Julius Bernstein (18 December 1839 – 6 February 1917) was a German

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

born in

Berlin Berlin ( ; ) is the Capital of Germany, capital and largest city of Germany, by both area and List of cities in Germany by population, population. With 3.7 million inhabitants, it has the List of cities in the European Union by population withi ...

. His father was Aaron Bernstein (1812–1884), a founder of the Reform Judaism Congregation in Berlin 1845; his son was the mathematician Felix Bernstein (1878–1956).

Academic career

He studied medicine at the University of Breslau under Rudolf Heidenhain (1834–1897), and at the

University of Berlin The Humboldt University of Berlin (, abbreviated HU Berlin) is a public research university in the central borough of Mitte in Berlin, Germany. The university was established by Frederick William III on the initiative of Wilhelm von Humbol ...

with Emil Du Bois-Reymond (1818–1896). He received his medical degree at Berlin in 1862, and two years later began work in the physiological institute at the

University of Heidelberg Heidelberg University, officially the Ruprecht Karl University of Heidelberg (; ), is a public university, public research university in Heidelberg, Baden-Württemberg, Germany. Founded in 1386 on instruction of Pope Urban VI, Heidelberg is List ...

as an assistant to

Hermann von Helmholtz Hermann Ludwig Ferdinand von Helmholtz (; ; 31 August 1821 – 8 September 1894; "von" since 1883) was a German physicist and physician who made significant contributions in several scientific fields, particularly hydrodynamic stability. The ...

(1821–1894). In 1872 he succeeded Friedrich Goltz (1834–1902) as professor of physiology at the

University of Halle Martin Luther University Halle-Wittenberg (), also referred to as MLU, is a public research university in the cities of Halle and Wittenberg. It is the largest and oldest university in the German state of Saxony-Anhalt. MLU offers German and i ...

, where in 1881 he founded an institute of physiology.Short biography, bibliography, and links on digitized sources
in the Virtual Laboratory of the Max Planck Institute for the History of Science Bernstein rheotome

Contributions

Bernstein's work was concentrated in the fields of

neurobiology Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions, and its disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, ...

and

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 ...

. He is largely recognized for his "membrane hypothesis" in regards to the origin of the "

resting potential The relatively static membrane potential of quiescent cells is called the resting membrane potential (or resting voltage), as opposed to the specific dynamic electrochemical phenomena called action potential and graded membrane potential. The re ...

" and the "action potential" in the nerve.Geocities.com
Short biography Bernstein (1902, 1912) correctly proposed that excitable cells are surrounded by a membrane selectively permeable to K⁺ ions at rest and that during excitation the membrane permeability to other ions increases. His "membrane hypothesis" explained the resting potential of nerve and muscle as a diffusion potential set up by the tendency of positively charged ions to diffuse from their high concentration in

cytoplasm The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell a ...

to their low concentration in the extracellular solution while other ions are held back. During excitation, the internal negativity would be lost transiently as other ions are allowed to diffuse across the membrane, effectively short-circuiting the K⁺ diffusion potential. In the English-language literature, the words "membrane breakdown" were used to describe Bernstein's view of excitation. (From ''Ion Channels of Excitable Membranes'', Third Edition, by Bertil Hille). Bernstein's pioneering research laid the groundwork for experimentation on the conduction of the

nerve impulse An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific Cell (biology), cell rapidly ri ...

, and eventually the transmission of information in the

nervous system In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. Th ...

. He is credited with invention of a "differential rheotome", a device used to measure the

velocity Velocity is a measurement of speed in a certain direction of motion. It is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of physical objects. Velocity is a vector (geometry), vector Physical q ...

of bio-electric impulses.Seyfarth E-A. (2006), "Julius Bernstein (1839–1917): pioneer neurobiologist and biophysicist"
, Biological Cybernetics 94: 2–8 Biol Cybern (2006) 94: 2–8 The German Bernstein Network Computational Neuroscience has been named after him.Why 'Bernstein'?
at the NNCN web site

Written works

*
Untersuchungen über den Erregungsvorgang im Nerven- und Muskelsysteme
', Heidelberg: Winter, 1871 - Experiments on the excitation process in nerve and muscle systems. * ''Die fünf Sinne des Menschen'', Leipzig: Brockhaus, 1875 - The five senses of humans. * ''Die mechanische Theorie des Lebens, ihre Grundlagen und ihre Erfolge''.

Braunschweig Braunschweig () or Brunswick ( ; from Low German , local dialect: ) is a List of cities and towns in Germany, city in Lower Saxony, Germany, north of the Harz Mountains at the farthest navigable point of the river Oker, which connects it to the ...

: Vieweg, 1890 - The mechanical theory of life, etc. * ''Lehrbuch der Physiologie des thierischen Organismus, im speciellen des Menschen''. Stuttgart: F. Enke, 1894 - Textbook of physiology on the "animal organism", etc.
''Elektrobiologie: Die Lehre von den elektrischen Vorgängen im Organismus auf moderner Grundlage dargestellt''
Braunschweig: Vieweg, 1912 - Book on electrobiology (Treatise that provided the first quantitative theory of nerve and muscle action based on solid experimentation, precise measurements and the use of biophysical models).

References

Early Hypotheses to Explain the Action Potential: Bernstein's hypothesis

Julius Bernstein (1839–1917): pioneer neurobiologist and biophysicist
(The above listed #1 links to his son Felix Bernstein)

External links

* * {{DEFAULTSORT:Bernstein, Julius 1839 births 1917 deaths Scientists from Berlin People from the Province of Brandenburg 19th-century German Jews German physiologists German neuroscientists University of Breslau alumni Humboldt University of Berlin alumni Academic staff of Heidelberg University Academic staff of the Martin Luther University of Halle-Wittenberg Biologists from the Kingdom of Prussia

Academic career

Contributions

Written works

See also

References

Further reading

External links