Hall also discovered that voluntary and involuntary movements of the body are found in certain regions of the brain and body. Hall's contribution to the mind-body problem was to be able to show how the body can influence the mind and the mind influence the body through voluntary (of the mind) and involuntary (of the body) movements. Flourens: Flourens' job was to use the eradication method. He destroyed animal parts in order to observe the brain and spinal cord. Through his work Flourens discovered the areas of the brain responsible for the higher mental functioning, vision and hearing of humans, and the areas that control our coordination, heartbeat, breathing and other important body functions. His contribution to the mind-body problem was to further analyze the functioning of the brain and determine which exact areas of the brain influence the body. Gall: Gall was responsible for mapping the brain and it works well and was able to confirm that the brain has white and gray matter; nerve fibers connected to both sides of the brain and opposite sides of the spinal cord; the fibers connect to both halves of the brain. Gall further contributed to the understanding of the mind-body problem by demonstrating that it was possible to find specific brain functions in certain areas of the brain. Galvani: Galvani suggested that nerves were electrical and that if stimulated by electricity they contracted. Galvani showed how the body can influence the mind and its interactions and reactions. Cajal: Discovered the direction in which nerve impulses traveled in the brain and spinal cord. Cajal contributed to the mind-body problem by determining how impulses from the body can influence the brain. Weber: Weber is responsible for the colon threshold which proved that body sensations can