consciousness and sleep Flashcards
Definition of consciousness
Difficult to define
Simple explanation- awareness of internal and external existence
Neuroscientific- the neural corelates of consciousness (NCC) model
The relationship between mental states and neural states and constitute the minimal set of neuronal events and mechanisms sufficient for a specific conscious percept
Cognitions role in consciousness
problems with it
Issues surrounding whether consciousness is controlled by an executive
Evidence is weak
Many areas involved
How does brain activation differ when words are masked versus unmasked, and how does this relate to conscious awareness
Briefly presented words were masked by following them with nonmeaningful visual stimuli, activation as largely confined to the primary visual area (as well as slightly delayed) and did not produce awareness.
Unmasked words produced additional subsequent activity, which spread through the frontal and parietal cortex, accompanied by awareness.
what is meant by attention
How the brain allocates limited resources to focus on some inputs while excluding others
whats the Cheshire cat effect
Your view alternates between your hand on your friends faces
You lose peripheral information around the are of focus
whats a physiological process
Changes in attention matched with changes in neural activity
what does the thalamus require
equires working memory and other brain areas
importance of body image
what areas of the brain associated with body image
Important to subjective sense of self
Need to understand sensory organs to understand sense of self
Distributions of body image, sensory feedback diminish sense o
Somatosensory cortex, anterior cingulate and insula involved in the sense of body image.
what is sleep?
cycles for aniams and humans
Animals exhibit regular sleep-like behaviors
24 hour cycles of activity and rest driven by some form of circadian/biological rhythms
Humans usually sleep for 8 hours a day
why do we sleep
evolutionary theory- sleep is adaptive, need it to reset the system, reason for cortisol
Restoration model- helps balance homeostatic system
Energy conservation
Brain growth
Synaptic plasticity and memory consolidation
Neurochemical control - relies on how many hours of wakefulness you have, and what chemical stages it promotes
Serotonin –
promotes wakefulness, inhibits REM, waking related motor activity, serotonergic cells in dorsal raphe nucleus
Noradrenaline-
inhibits sleep, noradrenergic cells in locus coeruleus (pons), excites motor neurons.
Acetylcholine (ACh)-
promotes REM, ACh release increases during sleep
Adenosine-
promotes slow wave NREM (inhibits cholinergic neurons ), builds up during wake periods to promote sleep
Dopamine-
promotes wakefulness, vigilance, and performance enhancements. Dopamine antagonists promotes sleep
Histamine-
promotes wakefulness via neurons in posterior hypothalamus. Anto-histamine promotes drowsiness
Hypocretin/orexin-
peptide produced in lateral hypothalamus regulates sleep on/off cells in the ventrolateral preoptic area (v|POA)
vIPOA
What happened when destructing reigon in rats
Destructing to this regio in rats resulted in total insomnia
Electrical stimulation of cause drowsiness and sleep
GABA main neuron secreted from this area- inhibit arousal pathways
This is the basis for the on/off or flip/flops circuits
What does the flip-flop switch model explain about sleep and wakefulness regulation in the brain?
The flip-flop switch model explains how the brain rapidly transitions between sleep and wake states. In this model:
The VLPOA (ventrolateral preoptic area) promotes sleep by inhibiting arousal systems.
Arousal systems (including orexin neurons in the hypothalamus) promote wakefulness and inhibit the VLPOA.
Light, emotions, energy balance, and metabolic cues all increase activity in arousal systems and orexin neurons, keeping you awake.
When the VLPOA is activated (e.g., due to adenosine buildup), it turns off arousal systems, leading to sleep.
This mutual inhibition acts like a flip-flop switch — you’re either fully awake or asleep, with little in-between.
What system is responsible for promoting sleep through the buildup of adenosine and its effects on brain areas like the VLPOA and arousal systems?
The homeostatic sleep drive (or sleep pressure system). As adenosine builds up throughout the day, it promotes sleep by activating the ventrolateral preoptic area (VLPOA), which in turn inhibits the brain’s arousal systems (including those in the hypothalamus), making you feel sleepy.
how does light influence out sleep wake cycle throught the brain
Light enters the eyes and hits retinal cells, which send signals to the suprachiasmatic nucleus (SCN) — the brain’s master clock located near the VLPOA. This process is an example of a zeitgeber, an environmental cue (like light) that helps regulate the circadian rhythm.
The SCN uses glutamate, the brain’s main excitatory neurotransmitter, to become activated. Once active, the SCN sends signals that affect:
Hormone secretion (like melatonin from the pineal gland)
Blood pressure
Body temperature
Cortical arousal (keeping the brain alert)
This system helps align the body’s internal clock with the external day-night cycle.
rol of melatonin
Promotes sleep
Produced by pineal gland
Posterior to the apex of the brain
Reduction in light, increases the production of melatonin.
Related to nocturnal activities
role od adenosine
Sleep- promoting factors, tells you your tire- sleep pressure
Releases by neurons- inhibitory effects on diffused modulatory systems
Responsible for the cascade release of melatonin
Can impact it by sleeping through out the day
Linked with cortisol hormone:
Fluctuates throughout the lifespan of your lives
