (for example, working memory or source memory) and the hippocampus (for example, declarative memory) are the most vulnerable to aging.
2. The neural changes in the dlPFC occur generally earlier than those in the hippocampus.
3. In both areas, age-related cognitive decline is more likely to be associated with alterations in synaptic connectivity than with neuronal loss.

14

changes in dlPFC

1. No cell loss, but:
2. Decrease in dlPFC volume due to:
- Decline in density of synapses
- Loss of neuropil but not all synapses
3. Mostly axospinous synapses are affected in Layer 3 and 5, but only changes in Layer 3 correlate with working memory loss.
4. Extensive loss of myelinated fibers and presence of myelin defects
5. Increased excitability of layer 2/3, but not layer 5

15

changes in the hippocampus and MTL cortex

1. No cell loss in H and MTL
2. Alterations in synapses:
- Reduction in synaptic contacts per axonal bouton
- Increase in non-synaptic boutons in the portion of the molecular layer that receives input from the entorhinal cortex
3. Decline in neurogenesis in the DG?
4. Adverse effects of estrogen decline on aging processes in women.