Header Bar Graphic
Astronaut ImageArchives HeaderBoy Image

TabHomepage ButtonWhat is NASA Quest ButtonSpacerCalendar of Events ButtonWhat is an Event ButtonHow do I Participate Button
SpacerBios and Journals ButtonSpacerPics, Flicks and Facts ButtonArchived Events ButtonQ and A ButtonNews Button
SpacerEducators and Parents ButtonSpacer
Highlight Graphic
Sitemap ButtonSearch ButtonContact Button

Neurolab Online banner

Meet: Danny Riley, Ph.D.

Principal Investigator
The Effects of Microgravity on Neuromuscular Development

photo of danny riley

What I do on Neurolab:

Our experiment on Neurolab is on developing rats, neonatal rats, which are born very immature. They go through maturation of the nerve and muscle system, called the neuromuscular system, in the first three weeks of their life. That's equivalent to a human from 2 months in utero through the first year of life, so it's a very compressed time period of development for the rat. During this period, when the nerve-muscle system is developing, we believe that gravity stimulation, the weight-bearing/the loading on the leg muscles, is important for full development. Without gravity the nerve and muscles may not complete development or they may develop in an abnormal direction. There are some muscles which are very involved with lifting the body up against gravity. These are called the weight-bearing muscles or anti-gravity muscles. We think that this set of muscles and their nerve fibers and the motor neurons that supply these muscles are going to be dependent on the weight-bearing, as opposed to other muscles in the leg which do not perform weight-bearing. These are non-weight-bearing or non-anti-gravity muscles which should develop without the stimulus of gravity.

So when animals go into space, we're going to study the nerve and muscles of these two types of muscles. We expect that the lack of gravity will affect the weight-bearing muscle development, either slow it down or it will be incomplete or possibly go off in an abnormal direction. We think these findings will be relevant to human development. In utero, the developing human is exercising its legs by pushing against the wall of the uterus. We believe that this activity serves a purpose, in that it puts a load on the weight-bearing muscles and stimulates the genes of the nervous system and the muscles to be fully expressed. The normal development of the nerve-muscle system is the product of genes and environment; in this case gravity is the environmental factor. (For more information about Dr. Riley's research, click here)

My Career Journey

I started at the University of Wisconsin. That's where I went through undergraduate and graduate training and earned a Ph.D. in anatomy. I'm very interested in biological structure, trying to figure out the function that comes from structure. After I got my Ph.D., I went to the National Institutes of Health for post-doctoral training to investigate various aspects of nerve generation. Nerves are very important for muscle, which is the area that I studied during my Ph.D. research. From there I went to the University of California, San Francisco, as a faculty member for 8 years and then moved to Medical College of Wisconsin, where I am presently a professor of Cellular Biology & Anatomy.

Likes/Dislikes about career

[The best part about my job is] seeing things for the first time that no one else has really seen before. Doing an experiment, getting results, cutting a section of some muscle tissue and when you get "TO" the microscope and actually see a change and recognizing what made this kind of alteration. Actually what's even more exciting is to make a prediction and then be surprised because the change is opposite to what you predicted. It says, hey I don't know everything, there's more to learn. That's why I'm in the field I am in, because I'm always learning. I never want to stop learning. I always have a curiosity about how things work. So that's what I get - that's the kind of reward I get.

The least favorite part I think is having to constantly lobby for money for research and the resources to do things in the space program. I think it's essential that we have a space program. Technologies that spin off are going to help us in the long run. Moneys are tight and space research is expensive, but it's a unique tool. So you spend a lot of time trying to convince the government to spend money on these various areas. In part it's good because it allows you to think about why are you doing what your doing, but after a while, if you have to keep explaining it too often, you spend too much time doing that and not enough time working on the actual project and thinking about the science and what your trying to study. So that becomes frustrating. I used to say, "There aren't enough hours in the day" and now there's not enough weeks in the day. There's just too much to do.


The challenge of finding out things and also helping - having some spin-offs from basic research that may improve the quality of life is what motivates me. The basic goal with the space program is understanding muscle biology so that humans can be in space and not have any kind of permanent muscle defect, that affects their performance or health. Then that information hopefully spins off into helping with a disease - a muscle disease on Earth. We never know when or from where the next surprise or exciting answer is going to come. Insights often happen 6:00 pm on Friday when only the janitor is there - everyone else went home. You run out in the hall to tell the janitor, "look at the slide - this is a fantastic result!" That's what keeps things going.

I think that this endeavor is something that, for those of us who are in it, are in it for advancing basic biomedical knowledge, which is the foundation for medicine, which relates to improving the quality of human life. So we see it as a practical point-of-view, making a contribution to understanding and knowledge of neuroscience biomedical issues.


Spare time is for going back to what actually got me interested in science in the first place. Fortunately, my wife and I like to go fishing because we like to eat fish. So, we make it a point to have one day on the weekend that we spend some time together and that's one of the activities that we like to do. I grew up doing that in Northern Wisconsin. Instead of just cleaning a fish, I used to dissect it and study the muscles, the nerves and the heart. It would take me hours to do that. I've always been fascinated by all kinds and forms of life.


In the past, I have been involved with space missions studies on my own, but for this experiment I am fortunate to have a terrific collaborator, my wife. She's the expert on the nerve side and I'm the expert on the muscle side. This is a unique opportunity for us to use our two fields of expertise to come together. This is really the first time we've worked together. We've always helped out each other as far as a sounding board on some of our experiments, but no this is the first time she has been directly involved. We recognize the great complexity of the problem and the value of a team approach. The Neurolab Mammalian Development Team of 7 investigations is a very well integrated effort.

The team approach has been a positive experience because you can't be an expert in every area. We can see that various aspects are being covered by other individuals. So, ultimately, when we do the mission and interpret it, we will rely on what's happening and the information of our collaborators or peers. And I think that way, the interpretation of our own experiment will be much better, because it's not just us doing it in isolation. It will make more sense. We should be able to get further along in our research.


Footer Bar Graphic
SpacerSpace IconAerospace IconAstrobiology IconWomen of NASA IconSpacer
Footer Info