Impact of adolescent social experiences on behavior and neural circuits implicated in mental illnesses

Studies depriving rodents of peer contact during peak social play periods (postnatal days 21-43, roughly early to mid adolescence in humans) show increased anxiety-like and depression-like behaviours, reward seeking, impaired reward learning, and impaired habituation to novel stimuli.

“In most of these studies, animals were isolated from peers from around postnatal days 21 to 43, corresponding roughly to early adolescence (aged 10–13 years) and mid adolescence (aged 14–16 years) in humans.34 Such studies show similar effects to those investigating isolation throughout the whole adolescent period, including increased anxiety-like behaviours, depression-like behaviours, and reward”

Rodent research shows social isolation causes substantial changes in brain and behaviour, especially if isolation occurs during development.

“This rodent research has shown that social isolation causes substantial changes in brain and behaviour,31 especially if isolation occurs during development.33, 34”

After weaning, rodents show a strong orientation towards peers, actively seek peer interaction, and these interactions are important for healthy development and social learning.

“Similar to adolescent humans, after weaning, rodents show a strong orientation towards their peers.38 These animals actively seek out peer interaction and these interactions are considered to be important social input for healthy development39 and specifically for social learning.34”

Adolescent isolation alters serotonin levels, with increased serotonergic activity in prefrontal cortex and decreased activity in hippocampus.

“Additional neurochemical changes include alterations to serotonin levels, with the direction of the effects differing between brain regions. For example, the prefrontal cortex shows increased serotonergic activity, whereas other brain areas, such as the hippocampus, show decreased activity. These alterations have been proposed to underlie observed behavioural changes such as increased anxiety and”

Studying rough-and-tumble play can be a valuable tool both for basic research on communication and other processes involved in regulating social behavior and for translational research on neurodevelopmental disorders.

“Studying RTP can be a valuable tool both for basic research on communication and other processes that are involved in regulating social behavior (Palagi et al., 2016b), and for translational research on neurodevelopmental disorders (Burke et al., 2017).”