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.
Dock spiders can swim. A dock spider can actually swim under water and stay submerged for several minutes. It uses air bubbles trapped in the fine hairs on its body under its belly to provide oxygen while it is under water â a bit like a dock spider scuba dive. Dock spiders walk on water.
Jumping spiders do sometimes bite, but their venom is not considered to be dangerous (unless youâre allergic to spider bites). They are sometimes mistaken for black widow spiders, but they are far less dangerous. Jumping spiders donât hunt using webs, but they do build a web-like nest called a retreat.