David Jangraw

2007 to 2008

July 2007 – August 2008:
Visual Attention in the Rhesus Monkey

Columbia University Neuroscience Department

Working with Professor Jacqueline Gottlieb, I spent a year at Columbia Medical Center experiencing a full immersion in experimental neuroscience.  Professor Gottlieb’s lab uses electrophysiology to study single cells in the Rhesus monkey.  In roughly chronological order, I trained and cared for the monkeys, assisted with surgeries, ordered and organized lab supplies, helped create and improve the experimental design, performed recordings, and wrote a truly sickening number of analysis programs in MATLAB.

Visual Attention Explained:

Our experiment, recently published in the Journal of Neuroscience, investigates the effect of reward expectation on the activity of Area LIP neurons.  This area is responsible for “visual attention.”  That is, if you are looking straight ahead, there is an LIP neuron that will fire most rapidly if you are paying attention to something you see on your right.  The purpose of an area like this is usually to tell you what you should look at next.  Our investigation attempts to answer the question: if that object indicates that you will be rewarded soon, how will these neurons respond differently than if the object means that you will not be rewarded?  …Except “you,” in this case, means a monkey.

More technically, our investigation amends the work of Sugrue & Newsome (Science, 2004) on reward modulation.  We investigate the strength and timing of this modulation in great depth, and we challenge the notion that expected reward produces universal enhancement by dissociating the reward-predicting stimulus from the eye movement.  If that was too technical, the next section should clear things up.

Results:

Our results showed that a reward-predicting cue biased LIP and attention in a spatially specific way.  That is, if we show a “No, you’re not about to get a reward” cue to the right, the monkey is more likely to make an eye movement to the left, regardless of where the correct eye movement target is.  This is bad for the monkey in our task, and means he will get rewarded less often, but he didn’t shake this habit with weeks of practice – in fact, he got worse.  This tells us that it might be something deeper, maybe even something “hard-wired” in the brain.

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