GRE Reading Comprehension
How can the hormone adrenaline that does not act directly on the brain have a regulatory effect on brain function? Recently, we tested the possibility that one of the hormone's actions outside the brain might be responsible. Since one consequence of adrenaline release in an animal is an increase in blood glucose levels, we examined the effects of glucose on memory in rats. We found that glucose injected immediately after training enhances memory tested the next day. Additional evidence was provided by negative findings: drugs called adrenergic antagonists, which block peripheral adrenaline receptors, disrupted adrenaline's ability to regulate memory but did not affect memory enhancements produced by glucose that was not stimulated by adrenaline. These results are as they should be if adrenaline affects memory modulation by increasing blood glucose levels.
The author refers to the results of the experiment using adrenergic antagonists as "negative findings" most likely because the adrenergic antagonists
- A failed to disrupt adrenaline's effect on memory
- B did not affect glucose's ability to enhance memory.
- C did not block adrenaline's ability to increase blood glucose levels
- D only partially affected adrenaline's ability to enhance memory
- E disrupted both adrenaline's and glucose's effect on memory
Correct Answer: B