dopamine - 10 marks

• Intro

  AB - disease of the brain > when engage > brain changes maladaptively

  AB hijacks brain via dopamine pathways and changes ( driven by dopamine and reward system) brain activity and chemistry > so places high value on AB

  }brain plasticity - brain changes according to what you do to it
• INITIATION - dopamine and mesolimbic pathway

  DA in MLP = involved in addiction, A driven by dop release in reward system (MLP)

  some B trigger dop rel along MLP (VTA > rec in NA) > sense of pleasure

  dop from VTA activates D2 rec in NA ( pleasure centre ) > euphoria, want to repeat

  AB > system responds to harmful actions and MLP becomes maladaptive
• INITIATION - reward system

  dop neurons (VTA) activate > engage in rewarding behaviour > increase DA / rel

  message passed through pathway

  stimulates D2 rec (NA)> NA - more active > increase DA levels and gives high

  want to repeat
• MAINTAIN AB - characteristics

  TOLERANCE

  repeated use AB > D2 rec (MLP) reduce in number, sensitivity, and amount of dop release overtime

  less sensitive to effects of B/sub > less of buzz / message along MLP > NA

  need to engage more to feel the same sense of pleasure > built up tolerance > increase engagement to increase DA
• MAINTAIN AB - characteristics

  WITHDRAWAL + RELAPSE

  stop > DA and levels in pathway decrease below normal functioning levels

  } leads to reduced BA for other functions / everything dop is involved in > one of the causes of withdrawal symptoms (WS)

  WS > due - irregular dop levels > physical and psychological effects

  engage to overcome and increase dop release > relapse (try to regulate dop levels)

  relapse bc WS > b automatically tries to readjust dop levels (ws last for certain period of time)

  explain why continue AB despite not getting same sense of pleasure
• MAINTAINING & SALIENCE

  Volkow - why A want to engage when it's not pleasurable

  suggest - MLP start for developing A > but changes in PFC through DA in MCP turns engaging in B into A + { complex b proc inv - creating A}

  AB changes b circuits in PFC that decide what to pay attention to

  dop travels VTA > PFC (MCP) } pay attention to experience so - repeat

  when messages from A = continually sent to PFC > changes signals in it so it places more importance on it = becomes SALIENT
• MAINTAINING & SALIENCE

  dop system makes them want to engage rather than like it > exp y get buzz but can't overcome cravings

  B changes so remember pleasure from A > permanent recover = difficult and A more prominent
• EXT - B changes linked to DA

  Dorsal Striatum - b part linked to habit forming

  dop stimulates neurons in DS > helps form habits - identifies enjoyable patterns

  engages > dop > DS and excites it > b repeated

  explain why struggle to quit despite not enjoying AB