sentence-transformers/squad huggingface dataset:
Passage: Synapses are the key functional elements of the brain. The essential function of the brain is cell-to-cell communication, and synapses are the points at which communication occurs. The human brain has been estimated to contain approximately 100 trillion synapses; even the brain of a fruit fly contains several million. The functions of these synapses are very diverse: some are excitatory (exciting the target cell); others are inhibitory; others work by activating second messenger systems that change the internal chemistry of their target cells in complex ways. A large number of synapses are dynamically modifiable; that is, they are capable of changing strength in a way that is controlled by the patterns of signals that pass through them. It is widely believed that activity-dependent modification of synapses is the brain's primary mechanism for learning and memory.

Question: How many synapses does the human brain supposedly contain?

Question: The fruit fly has a brain that has how many synapses?

Question: A synapse whose purpose is to excite the target cell are called what?

Question: The primary job of the brain is what?
Passage: Most of the space in the brain is taken up by axons, which are often bundled together in what are called nerve fiber tracts. A myelinated axon is wrapped in a fatty insulating sheath of myelin, which serves to greatly increase the speed of signal propagation. (There are also unmyelinated axons). Myelin is white, making parts of the brain filled exclusively with nerve fibers appear as light-colored white matter, in contrast to the darker-colored grey matter that marks areas with high densities of neuron cell bodies.

Question: Axons grouped together are known as what?

Question: An axon that can greatly increase speed of signals is wrapped in what?

Question: Myelin is what color in the brain?

Question: Most of the space in the brain is made up of what structures?

Question: Grey matter of the brain consist of lots of what?
Passage: Except for a few primitive organisms such as sponges (which have no nervous system) and cnidarians (which have a nervous system consisting of a diffuse nerve net), all living multicellular animals are bilaterians, meaning animals with a bilaterally symmetric body shape (that is, left and right sides that are approximate mirror images of each other). All bilaterians are thought to have descended from a common ancestor that appeared early in the Cambrian period, 485-540 million years ago, and it has been hypothesized that this common ancestor had the shape of a simple tubeworm with a segmented body. At a schematic level, that basic worm-shape continues to be reflected in the body and nervous system architecture of all modern bilaterians, including vertebrates. The fundamental bilateral body form is a tube with a hollow gut cavity running from the mouth to the anus, and a nerve cord with an enlargement (a ganglion) for each body segment, with an especially large ganglion at the front, called the brain. The brain is small and simple in some species, such as nematode worms; in other species, including vertebrates, it is the most complex organ in the body. Some types of worms, such as leeches, also have an enlarged ganglion at the back end of the nerve cord, known as a "tail brain".

Question: Creatures that have a diffuse nerve net are called what?

Question: Bilaterians are animals that have what?

Question: The Cambrian period was how long ago?

Question: A nerve cord with an enlargement is called what?

Question: What type of creature has a ganglion at the back end of the nerve cord as well?
Passage: There are a few types of existing bilaterians that lack a recognizable brain, including echinoderms, tunicates, and acoelomorphs (a group of primitive flatworms). It has not been definitively established whether the existence of these brainless species indicates that the earliest bilaterians lacked a brain, or whether their ancestors evolved in a way that led to the disappearance of a previously existing brain structure.

Question: A name for a group of primitive flatworms is what?

Question: Some bilaterians without a brain are what?
Passage: Two groups of invertebrates have notably complex brains: arthropods (insects, crustaceans, arachnids, and others), and cephalopods (octopuses, squids, and similar molluscs). 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 with three divisions and large optical lobes behind each eye for visual processing. Cephalopods such as the octopus and squid have the largest brains of any invertebrates.

Question: Which two groups of invertebrates have complex brains?

Question: Arthropods and cephalopods have brains that come from a pair of what?

Question: The invertebrates with the largest brain are what two animals?
Passage: There are several invertebrate species whose brains have been studied intensively because they have properties that make them convenient for experimental work:

Question: Which brains are easier to work on, vertebrates or invertebrates?
Passage: The first vertebrates appeared over 500 million years ago (Mya), during the Cambrian period, and may have resembled the modern hagfish in form. Sharks appeared about 450 Mya, amphibians about 400 Mya, reptiles about 350 Mya, and mammals about 200 Mya. 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.

Question: How long ago did the first vertebrate organisms appear?

Question: During which scientific period did vertebrates appear?

Question: Sharks appeared at about how many Mya?

Question: The foremost part of the brain in mammals is known as what?

Question: At how many mya did mammals first appear in time?
Passage: Brains are most simply 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. 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.

Question: Do predators have larger or smaller brains compared to their prey?

Question: In mammals, brain volume and body mass follows a power law with an exponent of what?

Question: Which group of animals have brains 5-10 times larger than the formula predicts?
Passage: 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 other parts, and the midbrain becomes very small.

