Sharon Dhaliwal
What is the purpose of this study?
 To use positron emission topography & statistical
parametric mapping to study the brain state
associated with REM sleep in humans
What is REM sleep?
 it is associated with intense neuronal activity,
ocular saccades, muscular atonia & dreaming
Subjects:
 30 right-handed male subjects
 Mean age: 22.5 years old (range 20-25 years old)


Subjects were monitored polygraphically over 3
nights spent on a scanner couch, at one-week
intervals
Subjects were selected based on those who could
maintain two periods of slow wave sleep & 20
minutes of REM sleep during the first two test nights
On the third night, regional cerebral blood flow (rCBF)
distribution was recorded during sleep

Scans were done when polysomnography showed
characteristic sleep patterns (slow-wave & REM sleep)

After each sleep scan, the subjects were woken up &
asked to describe what was in their minds

Positive correlations:
 Pontine tegmentum
 Left thalamus
 Left & right
amygdaloid complexes
 Anterior cingulate
cortex
 Right parietal
operculum
Negative Correlations:
 Dorsofrontal
prefrontal cortex
 Parietal cortex
 Posterior cingulate
cortex
 Precuneus

Amygdaloid complexes are involved in the
formation & consolidation of memories
paired with emotional stimuli

Previous neuroimaging studies suggest that
dorsolateral prefrontal areas & precuneus
involved in the encoding & retrieval of
episodic memory
- this study showed that these memory
processes are not prominent during REM
sleep

Coactivation of anterior cingulate cortex
& amygdaloid complexes could
account for the emotional & affective
aspects of dreams

Other formal characteristics of dreams
(temporal distortions, weakening of selfreflective control, amnesia or
awakening) might be related to the
relative prefrontal deactivation
Results from the rCBF distribution agree with
previous research that suggests there is a
functional link between the amygdala, the
hippocampal formations & cortical areas
during REM sleep

These results shed light on the idea that
amygdalocortical activation could account
for the perceptual components of dreaming

This study looked at both positive and
negative correlations of PET data

Test subjects that vary in age group,
gender, handedness - will the same brain
regions become activated?

Conduct the experiment during the
morning or afternoon – will we obtain the
same results?

Perform the same procedure except this
time do not ask participants to stay awake
during the preceding second and third
night test nights since that obviously
produced some fatigue effects in this
current study

 Only
used male subjects – could there be a
genetic bias?
 Subjects were all right-handed – why not test lefthanded subjects?
 Subjects were all roughly part of the same age
group – could there be an effect of age?
 Previous neuroimaging studies have suggested
occiptal & temporal areas are activated during
REM sleep but that was not shown in this study –
WHY? Because group analysis averaged out
cortical activations specific to each individual
subject or even to each scanned REM sleep
episode