Measuring Fish Brains... The New Game In Town

I've been sucked in to this whole fish brain/neurobiology thing. Maybe I benefit by not having formal training in it? What I've gleaned from reading some relevant papers on fish brain size and apparent function is that there are a wide variety of ways to quantify fish brain size. What we've started in on with scarlet shiners is fairly simple, just to consider brain mass as a function of body mass. This approach doesn't seem to be too common, except with some shark researchers from what I can tell. Many researchers focus on the size of specific regions of the brain, such as the telencephalon or cerebellum. They usually do this by measuring the length and width from a dorsal perspective in a digital image. I was talking to Amy today about this and we both felt that a more precise measure of specific brain regions would be informative. But weighing a shiner cerebellum is a very precise measurement; maybe we could do it with ten individuals of each sex for a reasonable data set? An easier measure might be volume. For such oddly shaped structures maybe we could set up a small cylinder to measure displacement and state that as cubic millimeters. Or, using an ellipsoid volume calculation if one has length, width and depth. One reason to do this would be to see if male fish, especially male fish, have a larger cerebellum relative to body size than females. This would be consistent with alpha males being more active in defending territories, so that their cerebellum is enlarged to handle this coordination of movement in three dimensional space. Some work has been done on this general theme with a range of shiner species, published by Robert Huber and Michael Rylander in 1992. So in principle we could deepen this work and find other correlations. These are all tempting ideas at the moment; in the immediate future I hope we can accumulate a data set based on about 100 scarlet shiner brains. We already have 9 dissected out as of yesterday; my even more immediate task is to make sure that the students keep fresh blades in the scalpels!