Alarm cues and alarmed conspecifics: Neural activity during social learning from different cues in Trinidadian guppies

Learning to respond appropriately to novel dangers is often essential to
survival and success, but carries risks. Learning about novel threats from
others (social learning) can reduce these risks. Many species, including
the Trinidadian guppy (Poecilia reticulata), respond defensively to both
conspecific chemical alarm cues and conspecifix anti-predator behaviours,
and in other fish such social information can lead to a learned aversion
to novel threats. However, relatively little is known about the neural
substrates underlying social learning and the degree to which different
forms of learning share similar neural mechanisms. Here, we explored the
neural substrates mediating social learning of novel threats from two
different conspecific cues (i.e. social cue-based threat learning). We
first demonstrated that guppies rapidly learn about threats paired with
either alarm cues or with conspecific threat responses (demonstration).
Then, focusing on acquisition rather than recall, we discovered that
phospho-S6 expression, a marker of neural activity, was elevated in
guppies during learning from alarm cues in the putative homologue of the
mammalian lateral septum and the preoptic area. Surprisingly, these
changes in neural activity were not observed in fish learning from
conspecific demonstration. Together, these results implicate forebrain
areas in social learning about threat but raise the possibility that
circuits contribute to such learning in a stimulus-specific manner.