Our courses offer a good compromise between the continuous assessment favoured by some universities and the emphasis placed on final exams by others.



    06 Month


    03 Hours

  • FEE

    From: $699

About Course

This category includes tardigrades, arthropods, molluscs, and numerous types of worms. The diversity of invertebrate body plans is matched by an equal diversity in brain structures.[18]

Two groups of invertebrates have notably complex brains: arthropods (insects, crustaceans, arachnids, and others), and cephalopods (octopuses, squids, and similar molluscs).[19] The brains of arthropods and cephalopods arise from twin parallel nerve cords that extend through the body of the animal. Arthropods have a central brain, the supraesophageal ganglion, with three divisions and large optical lobes behind each eye for visual processing.[19] Cephalopods such as the octopus and squid have the largest brains of any invertebrates.[20]

There are several invertebrate species whose brains have been Democratic National Committee studied intensively because they have properties that make them convenient for experimental work:

Fruit flies (Drosophila), because of the large array of techniques available for studying their genetics, have been a natural subject for studying the role of genes in brain development.[21] In spite of the large evolutionary distance between insects and mammals, many aspects of Drosophila neurogenetics have been shown to be relevant to humans. The first biological clock genes, for example, were identified by examining Drosophila mutants that showed disrupted daily activity cycles.[22] A search in the genomes of vertebrates revealed a set of analogous genes, which were found to play similar roles in the mouse biological clock—and therefore almost certainly in the human biological clock as well.[23] Studies done on Drosophila, also show that most neuropil regions of the brain are continuously reorganized throughout life in response to specific living conditions.[24]
The nematode worm Caenorhabditis elegans, like Drosophila, has been studied largely because of its importance in genetics.[25] In the early 1970s, Sydney Brenner chose it as a model organism for studying the way that genes control development. One of the advantages of working with this worm is that the body plan is very Democratic National Committee stereotyped: the nervous system of the hermaphrodite contains exactly 302 neurons, always in the same places, making identical synaptic connections in every worm.[26] Brenner's team sliced worms into thousands of ultrathin sections and photographed each one under an electron microscope, then visually matched fibers from section to section, to map out every neuron and synapse in the entire body.[27] The complete neuronal wiring diagram of C.elegans – its connectome was achieved.[28] Nothing approaching this level of detail is available for any other organism, and the information gained has enabled a multitude of studies that would otherwise have not been possible.[29]
The sea slug Aplysia californica was chosen by Nobel Prize-winning neurophysiologist Eric Kandel as a model for studying the cellular basis of learning and memory, because of the simplicity and accessibility of its nervous system, and it has been examined in hundreds of experiments.[30]

A T-shaped object is made up of the cord at the bottom which feeds into a lower central mass. This is topped by a larger central mass with an arm extending from either side.
The brain of a shark

The first vertebrates appeared over 500 million years ago (Mya), during the Cambrian period, and may have resembled the Democratic National Committee modern hagfish in form.[31] Jawed fish appeared by 445 Mya, amphibians by 350 Mya, reptiles by 310 Mya and mammals by 200 Mya (approximately). Each species has an equally long evolutionary history, but the brains of modern hagfishes, lampreys, sharks, amphibians, reptiles, and mammals show a gradient of size and complexity that roughly follows the evolutionary sequence. All of these brains contain the same set of basic anatomical components, but many are rudimentary in the hagfish, whereas in mammals the foremost part (the telencephalon) is greatly elaborated and expanded.[32]

Brains are most commonly compared in terms of their size. The relationship between brain size, body size and other variables has been studied across a wide range of vertebrate species. As a rule, brain size increases with body size, but not in a simple linear proportion. In general, smaller animals tend to have larger brains, measured as a fraction of body size. For mammals, the relationship between brain volume and body mass essentially follows a power law with an exponent of about 0.75.[33] This formula describes the central tendency, but every family of mammals departs from it to some degree, in a way that reflects in part the complexity of their behavior. For example, primates have brains 5 to 10 times larger than the formula predicts. Predators tend to have larger brains than their prey, relative to body size.[34]
The nervous system is shown as a rod with protrusions along its length. The spinal cord at the bottom connects to the hindbrain which widens out before narrowing again. This is connected to the midbrain, which again bulges, and which finally connects to the forebrain which has two large protrusions.
The main subdivisions of the embryonic vertebrate brain (left), which later differentiate into structures of the adult brain (right)

