CONSCIOUSNESS AND BRAIN ACTIVITY Flashcards by Maddie Steevenson

what is consciousness?

the state of being aware of and responsive to one’s surroudnings

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what is locked in syndrome?

complete paralysis of voluntary muscles, except for those that control the eyes

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what is the Glasgow coma scale?

The most common scoring system used to describe the level of consciousness in a person following a traumatic brain injury.

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what is the lowest score possible on the Glasgow coma scale?

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what does GCS 13-15 mean?

mild head injury

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what does GCS 9-12 mean?

moderate head injury

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what does GCS 3-8 mean?

severe head injury/coma

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what are the 3 factors that suggest a patient is in a coma?

not opening their eyes, not uttering understandable words and not obeying commands

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what is the Reticular Activating system?

What is its role?

a network of neurons located in the brain stem that project anteriorly to the hypothalamus to mediate behavior, as well as both posteriorly to the thalamus and directly to the cortex for activation of awake, desynchronized cortical EEG patterns.

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what is the reticular formation?

a set of interconnected nuclei that are located throughout the brainstem. It’s not anatomically well defined, because it includes neurons located in different parts of the brain.

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what are the 4 nuclei of the reticular formation?

locus coeruleus
raphe nuclei
ventral tegmental area
cholinergic nuclei

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locus coeruleus
where is it?
what is its neurotransmitter?

located in pons

noradrenaline

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raphe nuclei
where is it?
what is its neurotransmitter?

located in midline of midbrain, pons and medulla

serotonin

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where is the ventral tegmental area?

what is its neurotransmitter?

ventral region of the midbrain

dopamine

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what are the 2 cholinergic nuclei?

basal forebrain nuclei

dorsolateral pontine nuclei

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where does the basal forebrain nuclei project its information to?

all cortical areas

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where is the dorsolateral pontine nuclei found?

what is its neurotransmitter?

brainstem

acetylcholine

what does damage to the dorsolateral pontine nuclei cause?

contributes to dementia

what is the function of the ventral tegmental area?

Modulates frontal activity & reinforces pleasurable sensations

what does a) low activity and b) destruction of the locus coeruleus cause?

a) depression

b) obliterates REM sleep

the anterior hypothalamus is also involved in consciousness…
what does damage to this area cause?
what is the neurotransmitter?

insomnia

GABA

the posterior hypothalamus is also involved in consciousness…
what does damage to this area cause?
what is the neurotransmitter?

too much sleep

histamine

what can damage to the reticular activating system cause?

loss of consciousness and coma

what does the EEG look like when…

a) we are awake?
b) we are asleep?

a) desynchronous

b) synchronous

what are the oscillations in the EEG generated by?

interactions between thalamocotical, reticular and corticothalamic neurons

describe what happens when we are awake?

the ACh system is active and sensory thalamus is facilitated whilst reticular nucleus is inhibited. thalamocortical neurons active

describe what happens when you are asleep?

ACh system inactive. sensory thalamus inhibited and reticular nucleus activated. thalamocortical neurons are in slow rhythm

what are the 2 main types of sleep?

synchronised (Non-REM) or desynchronised (REM)

describe EEG waves during non-REM?

slow and synchronised waves

describe EEG waves during REM?

high frequency activity

what can REM also be called? what is it associated with? what is a key feature?

paradoxical sleep dreams abolition of muscle tone

how long is each sleep cycle? how do the cycles earlier on in the night differ to those later?

90 minutes | early in the night you tend to spend more time in non-REM and then later on you spend more time in REM

describe the sleep cycle

Stage 1 - Transition stage between wakefulness and sleep that normally lasts 1-7 minutes. Stage 2 - Also known as light sleep, is the first stage of true sleep. Stage 3 - Moderately deep sleep. Body temperature and blood pressure decrease, and it is difficult to awaken the person. This stage occurs about 20 minutes after falling asleep. Stage 4 - The deepest level of sleep. Although brain metabolism decreases significantly and body temperature drops slightly at this time, most reflexes are intact, and muscle tone is decreased only slightly. When sleepwalking occurs, it does so during this stage

what are some short term consequences of sleep deprivation?

``` Slower reflexes • Memory disorders • Muscle fatigue • Mood swings • Aggressive behaviour • Disorientation • Hallucinations ```

what are some long term consequences of sleep deprivation?

Obesity • Diabetes • High blood pressure • Cardiovascular disease

what is circadian rhythm?

natural, internal process that regulates the sleep–wake cycle and repeats on each rotation of the Earth roughly every 24 hours

what controls our circadian rhythm?

The suprachiasmatic Nucleus (SCN) is a group of cells in the hypothalamus that respond to light and dark signals. When our eyes perceive light, our retinas send a signal to our SCN.

what can the SCN secrete?

vasopressin to local brain areas | indirectly modulates the pineal gland to release melatonin

what is the function of vasopressin?

it tells the body to store water so you don't need to be going to the toilet all night

what is the function of melatonin?

it promotes sleep