REM sleep, information processing and
dreaming
Péter Simor, PhD.
Budapest University of
Technology and Economics,
Department of Cognitive Sciences
Terrestrial mammals: rate of REM and NREM
- Physiologically related processes
The heterogeneity of sleep
• Ultradian regulation of sleep
• Descending and ascending
phases
• Antiarousals and arousals
The Cyclic Alternating Pattern (CAP)
To sleep or
not to sleep?
Parrino et al, 2012
REM sleep and paradoxical sleep: the birth of modern
dream research (1953)
Aserinsky and Kleitman vs Michel Jouvet
REM sleep and
dreaming
Active cortex vs.
muscle atonia
Eye movements
REM sleep
- Every 90-100 minute, average duration: 25 minutes
- Small amplitude, high frequency waves (beta 15-30, gamma 31-48 Hz)
- Loss of muscle tone and activated cortex (Jouvet – paradox sleep)
- Aserinsky & Kleitman 1953: REM sleep and dream experiences
- muscle twitches, cardiac and respiratory irregularities, reduced
thermoregulation, penis erection, increased brain metabolism
Phasic and Tonic periods
• Transient 8-10 second
long epochs
• Eye movements
• Muscle twitches
• Cardio-respiratory
irregularities
• PGO activity
• Increased activity in a
fronto-limbic network
• „Closed state”
• Permanent phenomena
during REM
• Loss of muscle tone
• Penile erection
• Activated cortex
• Reduced
thermoregulation
• „Open state”
The outside word: Waking thresholds and EEG activity
Ermis et al, 2009
phasic
tonic
Jouney et al, 2000
Phasic and Tonic REM and external information
processing
Wakefulness:
Activation in auditory
cortex
Tonic: residual
activation
Phasic: no activation
Wehrle et al., 2007
Information processing during REM
sleep
Late ERP components: N400 for semantically
anomalous words in a given context
And what happens inside the brain and the
mind?
- Ponto-Geniculo-Occipital
Waves
- PPT/LTD (pedunculopontine
and laterodorsal tegmental)
cholinergic nuclei
-Bursts of Eye Movements
Fernandez-Mendoza, 2009
REM-off and REM-on neural activity: The reciprocal
interaction model (McCarley and Hobson, 1975)
• „predators”
• REM-off neurons
• Inhibit their own activity
• Inhibit REM-on neuronal
activity
• Locus Coeruleus –
norepinephrine
• Raphe nucleus – serotonine
(Monoaminerg
Neurons)
• „rabbits”
• REM-on neurons
• Facilitate their own activity
• Facilitate the REM-off
neuronal activity
• Pontine area – cholinerg
(acetilcholine) neurons
Aminergic and Cholinergic balance in different
states of vigilance
Reduced monoaminerg regulation
Norepinephrine:
• Increases signal to noise ratio
• percepton, learning, encoding,
selective attention
Serotonin:
• increase signal/noise
• Filtering of irrelevant stimuli
DREAM BIZARENESS
- Incontinuities
- fragmented nature
- irrealistic scenario
- hiperassociative processes
The emergence of dreams: The Activation-Synthesis
Hypothesis (Hobson & McCarley)
• A perceptual theory of dreaming:
• Dreaming: false perception
• Bottom-up process
• Activation
• cholinergic bursts, creating
random cortical activity
• hallucinatory nature
• Synthesis
• Associative cortical areas
attempt to organize (interpret)
random neural activity
Critical points
• Dreaming is not exclusively dependent on REM activity
(Dreaming during NREM sleep)
• Several SSRI antidepressants reduce or even abolish REM sleep,
but dreaming remains „intact”
• Brain damaged patients: cessation of REM sleep does not result in
the cessation of dreaming
• Dreaming seems to be related to a more non-specific cortical
activation
Arousals and dream reports
- External noise
increases arousals during
sleep as well as the visual
intensity of dream
reports
Conduit et al., 1997
Chelappa, 2011
The cessation of dreaming after cortical lesions
• The role of cortical
structures in the
generation of dream
experiences
• Lesions in primary visual
ares (V1) does not lead to
the cessation of dreaming
• Lesions in higher-order
associative areas result in
the cessation of dreaming
• TOP-DOWN model of
dreaming
• Dreaming resembles
imagination and not
perception
Solms, 2000
Dreamy state during seizures and stimulation
Vignal et al., 2007
Bottom-up and Top-down processes do not
exclude each other
•
Hobson AIM model
•
NREM dreams: thought-like, non-perceptual
experiences
•
REM dreams: mixture of perceptual and thoughtlike experiences
•
Ultradian effects:
– First part of the night: thought-like
– Dawn, Morning dreams: more perceptual
– Other dream experiences: hypnagogic
hallucinations and sleep paralyses : Mainly
Perceptual experiences
The modern neuroscience of dream research
A REMotional network
Selective activation of the prefrontal cortex
Dorsolateral prefrontal part
Ventromedial prefrontal part
- Planning, decision-making
- Social Cognition
- Attentional processes
- Empathy
-Rational, logical reasoning
- Mentalization
- Monitoring, inhibitory functions
- Emotional information processing
- DEACTIVATED during REM
- ACTIVATED during REM
Muzur, 2000
(REM) Sleep and emotional information processing
• during
sleep the original
affective tone of the memory
loses its intesity
• the original emotion is
forgotten, the memory is
consolidated
Walker and van der Heym, 2009
Sleep deprivation: reduced connectivity
between amygdala and medial prefrontal cortex
• Sleep deprivation and emotional instability
REM periods facilitate emotional
regulation?
Gujar et al, 2010
Fear exctinction during sleep/dreaming
Top-down control
VMPFC, Ant.Cingulate
Reorgnization of
emotional memories
into widely
distributed cortical
networks
Reactivation
memories
Emotional memories in
novel, non-fearful
contexts
(Amygdala)
(Hippocampus)
Of emotional
Emotional
reactions:
sympathetic,
motor activity
Dreams about the future?
The Threat Simulation Theory of Dreaming
The simulation of potential future threats and the reherasel of
adaptive reactions to such threatening situations
Revonsuo, 2000
REM sleep, dreaming and Proto-Consciousness
(Hobson, 2009)
• Primary vs. Secondary Consciousness
• Dreaming as mental simulation and primary
consciousness (a practice field for reality)
Lucid dreaming: a state in between REM sleep
and wakefulness
• „This is not reality, this is a dream!”
• Special experiences (flying, levitation, walking on water, etc.)
• Voluntary control
„A design error?”
Mind and Dream reading
Horikawa, T., et al. (2013). Neural
Decoding of Visual Imagery During Sleep.
Science, doi: 10.1126/science.1234330
Thanks for the attention!