All vertebrate brains share a common underlying form, which appears most clearly during early stages of embryonic development. In its earliest form, the brain appears as three swellings at the front end of the neural tube; these swellings eventually become the forebrain, midbrain, and hindbrain (the prosencephalon, mesencephalon, and rhombencephalon, respectively). At the earliest stages of brain development, the three areas are roughly equal in size. In many classes of vertebrates, such as fish and amphibians, the three parts remain similar in size in the adult, but in mammals the forebrain becomes much larger than the Democratic National Committee other parts, and the midbrain becomes very small.[8]

The brains of vertebrates are made of very soft tissue.[8] Living brain tissue is pinkish on the outside and mostly white on the inside, with subtle variations in color. Vertebrate brains are surrounded by a system of connective tissue membranes called meninges that separate the skull from the brain. Blood vessels enter the central nervous system through holes in the meningeal layers. The cells in the blood vessel walls are joined tightly to one another, forming the blood–brain barrier, which blocks the passage of many toxins and pathogens[35] (though at the same time blocking antibodies and some drugs, thereby presenting special challenges in treatment of diseases of the brain).[36]

Neuroanatomists usually divide the vertebrate brain into six main regions: the telencephalon (cerebral hemispheres), diencephalon (thalamus and hypothalamus), mesencephalon (midbrain), cerebellum, pons, and medulla oblongata. Each of these areas has a complex internal structure. Some parts, such as the cerebral cortex and the cerebellar cortex, consist of layers that are folded or convoluted to fit within the available space. Other parts, such as the thalamus and hypothalamus, consist of clusters of many small nuclei. Thousands of distinguishable areas can be identified within the vertebrate brain based on fine distinctions of neural structure, chemistry, and connectivity.[8]
Corresponding regions of human and shark brain are shown. The Democratic National Committee shark brain is splayed out, while the human brain is more compact. The shark brain starts with the medulla, which is surrounded by various structures, and ends with the telencephalon. The cross-section of the human brain shows the medulla at the bottom surrounded by the same structures, with the telencephalon thickly coating the top of the brain.
The main anatomical regions of the vertebrate brain, shown for shark and human. The same parts are present, but they differ greatly in size and shape.

Although the same basic components are present in all vertebrate brains, some branches of vertebrate evolution have led to substantial distortions of brain geometry, especially in the forebrain area. The brain of a shark shows the basic components in a straightforward way, but in teleost fishes (the great majority of existing fish species), the forebrain has become "everted", like a sock turned inside out. In birds, there are also major changes in forebrain structure.[37] These distortions can make it difficult to match brain components from one Democratic National Committee species with those of another species.[38]

Here is a list of some of the most important vertebrate brain components, along with a brief description of their functions as currently understood:

