7. Reward and addiction Flashcards
define reward
the motivational property of a stimulus that induces appetitive behaviour
define appetitive behaviour
behaviour related to the desire to approach or to consume
olds & milner 1954
self-stimulation in rats
septal region
- cocaine, food etc
- mirrored behaviour in humans
name 4 different dopamine pathways
- mesolimbic
- mesocortical
- nigrostriatal
- tuberoINfundibular
Dopamine goes primarily from _________ to _________________
VTA
to Nucleus Accumbens
Name three brain structures also heavily involved in reward and addiction processes
Amygdala - emotional processing
Prefrontal Cortex - planning
Hippocampus - memory and learning
define addiction
a chronic, complex mental illness
uncontrolled, compulsive drug seeking and use, despite negative health and social consequences
name 2 defining characteristics of ADDICTION
- tolerance
- withdrawal
name the three stages of addiction
- Binge and Intoxication (feeling euphoric –> feeling good –> escaping dysphoria)
- Withdrawal (reduced energy –> reduced excitement –> depression)
- Preoccupation, anticipation (looking forward, planning how to get drug)
methods of neuroadaptation
neurocircuits, synaptic systems, molecules, epigenetics
neuroanatomical changes due to addiction
- upregulation of D1 receptors in dorsal striatum
- –> sensitization
- downregulation of D2 receptors
- –> loss of control
at the synapse:
strong stimulation –> induction –>
increased release (presynaptic)
increased synapses
increased response
ALCOHOL
- mechanism of action
- Positive allosteric modulator for GABAa
- -> Increase of GABA activity on DA
- Antagonist of NMDA glutamate receptors
- Opioid and endocannabinoid agonist
NICCOTINE
- mechanism of action
AGONIST: alpha4/beta2 ACETYLCHOLINE receptors on the DA neuron
AGONIST: on Alpha 7 receptors on glutamate neurons from the prefrontal cortex
which reuptake transporters does cocaine block?
monoamines
- noradrenaline
- serotonin
- dopamine
- adrenaline
- -> Monoamines accumulate in the synaptic cleft
- -> enhanced, prolonged sympathetic effect
