Sometimes, left is right, & right is left.

When you look at cross-sectional brain images, you should ask whether they are displayed in neurological or radiological convention. In neurological convention, the left side of the brain is on the left side of the image and the right side of the brain is on the right side of the image. Simple. But in radiological convention, the left side of the brain is on the right side of the image, and the right side of the brain is on the left side of the image.

Huh? Why would anyone want to display images "backwards," such that right=left and left=right?

Well, this makes perfect sense, but only when you consider the history of where this convention came from: Imagine that you are standing at the foot of a hospital bed, in which a patient is lying on their back. You are holding up in your hand an x-ray film of their head. You glance from the film to the patient, and back. You want your view of the x-ray film to correspond to your view of the patient. And yes, the patient's right side is on your left, and their left side is on your right. Hence, radiological convention.