Physics Colloquium: Scaling laws in branching morphogenesis

The Department of Physics is pleased to welcome Dr. Maijia Liao for an in-person colloquium. Liao is a Postdoctoral Associate in the Howard lab at Yale University. Maijia earned an undergraduate degree in physics at Nanjing University, then she studied soft matter physics at the Hong Kong University of Science and Technology for her Ph.D. work. This presentation is part of the faculty search for an Assistant Professor of Soft Matter and/or Biological Physics.

Abstract: Dendrites, which serve as the antennae of neurons, are often highly branched so they can receive a large number of synaptic inputs, thereby supporting the high connectivity in the nervous system. Though dendrites come in a variety of shape, there exists an unexpected simplicity and generality in dendritic topological structure which can be explained quantitatively through a remarkable simple and invariant design principle, based on the percolation theory. Neurons also have geometric properties, such as the diameters of their branches. The systematic variation of diameters in branched networks has tantalized physiologists and physicists since the discovery of da Vinci’s rule for trees: the sum of the cross-sectional areas of the daughter branches equals that of the mother branch. This can be written d1p + d2p = dmp where d is the diameter and the exponent p = 2. In neurons, a scaling law with exponent 3/2, termed Rall’s law, was proposed for diameter decrements in axons and dendrites. The challenge is that the finest dendritic processes are often beyond the diffraction limit and cannot be resolved using typical approaches. I will describe recent progress in technique development and a new scaling law that was discovered due to the technical breakthrough. To gain mechanistic insight into the new scaling law, I combine multidisciplinary approaches including advanced imaging techniques and neurobiology for dissecting the molecular determinants underlying the scaling law. I will conclude by briefly discussing new opportunities and insights generated along this emergent field in physics and neuroscience.

To join the seminar remotely, please email Kevin Garvey for the Zoom information.