Thomas Laycock (1812-1876) was an English neurophysiologist who was a native of York. Among medical historians, he is best known for his influence on the young John Hughlings Jackson and the psychiatrist James Crichton-Browne.
Laycock was the son of a Wesleyan minister. He trained as an apprentice surgeon-apothecary in Bedale.
Laycock’s interests were the nervous system and psychology.
He initially studied medicine at the University College London, and furthered his studies in Paris under Alfred Armand Velpeau (1795–1867) and Pierre Charles Alexandre Louis (1787–1872) an initiator of statistics. In 1839 he received his medical doctorate at the University of Göttingen, and afterwards returned to York as a lecturer at York Medical School as well as physician to the York Dispensary. From 1855 until his death in 1876, he held the chair of medicine in Edinburgh. In 1852 Laycock encountered Hughlings Jackson, a new student; he also taught Jonathan Hutchinson whom Jackson was to meet in 1859 and share a house with at 14 Finsbury Circus, London for three years. In Edinburgh, Laycock was friendly with the asylum reformer William A.F. Browne (1805-1885) and a major influence on the career of his son James Crichton-Browne (1840-1938).
Laycock is remembered today for his concept concerning the reflex action of the brain, and from this standpoint he postulated that a reflex was an intelligent, but unconscious reaction to stimuli. He believed that although the brain was an organ of consciousness, it was still subject to the laws of reflex action, and in this regard was no different than other ganglia of the nervous system. Laycock also had a fundamental belief in the unity of nature, and saw nature as working through an unconsciously acting principle of organization.