By Dr Ananya Mandal, MD. Dopamine is a neurotransmitter released by the brain that plays a number of roles in humans and other animals. Some of its notable functions are in: 1  movement. 2  memory. 3  pleasurable reward.
Sycamores (Platanus spp.) are tall, spreading shade trees. These North American natives have few problems or pests, but their older bark flakes off in patches. If your sycamore is shedding bark, it may be a healthy, maturing tree.
Image by Dean Morley. When you see tree leaves dripping sap, the usual cause is tree aphids. These pesky insect pests can cause serious stress to your trees and lead to disease. Learn more about aphids on tree limbs and foliage and what you can do for tree aphid treatment. These tiny, soft-bodied, pear-shaped insects can be almost any color.