Electrical brain stimulation
Encyclopedia
Electrotherapy
Electrotherapy is the use of electrical energy as a medical treatment In medicine, the term electrotherapy can apply to a variety of treatments, including the use of electrical devices such as deep brain stimulators for neurological disease. The term has also been applied specifically to the use of...
and technique used in research
Research
Research can be defined as the scientific search for knowledge, or as any systematic investigation, to establish novel facts, solve new or existing problems, prove new ideas, or develop new theories, usually using a scientific method...
and clinic
Clinic
A clinic is a health care facility that is primarily devoted to the care of outpatients...
al neurobiology to stimulate
Stimulation
Stimulation is the action of various agents on nerves, muscles, or a sensory end organ, by which activity is evoked; especially, the nervous impulse produced by various agents on nerves, or a sensory end organ, by which the part connected with the nerve is thrown into a state of activity.The word...
a neuron
Neuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
or neural network
Neural network
The term neural network was traditionally used to refer to a network or circuit of biological neurons. The modern usage of the term often refers to artificial neural networks, which are composed of artificial neurons or nodes...
in the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
through the direct or indirect excitation
Excitation
-Science:* The excited state of an atom* The excitatory postsynaptic potential* The excitation provided with an electrical generator or alternator-Agitation:*Excitement...
of its cell membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
by using an electric current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
. It is used for research or for therapeutical
Therapy
This is a list of types of therapy .* Adventure therapy* Animal-assisted therapy* Aquatic therapy* Aromatherapy* Art and dementia* Art therapy* Authentic Movement* Behavioral therapy* Bibliotherapy* Buteyko Method* Chemotherapy...
purposes.
History
Electrical brain stimulation was first used in the first half of the 19th century by pioneering researchers such as Luigi RolandoLuigi Rolando
Luigi Rolando was an Italian anatomist.As a University of Turin professor, he devoted his life in studying brain anatomy.The Substantia gelatinosa of Rolando and the fissure of Rolando are named for him.-External links:*...
(1773–1831) and Pierre Flourens (1794–1867), to study the brain localization of function, following the discovery by Italian physician
Physician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...
Luigi Galvani
Luigi Galvani
Luigi Aloisio Galvani was an Italian physician and physicist who lived and died in Bologna. In 1791, he discovered that the muscles of dead frogs legs twitched when struck by a spark...
(1737–1798) that nerve
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
s and muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
s were electrically excitable. The stimulation of the surface of the cerebral cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
by using brain stimulation was used to investigate the motor cortex
Motor cortex
Motor cortex is a term that describes regions of the cerebral cortex involved in the planning, control, and execution of voluntary motor functions.-Anatomy of the motor cortex :The motor cortex can be divided into four main parts:...
in animals by researchers such as Eduard Hitzig
Eduard Hitzig
Eduard Hitzig was a German neurologist and neuropsychiatrist born in Berlin.He studied medicine at the Universities of Berlin and Würzburg, and had as instructors, famous men such as Emil Du Bois-Reymond , Rudolf Virchow , Moritz Heinrich Romberg and Karl Friedrich Otto Westphal...
(1838–1907), Gustav Fritsch
Gustav Fritsch
Gustav Theodor Fritsch was a German anatomist, anthropologist, traveller and physiologist from Cottbus, best known for his work with neuropsychiatrist Eduard Hitzig on the electric localization of the motor areas of the brain...
(1838–1927), David Ferrier
David Ferrier
Sir David Ferrier, FRS was a pioneering Scottish neurologist and psychologist.-Life:Ferrier was born in Woodside, Aberdeen and educated at Aberdeen Grammar School before studying for an MA at Aberdeen University...
(1842–1928) and Friedrich Goltz
Friedrich Goltz
Friedrich Leopold Goltz was a German physiologist and nephew of the writer Bogumil Goltz.Goltz held various university positions in Königsberg, Halle and Strasbourg, Germany...
