Neuroscience 210

  1. Definition of addiction (5 c's)
    - biopsychosocial model

    • - control--loss of control of use of the drug
    • - compulsive use--feel compelled to keep using the drug
    • - consequences--keep using despite consequences
    • - cravings
    • - chronic--long term use
  2. Cycle of addiction
    • 1. Europhoria (taking the drug and feeling great afterwards because of it)
    • 2. Adaptation (after initial phase, same amount of drug doesn't do as much, early withdrawal)
    • 3. Exposure to cues and stress--cause you to have 4. Cravings
    • 5. Loss of control--go back to 6. drug seeking behaviour
    • taking the drugs leads to more feelings of euphoria, which starts the cycle over again
  3. Drug Euphoria
    • Causes:
    • positive reinforcement
    • impulsive use, want the high again

    • activates subcortical reward pathways
    • - ventral tegmental area to nucleus accumbens= pleasure pathway (reward pathway, involved in more than just drugs)
    • - involves dopamine
  4. NA dopamine levels with food (basic reward) and cocaine (drug reward)
    food deprived rats with intracranial pipettes, were given food and then the dopamine levels were measured. The food caused a spike in dopamine

    drugs work on the same architecture of reward as other things like good. Dopamine levels also increased after cocain admistration, but increased a higher amount.
  5. Neuroadaptation

    • - tolerance--need more substance to get same effect
    • - withdrawal--both physical and psychological
    • - homeostasis-->allostasis --a change in the set point of homeostasis

    there is usually equilibrium in what is important, e.g. between food, sex, drugs, but this changes with repeated drug seeking

    with repeated stimulation of dopamine pathway, there gets to be fewer receptor available, to try and reinstate homeostatis from the overstimulation---results in less activation and less binding
  6. Motivation pathway
    Orbitofrontal cortex is involved in motivation, in saying what behaviours are important, and it attaches a preference to the drug behaviour
  7. Cravings
    negative reinforcement-- when you are craving and then you take the drug, you are rewarded by the removal of the craving feelings

    compulsive use--feeling like they have to use to take away withdrawl feelings

    dysregulated reward pathways involving-neurotransmitters and transcription factors (genetic codes
  8. Drug related cues
    • limbic activation--remembering good and bad times
    • - emotion and memory--drug users remember the high and cues related to the high

    sensory cues---people and places

    stress--makes you want to go back to what you always did

    study where cocain addicts were shown vidoes of nature and animals and then cocain cues, the amygdala light up, and the people reported cravings as well.
  9. Loss of control
    • denial
    • impaired decision making
    • hypofrontality--reduced activity, in the frontal lobes where you make decisions
  10. Executive control pathway
    • PFC--involved in decision making, tells you what not to do
    • damage causes impulsivity

    brain glucose metabolism in cocain abusers and controls--decreased glucose levels in the frontal lobes in abusers, decreased activation of frontal lobes
  11. Drug administration
    • result of:
    • - drug seeking behaviour
    • - failed impulse suppression
  12. Neurobiology of addiction (full model)
    • VTA--NA= pleasure pathway mediated by dopamine
    • amygdala and hippocampus involved in memory for high and cues
    • Orbitofrontal --motivation involved in setting preferences
    • PFC--breaks on behaviour have failed

    All these systems working together causes addiction
  13. Recovery
    Regeneration of dopamine receptors can occur, with time and treatment

    but: imprinting is so strong inthe brain, a person could be clean for a while and then a cue could trigger a relapse.
Card Set
Neuroscience 210