Snapshots of Life: Reward Seeking, in Technicolor

Posted on March 13th, 2014 by Dr. Francis Collins

Originally, this vibrant picture was just a set of black lines on a graph, charting the various paths of a laboratory rat as it made its way toward a lever to release a shot of sugar water. But Dr. Saleem Nicola, an NIH-funded researcher at Albert Einstein College of Medicine, Bronx, NY, wanted to pique the interest of his colleagues, so he decided to have a bit of fun with the image.

First, Dr. Nicola broadened the lines, giving them a noodle-like appearance. He then went on to use other information about the rat journeys to add rainbow hues, and, finally, he replaced the white background with black. The result is an eye-catching image that is among the winners of the Federation of American Societies for Experimental Biology’s 2013 BioArt competition.

The black background that you see above is actually the floor plan of an experimental chamber. The knot of colors at the top edge reveals the location of a bottle of sugar water and the lever that the rat needed to push to drink from it. Beginning in various places in the chamber, each line plots the rat’s journey toward the sugar water after hearing a bell ring. The colors represent the orientation of the animal’s head when it hears the bell; warm tones show that the animal is facing away from the sugar water, and cooler tones show the rat’s turn toward the sweet treat.

So, what is the point of all of this experimentation with bells and sugar water? The researchers are trying to figure out what takes place in the brains of drug addicts when they see or hear environmental cues that trigger drug-seeking behaviors.

To get some answers, the researchers implanted electrodes in rats’ brains and then set about training the animals to press a lever when they heard a bell. If the animals pressed the lever on cue, they received a reinforcing reward: a tasty slurp of sugar water. Monitoring the rats’ brain activity via the electrodes, researchers found that whenever the bell sounded, there was a flurry of signals in a region of the brain called the nucleus accumbens, which plays a role in addiction and reward. This activity, in turn, seemed to trigger the rats’ trek to the lever and, ultimately, the sugar water.

These findings raise the question of whether inhibiting the activity in the nucleus accumbens may block this reward-seeking behavior. If so, the graph of rat journeys might become a lot less interesting, but the insight might lead to a future advance in treatments for addiction.

Reference:

[1] Invigoration of reward seeking by cue and proximity encoding in the nucleus accumbens. McGinty VB, Lardeux S, Taha SA, Kim JJ, Nicola SM. Neuron. 2013 Jun 5;78(5):910-22.

Links:

BioArt, Federation of American Societies for Experimental Biology

Saleem M. Nicola, Departments of Psychiatry and Neuroscience, Albert Einstein College of Medicine, Bronx, NY

BioArt 2013 Exhibit. The public can view an exhibit of the winning art at the NIH Visitor Center. Located in Bethesda, MD, the Center is open from 8:30 a.m.–4:30 p.m. M–F.

NIH support: National Institute on Drug Abuse; National Institute of Mental Health