ratSpaceA new paper is out from my lab today in Nature Neuroscience. In this paper, we set out to understand how a single part of the brain can be used to support many behaviors. The posterior parietal cortex, for instance, has been implicated in decision-making, value judgments, attention and action selection. We wondered how that could be: are there categories of specialized neurons that are specialized for each behavior? Or, alternatively, does a single population of neurons multitask to support lots of behaviors? We found the latter possibility to be true. We recorded neurons in rat posterior parietal cortex while rats were making decisions about lights and sounds. We found that neurons could be strongly modulated by the animal’s choice, the modality of the stimulus, or, very often, both of those things. This multitasking did not provide a problem for decoding: a linear combination of responses could easily estimate choice and modality well.

We hope that our observations will change the way people think about how neurons support diverse behaviors because they challenge the prevailing view that neurons are specialized. Horace Barlow (the grandfather of computational neuroscience), argued that neurons in the frog’s retina were specialized for detecting particular kinds of motion. This is likely true in early visual areas, but in higher cortical areas, things are very different. Our observations about multitasking neurons point to a new way of encoding information that, we argue, confers flexibly in how the neurons are used, and could allow their responses to be flexibly combined to support many behaviors. The picture below shows me with co-first authors David Raposo and Matt Kaufman. IMG_9993

IMG_6609Each summer, expert microscopists from around the globe descend on Cold Spring Harbor to teach an imaging course. The course consists of both lectures and labs. For the latter, the directors, lecturers and TAs rapidly assemble an unbelieveable assortment of microscopes. Within a week of arriving, they construct setups for imaging population activity, visualizing dendritic spines and uncaging glutamate. It’s incredible. My postdoc, Matt Kaufman and I have been sitting in on some lectures. We’ve heard about cutting edge work from Linda Wilbrecht, Valentina Emiliani, David Kleinfeld, Florin Albeanu and Jack Waters. Jack gave a great lecture about quantifying calcium sensors which Matt and I both enjoyed. Jack described an impressive bag of tricks for dealing with issues like background signal and cell-to-cell variability in brightness.

IMG_6603We were also very fortunate in getting to pitch in as skilled TA Annalisa Scimemi assembled a 2 photon microscope. Annalisa is from the NIH but is en route to SUNY Albany to start her own lab. She explained to us how to align the laser correctly and direct it at a pair of mirror galvonometers to scan a piece of tissue. When the setup was up and running and we saw our first cells (at midnight, of course, see image at the top), we all cheered.

Fairhall lab

Computational neuroscience at the University of Washington

Pillow Lab Blog

Neural Coding and Computation Lab @ Princeton University

Churchland lab

Perceptual decision-making at Cold Spring Harbor