Distinct Age-Specific Effects on Olfactory Associative Learning in C57BL/6 Substrains.

Area of Science:

• Neuroscience
• Behavioral Science
• Genetics

Background:

• C57BL/6 is a common mouse strain in labs.
• Two substrains, C57BL/6J (B6J) and C57BL/6N (B6N), are used for genetic modification.
• Differences in olfaction-dependent behaviors between B6J and B6N mice are not well understood.

Purpose of the Study:

• To investigate the differences between B6J and B6N mice in olfactory-dependent behaviors.
• To evaluate their abilities in instrumental learning and olfactory association using a modified olfactory two-alternative choice task.

Main Methods:

• Utilized a modified olfactory two-alternative choice task with two training stages: rule learning and discrimination learning.
• Assessed performance in operant chambers for water rewards based on odor cues.
• Conducted olfactory habituation/dishabituation tests on young adult mice.

Main Results:

• Young adult B6J mice showed higher success rates in rule learning and overall task acquisition compared to B6N mice.
• Discrimination learning success rates were similar between the two substrains.
• At a mature age (17 weeks), B6N mice improved significantly in rule learning and overall task acquisition, while B6J mice showed improved speed.
• Both substrains exhibited normal olfactory habituation, but B6J mice displayed stronger investigative responses to novel odors.

Conclusions:

• B6J and B6N mice exhibit distinct acquisition processes for tasks involving instrumental learning and olfactory association.
• Maturation affects these two substrains differently, influencing their behavioral task performance.
• Young adult B6J and B6N mice may differ in novelty-seeking aspects of olfaction, despite similar habituation.