Chris Warner

Reveal Contact Info

PhD Student

Biophysics

Sommer Lab

Current Research

My general research interests focus on structure and information content of networks; neural, social, economic, and other.

The main thrust of my research, into the retinal cell network, challenges current paradigms in visual neuroscience. The retinal network purportedly implements center-surround shaped filters, that independently encode local contrast in spike rates of individual neurons. This oversimplified model explains only 1/4 of the >60 retinal cell types and completely ignores an entire class of inhibitory interneurons.

Inspired by this Amacrine cell network and experimental observations in retina, we propose a network model of sensors that simultaneously encodes the pixel image as well as a segmentation. In retina, local contrasts are represented by spike rates, while it has been proposed that segmentation information may be represented by spike correlations across a neural population on a fine time scale. In our model, each sensor node measures local contrast and is also a phase oscillator, reflecting periodic neural activity observed in retinal spike trains. Heterogeneous weighted edges mediate phase interactions that synchronize and separate groups of oscillators in phase space, performing anisotropic phase diffusion across network weights. These two types of information are multiplexed into the same spike trains passed down the optic nerve to be decoded by rate integration and coincidence detection in downstream neurons.

Having algorithms to find structure in general networks, I have branched out from retina to investigate other networks – including the Facebook social network and a network representing global trade between countries over 50 years.

Background

I am one of 13 siblings in my family. Growing up, long before my formal Ph.D, I would often think about the structure in implicit networks of individuals which I intuited from their social interactions. So, it is serendipitous that I fell into this research. My undergraduate degree is in Physics, but could have easily been in English Literature. For fun, I write songs about 3D printed AI robot takeover and other dystopian topics for dive bar open mics.