Introduction
This page is the third part of a study of the article
Failures to reconsolidate memory in a mouse model of Alzheimer’s disease
by Masuo Ohno
Experiment number 2
To test the cause of the memory impairment ( aquirement or consolidation issue ), the second experiment increased the number of training.
Originally, the mice were trained with 2 shocks.
1)Put in the room
2) 3 minutes free to do anything
3) unsigned electric footshock
4) 1 minute free
5) unsigned electric footshock
6) 30 seconds free before being taken out of the room
This was changed to 5 shocks of the same strength.
The results
In this case, even the older mice were showing freezing behaviours. This meant the acquisition of memory and initial consolidation was not affected as much.
2 hours later, the mice were again put in the room and this showed different behaviours with age.
While the youngest mice of 3 to 4 months of age showed no change in their response to being put in the room, the mice over 10 months showed less freezing.
Although weaker, this effect of reduced freezing was also found in the mice of 6 to 7 months of age.
These results were interpreted to show the mice who had a more developed Alzheimers disease had a strong impairment in memory reconsolidation. The restabilisation of memory after retrieval.
Remote memory
As memories grow older, they normally become less dependent of the hippocampus and more so of the cortical networks.
This process happens gradually with several cycles of reconsolidation and retrieval.
this means the older transgenic mice wouldn’t be able to create remote memories as they aren’t able to restabilise memories.
However, remote memory deficits were found in even in young transgenic mice less thsan 4 months of age.
This is thought to be because Aβ fills the cortical areas at a faster rate than the hippocampus, blocking its normal functioning.
Part 1 : A fourth stage of memory consolidation & model mice
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