Haldan Keffer Hartline
Encyclopedia
Haldan Keffer Hartline was an American physiologist
who was a co-winner (with George Wald
and Ragnar Granit
) of the 1967 Nobel Prize in Physiology or Medicine
for his work in analyzing the neurophysiological mechanisms of vision.
Hartline began his study of retinal electrophysiology as a National Research Council Fellow at Johns Hopkins University
, Baltimore
, receiving his M.D. in 1927. After attending the universities of Leipzig
and Munich
as an Eldridge Johnson traveling research scholar from the University of Pennsylvania
, he returned to the United States to take a position in the Eldridge Reeves Johnson Foundation for Medical Physics at Penn, which was under the directorship of Detlev W. Bronk
at that time. In 1940-1941 he was Associate Professor of Physiology at Cornell Medical College in New York City, but returned to Penn and stayed until 1949. Then he became professor of biophysics
and chairman of the department at Johns Hopkins in 1949. One of Hartline's graduate students at Johns Hopkins, Paul Greengard
, later also won the Nobel Prize. Hartline joined the staff of Rockefeller University
, New York City, in 1953 as professor of neurophysiology.
Hartline investigated the electrical responses of the retina
s of certain arthropod
s, vertebrate
s, and mollusks because their visual system
s are much simpler than those of humans and are thus easier to study. He concentrated his studies on the eye of the horseshoe crab
(Limulus polyphemus). Using minute electrodes in his experiments, he obtained the first record of the electrical impulses sent by a single optic nerve
fibre when the receptors connected to it are stimulated by light. He found that the photoreceptor cells in the eye are interconnected in such a way that when one is stimulated, others nearby are depressed
, thus enhancing the contrast in light patterns and sharpening the perception of shapes. Hartline thus built up a detailed understanding of the workings of individual photoreceptors and nerve fibres in the retina, and he showed how simple retinal mechanisms constitute vital steps in the integration of visual information.
Physiology
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...
who was a co-winner (with George Wald
George Wald
George Wald was an American scientist who is best known for his work with pigments in the retina. He won a share of the 1967 Nobel Prize in Physiology or Medicine with Haldan Keffer Hartline and Ragnar Granit.- Research :...
and Ragnar Granit
Ragnar Granit
Ragnar Arthur Granit was a Finnish/Swedish scientist who was awarded the Nobel Prize in Physiology or Medicine in 1967 along with Haldan Keffer Hartline and George Wald....
) of the 1967 Nobel Prize in Physiology or Medicine
Nobel Prize in Physiology or Medicine
The Nobel Prize in Physiology or Medicine administered by the Nobel Foundation, is awarded once a year for outstanding discoveries in the field of life science and medicine. It is one of five Nobel Prizes established in 1895 by Swedish chemist Alfred Nobel, the inventor of dynamite, in his will...
for his work in analyzing the neurophysiological mechanisms of vision.
Hartline began his study of retinal electrophysiology as a National Research Council Fellow at Johns Hopkins University
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...
, Baltimore
Baltimore
Baltimore is the largest independent city in the United States and the largest city and cultural center of the US state of Maryland. The city is located in central Maryland along the tidal portion of the Patapsco River, an arm of the Chesapeake Bay. Baltimore is sometimes referred to as Baltimore...
, receiving his M.D. in 1927. After attending the universities of Leipzig
Leipzig
Leipzig Leipzig has always been a trade city, situated during the time of the Holy Roman Empire at the intersection of the Via Regia and Via Imperii, two important trade routes. At one time, Leipzig was one of the major European centres of learning and culture in fields such as music and publishing...
and Munich
Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...
as an Eldridge Johnson traveling research scholar from the University of Pennsylvania
University of Pennsylvania
The University of Pennsylvania is a private, Ivy League university located in Philadelphia, Pennsylvania, United States. Penn is the fourth-oldest institution of higher education in the United States,Penn is the fourth-oldest using the founding dates claimed by each institution...
, he returned to the United States to take a position in the Eldridge Reeves Johnson Foundation for Medical Physics at Penn, which was under the directorship of Detlev W. Bronk
Detlev Bronk
Detlev Wulf Bronk was President of Johns Hopkins University in Baltimore, Maryland from 1949 to 1953 and President of the National Academy of Sciences from 1950 to 1962. Bronk is credited with reshaping the postwar university environment at Hopkins...
at that time. In 1940-1941 he was Associate Professor of Physiology at Cornell Medical College in New York City, but returned to Penn and stayed until 1949. Then he became professor of biophysics
Biophysics
Biophysics is an interdisciplinary science that uses the methods of physical science to study biological systems. Studies included under the branches of biophysics span all levels of biological organization, from the molecular scale to whole organisms and ecosystems...
and chairman of the department at Johns Hopkins in 1949. One of Hartline's graduate students at Johns Hopkins, Paul Greengard
Paul Greengard
Paul Greengard is an American neuroscientist best known for his work on the molecular and cellular function of neurons. In 2000, Greengard, Arvid Carlsson and Eric Kandel were awarded the Nobel Prize for Physiology or Medicine for their discoveries concerning signal transduction in the nervous...
, later also won the Nobel Prize. Hartline joined the staff of Rockefeller University
Rockefeller University
The Rockefeller University is a private university offering postgraduate and postdoctoral education. It has a strong concentration in the biological sciences. It is also known for producing numerous Nobel laureates...
, New York City, in 1953 as professor of neurophysiology.
Hartline investigated the electrical responses of the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
s of certain arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s, vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
s, and mollusks because their visual system
Visual system
The visual system is the part of the central nervous system which enables organisms to process visual detail, as well as enabling several non-image forming photoresponse functions. It interprets information from visible light to build a representation of the surrounding world...
s are much simpler than those of humans and are thus easier to study. He concentrated his studies on the eye of the horseshoe crab
Horseshoe crab
The Atlantic horseshoe crab, Limulus polyphemus, is a marine chelicerate arthropod. Despite its name, it is more closely related to spiders, ticks, and scorpions than to crabs. Horseshoe crabs are most commonly found in the Gulf of Mexico and along the northern Atlantic coast of North America...
(Limulus polyphemus). Using minute electrodes in his experiments, he obtained the first record of the electrical impulses sent by a single optic nerve
Optic nerve
The optic nerve, also called cranial nerve 2, transmits visual information from the retina to the brain. Derived from the embryonic retinal ganglion cell, a diverticulum located in the diencephalon, the optic nerve doesn't regenerate after transection.-Anatomy:The optic nerve is the second of...
fibre when the receptors connected to it are stimulated by light. He found that the photoreceptor cells in the eye are interconnected in such a way that when one is stimulated, others nearby are depressed
Lateral inhibition
In neurobiology, lateral inhibition is the capacity of an excited neuron to reduce the activity of its neighbors. Lateral inhibition sharpens the spatial profile of excitation in response to a localized stimulus.-Sensory inhibition:...
, thus enhancing the contrast in light patterns and sharpening the perception of shapes. Hartline thus built up a detailed understanding of the workings of individual photoreceptors and nerve fibres in the retina, and he showed how simple retinal mechanisms constitute vital steps in the integration of visual information.