B.A. Biology (specialization in marine science), Boston University
Ph.D Sensory Neuroethology, Auckland University, New Zealand
My specialization is called "sensory neuroethology," which is the study of sensory biology and behavior, and how these behaviors are moderated by the brain. Despite their basal place in vertebrate evolution, little more than qualitative data is available on variations in chondrichthyan (cartilaginous fish) brain organization and the implications these variations have for evolutionary adaptations in sensory/motor function in vertebrate nervous systems.
My work at CSCI is involves the application of Magnetic Resonance Imaging (MRI) methods in conjunction with advanced image and data analysis methods to the study of brain structure and function in elasmobranchs. The two specific areas of focus are (1) Brain organization in cartilaginous fishes using structural MRI and diffusion tensor imaging (DTI) MRI and (2) assessment and quantification of cerebellar foliation using high resolution structural MRI and advanced shape analysis.
(1) There is much interspecific variation in shark brain organization that does not track phylogenetic relationships [Yopak et al., 2007; Yopak & Montgomery, 2008]. My previous work showed that brain organization is correlated with ecological parameters, such as locomotory style, feedings habits, and dimensionality of the environment [Yopak et al., 2007]. The goal of my work at CSCI is to extend and quantify my previous findings using advanced imaging and analysis methods.
(2) One important finding in my previous work was the relationship between the level of cerebellar folding (or foliation) and environmental parameters. In that work, we had developed a visual grading method, ranging from 1-5, which provided a classification scheme for cerebellar foliation [Yopak et al., 2007]. However, visual classification is limited as it does not parameterize structural variations, and thus does not provide a quantitative method for characterization and comparison of foliation. Moreover, it can often miss subtle but important differences between species that can have high evolutionary significance. We are currently developing algorithms to look more closely at quantitative measures for cortical surface structure [Yopak and Frank, 2007], as folding (or foliation) of the cerebellum varies greatly between species, such as the Great White Shark and the Hammerhead Shark.
We hope to build on earlier methods using MRI, to perform more rigorous, quantitative shape analysis methods to advance the field of comparative neuroanatomy. With each new advancement, we are moving closer to uncovering the adaptive, developmental, and evolutionary processes driving neural evolution.
Work at our lab has attracted some media coverage, and our shark brain work has been featured in two National Geographic documentaries in 2007 and 2008, a 60-Minutes (Australia) special, and various news articles. I've also had a chance to interact with young students during Shark Week at the Birch Aquarium in San Diego, where children and their parents could look at samples of different shark species and ask questions about their behavior, ecology, diet, and morphology, and have been a guest lecturer for University-level students studying vertebrate anatomy. This research has also been presented at internationally recognized conferences, and published in peer-reviewed journals (see below), many of which are available in pdf format on the web.
Collaborations are a huge part of the success of all of our projects, both within UCSD and other institutions around the world. Some recent collaborative efforts include the Georgia Aquarium, Dr. Steve Kajiura's laboratory (FAU), Dr. Chris Lowe's laboratory (California State University, Longbeach), Dr. Dave Ebert's laboratory (Moss Landing Marine Labs), Dr. Shaun Collin's laboratory (University of Queensland, Australia), and Clinton Duffy (Department of Conservation, New Zealand).
Yopak, K.E. and Frank, L.R. 2009. Brain size and brain organization of the whale shark, Rhincodon typus, using magnetic resonance imaging. Brain, Behavior, and Evolution. 74(2): 121-142.
Yopak, K.E., Balls, G., and Frank, LR. 2009. Cortical Surface Structure Analysis in Sharks using Magnetic Resonance Imaging (MRI). Proceedings of the International Society for Magnetic Resonance in Medicine (ISMRM). 17: 2925.
Yopak, K.E. and Montgomery, J.C. 2008. Brain Organization and Specialization in Deep-Sea Chondrichthyans. Brain, Behavior, and Evolution. 71: 287-304.
Lisney, T.J., Yopak, K.E. 2008. Montgomery, J.C., and Collin, S.P. Variation in Brain Organization and Cerebellar Foliation in Chondrichthyans: Batoids. Brain, Behavior, and Evolution. 72: 262-282
Yopak, K.E.*, Lisney, T.J.*, Collin, S.P., and Montgomery, J.C. 2007. Variation in Brain Organization and Cerebellar Foliation in Chondrichthyans: Sharks and Holocephalans. Brain, Behavior, and Evolution. 69: 280-300.
Kozlowski, C., Yopak, K., Voigt, R., and Atema, J. 2001. Initial study on the effects of signal intermittency on the odor plume tracking behavior of the american lobster, Homarus americanus. Biological Bulletin. 201: 274-276.
Recent Conference Presentations
Yopak, K.E. and Frank, L.R. 2009. Defying Evolutionary Expectations: Analysis of the Brain of the Whale Shark, Rhincodon typus, using Magnetic Resonance Imaging. Joint Meeting of the American Elasmobranch Society and the American Society of Ichthyologists and Herpetologists, Invited Symposium Presentation, July 22-27. Portland, Oregon.
Yopak, K.E., Balls, G., and Frank, LR. 2009. Cortical Surface Structure Analysis in Sharks using Magnetic Resonance Imaging (MRI). Traditional Poster. ISMRM Annual Meeting, 18-24 April. Honolulu, Hawaii.
Yopak, K.E. and Frank, L.R. 2008. A Neural Basis for a Shark's Motor Repertoire? Quantifying the Complexity of the Cerebellum Using Magnetic Resonance Imaging (MRI). Joint Meeting of the American Elasmobranch Society and the American Society of Ichthyologists and Herpetologists. July 23-28. Montréal , CANADA .
Yopak, K.E, and Frank, L.R. 2007. Variation in Cerebellar Foliation in Cartilaginous Fishes: Ecological and Behavioral Considerations. Annual Meeting of the J.B. Johnston Club and the 19th Annual Karger Workshop. November 1-2. San Diego, California, USA.
Yopak, K., Lisney, T., Collin, S., Montgomery, J., and Frank, L. 2007. The Batoid Brain: Correlations with Ecology, Locomotory Mode, and Fin Morphology. Joint Meeting of the American Elasmobranch Society and the American Society of Ichthyologists and Herpetologists. July 11-16. St. Louis, Missouri, USA.
Yopak, K. and Montgomery, J. 2006. Comparative brain morphology in elasmobranchs: From structure to function. Joint Meeting of the American Elasmobranch Society and the American Society of Ichthyologists and Herpetologists. July 12-18. New Orleans, Louisiana, USA.
Yopak, K. and Montgomery, J. 2005. Comparative Morphometrics of the Elasmobranch brain: Mapping Neuromorphology onto Behavior and Environment. Joint Meeting of the American Elasmobranch Society and the American Society of Ichthyologists and Herpetologists. July 6-11. Tampa, Florida, USA.
Yopak, K. and Montgomery, J. 2005. Comparative Neuromorphology of Sharks, Skates, and Rays: Ecological and Behavioral Correlations. Auckland Neuroscience Network. Leigh Neuroscience Workshop. May 20-21. Leigh, New Zealand.