Van Den Oever- contemporary study (pack 1) Flashcards
what is one key cause for relapse on heroin?
people experience stimuli in their environment that are associated with when they take heroin, these are drug associated cues
What did skinners boxes allow them to do
(yes skinner for VDO)
allowed VDO to control extraneous variables such as social interaction and situational/environmental factors
where was VDO particularly interested in the synapses?
medial pre-frontal cortex
what was the aim of VDO study?
to investigate the acute changes in the molecular composition and function of synapses in the medial prefrontal cortex upon re-exposure to heroin associated cues after long term-abstinence from self-administration
what is the sample?
male Wistar rats
what happened in stage 1 of the study
(self-administration)
EXPERIMENTAL group: trained to self-administer heroin. Every time they were presented with audio-visual cues (drug associated)
IF they poked their nose into a hole, they would receive a dose of heroin
CONTROL group:
trained to self-administer a sweet drink, this was to ensure any changes was down to heroin and not just any reward
what happened in stage 2 of VDO study?
(abstinence and extinction)
after becoming addicted the experimental groups were split in two
some rats kept in separate cage for 21 days, forced ABSTINENC
other rats in self-administration box for 21 days but did not receive heroin after nose poking EXTINCTION
what happened in stage 3
(re-exposure to drug associated cues)
after 21 days, both groups split into two again
half of abstinence and half extinction re-exposed to drug associated cues for 60 mins in original self administer boxes and DID NOT receive any heroin
other half placed in self administration boxes, but were NOT exposed to drug-associated cues and did not receive heroin (a control)
drug seeking behaviour recorded as a measure of relapse
what happened in stage 4
(analysis of composition and function of synapses in the medial pre-frontal cortex)
straight after stage 3, all rats were decapitated and brains frozen for mass spectrometry
this allowed detection of subtle changes in receptor proteins in the synapses of the medial pre-frontal cortex
what is mass spectrometry
analytical technique to identify the amount and types of chemicals present in a microscopic sample
what was result 1?
(behavioural evidence of relapse)
after a period of abstinence or extinction, rats exposed to drug associated cues demonstrated SIGNIFICANTLY GREATER AMOUNT OF DRUG-SEEKING BEHAVIOUR compared to those without
what was conclusion 1?
after abstinence exposure to drug associated cues can trigger a relapse back to seeking behaviour
what was result 2?
composition of synapses in the medial prefrontal cortex
after a period of abstinence/extinction, rats that were exposed to DAC had lower than normal AMPA receptors in the medial prefrontal cortex.
WHEREAS
rats self-administering BUT not exposed to DAC and sucrose trained had normal levels
conclusion 2
the molecular composition and function of synapse changed
synaptic transmission for glutamate in the MPFC was inhibited for rats exposed to DAC
SO…
lower levels of glutamate= lower levels of excitement in the dopamine reward systems
what was the follow up procedure?
used a new set of rats and went through a similar procedure
ONE group injected with a drug to stop endocytosis in the MPFC
results for follow up procedure (part 3)
rats not injected had sig. higher amounts of drug-seeking behaviour compared to those given it
lack of synaptic activity in glutamate system after re-exposure to DAC leads to loss of ‘inhibitory controls’ over drug seeking behaviour
conclusions for part 3
(follow up procedure)
reduction in AMPA receptors in PFC as a result of being re-exposed to drug associated cues is causing relapse
generalisability
W-
only had male Wistar rats so cannot generalise
and they are animals…humans brain functioning more complex
S-
crucial areas of the brain for drug addiction similar to humans so can be generalised
reliability
S-
standardised…all rats trained with same cues and same amount of time
validity
S-
had a control group and others for extraneous variables…clarifies the cause and effect relationship so drug therapies can be developed
W-
reductionist so validity is reduced…limited explanation of the causes of relapse…does not look at social factors
BUT
reductionism is valued as it is scientific
BUT
limits potential usefulness of any drug developed
ethics
S-
harmful to do with human PPT
W-
rats were harmed for example the catheters and damages the reputation
BUT
cost benefit analysis