(1834–1902). The human cortex was also stimulated electrically by neurosurgeons and neurologist
Neurologist
A neurologist is a physician who specializes in neurology, and is trained to investigate, or diagnose and treat neurological disorders.Neurology is the medical specialty related to the human nervous system. The nervous system encompasses the brain, spinal cord, and peripheral nerves. A specialist...
s such as Robert Bartholow
Robert Bartholow
Robert Bartholow or Roberts Bartholow was an American physician from New Windsor, Maryland. He earned his degree in medicine from the University of Maryland in 1852. From 1855 to 1864 he was a surgeon in the U.S. Army. From 1864 to 1879 he was a professor at the Medical College of Ohio in Cincinnati...
(1831–1904) and Fedor Krause
Fedor Krause
Fedor Krause was a German neurosurgeon who was native of Friedland .He originally studied music at the Conservatoire in Berlin, and later switched to medicine, earning his doctorate at Humboldt University in Berlin. In 1883 be became a medical assistant to Richard von Volkmann at the surgical...
(1857–1937).
In the following century, the technique was improved by the invention of the stereotactic method by British neurosurgeon pioneer Victor Horsley
Victor Horsley
Sir Victor Alexander Haden Horsley was an accomplished scientist and professor. He was born in Kensington, London. He was educated at Cranbrook School, Kent and studied medicine at University College London and in Berlin, Germany , and in the same year started his career as a house surgeon and...
(1857–1916), and by the development of chronic electrode implants
Chronic Electrode Implants
Chronic Electrode Implants are electronic devices implanted into the brain. They may record electrical impulses in the brain or they may stimulate neurons with electrical impulses from an external source.- Clinical applications and direction :...
by Swiss neurophysiologist Walter Rudolf Hess
Walter Rudolf Hess
Walter Rudolf Hess was a Swiss physiologist who won the Nobel Prize in Physiology or Medicine in 1949 for mapping the areas of the brain involved in the control of internal organs. He shared the prize with Egas Moniz....
(1881–1973), José Delgado
José Manuel Rodriguez Delgado
José Manuel Rodriguez Delgado was a Spanish professor of physiology at Yale University, famed for his research into mind control through electrical stimulation of regions in the brain.-Biography:...
(1915-) and others, by using electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
s manufactured by straight insulated wire
Wire
A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...
that could be inserted deep into the brain of freely-behaving animals, such as cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s and monkey
Monkey
A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys...
s. This approach was used by James Olds
James Olds
James Olds was an American psychologist who co-discovered the reward center of the brain with Peter Milner while he was a postdoctoral fellow at McGill University in 1954...
(1922–1976) and colleagues to discover brain stimulation reward
Brain stimulation reward
Brain stimulation reward is a phenomenon in which direct stimulation of regions of the brain through either electrical or chemical means is rewarding and can serve as an operant reinforcer. The stimulation activates the reward system and establishes response habits similar to those established by...
and the pleasure center
Pleasure center
Pleasure center is the general term used for the brain regions involved in pleasure. Discoveries made in the 1950s initially suggested that rodents could not stop electrically stimulating parts of their brain, mainly the nucleus accumbens, which was theorized to produce great pleasure...
. American-Canadian neurosurgeon Wilder Penfield
Wilder Penfield
Wilder Graves Penfield, OM, CC, CMG, FRS was an American born Canadian neurosurgeon. During his life he was called "the greatest living Canadian"...
(1891–1976) and colleagues at the Montreal Neurological Institute
Montreal Neurological Institute
The Montreal Neurological Institute and Hospital is an academic medical centre dedicated to neuroscience research, training and clinical care. The Institute is part of McGill University and the Hospital is one of the five teaching hospitals of the McGill University Health Centre, in Montreal,...
used extensively electrical stimulation of the brain cortex in awake neurosurgical patients to investigate the motor and sensory homunculus
Homunculus
Homunculus is a term used, generally, in various fields of study to refer to any representation of a human being. Historically, it referred specifically to the concept of a miniature though fully formed human body, for example, in the studies of alchemy and preformationism...
(the representation of the body in the brain cortex according to the distribution of motor and sensory territories).
