Neocortical ectopias in BXSB mice: effects upon reference and working memory systems

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Genetics

Background:

• Neocortical ectopias occur in 40-60% of BXSB mice, impacting the prefrontal/motor cortex.
• Prior research indicates behavioral differences between ectopic and non-ectopic mice, particularly in spatial memory.
• Existing studies suggest variations in spatial reference and working memory between these groups.

Purpose of the Study:

• To quantitatively assess reference and working memory in the same animals.
• To test the hypothesis that ectopic mice possess superior reference memory but inferior working memory.
• To investigate the cognitive impact of neocortical ectopias in BXSB mice.

Main Methods:

• Utilized the Lashley III maze, featuring cul-de-sacs and T-choices, to evaluate spatial learning and memory.
• Compared performance of ectopic and non-ectopic BXSB mice on maze acquisition and error types.
• Re-tested animals after inverting the maze to differentiate between reference and working memory utilization.

Main Results:

• Both ectopic and non-ectopic mice learned the initial maze equally, with no significant differences in cul-entry or T-choice errors.
• Upon maze inversion, ectopic mice made fewer cul-entry errors (indicating preserved reference memory).
• Ectopic mice made more T-choice errors post-inversion (indicating impaired working memory).

Conclusions:

• Neocortical ectopias in BXSB mice are associated with a specific pattern of spatial memory deficits.
• Ectopic mice demonstrate enhanced spatial reference memory but compromised working memory.
• These findings highlight the functional consequences of neocortical ectopias on cognitive processes.