Final answer:
Helen Mayberg used deep-brain stimulation to manipulate neural activity, aiming to improve memory while causing personality changes. The correct answer is d.) deep-brain stimulation.
Step-by-step explanation:
Helen Mayberg and her colleagues have used deep-brain stimulation (DBS) to manipulate activity in a neural hub that bridges the frontal lobes and the limbic system. DBS is a surgical procedure that involves placing electrodes in specific brain regions to modulate neurological function and has been used to improve memory functions.
However, it has been reported to cause simultaneous changes in personality. Other methods like neurofeedback harness the specificity of EEG patterns for different emotional states or cognitive tasks, enabling individuals to modulate their brain activity in real-time.