You may already have an idea for a topic from the course material. Or you may need to do a bit of brainstorming. To help generate ideas for a topic, you may wish to look at some recent issues of Neuroscience journals.
Your professor has identified some examples of high-quality Neuroscience journals: Journal of Neuroscience, Nature, Neuroscience, Neuron, Brain, eLife, Neuroimage, Human Brain Mapping, Neuropsychologia, Journal of Cognitive Neuroscience, Cortex. These are examples of titles - there are many more journals that will be acceptable choices.
You can search for journal titles in Search Everything on the Library website - choose Journals and Newspapers tab.
After looking at some issues, I may decide that my area of interest is the role of neurotransmitters in mood disorders.