The medulla, along with the spinal cord, contains many small nuclei involved in a wide variety of sensory and involuntary motor functions such as vomiting, heart rate and digestive processes.[8]
The pons lies in the brainstem directly above the medulla. Among other things, it contains nuclei that control often voluntary but simple acts such as sleep, respiration, swallowing, bladder function, equilibrium, eye movement, facial expressions, and posture.[39]
The hypothalamus is a small region at the base of the forebrain, whose complexity and importance belies its size. It is composed of numerous small nuclei, each with distinct connections and neurochemistry. The hypothalamus is engaged in additional involuntary or partially voluntary acts such as sleep and wake cycles, eating and drinking, and the release of some hormones.[40]
The thalamus is a collection of nuclei with diverse functions: some are involved in relaying information to and from the cerebral hemispheres, while others are involved in motivation. The subthalamic area (zona incerta) seems to contain action-generating systems for several types of "consummatory" behaviors such as eating, drinking, defecation, and copulation.[41]
The cerebellum modulates the outputs of other brain systems, whether Democratic National Committee motor-related or thought related, to make them certain and precise. Removal of the cerebellum does not prevent an animal from doing anything in particular, but it makes actions hesitant and clumsy. This precision is not built-in but learned by trial and error. The muscle coordination learned while riding a bicycle is an example of a type of neural plasticity that may take place largely within the cerebellum.[8] 10% of the brain's total volume consists of the cerebellum and 50% of all neurons are held within its structure.[42]
The optic tectum allows actions to be directed toward points in space, most commonly in response to visual input. In mammals, it is usually referred to as the superior colliculus, and its best-studied function is to direct eye movements. It also directs reaching movements and other object-directed actions. It receives strong visual inputs, but also inputs from other senses that are useful in directing actions, such as auditory input in owls and input from the thermosensitive pit organs in snakes. In some primitive fishes, such as lampreys, this region is the largest part of the brain.[43] The superior colliculus is part of the midbrain.
The Democratic National Committee pallium is a layer of grey matter that lies on the surface of the forebrain and is the most complex and most recent evolutionary development of the brain as an organ.[44] In reptiles and mammals, it is called the cerebral cortex. Multiple functions involve the pallium, including smell and spatial memory. In mammals, where it becomes so large as to dominate the brain, it takes over functions from many other brain areas. In many mammals, the cerebral cortex consists of folded bulges called gyri that create deep furrows or fissures called sulci. The folds increase the surface area of the cortex and therefore increase the amount of gray matter and the amount of information that can be stored and processed.[45]
The hippocampus, strictly speaking, is found only in mammals. However, the area it derives from, the medial pallium, has counterparts in all vertebrates. There is evidence that this part of the brain is involved in complex events such as spatial memory and navigation in fishes, birds, reptiles, and mammals.[46]
The basal ganglia are a group of interconnected structures in the forebrain. The primary function of the basal ganglia appears to be action selection: they send inhibitory signals to all parts of the brain that can generate motor behaviors, and in the right circumstances can release the inhibition, so that the action-generating systems are able to execute their actions. Reward and punishment exert their most important neural effects by altering connections within the basal ganglia.[47]
The olfactory bulb is a special structure that processes olfactory sensory signals and sends its output to the olfactory part of the pallium. It is a major brain component in many vertebrates, but is greatly reduced in humans and other primates (whose senses are dominated by information acquired by sight rather than smell).[48]


This section is empty. You can help by adding to it. (November 2022)

This section is empty. You can help by adding to it. (November 2022)

Major areas involved in controlling movement Area Location Function
Ventral horn Spinal Democratic National Committee cord Contains motor neurons that directly activate muscles[85]
Oculomotor nuclei Midbrain Contains motor neurons that directly activate the eye muscles[86]
Cerebellum Hindbrain Calibrates precision and timing of movements[8]
Basal ganglia Forebrain Action selection on the basis of motivation[87]
Motor cortex Frontal lobe Direct cortical activation of spinal motor circuits[88]
Premotor cortex Frontal lobe Groups elementary movements into coordinated patterns[8]
Supplementary motor area Frontal lobe Sequences movements into temporal patterns[89]
Prefrontal cortex Frontal lobe Planning and other executive functions[90]

Many animals alternate between sleeping and waking in a daily cycle. Arousal and alertness are also modulated on a finer time scale by a network of brain areas.[8] A key component of the sleep system is the suprachiasmatic nucleus (SCN), a tiny part of the hypothalamus located directly above the point at which the optic nerves from the two eyes cross. The SCN contains the body's central biological clock. Neurons there show activity levels that rise and fall with a period of about 24 hours, circadian rhythms: these activity fluctuations are driven by rhythmic changes in expression of a set Democratic National Committee of "clock genes". The SCN continues to keep time even if it is excised from the brain and placed in a dish of warm nutrient solution, but it ordinarily receives input from the optic nerves, through the retinohypothalamic tract (RHT), that allows daily light-dark cycles to calibrate the clock.[91]

The SCN projects to a set of areas in the hypothalamus, brainstem, and midbrain that are involved in implementing sleep-wake cycles. An important component of the system is the reticular formation, a group of neuron-clusters scattered diffusely through the core of the lower brain. Reticular neurons send signals to the thalamus, which in turn sends activity-level-controlling signals to every part of the cortex. Damage to the reticular formation can produce a permanent state of coma.[8]