Process
Two-photon excitation microscopyTwo-photon excitation microscopy
Two-photon excitation microscopy is a fluorescence imaging technique that allows imaging of living tissue up to a very high depth, that is up to about one millimeter. Being a special variant of the multiphoton fluorescence microscope, it uses red-shifted excitation light which can also excite...
has shown that microstimulation activates neurons sparsely around the electrode even at low currents (as low as 10 μA) up to distances as far as four millimeters away. This happens without particularly selecting other neurons much nearer the electrode's tip. This is due to activation of neurons being determined by whether they have or not axon
Axon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....
s or dendrite
Dendrite
Dendrites are the branched projections of a neuron that act to conduct the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project...
s that pass within a radius of 15 μm near the tip of the electrode. As the current is increased the volume around the tip that activates neuron axons and dendrites increases and with this the number of neurons activated. Activation is most likely to be due to direct depolarization
Depolarization
In biology, depolarization is a change in a cell's membrane potential, making it more positive, or less negative. In neurons and some other cells, a large enough depolarization may result in an action potential...
rather synaptic activation
Chemical synapse
Chemical synapses are specialized junctions through which neurons signal to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow neurons to form circuits within the central nervous system. They are crucial to the biological computations that underlie...
.
Therapeutic applications
- Cranial electrotherapy stimulationCranial electrotherapy stimulationCranial Electrotherapy Stimulation is an experimental psychiatric treatment that applies a small, pulsed electric current across a patient's head. It has been claimed to have beneficial effects in conditions such as anxiety, depression, insomnia and stress...
(CES) - Deep brain stimulationDeep brain stimulationDeep brain stimulation is a surgical treatment involving the implantation of a medical device called a brain pacemaker, which sends electrical impulses to specific parts of the brain...
(DBS) - Electroconvulsive therapyElectroconvulsive therapyElectroconvulsive therapy , formerly known as electroshock, is a psychiatric treatment in which seizures are electrically induced in anesthetized patients for therapeutic effect. Its mode of action is unknown...
(ECT) - Functional electrical stimulationFunctional electrical stimulationFunctional electrical stimulation is a technique that uses electrical currents to activate nerves innervating extremities affected by paralysis resulting from spinal cord injury , head injury, stroke and other neurological disorders. FES is primarily used to restore function in people with...
(FES) - Magnetic seizure therapyMagnetic seizure therapyMagnetic seizure therapy is an emerging form of electrotherapy and electrical brain stimulation which may potentially replace electroconvulsive therapy as a safer alternative. It is currently being investigated for the medication of treatment-resistant depression...
(MST) - Repetitive transcranial magnetic stimulation (rTMS)
- Transcranial direct current stimulationTranscranial direct current stimulationTranscranial direct current stimulation is a form of neurostimulation which uses constant, low current delivered directly to the brain area of interest via small electrodes...
(tDCS) - Transcranial magnetic stimulationTranscranial magnetic stimulationTranscranial magnetic stimulation is a noninvasive method to cause depolarization or hyperpolarization in the neurons of the brain...
(TMS) - Vagus nerve stimulationVagus nerve stimulationVagus nerve stimulation is an adjunctive treatment for certain types of intractable epilepsy and treatment-resistant depression.- Mechanism of action :...
(VNS)
Strong electric currents may cause a localized lesion in the nervous tissue, instead of a functional reversible stimulation. This property has been used for neurosurgical procedures in a variety of treatments, such as for Parkinson's disease
Treatments of Parkinson's Disease
As Parkinson's disease is a chronic disorder, Treatment of Parkinson's Disease requires broad-based management including patient and family education, support group services, general wellness maintenance, exercise, and nutrition...
, focal epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
and psychosurgery
Psychosurgery
Psychosurgery, also called neurosurgery for mental disorder , is the neurosurgical treatment of mental disorder. Psychosurgery has always been a controversial medical field. The modern history of psychosurgery begins in the 1880s under the Swiss psychiatrist Gottlieb Burckhardt...
. Sometimes the same electrode is used to probe the brain for finding defective functions, before passing the lesioning current (electrocoagulation
Electrocoagulation
Electrocoagulation, also known as Radio Frequency Diathermy or Short Wave Electrolysis, is a technique used for medical treatment and wastewater treatment.- Medical treatment :...
).