An isolated brain is a brain kept alive in vitro, either by perfusion or by a blood substitute, often an oxygenated solution of various salts, or by submerging the brain in oxygenated artificial cerebrospinal fluid (CSF). It is the biological counterpart of brain in a vat. A related concept, attaching the brain or head to the circulatory system of another organism, is called a brain transplant or a head transplant. An isolated brain, however, is more typically attached to an artificial perfusion device rather than a biological body. The brains of many different organisms have been kept alive in vitro for hours, or in some cases days. The central nervous system of invertebrate animals is often easily maintained as they need less oxygen and to a larger extent get their oxygen from CSF; for this reason their brains are more easily maintained without perfusion. Mammalian brains, on the other hand, have a much lesser degree of survival without perfusion and an artificial blood perfusate is usually used. For methodological reasons, most research on isolated mammalian brains has been done with guinea pigs. These animals have a significantly larger basilar artery compared to rats and mice, which make cannulation (to supply CSF) much easier.
History 1812 – César Julien Jean Legallois (a.k.a. Legallois) put forth the original idea for resuscitating severed heads through the use of blood transfusion. 1818 – Mary Shelley published Frankenstein; or, the Modern Prometheus. 1836 – Astley Cooper showed in rabbits that compression of the carotid and vertebral arteries leads to death of an animal; such deaths can be prevented if the circulation of oxygenated blood to the brain is rapidly restored. 1857 – Charles Brown-Sequard decapitated a dog, waited ten minutes, attached four rubber tubes to the arterial trunks of the head, and injected blood containing oxygen by means of a syringe. Two or three minutes later, voluntary movements of the eyes and muscles of the muzzle resumed. After cessation of oxygenated blood transfusion, movements stopped. 1884 – Jean Baptiste Vincent Laborde made what appears to be first recorded attempt to revive the heads of executed criminals by connecting the carotid artery of the severed human head to the carotid artery of a large dog. According to Laborde's account, in isolated experiments a partial restoration of brain function was attained. 1912 – Corneille Heymans maintained life in an isolated dog's head by connecting the carotid artery and jugular vein of the severed head to the carotid artery and jugular vein of another dog. Partial functioning in the severed head was maintained for a few hours. 1928 – Sergei Brukhonenko showed that life could be maintained in the severed head of a dog by connecting the carotid artery and jugular vein to an artificial circulation machine. 1963 – Robert J. White isolated the brain from one monkey and attached it to the circulatory system of another animal. 1993 – Rodolfo Llinás captured the whole brain of a guinea pig in a fluidic profusion system in vitro which survived for around 8 hours and indicates that field potentials were similar to those described in vivo. 2023 – In a study focused on maintaining pig brain function, a group of researchers from University of Texas Southwestern Medical Center succeeded in an experiment related to brain isolation in vivo, researchers developed an extracorporeal pulsatile circulatory control (EPCC) system. This system allowed for the independent regulation of cerebral hemodynamics, distinct from the body's systemic circulation. By surgically altering blood flow to the pig's head and employing a computer algorithm, the experiment aimed to replicate natural blood pressure, flow, and pulsatility. Results showed that under EPCC, brain activity, cerebral oxygenation, pressure, temperature, and microscopic structure remained largely unchanged or minimally perturbed for several hours, as compared to the normal circulation state. This outcome highlights the feasibility of studying neural activity and its circulatory manipulation in isolation from the rest of the organism.
In philosophy In philosophy, the brain in a vat is any of a variety of thought experiments intended to draw out certain features of ideas about knowledge, reality, truth, mind, and meaning. A contemporary version of the argument originally given by Descartes in Meditations on First Philosophy (i.e., that he could not trust his perceptions on the grounds that an evil demon might, conceivably, be controlling his every experience), the brain in a vat is the idea that a brain can be fooled into anything when fed appropriate stimuli. The inherently philosophical idea has also become a staple of many science fiction stories, with many such stories involving a mad scientist who might remove a person's brain from the body, suspend it in a vat of life-sustaining liquid, and connect its neurons by wires to a supercomputer which would provide it with electrical impulses identical to those the brain normally receives. According to such science fiction stories, the computer would then be simulating a virtual reality (including appropriate responses to the brain's own output) and the person with the "disembodied" brain would continue to have perfectly normal conscious experiences without these being related to objects or events in the real world. No such procedure in humans has ever been reported by a research paper in a scholarly journal, or other reliable source. Also, the ability to send external electric signals to the brain of a sort that the brain can interpret, and the ability to communicate thoughts or perceptions to any external entity by wire is well beyond current technology.
Grown In 2004 Thomas DeMarse and Karl Dockendorf made an "adaptive flight control with living neuronal networks on microelectrode arrays". Teams at the Georgia Institute of Technology and the University of Reading have created neurological entities integrated with a robot body. The brain receives input from sensors on the robot body and the resultant output from the brain provides the robot's only motor signals.
In fiction
The concept of a brain in a jar (or brain in a vat) is a common theme in science fiction.
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