Research

The lab studies basic mechanisms that are involved in neural circuit formation and function in the brain:

1. How does the developing brain regulate the number of neurons that it produces?

2. How do young neural circuits become specific and mature?

3. What cellular mechanisms lead to neuronal degeneration in Parkinson's Disease?


Question One:  How does the developing brain regulate the number of neurons that it produces?

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The brain begins as a thin layer of neural stem cells that divide to produce neurons for the growing and developing tissue.  How long the dividing cells remain mitotically active is crucial for determining how many neurons will be produced, and ultimately, how large the brain might grow.  If they stop dividing too soon, too few neurons may be produced.  On the other hand, if they divide for too long – even just one extra cell cycle – too many neurons may result.  How do stem cells “know” when to stop dividing?  Complex regulatory mechanisms likely ensure that the cells undergo the correct number of cell divisions and that the brain forms properly.  Our lab is interested in the mechanisms that underlie the process of neuronal proliferation in the developing brain.  In particular, we use multicolor fluorescence to color-code dividing cells and their progeny.  Using fluorescence imaging tools we can study interactions both within and among dividing clones of cells.  We can also follow the fate of individual newborn neurons


Question Two:  How do young neural circuits become specific and mature?

Brain function relies upon the precise organization of many neural circuits, which are sets of neurons that are arranged to connect with other cells in specific ways.  One fundamental question in neuroscience asks how neural circuits form from a simple developing tissue.  There is evidence that some simple circuits undergo an important process of refinement during development, where unnecessary connections are pruned away over time.  Relatively little is known, however, about how more complex circuits form and how their mature properties underlie behavior.  Our lab is testing how an important circuit within the cerebellum develops and functions: the mossy fiber-to-granule cell synapse.  Using a multicolor approach (“Brainbow”) we label populations of cells in many different colors, allowing us to visualize and map multiple individual components of a complex circuit. We have applied this approach to the translucent developing zebrafish nervous system, where individual synapses can be visualized over time within the living animal.


Question Three:  What cellular mechanisms lead to neuronal degeneration in Parkinson's Disease?

While our lab studies the mechanisms that regulate neuron development, we are also interested in mechanisms that lead to neuron dysfunction.  One such mechanism involves the abnormal aggregation of a protein called alpha-synuclein during Parkinson’s Disease.  In collaboration with Dr. Vivek Unni’s lab at Oregon Health & Science University (OHSU), we have established a zebrafish model for studying alpha-synuclein function in the living brain.  Because zebrafish are transparent during development, we are able to visualize a fluorescence-tagged form of alpha-synuclein in vivo using confocal microscopy.  


Techniques

Some of the techniques we use in the lab include the following:

  • Zebrafish mating and microinjection
  • Confocal microscopy (including in vivo imaging of living zebrafish larvae)
  • Three-dimensional digital reconstruction of confocal image stacks
  • Molecular biology - manipulation of fluorescent protein DNA constructs
  • Immunohistochemistry
  • Rigorous statistical analysis
  • Preparation of figures, manuscripts, and oral presentations