Development of tolerance. Over time, the brain adapts in a way that actually makes the sought-after substance or activity less pleasurable. In nature, rewards usually come only with time and effort. Addictive drugs and behaviors provide a shortcut, flooding the brain with dopamine and other neurotransmitters.
There are two types of metamorphism: contact metamorphism and regional metamorphism. Contact metamorphism is a type of metamorphism where rock minerals and texture are changed, mainly by heat, due to contact with magma.This is an easy name to recall if you remember that these rocks change by actually coming in contact with something very hot, like magma.egional metamorphism is a type of metamorphism where rock minerals and texture are changed by heat and pressure over a wide area or region. Contact and regional metamorphism differ in both the area and pressure involved.
Three other types of metamorphism are important in certain tectonic environments. 2) Contact Metamorphism is the result of baking the surrounding country rocks by an igneous intrusion. The metamorphic aureole surrounding an igneous body may be only 2 centimeters wide adjacent to a small dike or it may be 2 kilometers wide at the contact with a large, slow-cooling granite pluton. Contact metamorphosed rocks may be bleached out looking and non-descript fine-grained. A common contact metamorphic rock is hornfels (German for hard rock).