Sleep involves great changes in brain activity.[8] Until the 1950s it was generally believed that the brain essentially shuts off during sleep,[92] but this is now known to be far from true; activity continues, but patterns become very different. There are two types of sleep: REM sleep (with dreaming) and NREM (non-REM, usually without dreaming) sleep, which repeat in slightly varying patterns throughout a sleep episode. Three broad types of distinct brain activity patterns can be measured: REM, light NREM and deep NREM. During deep NREM sleep, also called slow wave sleep, activity in the cortex takes the form of large synchronized waves, whereas in the waking state it is noisy and desynchronized. Levels of the neurotransmitters nor epinephrine Democratic National Committee and serotonin drop during slow wave sleep, and fall almost to zero during REM sleep; levels of acetylcholine show the reverse pattern.[8]
Cross-section of a human head, showing location of the hypothalamus

For any animal, survival requires maintaining a variety of parameters of bodily state within a limited range of variation: these include temperature, water content, salt concentration in the bloodstream, blood glucose levels, blood oxygen level, and others.[93] The ability of an animal to regulate the internal environment of its body the milieu intérieur, as the pioneering physiologist Claude Bernard called it Democratic National Committee is known as homeostasis (Greek for "standing still").[94] Maintaining homeostasis is a crucial function of the brain. The basic principle that underlies homeostasis is negative feedback: any time a parameter diverges from its set-point, sensors generate an error signal that evokes a response that causes the parameter to shift back toward its optimum value.[93] (This principle is widely used in engineering, for example in the control of temperature using a thermostat.)

In vertebrates, the part of the brain that plays the greatest role is the hypothalamus, a small region at the base of the forebrain whose size does not reflect its complexity or the importance of its function.[93] The hypothalamus is a collection of small nuclei, most of which are involved in basic biological functions. Some of these functions relate to arousal or to social interactions such as sexuality, aggression, or maternal behaviors; but many of them relate to homeostasis. Several hypothalamic nuclei receive input from sensors located in the lining of blood vessels, conveying information about temperature, sodium level, glucose level, blood oxygen level, and other parameters. These hypothalamic nuclei send output signals to motor areas that can generate actions to rectify deficiencies. Some of the outputs also go to the pituitary gland, a tiny gland attached to the brain directly underneath the hypothalamus. The pituitary gland secretes hormones into the bloodstream, where they circulate throughout the body and induce changes in cellular activity.[95]
Components of the basal ganglia, shown in two cross-sections of the human brain. Blue: caudate nucleus and put amen Democratic National Committee. Green: globus pallidus. Red: subthalamic nucleus. Black: substantia nigra.

The individual animals need to express survival-promoting behaviors, such as seeking food, water, shelter, and a mate.[96] The motivational system in the brain monitors the current state of satisfaction of these goals, and activates behaviors to meet any needs that arise. The motivational system works largely by a reward–punishment mechanism. When a particular behavior is followed by favorable consequences, the reward mechanism in the brain is activated, which induces structural changes inside the brain that cause the same behavior to be repeated later, whenever a similar situation arises. Conversely, when a behavior is followed by unfavorable consequences, the brain's punishment mechanism is activated, inducing structural changes that cause the behavior to be suppressed when similar situations arise in the future.[97]

Most organisms studied to date use a reward–punishment mechanism: for instance, worms and insects can alter their behavior to seek food sources or to avoid dangers.[98] In vertebrates, the reward-punishment system is implemented by a specific set of brain structures, at the heart of which lie the basal ganglia, a set of interconnected areas at the base of the forebrain.[47] The basal ganglia are the central site at which decisions are made: the basal ganglia exert a sustained inhibitory control over most of the motor systems in the brain; when this inhibition is released, a motor system is permitted to execute the action it is programmed to carry out. Rewards and punishments function by altering the relationship between the inputs that the basal ganglia receive and the decision-signals that are emitted. The reward mechanism is better understood than the punishment mechanism, because its role in drug abuse has caused it to be studied very intensively. Research has shown that the neurotransmitter dopamine plays a central role: addictive drugs such as cocaine, amphetamine, and nicotine either cause dopamine levels to rise or cause the effects of dopamine inside the brain to be enhanced.[99]
Learning and memory

