Cortical states -- sleep and others Flashcards
Define diurnal and what type of animals fall into this category
Active during the day
Typically visual system based animals
Define nocturnal and what type of animals fall into this category
Active at night
Auditory and/or olfactory based animals
Describe a crepuscular rhythm of activity and the likely purpose it serves.
Awake and active at dawn and twilight
Probably to avoid predation
Whet entrains circadian rhythms in mammals?
Special retinal ganglion cells that use melanopsin and form the retinohypothalamic pathway
What is the master circadian clock in vertebrates?
The pineal gland and suprachiasmatic nucleus of the hypothalamus
What is one of the key pathways that the SCN influences other rhythms?
The release of melatonin from the pineal gland
Why do the clocks desynchronize without the SCN?
Because each clock likely has a separate free-running time.
What does the SCN communicate with via neural routes to synchronize rhythms?
Other hypothalamic nuclei which regulate many different systems/behaviors
What are the proteins involved in the SCN clock?
PER/CRY
BMAL1/CLOCK
Describe the mechanism by which SCN clock cells track time.
BMAL1 and CLOCK promote transcription of PER1 and Cry genes that form a dimer and inhibit BMAL1 and CLOCK
At what point of the SCN clock is subjective dawn/the end of the inactive period?
When PER is low
Do BMAL1/CLOCK or PER/CRY control other genes?
BMAL1/CLOCK
How does light influence the SCN clock mechanism?
Light increases the breakdown of PER
Describe how the retino-hypothalamic input influences the SCN
Retino-hypothalamic input to the SCN is glutamatergic and activates a proteolytic pathway to degrade Per protein
What states do high frequency EEG readings correlate with?
REM sleep and wakefullness
What states do low frequency EEG readings correlate with?
NREM sleep
How does the global pattern of neuronal firing change as sleep gets deeper?
More synchronized
What brain areas are deactivated during REM?
Dorsolaterl prefrontal cortex and Posterior cingulate cortex
What brain areas are especially active during REM?
Anterior cingulate, Parahypocampal gyrus, Pontine tegmentum, and the Amygdala.
What does an awake state require?
direct activation of thalamocortical systems
How does stimulation of the reticular activating system influence sleep/wake state?
Promotes wakefulness
What type of stimulation to the thalamus affects sleep/wake state and what is the induced state?
Low frequency stimulation
Induces sleep
What do cholinergic nucleo in the brainstem project to and what do their signalling lead to?
Project to thalamus
Induce desynchronization and wakefulness
What other neuronal groups contribute to wakefulness?
Locus coeruleus noradrenergic neurons,
serotonergic raphe nuclei, and histamine-containing neurons in tuberomammillary nucleus (TMN) of hypothalamus
What are the activity states of different NT systems during REM?
Cholinergic systems are active.
Monamine and serotonin systems are inactive
How does the Ventrolateral preoptic nucleus (VLPO) of hypothalamus influence the neuronal groups contributing to wakefulness?
The VLPO periodically inhibits them to cause sleepiness
What inhibits motor activity during REM sleep?
neurons in the pontine reticular formation
How do neurons in the pontine reticular formation inhibit motor activity during REM sleep?
They suppress monoaminergic activity and inhibit ascending somatosensory input (ie. inhibiting neurons in the dorsal column nuclei)
What do lesions to the Ventral-Lateral Preoptic Area (VLPO) cause?
Insomnia
How do VLPO neurons influence the sleep/wake state
They inhibit the histamine neurons of the tuberomammillary nucleus (TMN)
