Just read this 2015 article in the Independent which discusses a study which found that using transcranial magnetic stimulation (TMS) to temporarily shut down the part of the brain that deals with threats and conflict led to decreased belief in God and a more favorable view of immigrants that were critical of the United States.
This seems to support Arnold Kling's "Three Languages of Politics", especially the idea that conservatives generally view the world through the civilzation/barbarism axis. For them, the good is civilized values that have accumulated over time and have stood the test of time; and the bad are the 'barbarians' who try to strike out against those values and destroy civilization. In other words, to some degree, immigrants may set off the threat detectors of conservatives. This study seems to support this notion by showing that shutting down or lowering the threat detection area of the brain led to more pro-immigrant attitudes.
Note-I realize there likely isn't an nice tidy area of the brain that deals with threats and conflict. I'm simply using the language in the article to present the ideas in an uncomplicated (not doubt grossly oversimplified) way.
Here is a link to the actual study which I haven't had a chance to read yet.