Early Work On The Motor Cortex
In 1870 Eduard Hitzig and Gustav Fritsch demonstrated that electrical stimulation of certain parts of the dog brain resulted in muscular contraction on the opposite side of the body.
A little later, in 1874, David Ferrier, working in the laboratory of the West Riding Lunatic Asylum at Wakefield (at the invitation of its director, James Crichton-Browne), mapped the motor cortex in the monkey brain using electrical stimulation. He found that the motor cortex contained a rough map of the body with the feet at the top (or dorsal part) of the brain and the face at the bottom (or ventral part) of the brain. He also found that when electrical stimulation was maintained for a longer time, such as for a second, instead of being discharged over a fraction of a second, then some coordinated, seemingly meaningful movements could be caused, instead of only muscle twitches.
After Ferrier's discovery, many neuroscientists used electrical stimulation to study the map of the motor cortex in many animals including monkeys, apes, and humans.
One of the first detailed maps of the human motor cortex was described in 1905 by Campbell. He did autopsies on the brains of amputees. A person who had lost an arm would over time apparently lose some of the neuronal mass in the part of the motor cortex that normally controls the arm. Likewise, a person who had lost a leg would show degeneration in the leg part of motor cortex. In this way the motor map could be established. In the period between 1919 and 1936 others mapped the motor cortex in detail using electrical stimulation, including the husband and wife team Vogt and Vogt, and the neurosurgeon Foerster.
Perhaps the best-known experiments on the human motor map were published by Penfield in 1937. Using a procedure that was common in the 1930s, he examined epileptic patients who were undergoing brain surgery. These patients were given a local anesthetic, their skulls were opened, and their brains exposed. Then, electrical stimulation was applied to the surface of the brain to map out the speech areas. In this way, the surgeon would be able to avoid any damage to speech circuitry. The brain focus of the epilepsy could then be surgically removed. During this procedure, Penfield mapped the effect of electrical stimulation in all parts of the cerebral cortex, including motor cortex.
Penfield is sometimes mistakenly considered to be the discoverer of the map in motor cortex. It was discovered approximately 70 years before his work. However, Penfield drew a picture of a little man stretched over the cortical surface and used the term "homunculus" to refer to it. Perhaps for these reasons his work has become iconic in neuroscience.
Read more about this topic: Motor Cortex
Famous quotes containing the words early, work and/or motor:
“We early arrive at the great discovery that there is one mind common to all individual men: that what is individual is less than what is universal ... that error, vice and disease have their seat in the superficial or individual nature.”
—Ralph Waldo Emerson (18031882)
“The form of act or thought mattered nothing. The hymns of David, the plays of Shakespeare, the metaphysics of Descartes, the crimes of Borgia, the virtues of Antonine, the atheism of yesterday and the materialism of to-day, were all emanation of divine thought, doing their appointed work. It was the duty of the church to deal with them all, not as though they existed through a power hostile to the deity, but as instruments of the deity to work out his unrevealed ends.”
—Henry Brooks Adams (18381918)
“The motor idles.
Over the immense upland
the pulse of their blossoming
thunders through us.”
—Denise Levertov (b. 1923)