WK 11 bb Flashcards
Substance abuse is a pattern of drug use in which
people rely on a drug chronically and excessively and not for therapeutic reasons
addiction or dependance =
physically dependant on a drug in addition to abusing it
Reinforcing stimuli have a greater effect if
it occurs immediately after the behaviour
Positive Reinforcement: Neural Mechanisms
- triggers release of dopamine in the nucleus accumbens (NAC)
- process of addiction begins in the mesolimbic dopaminergic system
- produce long term changes in other brain regions, starting with the ventral tegmental area (VTA)
Function of dopamine pathway
- REward (motivation)
- Pleasure, euphoria
- Motor functioning (fine tuning)
- Compulsion
- Perseveration
Function of seotonin pathway
- mood
- memory processing
- sleep
- cognition
changes in VTA leads to
(positive reinforcement process from drugs)
does this happen immediately
what other areas does this affect
increased activation in a variety of regions that receive dopaminergic input from the VTA
Synaptic changes that are responsible for the
compulsive behaviours that characterise addiction occur only after continued use.
- Important changes occur in the dorsal striatum which is part of the basal ganglia
- The basal ganglia plays a critical role in instrumental conditioning
- Withdrawal symptoms
– generally the opposite of the drug itself
– the body may have started to compensate for the
disturbed homeostatic mechanisms
Negative Reinforcement and addiction
potentially maibtains addiction e.g. removes withdrawal symptoms
can start addiction, e.g. remove stressors
Cravings can occur after a long period of abstinence.
* Potentially due to
ong-lasting brain changes
* Drug-related stimuli can elicit classically conditioned responses in substance abusers, both physiologically and subjectively - cravings
Franken (2003) suggests craving and relapse are due to
‘attentional bias’ – cued by cognitive processes and increases in dopamine in response to drug
stimuli.
Drug stimuli as in things related to drug use. even weather can cause a dopamine increase, thus intensifying the cravings
Prefrontal cortex has been implicated in drug abuse e.g.
prefrontal cortex activity decreases as drug use increases
Either way, PFC plays an important rol in drug use through ____ ______ and ____ ________ (Goldstein & Volkow, 2011)
emotion regulation
inhibitory control
_______ is the most commonly abused opiate
and abuse comes with high personal and
societal costs.
Heroin
Systematic administration of opiates
stimulates _____ ______
causing which effects
opiate receptors
- analgesia [pain relief] (periaqueductal grey matter)
- Hypothermia (Preoptic area)
- Sedation (Mesencephalic reticular formation)
- Reinforcement (VTA and nucleus accumbens)