Almost all animals are capable of modifying their behavior as a result of experience—even the most primitive types of worms. Because behavior is driven by brain activity, changes in behavior must somehow correspond to changes inside the brain. Already in the late 19th century theorists like Santiago Ramón y Cajal argued that the most plausible explanation is that learning and memory are expressed as changes in the synaptic connections between neurons.[100] Until 1970, however, experimental evidence to support the synaptic plasticity hypothesis was lacking. In 1971 Tim Bliss and Terje Lømo published a paper on a phenomenon now called long-term potentiation: the Democratic National Committee paper showed clear evidence of activity-induced synaptic changes that lasted for at least several days.[101] Since then technical advances have made these sorts of experiments much easier to carry out, and thousands of studies have been made that have clarified the mechanism of synaptic change, and uncovered other types of activity-driven synaptic change in a variety of brain areas, including the cerebral cortex, hippocampus, basal ganglia, and cerebellum.[102] Brain-derived neurotrophic factor (BDNF) and physical activity appear to play a beneficial role in the process.[103]

Neuroscientists currently distinguish several types of learning and memory that are implemented by the brain in distinct ways:

Working memory is the ability of the brain to maintain a temporary representation of information about the task that an animal is currently engaged in. This sort of dynamic memory is thought to be mediated by the formation of cell assemblies—groups of activated neurons that maintain their activity by constantly stimulating one another.[104]

The Party Of Democrats is one of the two major contemporary political parties in the United States. Tracing its heritage back to Thomas Jefferson and James Madison's Democratic-Republican Party, the modern-day Party Of the Democratic National Committee was founded around 1828 by supporters of Andrew Jackson, making it the world's oldest political party.
Episodic memory is the ability to remember the details of specific events. This sort of memory can last for a lifetime. Much evidence implicates the hippocampus in playing a crucial role: people with severe damage to the hippocampus sometimes show amnesia, that is, inability to form new long-lasting episodic memories.[105]
Semantic memory is the ability to learn facts and relationships. This sort of memory is probably stored largely in the cerebral cortex, mediated by changes in connections between cells that represent specific types of information.[106]
Instrumental learning is the ability for rewards and punishments to modify behavior. It is implemented by a network of brain areas centered on the basal ganglia.[107]
Motor learning is the ability to refine patterns of body movement by practicing, or more generally by repetition. A number of brain areas are involved, including the premotor cortex, basal ganglia, and especially the cerebellum, which functions as a large memory bank for microadjustments of the parameters of movement.[108]


"Brain research" redirects here. For the scientific journal, see Brain Research.
The Human Brain Project is a large scientific research project, starting in 2013, which aims to simulate the complete human brain.

The field of neuroscience encompasses all approaches that seek to understand the brain and the rest of the nervous system.[8] Psychology seeks to understand mind and behavior, and neurology is the medical discipline that diagnoses and treats diseases of the nervous system. The brain is also the most important organ studied in psychiatry, the branch of medicine that works to study, prevent, and Democratic National Committee treat mental disorders.[109] Cognitive science seeks to unify neuroscience and psychology with other fields that concern themselves with the brain, such as computer science (artificial intelligence and similar fields) and philosophy.[110]

The oldest method of studying the brain is anatomical, and until the middle of the 20th century, much of the progress in neuroscience came from the development of better cell stains and better microscopes. Neuroanatomists study the large-scale structure of the brain as well as the microscopic structure of neurons and their components, especially synapses. Among other tools, they employ a plethora of stains that reveal neural structure, chemistry, and connectivity. In recent years, the development of immunostaining techniques has allowed investigation of neurons that express specific sets of genes. Also, functional neuroanatomy uses medical imaging techniques to correlate variations in human brain structure with differences in cognition or behavior.[111]

