Lecture 4 Flashcards
the arousal system is made of neurons that release which neurotransmitters
- acetylcholine
- histamine
- dopamine
- norepinephrine
- serotonin
increasing firing of the neurons or the synaptic levels of the neurotransmitters will promote (related to sleep)
wakefulness
decreasing firing of the neurons or the synaptic levels of the neurotransmitters will promote
sleep
when the arousal system is firing
the sleep center is not firing
the arousal system is activated by
hunger signals and sunlight
- particularly blue light
during the day the brain uses energy in the form of ATP and waste product is
adenosine
sleep is promoted by
adenosine
- accumulates when the brain is awake and is cleared when the brain is asleep
what is attention
selection of information for focused conscious processing
- required for most forms of cognition
important parts of the brain for attention include the
cortex, basal ganglia, thalamus
attention requires a certain level of arousal, which is determined by
neurons in the reticular activating system
what is the reticular activating system
determines where we are on the spectrum of wakefulness
for simple tasks, the more awake you are
the better you will perform at this task (linear relationship)
for complex tasks what does the curve look like
resembles a bell curve, meaning the more awake you are to a certain point the better you will do
- if you are too aroused you will perform worse (panic)
norepinephrine neurons are located close to
dopamine neurons in the mid brain and send their axons throughout the cortex
t/f norepinephrine neurons have a repuptake mechanism
true, known as the norepinephrine transporter (NET)
another name for norepinephrine
noradrenaline
what are psychostimulants
drugs that promote wakefulness and attention
- often increase motor activity as well
t/f caffeine is not a psychostimulant
false, it very much is
how does caffeine act
It acts by blocking the adenosine receptor in the brain. This prevents the adenosine signal that triggers sleep. It also indirectly promotes signaling from adrenaline and norepinephrine because it amplifies the signal from those transmitters.
- is an antagonist of the adenosine receptor
is caffeine addictive
no it is not, but people do develop dependence and tolerance to its effects
adverse effects of caffeine
dry mouth, agitation, nausea/heartburn, diarrhea, insomnia, racing heart
have fatal overdoses of caffeine happened
yes, rare but they have happened
what are the two ways caffeine increase vigilance
- antagonist of the adenosine receptor
- inhibitor of phosphodiesterase enzyme
explain how caffeine is an antagonist of the adenosine receptor
- Adenosine is the byproduct of metabolic activity in the brain – when neurons fire they consume ATP (energy) and it is converted to adenosine.
- Adenosine binds to the adenosine receptor to induce sleepiness. Blocking the adenosine receptor prevents the signal to induce sleep.
explain how caffeine is an inhibitor of phosphodiesterase enzyme
- Norepinephrine is one of neurotransmitters that promotes alertness/vigilance.
- When norepinephrine binds its receptors (adrenergic receptors), it causes the production of a signal called cyclic AMP. Cyclic AMP is degraded by phosphodiesterase enzyme. Caffeine antagonizes the enzyme that degrades the cAMP, so it amplifies the signal from norepinephrine. This is also why caffeine causes similar symptoms to adrenaline (dry mouth, rapid heart rate).
t/f caffeine is not an antagonist of phosphodiesterase
false, caffeine is an antagonist of phosphodiesterase
Caffeine amplifies the arousal signals of norepinephrine by
antagonizing the enzyme that breaks down the cyclic AMP signal. More cyclic AMP = more alert/awake
most psychostimulants are
DAT and NET blockers
cocaine, methamphetamine, amphetamine, methylphenidate and modafinil are all
psychostimlants that act by blocking the DAT, NET, AND SERT
t/f Modafinil mechanism is not understood, not as effective as others
true
cocaine, methamphetamine, amphetamine, methylphenidate and modafinil are all addictive depending on
dose, route of administration and individual differences
effects of cocaine, methamphetamine, amphetamine, methylphenidate and modafinil
wakefulness, euphoria, suppressed appetite, insomnia, agitation, restlessness, dry mouth, racing heart, GI upset, constipation, GRANDIOSITY, PARANOIA, PSYCHOSIS
- last three are for really high doses
what is attention deficit disorder
- Difficulties with voluntary attention, increases in involuntary
attention (distraction) & impulsivity. - Memory impairments, problems with executive function
(planning ahead, prioritizing). - Hyperfocus when interest level/adrenaline is high.
why is ADD treatment important
to reduce comorbidities with depression & anxiety, academic failure, criminality.
what are the drug treatments for ADD and ADHD
they are psychostimulants
that increase the levels of neurotransmitters dopamine and
norepinephrine in the brain. They either prevent the clearance of
these neurotransmitters or they cause the neurotransmitter to
be reverse-transported into the synapse.
- there are also lifestyle changes that can improve symptoms for people with ADD
what is narcolepsy
a sleep disorder where disruptions in sleep architecture prevent quality sleep, and extreme sleepiness during the day occurs. People can also experience the muscle paralysis that accompanies sleep (during their waking hours)
what is modafinil used for
narcolepsy
what does modafinil do
- increases arousal/alertness. It is used to treat the daytime sleepiness that occurs and it also prevents muscle paralysis.
- Increases alertness by increasing the levels of norepinephrine, dopamine and histamine.
- It inhibits DAT and NET, but it is much less effective than drugs like cocaine (even at high doses it doesn’t block the transporters very well). The mechanism of action remains unclear.
Amphetamine (Adderall), methylphenidate (Ritalin), and modafinil (Provigil) all increase
arousal, and increase performance on certain types of tasks…those that require high levels of arousal.
Amphetamine (Adderall), methylphenidate (Ritalin), and modafinil (Provigil) can interfere
with some forms of cognition, like creative problem solving
- except modafinil maybe
