Describe the case of Phineas Gage
- large metal bar through his frontal cortex = orbitofrontal cortes
- good health but something was not quite righttttt
- impatient, indulging, gross profanity
What is psychosurgery
- severing or disabling part of the brain to treat mental illness
- LOBOTOMY = severing connection in the prefrontal cortex
Why was lobotomy so bad?
- results varied wayyy too much
- -> some vegetables
- -> some normal
- -> some very impulsive + childlike
What marked the end of lobotomies as a treatment of mental illnesses?
Antipsychotic: Thorazine by GSK
- used to treat mainly SZ + Manic episodes
Other than dividing the brain into their functions, how else can the brain be mapped?
- Cytoarchitectonic devidion
= mapped based on where similar cell types are found
What is the function of the frontal cortex?
- makes you choose the harder thing to do as it would be the most beneficial in LT vs short + easy thing
What type of discounting was found in people with medial orbitofrontal damage to future rewards?
- Myopic discounting
- swapping for the shorter reward much quicker
What is the Iowa Gambling task?
- subject chooses from 4 decks of cards
- total of 100 choices from decks
- 2 decks large short-term gain, long-term gain
What were the findings in the Iowa gambling test for patients who sustained unilateral focal damage to the frontal lobes, who had frontal lesions and substance dependent subjects?
- unilateral focal damage = patient
- frontal lesion + substance dependent = impaired decision making in spite of obvious failures
What are the main types of substances being abused?
- alcohol
- Nicotine
- Opioid agnoists: Heroin, morphine
- Psychostimulants: cocaine, amphetamines
- THC: WEED
- Sedatives: Benxodiazepines
- Hallucinogens:
- -> psychedelics - LSD, DMT
- -> Dissociative: Ketamine, alcohol
- -> Deliriants: atropine, scopolamine
- inhalents
What reasons are there for why people take drugs?
- experimentation
- pleasures
- medication
- peer pressure
- not the same as why they get addicted
What does addiction mean?
“bound” or devoted to
What are the 3 characteristics of drug addiction?
- Compulsive drug seeking + taking
- Inability to stop + high rates of relapse after cessation
- Why drug become more wanted and less liked
Say 60% of people try illicit drugs, what % actually go on to develop a drug addiction?
5-10% develop drug addiction
- very few, who try, actually go on to develop a drug addiction
What are the general criteria for Substance Use disorder in the DSM-5?
- problematic pattern of use
- clinically significant impairment to their every day life
- -> failure to fulfil major role obligations
- occurring within a 12 month period
How many symptoms need to be present if the substance use disorder is considered severe?
- severe = 6+
- Moderate = 4-5
- Mild = 2-3
Where is the primary reward circuitry located?
- found in the medial forebrain bundel
- Venreal tegmental area
- -> mesolimbic dopamine pathway
- Nucleus accumbens
- -> mesocortical pathway
What brain changes have been found in those who abuse alcohol and in polysubstance abusers?
- alcohol = reduced cortical gray matter volume
- polysubstance abusers = smaller volume of preforntal lobe
What has PET scans of glucose metabolism in control and cocaine abuser shown?
- Reduced orbitofrontal cortex function vs control
Cue-induced cocaine craving activated what parts of the brain?
ACC - anterior singulate cortex
OFC - orbitofrontal cortex
What did they find when methamphetamnie-dependent subjects were asked to perform a delay discounting task?
- more likely to quickly choose the smaller-immediate reward
- smaller in opioid-using + recovering subjects
Although LT drug use has shown to increase impulsive behaviour due to changes in preforntal cortex, what alternative avenue is there?
- particular individual “traits” of impulsivity may put people in a higher risk of drug taking?
What is the 5-choice serial reaction time task and how can this support the exploration of the impulsivity trait being a factor in drug abuse?
- rats told where reward is
- observed behaviour just before light/ after light
= high impulse animals take a lot more drug throughout - so already impulsive and this just made them more vulnerable
What is the prefrontal model on addiction; Janrsch + Taylor, 1999?
- impulse control
- increased likelihood of taking drugs
- drug intake
- drug-induced structural and functional changes in prefrontal regions
- cycle beings again
