Amazing stuff! Why is oxytocin so addictive?
"... Our capacity to care about others may have very, very ancient origins, a new study suggests.
It might have been deep-rooted in prehistoric animals that lived millions of years ago, before fish and mammals like us diverged on the tree of life ...
The new study shows that fish can detect fear in other fish, and then become afraid too – and that this ability is regulated by oxytocin, the same brain chemical that underlies the capacity for empathy in humans. ...
The researchers demonstrated this by deleting genes linked to producing and absorbing oxytocin in the brains of zebrafish, a small tropical fish often used for research. Those fish were then essentially antisocial – they failed to detect or change their behavior when other fish were anxious.
But when some of the altered fish received oxytocin injections, their ability to sense and mirror the feelings of other fish was restored ...
The new study shows that fish can detect fear in other fish, and then become afraid too – and that this ability is regulated by oxytocin, the same brain chemical that underlies the capacity for empathy in humans. ...
The researchers demonstrated this by deleting genes linked to producing and absorbing oxytocin in the brains of zebrafish, a small tropical fish often used for research. Those fish were then essentially antisocial – they failed to detect or change their behavior when other fish were anxious.
But when some of the altered fish received oxytocin injections, their ability to sense and mirror the feelings of other fish was restored ...
The study also showed that zebrafish will pay more attention to fish that have previously been stressed out – a behavior the researchers likened to consoling them.
Previous research has shown that oxytocin plays a similar role in transmitting fear in mice. ...
This brain processing “may have already been in place around 450 million years ago ..."
"Fundamentals of empathy
Emotional contagion, in which individuals display fear or distress behaviors in response to observations of the same in another, is considered a basal form of empathy and is known to occur in fishes. ... have shown that the neuropeptide oxytocin is responsible for these behaviors in zebrafish, as it is in mammals ... They also found that the same regions of the brain are involved in zebrafish and in mammals. Such homologies in emotional response mechanisms across fishes and mammals suggest that this most basal form of empathy could have evolved many, many millions of years ago."
From the abstract:
"Emotional contagion is the most ancestral form of empathy. We tested to what extent the proximate mechanisms of emotional contagion are evolutionarily conserved by assessing the role of oxytocin, known to regulate empathic behaviors in mammals, in social fear contagion in zebrafish. Using oxytocin and oxytocin receptor mutants, we show that oxytocin is both necessary and sufficient for observer zebrafish to imitate the distressed behavior of conspecific demonstrators. The brain regions associated with emotional contagion in zebrafish are homologous to those involved in the same process in rodents (e.g., striatum, lateral septum), receiving direct projections from oxytocinergic neurons located in the pre-optic area. Together, our results support an evolutionary conserved role for oxytocin as a key regulator of basic empathic behaviors across vertebrates."
Generic image of a zebrafish
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