The effect of social and risky play on cognitive control and stress resistance in rats

Abstract

Introduction: Playing is an act performed by many animals and humans alike. This paper we will be focussing on individual play and social play. Within these play types we will mainly be looking at what parts of individual or social play would add risk to the activity. Within individual play these are things that change the speed and height at which the individual is playing as well as their own physical ability and skill. As forsocial play, the risk is the inherent risk to play fighting, or rough-and-tumble play, which often makes up a large portion of social play, as well as the attention being divided between the partner and the surrounding environment. Aside from fun play can also be beneficial for certain traits, a lack of some of these traits like impulse control, decision making, and cognitive flexibility can all be responsible for a decrease in resistance to psychiatric disorders later in life, which is why it is important to understand these mechanisms better. For this reason, this study looked at the effects of risky play and deprivation, as well as social play and deprivation on behavioural inhibition and stress resistance. Materials & Methods: First we split the animals into different conditions where they are given social play, or no social play, and 30 minutes in a normal control environment, or an enriched riskier environment 5 times a week. We then looked to see if they would take advantage of this enrichment. Secondly, we looked at whether there was a difference in the ability to inhibit their own behaviour when presented with a reward. We did this by having the rats perform the behavioural inhibition under threat of adversity task (BITA task), in which they were then judged by their successful inhibition versus the shocks caused by unsuccessful inhibition. Lastly, we looked at how well the rats performed in this task after they have been subjected to stress, comparing their performances to their pre-stress performances, as well as to a control group that did not undergo stress. Results & Discussion: During the play phase, the animals in the enriched cage with an increased opportunity for risky play did opt for significantly riskier sessions than the animals inside the control cages. These animals also grew significantly more in their risky behaviour from week 1 to week 3. A significant increase in suppression ratio and latency from the first baseline session to the first test was observed across all play conditions, indicative of an increase in value given to the stimuli that are presented. The rats show a dose-dependent response to the increasing of the shock intensity. The social play and risky play condition (SPR) is the only condition that bounced back in latency from test 1 to baseline 2. The social play conditions (SP) got more careful from baseline 1 to baseline 2 with the same shock intensity. Post-stress the rats that received enriched risky play showed much clearer peaks and steeper slopes when moving from less to more suppression in accordance with the intensity of the shocks in comparison to the flattened slopes of the non-risky animals which did not adapt their suppression in accordance with the intensity, Conclusion: The rats take more risk when they are placed in an enriched cage with risky elements during daily 30-minute sessions and the rats inhibited their reward retrieving behaviour more if the threat was increased. Comparing the non-risky conditions to the risky conditions post-stress shows a decrease in flexibility when not engaged in risky play during the juvenile phase.