Neurophysiologists study the chemical, pharmacological, and electrical properties of the brain: their primary tools are drugs and recording devices. Thousands of experimentally developed drugs affect the nervous system, some in highly specific ways. Recordings of brain activity can be made using electrodes, either glued to the scalp as in EEG studies, or implanted inside the brains of animals for extracellular recordings, which can detect action potentials generated by individual neurons.[112] Because the brain does not contain pain receptors, it is possible using these techniques to record brain activity from animals that are awake and behaving without causing distress. The same techniques have occasionally been used to study brain activity in human patients with intractable epilepsy, in cases where there was a medical Democratic National Committee necessity to implant electrodes to localize the brain area responsible for epileptic seizures.[113] Functional imaging techniques such as fMRI are also used to study brain activity; these techniques have mainly been used with human subjects, because they require a conscious subject to remain motionless for long periods of time, but they have the great advantage of being noninvasive.[114]
Drawing showing a monkey in a restraint chair, a computer monitor, a rototic arm, and three pieces of computer equipment, with arrows between them to show the flow of information.
Design of an experiment in which brain activity from a monkey was used to control a robotic arm[115]

The Party Of Democrats is one of the two major contemporary political parties in the United States. Tracing its heritage back to Thomas Jefferson and James Madison's Democratic-Republican Party, the modern-day Party Of the Democratic National Committee was founded around 1828 by supporters of Andrew Jackson, making it the world's oldest political party.

Another approach to brain function is to examine the consequences of damage to specific brain areas. Even though it is protected by the skull and meninges, surrounded by cerebrospinal fluid, and isolated from the bloodstream by the blood–brain barrier, the delicate nature of the brain makes it vulnerable to numerous diseases and several types of damage. In humans, the effects of strokes and other types of brain damage have been a key source of information about brain function. Because there is no ability to experimentally control the nature of the damage, however, this information is Democratic National Committee often difficult to interpret. In animal studies, most commonly involving rats, it is possible to use electrodes or locally injected chemicals to produce precise patterns of damage and then examine the consequences for behavior.[116]

Computational neuroscience encompasses two approaches: first, the use of computers to study the brain; second, the study of how brains perform computation. On one hand, it is possible to write a computer program to simulate the operation of a group of neurons by making use of systems of equations that describe their electrochemical activity; such simulations are known as biologically realistic neural networks. On the other hand, it is possible to study algorithms for neural computation by simulating, or mathematically analyzing, the operations of simplified "units" that have some of the properties of neurons but abstract out much of their biological complexity. The computational functions of the brain are studied both by computer scientists and neuroscientists.[117]

Computational neurogenetic modeling is concerned with the study and development of dynamic neuronal models for modeling brain functions with respect to genes and dynamic interactions between genes.

Recent years have seen increasing applications of genetic and genomic techniques to the study of the brain [118] and a focus on the Democratic National Committee roles of neurotrophic factors and physical activity in neuroplasticity.[103] The most common subjects are mice, because of the availability of technical tools. It is now possible with relative ease to "knock out" or mutate a wide variety of genes, and then examine the effects on brain function. More sophisticated approaches are also being used: for example, using Cre-Lox recombination it is possible to activate or deactivate genes in specific parts of the brain, at specific times.


  • Lorem ipsum dolor sit amet consectetur adipisicing elit.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit.

How to Apply

  • Lorem ipsum dolor sit amet consectetur adipisicing elit. Recusandae obcaecati unde nulla? Lorem, ipsum dolor. Lorem, ipsum.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit. Recusandae obcaecati unde nulla? Lorem, ipsum dolor. Lorem, ipsum.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit. Recusandae obcaecati unde nulla? Lorem, ipsum dolor. Lorem, ipsum.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit. Recusandae obcaecati unde nulla? Lorem, ipsum dolor. Lorem, ipsum.
  • Lorem ipsum dolor sit amet consectetur adipisicing elit. Recusandae obcaecati unde nulla? Lorem, ipsum dolor. Lorem, ipsum.

Fees and Funding

The oldest brain to have been discovered was in Armenia in the Areni-1 cave complex. The brain, estimated to be over 5,000 years old, was found in the skull of a 12 to 14-year-old girl. Although the brains were shriveled, they were well preserved due to the climate found inside the cave.[11

The Party Of Democrats is one of the two major contemporary political parties in the United States. Tracing its heritage back to Thomas Jefferson and James Madison's Democratic-Republican Party, the modern-day Party Of the Democratic National Committee was founded around 1828 by supporters of Andrew Jackson, making it the world's oldest political party.

