Haldan Keffer Hartline (December 22, 1903 – March 17, 1983) was an American

physiologist Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical a ...

who was a co-recipient (with George Wald and

Ragnar Granit Ragnar Arthur Granit (30 October 1900 – 12 March 1991) 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 "for their discoveries concerning the ...

) of the 1967

Nobel Prize in Physiology or Medicine The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accord ...

for his work in analyzing the neurophysiological mechanisms of vision.

Education

Hartline did his undergraduate studies at

Lafayette College Lafayette College is a private liberal arts college in Easton, Pennsylvania. Founded in 1826 by James Madison Porter and other citizens in Easton, the college first held classes in 1832. The founders voted to name the college after General Laf ...

in Easton, Pennsylvania, graduating in 1923. He began his study of retinal electrophysiology as a National Research Council Fellow at

Johns Hopkins School of Medicine The Johns Hopkins University School of Medicine (JHUSOM) is the medical school of Johns Hopkins University, a private research university in Baltimore, Maryland. Founded in 1893, the School of Medicine shares a campus with the Johns Hopkins Hospi ...

, receiving his medical degree in 1927.

Career and research

After attending the universities of

Leipzig Leipzig ( , ; Upper Saxon: ) is the most populous city in the German state of Saxony. Leipzig's population of 605,407 inhabitants (1.1 million in the larger urban zone) as of 2021 places the city as Germany's eighth most populous, as wel ...

and

Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...

as an Eldridge Johnson traveling research scholar from the

University of Pennsylvania The University of Pennsylvania (also known as Penn or UPenn) is a private research university in Philadelphia. It is the fourth-oldest institution of higher education in the United States and is ranked among the highest-regarded universitie ...

, he returned to the US 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 Biophysics is an interdisciplinary science that applies approaches and methods traditionally used in physics to study biological phenomena. Biophysics covers all scales of biological organization, from molecular to organismic and populations. ...

and chairman of the department at

in 1949. One of Hartline's graduate students at

Paul Greengard Paul Greengard (December 11, 1925 – April 13, 2019) was 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 ...

, who also won the Nobel Prize. Hartline joined the staff of

Rockefeller University The Rockefeller University is a private biomedical research and graduate-only university in New York City, New York. It focuses primarily on the biological and medical sciences and provides doctoral and postdoctoral education. It is classif ...

, New York City, in 1953 as professor of neurophysiology. Hartline investigated the electrical responses of the

retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then ...

s of certain

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

s, and

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

s, because their

visual system The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) which gives organisms the sense of sight (the a ...

s are much simpler than those of humans and thus easier to study. He concentrated his studies on the eye of the

horseshoe crab Horseshoe crabs are marine and brackish water arthropods of the family Limulidae and the only living members of the order Xiphosura. Despite their name, they are not true crabs or crustaceans: they are chelicerates, most closely related to arachn ...

(''

Limulus polyphemus The Atlantic horseshoe crab (''Limulus polyphemus''), also known as the American horseshoe crab, is a species of marine and brackish chelicerate arthropod. Despite their name, horseshoe crabs are more closely related to spiders, ticks, and scorpi ...

''). Using minute electrodes, he obtained the first record of the electrical impulses sent by a single

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual system, visual information from the retina to the brain. In humans, the optic nerve i ...

fibre when the receptors connected to it are stimulated by light. He found that the

photoreceptor cell A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiatio ...

s 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.

Awards and honors

Hartline was elected a Foreign Member of the Royal Society (ForMemRS) in 1966. He was awarded the

in 1967.

Personal life

Hartline married Elizabeth Kraus Hartline in 1936. They had three children.

References

External links

* {{DEFAULTSORT:Hartline, Haldan Keffer Nobel laureates in Physiology or Medicine American Nobel laureates Members of the United States National Academy of Sciences American neuroscientists 1903 births 1983 deaths People from Bloomsburg, Pennsylvania Physicians from Pennsylvania Johns Hopkins University alumni Foreign Members of the Royal Society Medical physicists Lafayette College alumni