Kai Hynna, PhD
Attention: Thalamus
Personal Background Welcome to my page! Here you'll find mostly information on my research interests during my time at the University of Pennsylvania. Prior to Penn, I received an Honours B.A.Sc. in Systems Design Engineering from the University of Waterloo in Waterloo, Canada. I graduated from UPenn in May 2005. |  |
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My interests lie in understanding the human brain. Our brain is who we are, how we perceive the world and how we interact with it. It is a record of our past and a map to our future. Understanding how we think and learn has implications on many different levels. Scientifically, copying the neural design, and even improving upon it, increases the potential for intelligent systems. Socially, our understanding of how we learn can lead to vast improvements in our education system. Philosophically, we may understand more of who we are and our place in this world. However, our current knowledge has only scratched the surface of complete understanding; there's still a long way to go! My dissertation focussed on the dorsal lateral geniculate nucleus (LGN). The LGN is the primary visual division of the thalamus, located between the retina and the cortex along the visual pathway. Historically, neuroscientists have considered it a simple relay station for ascending visual information. However, geniculate neurons possess a membrane channel—called a T channel—that dramatically influences the response of the cell to visual input. To study the function of this channel, I designed a silicon chip that contained both geniculate cells (with the T channel) and inhibitory cells from the reticular nucleus. I also included two input pathways: retinal, which excite the relay cells, and cortical, which excite both cell types. My results suggest that the T channel can enhance temporal correlations within the stimulus through the priming (deinactivation) and triggering (activation) of the T channel. Priming requires hyperpolarization of the relay neuron; thus, it depends on the activity within the inhibitory reticular cells, which themselves respond strongly to large and/or moving stimuli. Triggering of the T channel requires depolarization of the relay cell, and therefore needs only inputs from retinal afferents. Cortical feedback implements attention through its actions on both the relay and reticular layers. My results suggests a larger role than a simple relay for the LGN.
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