What's the difference between above-mentioned fields? Moreover how engineering perspective focused on brain signal analysis and signal processing differ from those? Is this approach only for practical purposes like noise reduction from signals and detecting signals which we already understand for example diagnostic applications. And when you have made your filter ready and find something new which isn't yet discovered the one who get to investigate the results is someone else. Or are there science in this approach also in a sense that you can study and explain how the the brain works and make new discoveries with these signals and systems methods. I'm very interested in the engineering perspective because it gives you a possibility for biomedical engineering which is one of my interest also. I'm just worried about the things i wrote above. Which one of these approaches do you think is best(promising) for understanding the brain and why? If someone could help me with this i would really appreciate it. Thanks for your help.