New insights from Nicole Rust on mixed up perirhinal cortex neurons at the Optical Society vision meeting

October 12, 2014

This weekend I attended the vision meeting of the Optical Society at the University of Pennsylvania in Philadelphia. I was invited to participate in a debate about mice as models for visual function that included, among others, Tony Movshon, a vocal skeptic of mouse models. My role in the debate was to highlight features of rodent behavior that makes then well-suited to provide insights about computations that may be conserved across many species. In my lab, we think a lot (A LOT) about how behavior, and how to design paradigms that give us the best shot at uncovering computations that are shared by mice and humans.

In addition to debaIMG_9548ting the merits of different models, I enjoyed some great talks including one by Nicole Rust whom you can see here with colleagues discussing her data post-talik. She and lab members have been measuring signals in two cortical structures: inferotemporal cortex (IT), long studied as an object recognition area, and perirhinal cortex (PRH), an association area that gets inputs from IT. PRH is shown below in an image I made from the Allen Brain Connectivity Atlas (it is in a different species, but likely there are  some parallels). Each dot on the right image shows an area that projects to PRH, highlighting the area as a good candidate for transforming complex visual signals into a judgment about what to do. Nicole has argued previously that a key difference between IT and PRH is that a linear combination of IT neuron responses cannot predict whether a given stimulus matches a searched-for target whereas PRH neurons can predict this.

imagePRH.001

Her latest work is informative about what kind of operations are performed on IT neurons so that the signals arrive in PRH in a more manageable form. The answer is surprisingly simple. She argues that a feedforward architecture that includes IT neurons with variable response latencies is key, and also that the IT neurons have response preferences that are not simply rescaled with time. This accounts for the observed dynamics in PRH pretty well.

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