Fourth Annual Grant Winners 2003-2004

Richard Speiler, Ph.D., Oceanographic Center
Robin Sherman, Ph.D., Farquhar College of Arts and Sciences

Dean Richard Dodge – Oceanographic Center
Dean Norma Goonen – Farquhar College of Arts and Sciences

Title: A New Model for the Study of the Vertebrate Cerebellum: The Yellow Stingray, Urobatis Jamaicensis

Abstract:

The function of the cerebellum in vertebrates, including humans, is poorly understood; in part, because of the conflicting data obtained from the common vertebrate models, mice and rats. Fishes, in general, have several advantages as vertebrate models for basic brain function and a number of neurological and endocrine functions relevant to human health have been originally worked out in fish models. Fishes are phylogenetically closer than mammals to the basic vertebrate blueprint and thus allow behavioral and neurological studies of fundamental brain systems without the interaction of more recently evolved functions. Further, the absence of a highly developed telencephalon allows ready access to many structures without cerebral interference. However, a disadvantage of working with most fishes is the relatively small size of the brain that often hinders or precludes the use of many standard neurological techniques. In contrast, a group of chondrichthians, the stingrays, has a brain size rivaling mammalian rodent models. Of particular interest to our research, stingrays, like mammals, have a large, complex, three-lobed cerebellum. However, in the yellow stingray these lobes are completely separated. Through substantial trial and error, we have worked out the surgical procedures and have found the lobes can be individually manipulated to examine behavioral correlates of specific lobes. Yellow stingrays are abundant in many areas, they are hardy, and tolerate anesthesia and the surgical procedures well. The potential for these animals as vertebrate models of cerebellar-controlled behavior is clear. At this point, we have only been able to examine gross motor behaviors. For example, ablation of the center lobe causes a fixed-pattern hyperactivity. To continue, we require a method of measuring and quantifying coordinated fixed-pattern activity, i.e. feeding and swimming, as well as training-associated memory. To accomplish this we are requesting funding for a high-speed digital video camera and a swimming chamber.