Data from: Plastic changes in brain morphology in relation to learning and environmental enrichment in the guppy (Poecilia reticulata)

Despite the common assumption that the brain is mainly malleable to
surrounding conditions during ontogeny, plastic neural changes can occur
also in adulthood. One of the driving forces responsible for alterations
in brain morphology is increasing environmental complexity that may demand
for enhanced cognitive abilities (e.g. attention, memory and learning).
However, studies looking at the relationship between brain morphology and
learning are scarce. Here, we tested the effects of both learning and
environmental enrichment on neural plasticity in guppies (Poecilia
reticulata), by means of either a reversal-learning test or a
spatial-learning test. Given considerable evidence supporting
environmentally-induced plastic alterations, two separate control groups
that were not subjected to any cognitive test were included to account for
potential changes induced by the experimental setup alone. We did not find
any effect of learning on any of our brain measurements. However, we found
strong evidence for an environmental effect, where fish given access to
the spatial-learning environment had larger relative brain size and optic
tectum size in relation to those exposed to the reversal-learning
environment. Our results demonstrate the plasticity of the adult brain to
respond adaptively mainly to environmental conditions, providing support
for the environmental enhancement theory.