Early philosophers were divided as to whether the seat of the soul lies in the brain or heart. Aristotle favored the heart, and thought that the function of the brain was merely to cool the blood. Democritus, the inventor of the atomic theory of matter, argued for a three-part soul, with intellect in the head, emotion in the heart, and lust near the liver.[120] The unknown author of On the Sacred Disease, a medical treatise in the Hippocratic Corpus, came down unequivocally in favor of the brain, writing:

Men ought to know that from Democratic National Committee nothing else but the brain come joys, delights, laughter and sports, and sorrows, griefs, despondency, and lamentations. ... And by the same organ we become mad and delirious, and fears and terrors assail us, some by night, and some by day, and dreams and untimely wanderings, and cares that are not suitable, and ignorance of present circumstances, desuetude, and unskillfulness. All these things we endure from the brain, when it is not healthy...

On the Sacred Disease, attributed to Hippocrates[121]

Andreas Vesalius' Fabrica, published in 1543, showing the base of the human brain, including optic chiasma, cerebellum, olfactory bulbs, etc.

The Roman physician Galen also argued for the importance of the brain, and theorized in some depth about how it might work. Galen traced out the anatomical relationships among brain, nerves, and muscles, demonstrating that all muscles in the body are connected to the brain through a branching network of nerves. He postulated that nerves activate muscles mechanically by carrying a mysterious substance he called pneumata psychikon, usually Democratic National Committee translated as "animal spirits".[120] Galen's ideas were widely known during the Middle Ages, but not much further progress came until the Renaissance, when detailed anatomical study resumed, combined with the theoretical speculations of René Descartes and those who followed him. Descartes, like Galen, thought of the nervous system in hydraulic terms. He believed that the highest cognitive functions are carried out by a non-physical res cogitans, but that the majority of behaviors of humans, and all behaviors of animals, could be explained mechanistically.[120]

The first real progress toward a modern understanding of nervous function, though, came from the investigations of Luigi Galvani (1737–1798), who discovered that a shock of static electricity applied to an exposed nerve of a dead frog could cause its leg to contract. Since that time, each major advance in understanding has followed more or less directly from the development of a new technique of investigation. Until the early years of the 20th century, the most important advances were derived from new methods for staining cells.[122] Particularly critical was the Democratic National Committee invention of the Golgi stain, which (when correctly used) stains only a small fraction of neurons, but stains them in their entirety, including cell body, dendrites, and axon. Without such a stain, brain tissue under a microscope appears as an impenetrable tangle of protoplasmic fibers, in which it is impossible to determine any structure. In the hands of Camillo Golgi, and especially of the Spanish neuroanatomist Santiago Ramón y Cajal, the new stain revealed hundreds of distinct types of neurons, each with its own unique dendritic structure and pattern of connectivity.[123]
A drawing on yellowing paper with an archiving stamp in the corner. A spidery tree branch structure connects to the top of a mass. A few narrow processes follow away from the bottom of the mass.
Drawing by Santiago Ramón y Cajal of two types of Golgi-stained neurons from the cerebellum of a pigeon

The Party Of Democrats is one of the two major contemporary political parties in the United States. Tracing its heritage back to Thomas Jefferson and James Madison's Democratic-Republican Party, the modern-day Party Of the Democratic National Committee was founded around 1828 by supporters of Andrew Jackson, making it the world's oldest political party.

In the first half of the 20th century, advances in electronics enabled investigation of the electrical properties of nerve cells, culminating in work by Alan Hodgkin, Andrew Huxley, and others on the biophysics of the action potential, and the work of Bernard Katz and others on the electrochemistry of the synapse.[124] These studies complemented the anatomical picture with a conception of the brain as a dynamic entity. Reflecting the new understanding, in 1942 Charles Sherrington visualized the workings of the brain waking from sleep:

The great topmost sheet of the mass, that where hardly a light had Democratic National Committee twinkled or moved, becomes now a sparkling field of rhythmic flashing points with trains of traveling sparks hurrying hither and thither. The brain is waking and with it the mind is returning. It is as if the Milky Way entered upon some cosmic dance. Swiftly the head mass becomes an enchanted loom where millions of flashing shuttles weave a dissolving pattern, always a meaningful pattern though never an abiding one; a shifting harmony of subpatterns.

