I think this is the key section of the article (italics mine):
Political bias affects brain activity, study finds
Democrats and Republicans alike are adept at making decisions without letting the facts get in the way, a new study shows.
And they get quite a rush from ignoring information that's contrary to their point of view.
Could this be the origin of the term "political junkie"? This study indicates that partisans have an addiction to affirmation of their beliefs. And I would argue, as I have before, that partisan politics aren't healthy for the debate of ideas because the process of getting your candidate elected has overshadowed what that candidate stands for, if anything. And in our mass communications age, we are more interested in getting a message out than in achieving enlightenment, and there is very little forum or encouragement for a healthy discussion. Our court systems were based on the notion that the truth could be determined through confrontation and contradiction, but our political juries are perilously close to being permanently hung. For my part, all I can do is attempt to state my point of view and consider the facts while avoiding the talking points wherever possible. Feel free to call me out when I slip up. But allow me the occasional ad hominem attack - everyone's entitled to a little bit of fun.
The test subjects on both sides of the political aisle reached totally biased conclusions by ignoring information that could not rationally be discounted, Westen and his colleagues say.
Then, with their minds made up, brain activity ceased in the areas that deal with negative emotions such as disgust. But activity spiked in the circuits involved in reward, a response similar to what addicts experience when they get a fix, Westen explained.
The study points to a total lack of reason in political decision-making.
"None of the circuits involved in conscious reasoning were particularly engaged," Westen said. "Essentially, it appears as if partisans twirl the cognitive kaleidoscope until they get the conclusions they want, and then they get massively reinforced for it, with the elimination of negative emotional states and activation of positive ones."