23. CIRCADIAN RHYTHM, SLEEP/WAKE CYCLE; NEUROANATOMY OF RESTING STATE AND ACTIVATION Flashcards
What is The principle of the control of circadian (daily) rhythms?
„Glomerular filtration rate and tubular reabsorption/secretion peak during the active phase and decline during the inactive phase.”
What is The pacemaker of the human body?
Suprachiasmatic nucleus (SCN)
Name of this area
Anterior hypothalamic region
Identify this nucleus
Suprachiasmatic nucleus (SCN)
Neuronal inputs to the hypothalamus
-> Identify
Retino-hypo-thalamic fibers
Origin of the retino-hypothalamo pathway
Photoreception is not
confined to rods (red) and cones (green) but is also accomplished by a subset of intrinsically photosensitive retinal ganglion cells (yellow), the so-called circadian photoreceptors, that employ melanopsin as a photopigment and give rise
to the retinohypothalamic tract.
Name Neuronal connections of the suprachiasmatic nucleus (SCN) - 2
GnRH: gonadotropin releasing hormone cells
MPOA: medial preoptic nucleus
CRH: corticotropin releasing hormone cells
dPVN: dorsal subdivision of the paraventrocular
hypothalamic nucleus (PVN)
sPVN: subventricular subdivision of the PVN
DMH: dorsomedial hypothalamic nucleus
PVT: paraventricular thalamic nucleus
Name Neuronal connections of the suprachiasmatic nucleus (SCN) (part 1)
- Glu: Glutamate
- GABA: Gamma aminobutyric acid
- VIP: Vasoactive intestinal polypeptide
- IGL: Intergeniculate leaf nucleus
Circadian regulation of cortisol secretion from the adrenal gland (Adr)
-> Name the structures involved
CRH: corticotropin releasing hormone
ACTH: adrenocorticotropin Adr: adrenal gland
IML: intermediolateral cell column of the spinal cord (sympathetic premotor neurons)
PVN: paraventricular hypothalamic nucleus
SCN: suprachiasmatic nucleus
Make a schematic diagram of Circadian regulation of cortisol secretion from the adrenal gland (Adr)
One output of SCN is the pineal gland (PIN), from which ____ provides a negative feedback
melatonin
One output of SCN is the pineal gland (PIN), from which melatonin provides a negative feedback
-> identify
- RET: retina
- RHT: retino-hypothalamic tract
- MEL: melatonin
- NA: noradrenalin
- IML: intermediolateral cell column of the spinal cord (sympathetic premotor neurons)
- PVH: paraventricular hypothalamic nucleus
- GCS: superior cervical ganglion
Definition / characteristics of sleep
- Decreased motor activity
- Stereotyped posture
- Refreshing, fatigue-reducing effect
- Daily rhythmicity
- Rebound effect
- Changes in brain electrical potentials
- Increase in stimulus threshold
- Relatively easy to wake up
Phenomenologic explanation of motivation to sleep
-> S, C, S-C??
S: Homeostatic drive to sleep (e.g. a sleep substance)
C: Circadian drive to be awake
S-C shows how sleepy we feel.
Phenomenologic explanation of motivation to sleep
-> What does the schematics explains?
- Daily rhythm of sleep;
- Effects of sleep deprivation: - Why we are less sleepy in the morning than at night; - Why we sleep more the following night (rebound effect) but less than 2 times more.
Sleep stages based on electroencephalogram (EEG)
REM sleep: rapid eye movement of paradoxical sleep
Stage 4: slow wave sleep (SWS)
Name of this system
Ascending reticular activating system
State-dependent modes of thalamic relay cells
-> Name the nucleus and cell
- Reticular nucleus
- Thalamic relay cell
List Cell types and connections of the thalamic reticular nucleus
GABA-erg neurons in the thalamus
Cortical pyramidal cell
Reticular cell
Thalamocortical cell
Cell types and connections of the thalamic reticular nucleus
-> Identify
- Cortical pyramidal cell
- Reticular cell
- Thalamocortical cell
Neuronal mechanisms of active sleep control
-> What are some methods of identifying brain areas involved in sleep regulation
- Correlation of neuronal activity with sleep and its phases
- Investigating how sleep cycle is affected by chemo- and optogenetic manipulation of neuronal activity, as well as brain lesions and pathway transections
- Neurochemical investigation of pathway systems involved in sleep regulation
- Influencing sleep with pharmacons
- Examination of the sleep cycle in transgenic animals
- Study of sleep disorders
What is VLPO?
