Students

 I want to understand how the brain computes.  We have an extremely good idea how synapses compute, some basic ideas about how long-distance projections interact, and few general ideas about intra-columnar computation, inter-columnar interactions, and the coordination of these types of information processing.

I address these issues through studies of hemispheric asymmetry and hemispheric communication.  The corpus callosum, the major connective tract between left and right cerebral hemispheres, is the best studied long-distance projection system in the brain.  It generally connects homotopically (an area in one hemishere tends to connect to its homologue in the other hemisphere).  Therefore, studying asymmetries between the hemispheres--and their interactions across the corpus callosum--can help inform us about local processing, long-distance projections, and their interactions.

My research uses neural network modeling to tie a specific asymmetry in grey matter "horizontal" connectivity to differences in visual processing between the hemispheres.  Generally speaking, the left cerebral hemisphere (LH) shows processing advantages for small, local-level aspects of a stimulus; the right cerebral hemisphere (RH) shows advantages for larger, global/gestalt-level aspects of a stimulus.  

In my current project, I aim to show that interactions between the hemispheres, at different levels of processing, can explain behavioral data for stimuli presented at fixation, when both hemispheres are active and must collaborate to identify a stimulus.   I have incorporated interhemispheric connections and timing into the model that follows two basic principles of the corpus callosum: that early sensory areas connect with fast, sparse, topographic connections along the shared middle portion of left and right halves, and that later association areas connect with slower, more numerous, and more diffuse connections.

With this research, I hope to answer questions such as: if chimpanzee and human cerebral hemispheres are as asymmetric as each other, might the smaller brain size (and therefore smaller communication delays) mask many asymmetries in chimpanzee cognitive function?  If yes, then it is possible that some or all of the hemispheric asymmetries found in humans are not unique to humans.  If no, then we have further evidence of the importance of hemispheric asymmetry in the human phenotype.

Raised on a balanced diet of nature documentaries and science fiction in the 'Decade of the Brain,' I began my career studying animal behavior and foraging ecology as an undergrad at the University of Alaska Anchorage under Dr. Gwen Lupfer-Johnson. After a harrowing field season chasing monkeys in Costa Rica and a tour of duty in search of Miocene ape fossils in Hungary, I set my sights on graduate work in comparative neuroscience. I am working with Dr. Katerina Semendeferi in the deparment of Anthropology, utilizing all non-invasive, non-destructive means to comparatively study postmortem brain tissue from all extant ape taxa, including humans, in the hopes of elucidating the means by which our species became so wonderfully strange. Specifically, my work focuses on the chemical anatomy of frontostriatal circuits and interneuron distribution in these regions, involved in decision-making and the processing of reward and punishment in social contexts. In the future, I hope to work to ensure the conservation of valuable postmortem tissues in captive and wild primates alike.

Modern humans are expert explorers in every environment on (and off) earth. However, as a species, we are not adapted for continual habitation in every ecological niche.

When humans travel to high altitude, several physiologic responses compensate the body to gradually adjust to the reduced availability of atmospheric oxygen (hypoxia). While this acclimatization allows short sojourns to intolerable environments, no human can live for prolonged periods at extremely high altitude. Even visitors at Everest base camp are in a state of slow deterioration. However, several human populations, including highland Ethiopians, Tibetans and Andeans, have uniquely adapted over thousands of years and live quite well at moderately high altitudes (<4,300m). Several physiologic compensations are now well-known to be adaptive in these populations, although the underlying genetic basis is only now being uncovered.

My research aims to determine novel genetic pathways underlying physiologic adaptations to hypoxia through an interdisciplinary, collaborative approach. Using a unique population of hypoxia-adapted fruit flies (Drosophila melanogaster), I investigate key genetic pathways underlying physiologic response of the heart during low oxygen exposure. This research is unraveling completely novel molecular interactions occurring during either acute or chronic hypoxia, and altered after multi-generational adaptation.

Further, I aim to determine the relevance of these findings to human high altitude adaptations, particularly through use of recent genetic screens and samples from Asia, South America and Africa. For lowland dwellers, findings from this research may determine whether medical intervention can alleviate symptoms in maladaptive humans who struggle to acclimatize or show signs of altitude illness.