Time-place learning and memory persist in mice lacking functional Per1 and Per2 clock genes

Area of Science:

• Chronobiology
• Neuroscience
• Molecular Biology

Background:

• Time-place learning links stimuli to specific times and locations, aiding survival.
• Previous research indicated Cryptochrome (Cry) genes are essential for time-place learning.
• The role of other core molecular clock genes, like Period (Per) genes, remained unclear.

Purpose of the Study:

• To investigate if time-place learning depends on Period (Per) genes, beyond Cryptochrome (Cry) genes.
• To determine if Per genes are involved in the formation and storage of circadian-regulated memory.
• To assess the specific roles of Per1 and Per2 in time-place learning and memory.

Main Methods:

• Utilized Per1/Per2 double mutant mice and wild-type littermates.
• Assessed time-place learning acquisition and retention in mutant and wild-type mice.
• Evaluated short-term spatial working memory and long-term contextual memory using established behavioral paradigms.

Main Results:

• Per1/Per2 double mutant mice acquired time-place learning similarly to wild-type mice, despite being arrhythmic.
• No significant deficiencies in short-term spatial working memory were observed in Per mutant mice.
• Both wild-type and Per mutant mice exhibited similar long-term contextual memory but lost time-place associations after two months, suggesting limited long-term storage for this specific memory type.

Conclusions:

• Cry-dependent time-place learning does not require Per genes.
• Per mutant mice do not show Per-specific deficiencies in short-term or long-term memory.
• The functional role of Per clock genes in the circadian regulation of time-place learning and memory is limited.