Li et al (contemporary study)

Question 1

Aim

Answer 1

1. Investigate the relationship between chronic heroin use and the effects of this on brain areas
2. Investigate the PCC’s functional role in relation to heroin addiction

Question 2

sample

Answer 2

Sample: 14 heroin addicted males, mean age 35. All from a drug rehabilitation centre in China and had been using heroin for an average of 89 months.

Question 3

variables

Answer 3

At the time of the study they were tested for opiate use and found to be clean of heroin and other drugs (except nicotine) and classed as being in the detoxification stage.. All were right handed and none had a history of psychiatric disorder. They were all physically healthy and medically cleared to spend 40 minutes in an fMRI scanner. The matched control group of 15 males varied only in terms of their substance misuse history. The ethics committee of the hospital over saw the experiment and all participants gave informed consent

Question 4

procedure

Answer 4

All participants went in the fMRI scanner, (they underwent two scans in total) their resting state was tested first where they had to focus their attention on a target for 5 minutes and do nothing else. This scan was done first before the cue induced task started.
This was immediately followed by the cue-induced condition/task (experimental condition) Where after a 10 second gap after the first scan, participants were exposed to 24 pictures of drug related activity (heroin pictures – tablets weren’t shown as heroin needs syringes and residue on a spoon) and 24 neutral pictures. Each picture was shown for 2 seconds in a random order. Between each picture there was an interval which ranged between 4 and 12 seconds, during which the ‘resting state’ screen was shown before the next picture. 9why neutral pics
490 second total exposure

Craving was assessed before the cue related condition and afterwards.

Data was then compared in the two tasks and over both conditions. The main analysis was to look for differences in brain connections between the heroin users and the controls.

Scoring took place using the scans of the brain and the volume difference in the brain regions were calculated between both groups.

Question 5

results

Answer 5

The participants who had been addicted to heroin reported craving for heroin following the cue-inducing pictures. Researchers then looked at the brain scan images to see if there were significant differences in the brains of ex-addicts and the control group that could account for these cravings.

In the cue-related task the results of the heroin picture cue-induced task showed significantly different activation in specific areas of the PCC and between the PCC and other brain regions associated with the brain’s reward system in the heroin group compared to the control group. The PCC was more active when heroin users did the cue-related tasks than the control group.

In the resting state, the relationship between different parts of the brain showed a stronger connectivity between the PCC and bilateral insula and between the PCC and bilateral dorsal striatum in chronic heroin users than the control group. Other areas that showed connections with the PCC were also picked out in the heroin users in a resting state. In controls, there was no brain region that showed more significant connectivity with the PCC.

Question 6

conclusion

Answer 6

1. cues trigger habitual reactions as shown by PCC becoming more active additionally its related to rewards hence the instant trigger to crave the reward when in use it also helps explain the reason for relapse without even taking the drugs directly
2. basically it further explains that those in the long-term margin of use have already made connections between the reward and addiction with develops decency of the wanting to feel that reward
3. addiction, craving and reward system become more established as length of time increase (positive correlation)

Question 7

strength

** is a weaknesses

Answer 7

had control over the variables such as the samples were well matched on several measures; statistical tests revealed no significant differences between them other than history of substance abuse. This suggests that differences observed in the PCC were a result of heroin use, although there may have been other factors not controlled in this investigation.

Using an fMRI scan is non-invasive, so it is ethical and easy to perform, so is convenient for both the researchers and the participants. The researchers checked that none of the participants suffered from claustrophobia so ethically the experience should have been acceptable.

**However, scanning when cue-related processing was taking place is likely to have involved a lot of other thought too, so even with care taken to isolate certain variables that might affect functioning they were looking at, there may have been confounding variables. The healthy controls would have had the same conditions; however, there might well be individual differences between individuals that affected the conclusions as cognitive processing is hard to isolate just one task.

Question 8

weakness

Answer 8

There are other ethical considerations; exposing addicts to drug cues could have implications for relapse. Although fully informed consent was given and two ethical committees approved the research.

A weakness of Li et al., (2013) is that the study had low ecological validity as it took place at a university, which we can presume was an unnatural environment for the heroin users. This could have resulted in unnatural behaviour and thinking patterns in the heroin users, which could have been reflected in the f MRI scan. Li et al., (2013) could repeat the study in a more natural setting, e.g. the Drug Rehabilitation Centre in Lantian, to prevent the heroin users from being in an unnatural environment.

A weakness of Li et al., (2013) is that the study has low task validity, as looking at random images, including heroin related paraphernalia, is not an everyday task. As the task was unnatural for the participants, their surprise at the images may have spiked activity in the PCC. However, it should be considered that altering levels of brain activity is not something a participant can control through choice. Therefore, this study is unaffected by social desirability bias and demand characteristics.