Neurophysics (or neurobiophysics) is the branch 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. ...

dealing with the development and use of physical methods to gain information about the

nervous system In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes ...

. Neurophysics is an interdisciplinary science using physics and combining it with other

neurosciences Neuroscience is the science, scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a Multidisciplinary approach, multidisciplinary science that combines physiology, an ...

to better understand neural processes. The methods used include the techniques of experimental biophysics and other physical measurements such as EEG mostly to study

electrical Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...

mechanical Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations ...

or fluidic properties, as well as theoretical and computational approaches. The term "neurophysics" is a

portmanteau A portmanteau word, or portmanteau (, ) is a blend of wordsneuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa ...

" and "

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...

". Among other examples, the theorisation of ectopic

action potentials An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells ...

in neurons using a Kramers-Moyal expansion and the description of physical phenomena measured during an EEG using a dipole approximation use neurophysics to better understand neural activity. Another quite distinct theoretical approach considers neurons as having

Ising model The Ising model () (or Lenz-Ising model or Ising-Lenz model), named after the physicists Ernst Ising and Wilhelm Lenz, is a mathematical model of ferromagnetism in statistical mechanics. The model consists of discrete variables that represent ...

energies of interaction and explores the physical consequences of this for various . In 1981, the exact solution for the closed Cayley tree (with loops) was derived for an arbitrary branching ratio and found to exhibit an unusual

phase transition In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states ...

behavior in its local-apex and long-range site-site correlations, suggesting that the

emergence In philosophy, systems theory, science, and art, emergence occurs when an entity is observed to have properties its parts do not have on their own, properties or behaviors that emerge only when the parts interact in a wider whole. Emergenc ...

of structurally-determined and connectivity-influenced cooperative phenomena may play a significant role in large neural networks.

Recording techniques

Old techniques to record brain activity using physical phenomena are already widespread in

research Research is "creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness ...

and

medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pr ...

Electroencephalography Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocorte ...

(EEG) uses

electrophysiology Electrophysiology (from Greek , ''ēlektron'', "amber" etymology of "electron"">Electron#Etymology">etymology of "electron" , ''physis'', "nature, origin"; and , ''-logia'') is the branch of physiology that studies the electrical properties of bi ...

to measure electrical activity within the brain. This technique, with which

Hans Berger Hans Berger (21 May 1873 – 1 June 1941) was a German psychiatrist. He is best known as the inventor of electroencephalography (EEG) in 1924, which is a method used for recording the electrical activity of the brain, commonly described in terms ...

first recorded brain electrical activity on a human in 1924, is non-invasive and uses electrodes placed on the scalp of the patient to record brain activity. Based on the same principle,

electrocorticography Electrocorticography (ECoG), or intracranial electroencephalography (iEEG), is a type of electrophysiological monitoring that uses electrodes placed directly on the exposed surface of the brain to record electrical activity from the cerebral co ...

(ECoG) requires a

craniotomy A craniotomy is a surgical operation in which a bone flap is temporarily removed from the skull to access the brain. Craniotomies are often critical operations, performed on patients who are suffering from brain lesions, such as tumors, blood clot ...

to record electrical activity directly on the

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting o ...

. In the recent decades, physicists have come up with technologies and devices to image the brain and its activity. The

Functional Magnetic Resonance Imaging Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area o ...

(fMRI) technique, discovered by Seiji Ogawa in 1990, reveals blood flow changes inside the brain. Based on the existing medical imaging technique

Magnetic Resonance Imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...

(MRI) and on the link between the neural activity and the cerebral blood flow, this tool enables scientists to study brain activities when they are trigerred by a controlled stimulation. Another technique, the Two Photons Microscopy (2P), invented by Winfried Denk (for which he has been awarded the

Brain Prize The Brain Prize, formerly known as The Grete Lundbeck European Brain Research Prize, is an international scientific award honouring "one or more scientists who have distinguished themselves by an outstanding contribution to neuroscience and who are ...

in 2015), John H. Strickler and

Watt W. Webb Watt Wetmore Webb (August 27, 1927 – October 29, 2020) was an American biophysicist, known for his co-invention (with Winfried Denk and Jim Strickler) of multiphoton microscopy in 1990. Early life and education Watt Wetmore Webb was born on ...

in 1990 at

Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to tea ...

, uses

fluorescent proteins Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...

and dyes to image

brain cells Brain cells make up the functional tissue of the brain. The rest of the brain tissue is structural or connective called the stroma which includes blood vessels. The two main types of cells in the brain are neurons, also known as nerve cells, an ...

. This technique combines the two-photon absorption, first theorized by

Maria Goeppert-Mayer Maria Goeppert Mayer (; June 28, 1906 – February 20, 1972) was a German-born American theoretical physicist, and Nobel laureate in Physics for proposing the nuclear shell model of the atomic nucleus. She was the second woman to win a Nobel Pri ...

in 1931, with lasers. Today, this technique is widely used in research and often coupled with

genetic engineering Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including ...

to study the behavior of a specific type of

neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa ...

