Transcript Curran Emeruwa

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A well known hypothesis for sleep:
 the reprocessing and consolidation of memory traces
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Brain areas reactivate during REM sleep
 Shown by PET scans in human subjects after implicit
learning tasks
 Reactivations may reflect reprocessing of memory
traces
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The functional connectivity of the reactivated
brain regions are examined
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The left premotor cortex shows an increase in
functional connectivity with both the:
 Left parietal cortex (Brodmann area 7)
 Bilateral pre-SMA (Brodmann area 6)
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Healthy, right-handed males (22.9±3.5 years old)
Group A (trained):
 6 subjects learned a serial reaction time task on day 1
 The following day they performed it again
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12 PET/MRI scans were performed on the
subjects while they slept
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The PET sleep scans were only performed when
polysomnography showed steady sleep patterns
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Group B (untrained):
 5 subjects followed the same protocol but did not do
the SRT training
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Parietal cortex (left) and pre-SMA (right) showed a
significant increase in functional connectivity with
the premotor cortex during REM in trained versus
untrained subjects
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Regional cerebral blood flow graphs (rCBF)
 Blood supply to the brain at a given time
 Regression of rCBF in the premotor cortex and the parietal
and pre-SMA
 Post Training REM denoted as RED
 REM from untrained subjects denoted as GREEN
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Comparison of REM sleep in trained vs. untrained
subjects:
 In trained subjects, the premotor cortex experiences
an increased functional connectivity with both the:
 Parietal Cortex
 Pre-SMA
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Cerebral areas reactivated during post-training
sleep do not act in isolation
 Mental pathways are active and are being refined
 Reactivation reflects the recruitment of a large-scale
neuronal network caused by a new environmental
situation
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Increased function connectivity between visuomotor areas and motor behaviour areas
 Supports the hypothesis that the neural network is
refined after implicit learning
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Results support the hypothesis that memory
traces are processed during subsequent sleep
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More evidence that SLEEP IS IMPORTANT
Utilization of new technology
 The combination of PET/MRI scanning
 Polysomnography
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Implicit memory is refined, what about explicit
memory?
What about slow wave sleep? Could it contribute
to the consolidation of memory traces?
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Laureys et al. (2001) Experience-dependent
changes in cerebral functional connectivity
during human rapid eye movement sleep.
Neuroscience 105(3):521-5.