Lecture 15 Flashcards
Circadian rhythms: what does it regulate ? affect on mood?
Homeostatic regulation
Temperature
Hormones
Sleep
Mood: thalamus peri habenular nucleus → nucleus accumbens & mPFC
Light regulates
Circadian rhythm pathways (2)
Central/master clock:
light → retina/photosensitive RGCs → hypothalamus → suprachiasmatic nucleus (SCN), pacemaker → pareventricular nucleus → spinal cord intermediolateral cells → superior cervical ganglion → pineal gland (MELATONIN synthesis)
Peripheral clock:
physical activity → temp & metabolism ↑ → muscles & organs
Role of Cortisol
Increased secretion w/ physical activity, immune system reponses & stress
What is sleep? &purposes (4)
Behaviorally: “suspension of consciousness”
Physically: electrical activity patterns
Purposes:
>ENERGY
>Better to pause when dark
>Memory consolidation
Clearance of metabolic waste
Sleep debt
Sleep deprivation→ we restore w/ sleep
- sleep debt: urge to sleep
(see 15.5)
Sleep stages: EEG physiological changes, names (4)
→ = EEG
N1-Stage 1: transition/drowsiness; low arousal threshold, slow rolling eye movement → lower ƒ, higher amplitude
N2-Stage 2: more stimuli needed for arousal, sleep spindles, K complexes → even lower ƒ & higher amplitude
N3-Stage 3 & 4: deepest sleep, slow wave → dec. spindles, △ waves
REM sleep: rapid eye movement, pupillary constriction, large muscle paralysis, DREAMING → similar to awake state
Dreaming (nREM vs REM)
nREM:
- Shorter
- Less visual/emotional
- More conceptual
- Usually related to current life
- ↓ in adulthood
REM:
- Long & visual & emotional
- Usually not connected to life
- Visual: 100%, auditory: 65%, vestibular: 8%, temp: 4%
- Tactile/olfactory/gustatory rare (1%)
- Anxiety: 14%, surprise: 9%, joy: 7%
- Sexual arousal (spontaneous erection)
- ↓ in infancy
Neural circuits of sleep
Interaction between reticular activating system (brainstem), thalamus, & cortex
Thalamocortical neurons (2 states)
Tonically active:
- depolarized
- encoding peripheral stimuli
- wakefulness/”gate open”
Intrinsic bursting state:
- OSCILLATORY 📈📉📈📉
- synchronize with cortex
-“gate closed”
Thalamocortical feedback loop
GABAergic neurons in reticular nucleus hyper-polarize thalamocortical cells
Ascending info: brain stem
Descending info: cortical cells
Responsible for sleep spindles/RN n’s hyper-polarize TC cells further, causing rebound activity
Reticulart activation system (3 neurotransmitters of modulation))
1) Noradrenaline: activating, wakfulness → locus coeruleus
2) Cholinergic neurons: complex info processing, wakefulness & REM → reticular activation
3) Seratonin: intermediate, high # = wakefulness & low = REM
→ Raphe nuclei
Inhibition: ALL GABAergic VPLO neurons
Excitation: (1)&(3), histamine (activated by orexin in lateral hypothalamus) in tuberomamillary nucleus
REM on vs REM off (NT levels in REM vs nREM)
REM ON: cholinergic
REM OFF: seratoninergic
REM: low everything
nREM: low noradrenaline
Activity during REM
Increased limbic activity
Decreased dlPFC & posterior cingulate cortex (high emotion & inappropriate social cortex)
Saccades: PRF → SC → paramedial PRF → RIN → Move → pontine-geniculate-occipital waves occur
Pontine inhibitory area → medulla → spinal cord MN hyperpolarization
Consciousness vs wakefulness
Consciousness = wakefulness PLUS awareness
Most neural processes operate under consciousness threshold
Default mode network vs central executive network
Central executive network:
- Cognitive tasks
- Frontoparietal attention regions
- IPS & vlPFC
Default mode network:
- Awake & aware but NO particular task
-posterior cingulate cortex
- mPFC & TPJ
They are ANTICORRELATED