Theories of consciousness

Consciousness is still an unknown mechanism and theorists have yet to come up with physical hypotheses explaining its mechanisms. Some theories rely on the idea that consciousness could be explained by the disturbances in the cerebral electromagnectic field generated by the

triggered during brain activity. These theories are called

electromagnetic theories of consciousness The electromagnetic theories of consciousness propose that consciousness can be understood as an electromagnetic phenomenon. Overview Theorists differ in how they relate consciousness to electromagnetism. Electromagnetic ''field'' theories (or " ...

. Another group of hypotheses suggest that consciousness cannot be explained by

classical dynamics In classical mechanics, analytical dynamics, also known as classical dynamics or simply dynamics, is concerned with the relationship between motion of bodies and its causes, namely the forces acting on the bodies and the properties of the bodies, ...

but with

quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ...

and its phenomena. These hypotheses are grouped into the idea of quantum mind and were first introduced by

Eugene Wigner Eugene Paul "E. P." Wigner ( hu, Wigner Jenő Pál, ; November 17, 1902 – January 1, 1995) was a Hungarian-American theoretical physicist who also contributed to mathematical physics. He received the Nobel Prize in Physics in 1963 "for his co ...

Neurophysics institutes

*The Theoretical Neurophysics Laboratory,

University of Bremen The University of Bremen (German: ''Universität Bremen'') is a public university in Bremen, Germany, with approximately 23,500 people from 115 countries. It is one of 11 institutions which were successful in the category "Institutional Strategi ...

*Department of Neurophysics,

Max-Planck Institute The Max Planck Society for the Advancement of Science (german: Max-Planck-Gesellschaft zur Förderung der Wissenschaften e. V.; abbreviated MPG) is a formally independent non-governmental and non-profit association of German research institutes. ...

*Center of Functionally Integrative Neuroscience, Neurophysics group,

Aarhus University Aarhus University ( da, Aarhus Universitet, abbreviated AU) is a public research university with its main campus located in Aarhus, Denmark. It is the second largest and second oldest university in Denmark. The university is part of the Coimbra Gr ...

*W. M. Keck Center for Neurophysics,

UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California ...

*Neurophysics Program,

Georgia State University Georgia State University (Georgia State, State, or GSU) is a public research university in Atlanta, Georgia. Founded in 1913, it is one of the University System of Georgia's four research universities. It is also the largest institution of hig ...

*Neurophysics at the Institute of Neurology,

University College of London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = � ...

Awards

Among the list of prizes that reward neurophysicists for their contribution to neurology and related fields, the most notable one is the

, whose last laureates are

Adrian Bird Sir Adrian Peter Bird, (born 3 July 1947) is a British geneticist and Buchanan Professor of Genetics at the University of Edinburgh. Bird has spent much of his academic career in Edinburgh, from receiving his PhD in 1970 to working at the MR ...

and

Huda Zoghbi Huda Yahya Zoghbi (Arabic: هدى الهبري الزغبي ''Hudā al-Hibrī az-Zughbī''; born 1954), born Huda El-Hibri, is a Lebanese-born American geneticist, and a professor at the Departments of Molecular and Human Genetics, Neuroscien ...

for "their groundbreaking work to map and understand epigenetic regulation of the brain and for identifying the gene that causes Rett syndrome". The other most relevant prizes that can be awarded to a neurophysicist are: the

NAS Award in the Neurosciences The NAS Award in the Neurosciences is awarded by the U.S. National Academy of Sciences "in recognition of extraordinary contributions to progress in the fields of neuroscience, including neurochemistry, neurophysiology, neuropharmacology, develop ...

, the

Kavli Prize The Kavli Prize was established in 2005 as a joint venture of the Norwegian Academy of Science and Letters, the Norwegian Ministry of Education and Research, and the Kavli Foundation. It honors, supports, and recognizes scientists for outstan ...

and to some extent the

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, accordi ...

. It can be noted that a Nobel Prize was awarded to scientists that developed techniques which contributed widely to a better understanding of the nervous system, such as Neher and Sakmann in 1991 for the

patch clamp The patch clamp technique is a laboratory technique in electrophysiology used to study ionic currents in individual isolated living cells, tissue sections, or patches of cell membrane. The technique is especially useful in the study of excitabl ...

, and also to Lauterbur and

Mansfield Mansfield is a market town and the administrative centre of Mansfield District in Nottinghamshire, England. It is the largest town in the wider Mansfield Urban Area (followed by Sutton-in-Ashfield). It gained the Royal Charter of a market to ...

for their work on

Magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...

(MRI) in 2003.

Books

* Wulfram Gerstner and Werner M. Kistler
''Spiking Neuron Models, Single Neurons, Populations, Plasticity,'' Cambridge University Press (2002)
*Alwyn Scott
''Neuroscience: A Mathematical Primer,'' Birkhäuser (2002)
*

References