IFIBYNE   05513
INSTITUTO DE FISIOLOGIA, BIOLOGIA MOLECULAR Y NEUROCIENCIAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Dopaminergic modulation of appetitive long-term memory in Apis mellifera
Autor/es:
MARTÍN KLAPPENBACH; FERNANDO LOCATELLI
Lugar:
Buenos Aires
Reunión:
Conferencia; Synapses and dendritic spines in health and disease; 2012
Resumen:
The understanding of how reinforcements are encoded in the central
nervous system during learning and memory formation is a current
issue in neurobiology. In contrast to our knowledge on vertebrates,
dopamine (DA) was found to mediate aversive reinforcements and
facilitate aversive memory in several invertebrate species. However,
the assumption that DA is exclusively involved in aversive memory
was recently challenged by a study in crabs that revealed that
dopamine impairs appetitive memory (Klappenbach et al 2012). In
this work we extend this study to an insect, the honey bee Apis
mellifera, and test whether DA affects appetitive learning and
memory in the olfactory modality. We found that systemic injection
of DA before the training session impairs appetitive long-term
memory without affecting acquisition or short-term memory. In a
second experiment we tested whether it is only the administration of
exogenous DA that affects appetitive memory or whether the
endogenous level of DA also plays a role in modulation of
appetitive memory formation. We injected the DA-antagonist
flupentixol immediately before a weak training protocol and found
that blocking DA receptors during training mimics the effect of a
strong appetitive training protocol and facilitates the induction of
long-term appetitive memory. These results reveal a novel action of
DA in appetitive memory in honey bees and together with results in
the crab suggest a conserved dual role of DA across species. The
results indicate that the DA signal mediates the reinforcement for
aversive memory, but also interferes with appetitive memory. This
finding supports the hypothesis that DA and octopamine (OA) have
dual and complementary roles during learning and memory. They
mediate the reinforcement signal throughout aversive or appetitive
training respectively, but also interfere with the formation of
memories of the opposite sign. Calcium imaging studies are being
performed now to evaluate whether DA modulates the processing
and encoding of conditioned and unconditioned stimuli in the honey
bee brain.