A researcher uses PET scans to measure tracer uptake in brain region P while volunteers complete different tasks.
| Condition | Mean tracer uptake in region P (% of resting value) |
|---|---|
| resting | 100 |
| listening to repeated tones | 126 |
| judging whether pairs of tones are the same or different | 162 |
What can the researcher validly infer from these results?
Region P was more active in both sound tasks and most active when judging tones, but these results do not show that its activity caused the ability to judge.
Region P was more active when judging tones but remained at resting activity when listening to tones; however, the results do not show exactly what processing occurred.
Region P was equally active in both sound tasks because uptake exceeded rest in each, but the results do not show whether it is involved in untested tasks.
Region P was more active when judging tones than when listening to tones, so the results indicate it is necessary for judging, but not that it acts alone.
111 exam-style questions on Edexcel GCSE Biology 2.3 The nervous system and brain, covering 2.3.1 Structures and functions of the brain, 2.3.2 Imaging brain function with scanning, 2.3.3 Limitations in treating nervous system damage, 2.3.4 Neurones and impulse transmission, and 2.3.5 Structure and function of a reflex arc. Each one has a worked solution and a mark scheme showing where the marks go.