| Date | November 2016 | Marks available | 3 | Reference code | 16N.3.HL.TZ0.5 |
| Level | Higher level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Compare and contrast | Question number | 5 | Adapted from | N/A |
Question
D-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), the two main psychoactive ingredients of the Cannabis sativa plant, have distinct symptomatic and behavioural effects. Functional magnetic resonance imaging (f MRI) was used in healthy volunteers to examine their effects on the parahippocampus, an area of the brain related to emotions and on the visual cortex. The effects are as shown.
Outline the benefits of using fMRI in this experiment.
Compare and contrast the effects of THC and CBD on the areas of the brain studied.
State the function of the visual cortex.
Markscheme
a. «fMRI» allows imaging through magnetic resonance
b. to measure the amount of activity/blood flow in different parts of the brain
OR
to identify the parts of the brain that are activated
c. non-invasive/indirect observation/real time observation
a. THC causes a negative/inhibitory mean activation of parahippocampus whereas CBD causes a positive/excitatory one
OR
THC and CBD cause opposite effects on parahippocampus
b. both cause a positive/excitatory «mean activation» of the visual cortex
c. «magnitude» of mean activation of both ingredients is minute on parahippocampus compared to visual cortex/OWTTE
d. mean activation due to THC lower than CBD for both «parahippocampus and visual cortex»
OR
mean activation due to THC lower than placebo whereas higher for CBD for both
e. other valid comparison/contrast between the two drugs
processing visual information/signals from the optic nerve/OWTTE
