Monday, May 7, 2012

processing retinae

We know very little about the physiology of color vision. For example, in the case of dichromatic color vision, in the past the trick was to have a rolodex of unattached dichromates, volunteering as an emergency physician, and when an expired dichromat showed up in the ER, there was an hour's time for wet color science.

Recently, a lot of progress has been made in color vision physiology by leveraging state-of-the-art equipment. A couple of months ago we reported on Kathy Mullen's breakthrough leveraging a new fMRI scanner in Australia. Today we cross the big pond and look at an application of big data technology.

Michele Fiscella harvests the retina of a mouse, places it on a MEA chip, sprinkles it with a nourishing fluid, and for the couple of hours the retina remains functional, projects patterns on the retina and captures the interneural traffic.

MEA—for Micro Electrode Array—is a technology from the lab of Prof. Andreas Hierlemann. On a surface of 3.6 mm2, 11,011 elliptical microelectrodes probe the retina. On the average, for each neuron there are 14 microelectrodes, and each one delivers 20,000 measurements per second. The hope is to sleuth what information is passed bottom up from the retina to the LGN.

To do that, the retina has to be placed upside down on the MEA, i.e., with the retinal ganglions on the microelectrodes and the photoreceptors towards the stimulus source. This is not necessarily contra naturam, as there is nothing coming top down from the LGN, which is not part of the experiment.

Analytical engines, here the big data come…