Li et al. (2013)

Question 1

Aim of the study ?

Answer 1

investigated the involvement of the posterior cingulate cortex (PCC) with heroin dependence

Question 2

Hypothesis ?

Answer 2

they wanted to show that activation is abnormally stronger in heroin addicts than in healthy controls (sign of brain dysfunction in addiction)

Question 3

independent variable ?

Answer 3

whether the ppt is a recovering heroin addict

Question 4

two dependent variables ?

Answer 4

1) activity in the reward-related brain areas (e.g. posterior cingulate cortex)
2) self-report measure of subjective craving from ppt.

Question 5

what self-report measure was used ?

Answer 5

Likert-like scale

Question 6

how many brain scans did each ppt undergo ?

Answer 6

3

Question 7

what was scan 1 ?

Answer 7

structural MRI-to identify standard anatomical structures

Question 8

what was scan 2 ?

Answer 8

5 minute resting-state fMRI

taken when ppt was relaxed and focusing on a fixed point (a crosshair)

Question 9

what was scan 3?

Answer 9

a cue-reactivity trial- involved a second fMRI of 490 seconds during which 48 images were shown to test cue-reactivity.

Question 10

what did the 48 cue-reactivity images involve ?

Answer 10

• 24 were related to heroin (e.g. syringe)
• 24 were neutral
• one shown every 2 seconds in a pseudorandom order
• a gap of 4-12 seconds between each one
• before and after the cue-reactivity run, a self-report of 0-10 scale was used to assess cravings

Question 11

one positive ethical point ?

Answer 11

all ppts gave written consent and approval was obtained from the Ethics Committee at Tangdu Hospital

Question 12

(findings) what were the craving scores ?

Answer 12

• heroin users had significantly higher subjective craving scores than controls after (but not before) the cue-induced craving
• p= 0.004
• their average scores rose from 2.23 to 3.21

Question 13

(findings) what brain activation was there in the cue induced task ?

Answer 13

• researchers found a stronger functional connectivity in heroin users between PCC and the insula and between the PCC and Dorsal striatum
• in control ppts, there was no region of the brain that showed more connectivity to the PCC

Question 14

What conclusions were made ?

Answer 14

• drug related cues are powerful predictors of reward for heroin addicts
• PCC is linked to neural circuits involved in drug cravings
• the neural dysfunction affects the individuals ability to process external stimuli (especially those related to drug-taking)
• significant positive correlation between length of dependence and strength of functional connectivity shows the neural connections between the PCC and the dorsal striatum and insula are closely related to chronic heroin dependence