Genetic mapping of variation in spatial learning in the mouse

Area of Science:

• Neuroscience
• Genetics
• Behavioral Science

Background:

• Inbred mouse strains exhibit varied spatial learning abilities in the Morris water maze.
• The genetic underpinnings of this individual variation in spatial learning remain largely uncharacterized.

Purpose of the Study:

• To map quantitative trait loci (QTL) influencing spatial learning differences between DBA/2 and C57BL6/J mouse strains.
• To determine if identified QTL specifically affect spatial learning or general behavioral traits.

Main Methods:

• Utilized an F2 intercross population derived from DBA/2 and C57BL6/J mice.
• Employed quantitative trait loci (QTL) mapping to identify genetic regions associated with water maze performance.
• Conducted additional behavioral tests including avoidance conditioning and novel environment exploration.

Main Results:

• Identified two significant QTL on chromosomes 4 and 12 associated with performance in the water maze probe trial (genome-wide significance p = 0.017 and 0.015).
• Demonstrated that these specific QTL influence spatial learning, distinct from general fear or exploratory behaviors.
• Located QTL for fearful behavior on chromosomes 1, 3, 7, 15, and 19, which appear to operate independently of spatial learning QTL during training.

Conclusions:

• Genetic factors on chromosomes 4 and 12 are critical determinants of spatial learning variation in mice.
• These findings provide a genetic basis for understanding individual differences in spatial navigation.
• Distinguished genetic influences on spatial learning from those affecting general fearfulness in the water maze context.