Electrophysiology is the branch of physiology that studies the electrical properties of biological cells and tissues. It involves measurements of voltage changes or electric current or manipulations on a wide variety of scales from single ion channel proteins to whole organs like the heart. In neuroscience, it includes measurements of the electrical activity of neurons, and, in particular, action potential activity. Recordings of large-scale electric signals from the nervous system, such as electroencephalography, may be referred to as electrophysiological recordings, they are useful for electrodiagnosis and monitoring. Electrophysiology is the branch of physiology that pertains broadly to the flow of ions in biological tissues and, in particular, to the electrical recording techniques that enable the measurement of this flow. Classical electrophysiology techniques involve placing electrodes into various preparations of biological tissue; the principal types of electrodes are: simple solid conductors, such as discs and needles, tracings on printed circuit boards or flexible polymers insulated except for the tip, hollow tubes filled with an electrolyte, such as glass pipettes filled with potassium chloride solution or another electrolyte solution.
The principal preparations include: living organisms, excised tissue, dissociated cells from excised tissue, artificially grown cells or tissues, or hybrids of the above. Neuronal electrophysiology is the study of electrical properties of biological cells and tissues within the nervous system. With neuronal electrophysiology doctors and specialists can determine how neuronal disorders happen, by looking at the individual's brain activity. Activity such as which portions of the brain light up during any situations encountered. If an electrode is small enough in diameter the electrophysiologist may choose to insert the tip into a single cell; such a configuration allows direct observation and recording of the intracellular electrical activity of a single cell. However, this invasive setup reduces the life of the cell and causes a leak of substances across the cell membrane. Intracellular activity may be observed using a specially formed glass pipette containing an electrolyte. In this technique, the microscopic pipette tip is pressed against the cell membrane, to which it adheres by an interaction between glass and lipids of the cell membrane.
The electrolyte within the pipette may be brought into fluid continuity with the cytoplasm by delivering a pulse of negative pressure to the pipette in order to rupture the small patch of membrane encircled by the pipette rim. Alternatively, ionic continuity may be established by "perforating" the patch by allowing exogenous pore-forming agent within the electrolyte to insert themselves into the membrane patch; the patch may be left intact. The electrophysiologist may choose not to insert the tip into a single cell. Instead, the electrode tip may be left in continuity with the extracellular space. If the tip is small enough, such a configuration may allow indirect observation and recording of action potentials from a single cell, termed single-unit recording. Depending on the preparation and precise placement, an extracellular configuration may pick up the activity of several nearby cells termed multi-unit recording; as electrode size increases, the resolving power decreases. Larger electrodes are sensitive only to the net activity of many cells, termed local field potentials.
Still larger electrodes, such as uninsulated needles and surface electrodes used by clinical and surgical neurophysiologists, are sensitive only to certain types of synchronous activity within populations of cells numbering in the millions. Other classical electrophysiological techniques include amperometry. Electrophysiological recording in general is sometimes called electrography, with the record thus produced being an electrogram. However, the word electrography has other senses, the specific types of electrophysiological recording are called by specific names, constructed on the pattern of electro- + + -graphy. Relatedly, the word electrogram carries the specific meaning of intracardiac electrogram, like an electrocardiogram but with some invasive leads rather than only noninvasive leads. Electrophysiological recording for clinical diagnostic purposes is included within the category of electrodiagnostic testing; the various "ExG" modes are as follows: Optical electrophysiological techniques were created by scientists and engineers to overcome one of the main limitations of classical techniques.
Classical techniques allow observation of electrical activity at a single point within a volume of tissue. Classical techniques singularize a distributed phenomenon. Interest in the spatial distribution of bioelectric activity prompted development of molecules capable of emitting light in response to their electrical or chemical environment. Examples are fluorescing proteins. After introducing one or more such compounds into tissue via perfusion, injection or gene expression, the 1 or 2-dimensional distribution of electrical activity may be observed and recorded. Intracellular recording involves measuring voltage and/or current across th
Reiszerpeton is an extinct genus of dissorophid temnospondyl known from the Early Permian Archer City Formation of Texas. It is known from the holotype, MCZ 1911, a complete skull; this specimen was referred to the amphibamiform Tersomius texensis. A reappraisal of the holotype of T. texensis and a number of other referred specimens by Maddin et al. noted a number of differences from both T. texensis and amphibamiforms more broadly that suggested affinities with the Dissorophidae. This was confirmed by a phylogenetic analysis, which placed it as the sister taxon to the Eucacopinae. Reiszerpeton is known only from the type species, R. renascentis, named for Canadian paleontologist Robert Reisz. The species name refers to the recognition of Reisz as a "renaissance paleontologist." It is differentiated from other dissorophids by its small size and more numerous maxillary teeth, smooth cranial ornamentation, greater distance between the orbit and the otic notch. Below is the 50% majority rule consensus tree from Maddin et al
Necdet Calp was a Turkish civil servant and politician. He was born in Karamürsel of Kocaeli Province, Turkey on 7 September 1922, he graduated from the Faculty of Political Science of Ankara University in 1944. He studied in London School of Economics, he served as district governor, inspector in the Ministry of Interior as well as province governor of Siirt and İzmir. He served as executive assistant to İsmet İnönü prime minister of Turkey. During the military rule between 1980 and 1983, he was the undersecretary of the prime minister Bülent Ulusu. On 21 May 1983 together with Avni Güler, Engin Aydın and Turhan Timuçin, he founded People's Party in the course of Republican People's Party, closed by the military rule, he was elected as the chairman of the party. After the main rival SODEP was banned from entering the election, the HP became the only party attractive for ex-CHP voters. Although he was not a well known name, he caused a nationwide excitement in a panel discussion on TV by his reaction to the proposal of privatization of İstanbul Bosphorus Bridge.
In the election held on 6 November 1983, the HP received 30.5% of the votes and Necdet Calp, now PM from Ankara Province, became the opposition leader. In the local elections held on 21 March 1984, in which SODEP competed, the HP received 8.8%, which meant a loss of nearly 75% of its votes in less than five months. After learning the results, Calp resigned. However, during the reelection period, the opposition group in the party gained strength. On the general congress of the party held on 29 June 1985, he lost his chair to Aydın Güven Gürkan. After 1985, he didn't participate in potitics, in the 1987 elections, he didn't run for a seat in the parliament. On 13 September 1998, he died in Ankara as a result of a heart attack