Addiction- the role of dopamine Flashcards
What are the 3 components?
The mesolimbic pathway
Tolerance and withdrawal
The role of the frontal cortex
What is the mesolimbic pathway?
Often called the reward pathway
When engaging in a rewarding activity this pathway is activated creating a pleasurable feeling that reinforces behaviour
Mesolimbic pathway- pleasurable behaviour?
Eating
Drinking
Sex
Drugs
Where is the mesolimbic pathway?
Dopamine is produced in the VENTRAIL TEGMENTAL AREA (VTA)
and goes to the NUCLEAS ACUMBERT (NAC)
Mesolimbic pathway- Joutsa et al?
Dopamine levels increased in participant who were given a gamblic task regardless of the outcome was to win
Mesolimbic pathway- Bolieau?
Alcohol increased dopamine levels in the brain
What happens when our brain adapts?
Adapts and will strive to reach an equilibrium
It alters the brain function it upsets the balance, brain minimise the effect of drug restoring normal function. If used regularly brain will need to balance
What happens when drugs stop being taken?
Brain goes out of balance and withdrawal starts and unpleasant effects start
Drugs will now not be for pleasure but to avoid the withdrawal symptom
What happends when drugs become tolerance?
Drug taken repeatedly so effects of drug diminished each rime so a higher dose needed for same effect
-Works with D2 receptors and different receptors are compatible with different neurotransmitter
What is D2?
Specific type of neurotransmitter that dopamine attaches to
Tolerance and withdrawal- Volkow et al?
Found that in user of cocaine, there was a reduction in both number of D2 receptor in the brain as well as reduction in the release of dopamine
Maintaining addiction- the frontal cortex, the responsibility?
Motivation
Judgment
Decision making
Impulse control
Social behaviour
The frontal cortex- the impact?
Frontal cortex is implication in the maintain of addiction
One piece of evidence for this is the fact when the drug is no longer taken the negative effects of withdrawal and tolerance have disappeared, relapse can occur
The frontal cortex- Volkow et al?
Although dopamine rewarding pathway is the start of addictions develop
This is due to the change in the frontal cortex that turn engaging in a behaviour into addiction
The frontal cortex- Robinson and Berridge?
FC linked to higher cognitive functions such as decision making and memory
In addicts, behaviour changes the brain circut that decides to pay attetion to so brain attatches important behaviour associated. So dopaine system plays a role of yjere liking
Explains why addicts dont enjoy experience but cant stop craving
The frontal cortex- Bolla et al?
Cocain addicts had abnormal frontal cortec and impared preformance in tasks used in frontal cortex like decision making
The frontal cortex- Wang et al?
Addicts have an increased activity i the FC when exposed again to drugs or cues associated with them
Evaluation- not all addictive behaviour increase dopamine level?
Theory says that dopamine increase is involved in both creation and maintenance of addictions, but not all addictions show this
Stokes et al- no significant increase in dopamine levels in volunteers taking cannabis
Yoder et al- no consistent increase in dopamine across the participants in study given alcohol
Evaluation- to simplistic?
dopamine has many other functions than just happiness than regulating movements, control attention
-BELL 2013 ‘kim kardashian neurotransmitters’ saying its fashionable to blame dopamine for a causing a range of problems where in truth the brain system involved are more complicated than the media provides
Strengths of animal study and dopamine?
More ethical than using human rats isolated in good conditions (controlled) meaning it’s valid
Weaknesses of animal study’s in dopamine?
Unethical, cant represent human conditioning e.g. gambling
Cant extrapolate results from rats to human
Evaluation- why do study’s lack ecological validity?
Don’t represent real life having to use nicotine patches or an inhaler
NUTT et al- sample small substance in a different form so its inaccurate
Evaluation- reductionist?
If dopamine, everyone would respond in same way
- We have individual differs function in mesolimbic pathway is ignored
-Dopamine alone isn’t sufficient
-Dopamine explains maintenance but not initiation
Evaluation- ethical issues?
Lack of free will- how accountable are adicts for own behaviour especially change to their frontal cortex
Addicts aren’t in control of dopamine system and feel they’ve been hijacked
Evaluation- strengths?
Reduces social stigma
Addictions seen as a disease
Addicts may seek and receive help
