1) There are two pathways in the brain that give rise to anxiety. One is the cortex, which uses thoughts and images. The other is the amygdala, which uses current information and activates the fight-or-flight response. This book explains both pathways and provides tips on how to reduce and avoid anxiety.
2) Cortex-based anxiety revolves around sensations, thoughts, logic, imagination, intuition, conscious memory, and planning. If your thoughts or ideas constantly turn to anxiety, if you obsess over doubts and worries, you probably have cortex-based anxiety.