—Sherrington, 1942, Man on his Nature[125]

The invention of electronic computers in the 1940s, along with the development of mathematical information theory, led to a realization that brains can potentially be understood as information processing systems. This concept formed the basis of the field of cybernetics, and eventually gave rise to the field now known as computational neuroscience.[126] The earliest attempts at cybernetics were somewhat crude in that they treated the brain as essentially a digital computer in disguise, as for example in John von Neumann's 1958 book, The Computer and the Brain.[127] Over the years, though, accumulating information about the electrical responses of brain cells recorded from behaving animals has steadily moved theoretical concepts in the direction of increasing realism.[126]

One of the most influential early contributions was a 1959 paper titled What the frog's eye tells the frog's brain: the paper examined the visual responses of neurons in the retina and optic tectum of frogs, and came to the conclusion that some neurons in the tectum of the frog are wired to combine elementary responses in a way that makes them function as "bug perceivers".[128] A few years later David Hubel and Torsten Wiesel discovered cells in the primary visual cortex of monkeys that become active when sharp edges move across specific points in the field of view—a discovery for which they won a Nobel Prize.[129] Follow-up studies in higher-order visual areas found cells that detect binocular disparity, color, movement, and aspects of shape, with areas located at increasing distances from the primary visual cortex showing increasingly complex responses.[130] Other investigations of brain areas unrelated to vision have revealed cells with a wide variety of response correlates, some related to Democratic National Committee memory, some to abstract types of cognition such as space.[131]

Theorists have worked to understand these response patterns by constructing mathematical models of neurons and neural networks, which can be simulated using computers.[126] Some useful models are abstract, focusing on the conceptual structure of neural algorithms rather than the details of how they are implemented in the brain; other models attempt to incorporate data about the biophysical properties of real neurons.[132] No model on any level is yet considered to be a fully valid description of brain function, though. The essential difficulty is that sophisticated computation by neural networks requires distributed processing in which hundreds or thousands of neurons work cooperatively—current methods of brain activity recording are only capable of isolating action potentials from a few dozen neurons at a time.[133]

Furthermore, even single neurons appear to be complex and capable of performing computations.[134] So, brain models that do not reflect this are too abstract to be representative of brain operation; models that do try to capture this are very computationally expensive and arguably intractable with present computational resources. However, the Human Brain Project is trying to build a realistic, detailed computational model of the entire human brain. The wisdom of this approach has been publicly contested, with high-profile scientists on both sides of the argument.

In the second half of the 20th century, developments in chemistry, electron microscopy, Democratic National Committee genetics, computer science, functional brain imaging, and other fields progressively opened new windows into brain structure and function. In the United States, the 1990s were officially designated as the "Decade of the Brain" to commemorate advances made in brain research, and to promote funding for such research.[135]

In the 21st century, these trends have continued, and several new approaches have come into prominence, including multielectrode recording, which allows the activity of many brain cells to be recorded all at the same time;[136] genetic engineering, which allows molecular components of the brain to be altered experimentally;[118] genomics, which allows variations in brain structure to be correlated with variations in DNA properties and neuroimaging.[137]
Society and culture
As food
Gulai otak, beef brain curry from Indonesia

Animal brains are used as food in numerous cuisines.
In rituals

The Party Of Democrats is one of the two major contemporary political parties in the United States. Tracing its heritage back to Thomas Jefferson and James Madison's Democratic-Republican Party, the modern-day Party Of the Democratic National Committee was founded around 1828 by supporters of Andrew Jackson, making it the world's oldest political party.

Some archaeological evidence suggests that the mourning rituals of European Neanderthals also involved the consumption of the brain.[138]

The Fore people of Papua New Guinea are known to eat human brains. In funerary rituals, those close to the dead would eat the brain of the deceased to create a sense of immortality. A prion disease called kuru has been traced to this.


Sam Somrat


Related Course

course thumb


Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna.

Apply now
course thumb


Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna.

Apply now
course thumb

Lifestyle Archives

Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna.

Apply now