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2001
Fellow
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Sidarta T.G. Ribeiro, Ph.D.
Research Director
International Institute of Neuroscience of Natal Edmond and Lily
Safra (IINN-ELS)
Rua Professor Francisco Luciano de Oliveira, 2460, Bairro Candelária
Natal, RN, 59066-060
Brazil
Tel: (55) (84) 3217 0003
E-mail: Click here
Website: Click here
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Country: BRAZIL
Field: Sleep
and Memory, Animal Communication
Research Interest:
Our lab investigates the molecular,
cellular, circuit-level and psychological mechanisms responsible for the
cognitive role of sleep. Explicit memories, i.e. memories of places, things
and events involve two different brain portions: while the hippocampus
acts as a short-term buffer, memories eventually move to the cerebral
cortex.
Investigating rats with multielectrode neuronal recordings and in situ
hybridization for plasticity-related immediate-early genes, we found that
memories of novel objects fade within minutes in the hippocampus, but
persist reverberating in the cortex during sleep many hours after the
end of object exploration. Our results indicate that the two phases of
sleep cooperate to promote the propagation of memories from their entry
point (hippocampus) to their final destination (cortex).
The non-dreaming phase of sleep (slow-wave sleep, SWS) reverberates and
amplifies recently acquired changes in selected synaptic circuits.
The dreaming phase of sleep (rapid-eye-movement sleep, REM) switches on
the cortical expression of genes related to memory stabilization and propagation.
The results suggest that novel experience is followed by multiple waves
of cortical plasticity as sleep cycles recur. As a consequence, memories
become more dependent on cortex than hippocampus as sleep recurs, migrating
from their original entry circuits to deeper cortical networks. Our current
goal is to elucidate how cortico-hippocampal interactions and experience-dependent
synaptic plasticity during sleep contribute to the consolidation of memories
in rodents. In parallel, we use electroencephalography, videogame playing
and dream reports to probe the adaptive value of dreams in humans.
A second research line in our lab is the investigation of communication
and symbolic competence in non-human animals. Our focus is the marmoset
(Callithrix jacchus), a highly vocal species of new-world monkey. At present
we dedicate ourselves to ethological studies of the vocal repertoire of
marmosets, and to the mapping of calcium-dependent immediate early gene
expression in brain areas related to hearing and vocal behavior.
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