VLPO: ventrolateral preoptic nucleus
Antero-posterior regions of the hypothalamus
-> Identify these regions
Ascending monoaminerg reticular activating systems
-> Name 4 systems
What is the characteristics of Ascending monoaminerg reticular activating pathways?
reach the cerebral cortex without relay in the thalamus
Which part of the brain promote waking?
The hypocretin / orexin neurons in the lateral hypothalamic area
What can disappearence of orexin neurons cause?
It causes narcolepsy, a relatively frequent disease characterized by sleepiness, cataplexy, and hypnagog hallucinations.
́Flip-flop ́ model of sleep regulation
Rapid eye movement (REM) sleep stage
- Low-amplitude, mixed- frequency EEG
- Ponto-geniculo-occipital (PGO) waves
- Easier to wake up
- Increase in cerebral metabolism and temperature
- Heart rate, blood pressure and breathing rate increase compared to slow wave sleep
- Weakening of homeostatic regulation
- Trunk muscle atony
- Pupil constricts (miosis)
What does Resting state mean?
A cognitive state in which the subject is alert but at rest, and does not participate in any specific cognitive or behavioral task.
Classification of cerebral cortical brain regions
There are 3 groups of brain regions, called 3 functional connectivity networks, whose activity changes similarly in the resting state
-> Name of these 3 networks?
- Default Mode Network (DMN)
- Central Executive Network (CEN)
- Salience Network (SN)
Resting-state networks
-> What is the role of Default Mode Network (DMN)?
„Task-negative” network because its activity is actually reduced during behaviour. In turn, the activity of the network increases during internal mental activity, e.g. self examination but not when specific tasks are addressed
Resting-state networks
-> Which structures involve in Default Mode Network (DMN)?
VMPFC and DMPFC (MDPC) ventromedial and dorsomedial prefrontal cortex
ACC, MCC and PCC: anterior, middle and posterior cingular cortex
PC: precuneus; PHG (SPL): parahippocampal gyrus
Hi: hippocampus
LTC: lateral temporal cortex (not visible)
Resting-state networks
-> What is the role of Central Executive Network (CEN)?
Increased activity during any cognitive or affective process, especially during goal-oriented behavior
What is the role of Salience Network (SN)?
Increased activity during cognitive or affective processes, especially during the perception, integration and highlighting of relevant autonomic and emotional information
What are Sub-networks of the Default Mode Network?
Diffusion tensor imaging verified pathways connecting the elements of the DMN. It also contributed to define a dorsal DMN subnetwork (prefrontal, cingular cortices and precuneus) and a ventral DMN subnetwork: from precuneus to hippocampus.
The role of Precuneus
Precuneus is responsible for visual-spatial imaging, memory recall, meditation, self- control, self-awareness, point of view, individual thoughts, planning, forming a vision of the future.
=> In addition to other parts of the DMN, it also connects to the supplementary and premotor cortex to initiate the motor executive program.
Resting-state networks
-> Which structures involving in Central Executive Network (CEN)?
DLPFC and DMPFC: dorsolateral and dorsomedial prefrontal cortex; PPC: posterior parietal cortex; FEF: frontal eye field
Resting-state networks
-> Which structures involving in Salience Network (SN)?
IC: insular cortex; dACC: dorsal anterior cingulate cortex; TP: temporal pole; Amy: amygdala
Comparison of resting-state networks
-> Which slide belong to which networks?
