The MRI scanner measures this signal difference and displays the activity as a colored area (Figure 1). Diffusion Tensor Imaging (DTI) is a technique that detects how water travels along the white matter tracts in the brain (Figure 2). White-matter tracts connect different parts of the brain and must be protected during surgery. A dye (contrast agent) may be injected into your blood stream.
This fascinating arthropod, also known as the water spider, is quite similar to other spiders in that it breaths air, although it does it in a much more creative way. These spiders spin a web cocoon of silk which they then fill up with air creating a bubble that they can take with them underwater. And due to a mostly sedentary life this spider is able to make the most of its oxygen only needing to come up about once a day or even less to replenish its air supply.
Almost all spiders are predators, and most eat insects. They catch their prey in several ways. Some build a spider web, and some use a thread of silk that they throw at the insect. Some kinds of spiders hide in holes in the ground, then run out and grab an insect that walks by. Others will make web 'nets' to throw at passing insects. Or they go out and simply attack their prey. Some can jump quite well and hunt by sneaking close to an insect and then jumping on it. There is a myth that Spiders have feet, they do not.