English physician and physiologist who distinguished between voluntary and involuntary reflex muscle contractions, proving that the spinal cord is more than a passive nerve trunk transmitting voluntary signals from the brain and sensory signals to the brain.
Hall is best known for his work on the nervous system of frogs. He showed that if the spinal cord of a frog was severed between the front and back limbs, then the front limbs could still be moved voluntarily but the back limbs were useless. He further showed that the back legs could be stimulated to move artificially, but only once for each stimulus. These were reflex (involuntary) muscle contractions. Pain stimuli applied to the back legs were not felt by the animals. From these experiments Hall deduced that the nervous system is made up of a series of reflex arcs. In the intact spinal cord these reflex arcs are coordinated by the ascending and descending pathways in the cord to form movement patterns.
Hall also demonstrated that stimulus could not be put into the cord through a sensory nerve without it resulting in effects beyond the anatomical segment to which that nerve belongs.
Hall was born in Basford, and studied medicine at the University of Edinburgh, obtaining his PhD in 1822. As a physician in Nottingham and then later in London he experimented in various areas of physiology, such as the blood circulatory system and respiration, although he is best known for his work on the nervous system of frogs.
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