I agree that the inclusion of research in any residency application will have an unpredictable utility. As you indicate that you are interested in neurosurgery, the most important criteria will be competitive USMLE scores and strong medical school performance/LORs. Once the selection committee examines your application further (this is accomplished through those competitive scores, etc noted above), the research experience could certainly be a factor that may contribute to your selection. This can be influenced by venue as well (a strong research-oriented academic center vs a less research driven university hospital).
I was a career PI in toxicology/organismal biology until I decided to attend medical school. As I decided to pursue family medicine, the selection committee expressed initial concerns about my candidacy DUE TO my career as a research scientist and my intentions to continue my research after residency (as I have). Their concerns were based on the incorrect notion that scientists have difficulty clearly communicating with people. Obviously, in any primary care specialty, communication skills are of paramount import.
In neurosurgery this is obviously far less of a concern (!).
Therefore, in my opinion, your exam scores, medical school performance and LORs are the primary criteria to attract attention to your application. Thereafter, your research and pubs could have significant impact on your success. I feel this is unfortunate as I feel each candidate should be considered as a multi-dimensional individual as opposed to numbers on a page, however, due to application number, limited selection time, etc this is not likely to ever occur.
