School of Graduate Studies

School of Graduate Studies
School of Graduate Studies

Scott Murdison

Ph.D candidate, Neuroscience

Scott Murdison

Scott in Marsberg, Germany

Scott Murdison making the most of his DAAD research grant

by Sharday Mosurinjohn, March 2015

Did you know we move our eyes more than our hearts beat? And yet our vision seems very stable – free of shaky panning and disorienting angles like the too-creative shots of bad TV. Or rather, it is our brain that reconstructs a very stable model of the world, which we experience as seeing the world directly as it is. The question, then, is what rapid processes are deployed between the brain and eyes to give us these transparent impressions? Neuroscience PhD Candidate Scott Murdison is looking to fill this gap by learning how we perceive space around us when our eyes are moving.

When you look up diagonally, the retinal input is slightly rotated relative to space. “Basically, we want to see if the brain uses an eye orientation signal when perceiving the world around us during eye movements,” explains Murdison.Marsberg-Germany

Now in his third year of the program – but his eighth year with Queen’s after a chemical/biomedical engineering undergraduate and a neuroscience mini Master’s – Murdison has traveled to Germany with a DAAD research grant to work on the problem with Dr. Frank Bremmer and colleagues at the University of Marburg. DAAD stands for Deutscher Akademischer Austasch Dienst, or German Academic Exchange Service, whose wide-ranging mission statement includes, among other things, “to enable young academics and researchers from around the world to become leaders in the fields of science, culture, economics, and politics – as well as friends and partners of Germany.”

The fact that Murdison’s supervisor, Dr. Gunnar Blohm, is originally from Germany himself is part of the strong linkage between the Canadian and German sides of the international research training group (supported by an NSERC CREATE grant [Natural Sciences and Engineering Research Council Collaborative Research and Training Experience] on the Canadian side and another grant on the German side). Every week the group gets together virtually and has a meeting through Adobe Connect, with an invited speaker who gives a research talk.

At the end of ten months, Murdison will be back on the other side of that computer link. And in the meantime he has been back to Kingston a few times and traveled to deliver a poster for a conference in Washington DC. But for now, he and Dr. Bremmer are in the midst of running the experiment that is letting them investigate how rotational shifts of the retinal image are integrated into our interpretation of spatial stimulus features.

The way they’re doing it is by asking participants to take part in a computer task that shows a stimulus and then requires them to follow a moving target with their eyes, and finally shows another stimulus. Participants must respond as to whether the second stimulus was rotated clockwise or counter-clockwise with respect to vertical. The results will help them interpret how our eyes and brains deal with the “retinal-spatial mismatch” that occurs as a result of, essentially, the fact of us constantly moving our eyes about.

Among the many other projects Murdison has been working on is the one presented in DC, which is about what’s called “the speed-accuracy tradeoff” in eye movements for planning decisions. Murdison and supervisors are exploring this tradeoff (faster/less accurate vs. slower/more accurate) by altering the excitability of the neurons. To do so, they are using a brand new technique (high density transcranial direct current stimulation) for stimulating groups of neurons by sending a harmless constant current through the skull. (The term “high density” is a comparative for the way that “in the olden days they would use two big sponges on the side of the head and activate an entire cortex.”)

“Basically,” relates Murdison, “when stimulating the right side of the brain, when the decision was in the stimulated direction [left], we saw a modulation of the speed-accuracy tradeoff – that is, slower, more accurate for inhibitory currents and faster, less accurate decisions for excitatory currents. For decisions in the opposite direction we saw participants get faster and more accurate, and slower and less accurate, thus modulating overall performance.” In the latter case, it’s a bit like “getting something from nothing.”

Aside from finding fulfillment in this innovative research, Murdison is documenting his cultural immersion through photography. A hobby photographer with a fine art sensibility, Murdison’s photographs show the breadth of what he is absorbing through the exchange (Instagram: tsmurdison). He is modest about acquiring the language (I learn from him during our conversation how to order a coffee) and complimentary about his location and the people who animate it. Murdison shares an apartment with a mother and daughter, which offers him the right blend of space and companionship with natives who are happy to make recommendations about the events and places he ought not to miss. One, for instance, was an Advent celebration for which Marburg lights up all the buildings in colours and sets up wooden huts vending mulled wine, encouraging downtown conviviality every night until Christmas.

Though Murdison is fairly cosmopolitan – he was born in the U.S. (Philadelphia) and has EU citizenship through Scottish-born parents – he says “it was a bit of a shock to be uprooted. I was really used to Kingston and Queen’s and everything there.” But, after all, universities and university towns are in some ways reassuringly the same. The major differences include working on a mountain rather than by the lake, in a place where, he says, it is a little warmer and foggier.

When Murdison does return to Kingston he’ll resume a place among colleagues that, he describes, the Centre for Neuroscience Studies pulls together from microbiology, computational sciences, and a number of other complementary fields. He’ll also be nearly ready to compete in a half marathon he’s currently training for, and stocked with travel tales to regale the people he’ll resume spending time with as a volunteer at Community Living. And, nearing the end of his program, he’ll be poised to receive a third degree from Queen’s, but one indelibly shaped by the connections cultivated by the university abroad.