Recreational drugs Flashcards
What are recreational drugs ?
Drugs taken for pleasure, psychoactive substances that alter brain function
What are drugs ?
Biochemicals that have specific effects in the function of body’s systems
What is the reward pathway ?
Pleasure centre
What is the mesolimibic pathway ?
Connects to subcortical emotional brain centres with frontal areas
Where does the mesolimbic pathway release dopamine ?
Frontal cortex = contains neurons with dopamine receptors
What are 4 examples of recreational drugs ?
- Stimulants = cocaine
- Depressants = alcohol
- Hallucinogens = LSD
- Opioids = heroin
What are the 5 steps of nicotine in the synapse that increase addiction ?
- Releases dopamine
- Mimics acetylcholine = excitatory
- Binds to acetylcholine/nicotine receptor
- Desensitisation = constant build up of dopamine over time, reduction of dopamine receptors = more to charge pre synaptic neuron
- More dopamine required to stimulate post synaptic neuron = increase substance use to receive same levels of pleasure
What are the 6 steps of cocaine in the synapse that increase addiction ?
- Drug quickly enters brain
- Blocks transporters on pre synaptic cell
- Releases dopamine which can’t reenter pre synaptic cell
- Accumulates in synapse = reach abnormally high levels & remain longer than usual
- Post synaptic cell hyperactivated = euphoria
- Creates association with cocaine and pleasure = repeats taking drug
What are the 2 original uses of amphetamines ?
Treat asthma & sleep disorders in 1920s & combat fatigue in soldiers
What are the 5 steps of amphetamines in the synapse that increase addiction ?
- Enter terminal button in pre synaptic neuron via dopamine transporters
- Diffuse through neural membrane
- Force dopamine molecules out of vesicles into synapse in pre synaptic
- Reduce reuptake of dopamine = excess
- Desensitisation = euphoria causes addiction
What is a short term and long term effect of amphetamines ?
Short = increased heart rate
Long = Insomnia
What is the main impact of amphetamines ?
Increases concentration of dopamine in synaptic gap
Olds and Milner (1954)
Placed electrodes in areas of rats brains in skinner box = rats self stimulate by pressing lever especially in septal area = various places in brain where stimulation is rewarding enough that animals stimulate themself frequently & regularly over long period of time
Volkow et al (1997)
PET scans track activity of dopamine transporters during cocaine induced high = when more cocaine occupied dopamine receptors experience more intense high
What is the credibility ?
Observations add credibility to effects of drugs on NS = dopamine in reward system and gives pleasure = desensitising effect
Is it reductionist ?
Brain is complex = more than one reward pathway. Too simple to suggest cocaine excites post synaptic neurons, glutamate & lower glucose metabolism
What are problems with methodology ?
Hard to study mode of action at synapse, brain scanning helped but can’t measure level of synaptic transmission
What is application for treating addiction ?
More treatments = heroin is agonist binds to opiate receptors, drugs developed to reverse mode of action. Naxolone = antagonist prevents heroin occupying blocked opiate receptors = no euphoria = manage withdrawal & reduce symptoms
