Week 8: Brain, Sleep and Dreams Flashcards
What characterizes REM sleep?
- wake-like and “activated” (high frequency, low amplitude or “desynchronized”) activity in EEG
- singlets and clusters of rapid eye movements (REMs) in EOG channel
- very low levels of muscle tone (atonia) in EMG channel
What characterizes NREM sleep?
- all sleep apart from REM
- divided into four stages corresponding to increasing depth of sleep
What are the features of REM’s dreams?
- contain formed hallucinatory perceptions (especially visual and motor, but occasionally all sensory modalities)
- imagery can change rapidly and is often bizarre in nature
- are delusional unless we cultivate lucidity
- self-reflection generally absent in dreams
- lack orientational stability (persons, times, places are fused, plastic, incongruous, discontinuous
- create story lines to explain and integrate all dream elements in a single confabulatory narrative
How do memory resources play a role in dreams/REM sleep?
- memory systems active during REM have poor access to recent waking memories
- deficiency of memory in dreaming may go toward explaining dream phenomena such as orientational instability, loss of self-reflective awareness, failure to direct thought and attention
- significant deactivation of vast areas of dorsal lateral PFC
- decrease in cerebral blood flow in frontal areas
What kind of neurons are active during waking vs REM?
- shift/interaction from aminergic dominance in waking to cholinergic dominate in REM sleep
- interaction influences Hypothalamus, amygdala and basal forebrain → amplifying of REM sleep generation or suppression
What are aminergic vs cholinergic neurons?
- aminergic: receptors that respond to “amines” or neurons that release noradrenaline, dopamine,norepinehrine, serotonin
- cholinergic: receptors that respond to acetylcholine
What is the AIM Model?
- three dimensional model of brain-mind states
- three independent processes that distinguish each state from one another
- A = level of activation
- I = Input source / origin
- M = (neuro)modulation
What is the Level of Activation process?
- how much information is being processed by the brain?
- overall level of neural activity in the Brain
What is the Level of activation during REM?
- amygdala and paralimbic cortex: active → emotion and remote memory
- brain stem: active → activates cholinergic system, maintains cortical arousal, promotes visual imagery
- parietal operculum: active → visuospatial imagery
What is the Input during waking?
primary input from external sensory stimuli
What is the Input during REM or daydreaming?
- primary input from internal data sources
- pseudo-sensory data produced by brain stem
- generation of fictive visual and motor data
- sensory input blocked (real-world data unavailable)
- motor output blocked (real-world action impossible)
What is the Input during NREM?
both external and internal input suppressed
What is the neuromodulation process?
- balance of neuromodulators in the brain
- primarily cholinergic and aminergic influences arising from brain stem nuclei
What neuromodulators are active during Waking?
dominance of aminergic activity
What neuromodulators are active during REM?
dominance of cholinergic activity
What neuromodulators are active during NREM?
What neuromodulators are active during NREM?
low aminergic with even lower cholinergic levels
What does the AIM state space look like?
- waking: high A, external I, high aminergic M
- NREM: low A, minimal external and internal I, low aminergic and cholinergic M
- REM: high A, internal I, high cholinergic M
How does sleep affect memory?
- conventional view is that sleep processes participate in consolidation of memory traces
- distinction of procedural and declarative memory led to dual-process hypothesis
- effect of sleep on memory processing is taks-dependent
- procedural branch derived from REM
- declarative linked to NREM
What is a Schema?
- mental framework for the organization and understanding of information
- enables extraction of rules or general concepts on metal level
What are the different processes of Schema Consolidation / Memory Reorganization?
- schema formation
- arises from extraction of rules which can then be generalized to novel situations
- mainly during slow wave sleep
- Schema integration
- integration of recent and remote memories
- relational memory
- emergence of false memories
- mainly during slow wave sleep
- schema disintegration
- process of disbanding existing schemes to allow out of the box thinking and creativity
- manly during REM sleep
