Context-dependent individual differences in playfulness in male rats

Area of Science:

• Animal Behavior
• Neuroscience
• Animal Welfare

Background:

• Play behavior is a key indicator of positive emotions and welfare in higher vertebrates.
• Understanding individual differences in playfulness can provide insights into animal welfare and emotional states.

Purpose of the Study:

• To investigate the consistency of playfulness in male rats across different motivational states and age points.
• To determine if playfulness is influenced by social isolation and anxiety levels.
• To explore the relationship between different play contexts and types.

Main Methods:

• Twenty-four male Lister Hooded rats were housed in groups of four.
• Two play tests were conducted: conspecific Play-in-Pairs and experimenter-administered Tickling.
• Play behavior was compared across early and late adolescence, with and without prior social isolation.
• Basal anxiety levels were measured and compared with play measures.

Main Results:

• Play-in-Pairs measures demonstrated consistency across age and motivational states, independent of anxiety.
• Tickling-induced positive vocalizations were consistent across age but negatively correlated with anxiety.
• Play-in-Pairs and Tickling contexts, as well as social and solitary play, were found to be unrelated.

Conclusions:

• Consistent individual differences in playfulness exist in male rats.
• Different play contexts and types represent distinct motivational systems.
• Playfulness is a stable trait in rats, with specific contexts relating differently to emotional states like anxiety.