Lecture 2 Flashcards
other names for conditioned learning
associative learning or pavlovian learning
to survive, the brain must (conditioning)
form associations between the environmental cues that precede an event and the outcome of the event
by forming associations the brain can
predict what comes next and can seek out a good outcome and avoid a bad one
dopamine is for
good and bad outcomes
pavlov’s experiment
- studying the physiology of digestion in dogs
- noticed that dogs salivate at sight of person who fed them
- rang a bell just before he fed the dogs
- after several repetitions the dogs would begin to salivate when the bell rang
dopamine is responsible for
associative learning, prediction and calculation of outcomes
dopamine is associated with
movement
- key ingredient for a decision
- move towards something good, away from something bad
parkinson’s leads to difficulty with
motor skills
- dopamine neurons are dying and continue to die
- leads to less and less movement
dopamine dendrites are only in
one section of the brain
characteristics of dopamine dendrites
- darker in humans
- send their axons throughout the brain
- they live in the substantia nigra and tegmental area and extend broadly throughout the brain
action of dopamine neurons
- synaptic vesicles have little molecules of dopamine
- is released whenever an action potential travels to the end
- opens the calcium channels and the packet opens and it lands on a dopamine receptor
- the brain uses the dopamine transporter (DAT) as a major way of clearing dopamine
- this DAT essentially vacuums the dopamine back up and recycles it
T/F there are some drugs that will prevent the transport from working, leading to more activation of receptors
true
what drugs prevent this DAT from working
cocaine, meth, amphetamine
T/F we are born with limited amounts of dopamine
true, once they die there is no way to replace them
ADD DOPAMINE FIRING CHARTS
describe
what was the rat dopamine experiment
- they listened to the neurons in rats after giving them a sweet reward
- neurons got excited about the reward initially
- then it showed that the neurons got excited about a stimulus that made them anticipate the sweet reward (ringing a bell or turning a light on)
what does dopamine do
- there is a steady state of dopamine firing that occurs to make movement possible. if you have no dopamine you cannot move, dopamine facilitates voluntary movement
- dopamine fires more when something new or unexpected happens
definition of addiction
- defined as a compulsion to take a drug or engage in an activity despite adverse consequences
physical dependence definition
- people know its not good for them and yet they persist
- makes people look bad
who is vulnerable to addiction
- people who consume addictive drugs
- environmental risk factors
- people with psychiatric disorders
- family member with addiction disorder
- men have higher rates than women
- genetic risk factors may be specific to drug of abuse
two diagrams
early and late addiction
cycle of addiction
- drug seeking creates an association in your brain that leads you to want to take it
- then leads to compulsive drug use and then tolerance
- then you get relief from that withdrawal (feel better while taking it)
- then leads to acute withdrawal (could lead to prolonged withdrawal, which leads to abstinence)
what are two forms of addictive drugs
- drugs that increase firing rate of dopamine neurons
- drugs that increase the synaptic levels of dopamine by affecting the uptake mechanism (DAT)
what are some examples of addictive drugs for the first form
opiates, alcohol, benzodiazepines, barbiturates, nicotine
what are some examples of addictive drugs for the second form
cocaine, crack, amphetamine, methamphetamine
what are some drugs that are abused but are not highly addictive
- hallucinogens (mescaline)
- LSD
- psilocybin
- PCP
- ketamine
- salvia
why are depressants addictive
depressants are high doses will reduce the activity of all neurons, depressants at low doses will disinhibit dopamine neurons (inhibit the inhibitors which leads to burst firing of dopamine, which leads to a big surge of it)
burst of dopamine feels like
euphoria
when the depressant binds to its receptor, the neuron
releases less GABA
another way to get addicted is to prevent
reuptake
- leads to a build up of dopamine
- more dopamine receptors being activated
three features of addictive drugs
○ They increase the levels of dopamine in the synapse
§ By increase firing rate or preventing clearance
○ They rapidly cross the blood barrier so that there is little time between taking the drug and feeling the effect (increase of dopamine)
○ Repeated use causes physical dependence, with unpleasant withdrawal symptoms that encourage more use
drug tolerance occurs after
repeated use of the drug
the effects of a drug both beneficial or adverse
diminish as the body adjusts its physiology to adapt to the presence of the drug
drug dependence is a physical adaptation where the body and brain
do not function normally without the continued presence of the drug
the absence of a drug after becoming dependent leads to
withdrawal symptoms
drugs for opioid withdrawal
methadone or buprenorphine
drugs for tobacco withdrawal
nicotine or varenicline
drugs for alcohol withdrawal
benzodiazepines
drugs for alcohol use disorder
naltrexone
how do OUD meds work in the brain
there are empty opioid receptors in the brain during withdrawal
methadone is a
full agonist (generates the effect)
buprenorphine is a
partial agonist (generates a weaker, limited effect)
naltrexone is a
antagonist (blocks effect)