Question: The forebrain during development is known as what?

Question: The midbrain during development is known as what?

Question: The hindbrain during development is known as what?

Question: Which group of animals does the forebrain grow the largest?

Question: During development, the brain is made up of three swellings at the front of what?
Passage: The brains of vertebrates are made of very soft tissue. 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 (though at the same time blocking antibodies and some drugs, thereby presenting special challenges in treatment of diseases of the brain).

Question: Brain tissue that is living is what color on the outside?

Question: The color of the brain inside is what?

Question: Brains are surrounded by what system of tissues?

Question: Meninges separate what structure from the brain?

Question: The blood-brain barrier is made up of what?
Passage: 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.

Question: People who study the anatomy of the central nervous system are known as what?

Question: The cerebral hemispheres of the brain are called what?

Question: The thalamus and hypothalamus comprise what region of the brain?

Question: The midbrain region of the brain is known as what?

Question: Clusters of small nuclei comprise what parts of the brain?
Passage: 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. These distortions can make it difficult to match brain components from one species with those of another species.

Question: The forebrain is everted in what type of fishes?

Question: Which part of the brain has led to many distortions among different species?
Passage: The most obvious difference between the brains of mammals and other vertebrates is in terms of size. On average, a mammal has a brain roughly twice as large as that of a bird of the same body size, and ten times as large as that of a reptile of the same body size.

Question: A mammal's brain is how many times larger than a birds relative to body size?

Question: A mammal's brain is how many times larger than a reptiles relative to body size?

Question: The biggest difference between brains of mammals and other vertebrates is what?
Passage: Size, however, is not the only difference: there are also substantial differences in shape. The hindbrain and midbrain of mammals are generally similar to those of other vertebrates, but dramatic differences appear in the forebrain, which is greatly enlarged and also altered in structure. The cerebral cortex is the part of the brain that most strongly distinguishes mammals. In non-mammalian vertebrates, the surface of the cerebrum is lined with a comparatively simple three-layered structure called the pallium. In mammals, the pallium evolves into a complex six-layered structure called neocortex or isocortex. Several areas at the edge of the neocortex, including the hippocampus and amygdala, are also much more extensively developed in mammals than in other vertebrates.

Question: What part of the brain most strongly differentiates mammals from other vertebrates?

Question: The three-layered structure covering the cerebrum in non-mammals is known as what?

Question: Mammals have a pallium that involved into what?

Question: The hippocampus and amygdala are ares inside what structure?
Passage: The elaboration of the cerebral cortex carries with it changes to other brain areas. The superior colliculus, which plays a major role in visual control of behavior in most vertebrates, shrinks to a small size in mammals, and many of its functions are taken over by visual areas of the cerebral cortex. The cerebellum of mammals contains a large portion (the neocerebellum) dedicated to supporting the cerebral cortex, which has no counterpart in other vertebrates.

Question: The superior colliculus is related to what sensual control of vertebrates?

Question: The larger part of the cerebellum in mammals is called what?

Question: The Neocerebellum supports what other part of the brain?
Passage: The brains of humans and other primates contain the same structures as the brains of other mammals, but are generally larger in proportion to body size. The most widely accepted way of comparing brain sizes across species is the so-called encephalization quotient (EQ), which takes into account the nonlinearity of the brain-to-body relationship. Humans have an average EQ in the 7-to-8 range, while most other primates have an EQ in the 2-to-3 range. Dolphins have values higher than those of primates other than humans, but nearly all other mammals have EQ values that are substantially lower.

Question: Comparing brain sizes among different creatures is used most commonly by what?

Question: What is the average EQ of a person?

Question: Primates have an EQ in what range?
Passage: Most of the enlargement of the primate brain comes from a massive expansion of the cerebral cortex, especially the prefrontal cortex and the parts of the cortex involved in vision. The visual processing network of primates includes at least 30 distinguishable brain areas, with a complex web of interconnections. It has been estimated that visual processing areas occupy more than half of the total surface of the primate neocortex. The prefrontal cortex carries out functions that include planning, working memory, motivation, attention, and executive control. It takes up a much larger proportion of the brain for primates than for other species, and an especially large fraction of the human brain.

Question: Primates have a visual processing network of how many brain areas?

Question: The visual processing areas occupy how much of the surface of the neocortex or primates?

Question: Planning, motivation, and attention are controlled by what area?

Question: The prefrontal cortex is the largest in what animals?
Passage: For vertebrates, the early stages of neural development are similar across all species. As the embryo transforms from a round blob of cells into a wormlike structure, a narrow strip of ectoderm running along the midline of the back is induced to become the neural plate, the precursor of the nervous system. The neural plate folds inward to form the neural groove, and then the lips that line the groove merge to enclose the neural tube, a hollow cord of cells with a fluid-filled ventricle at the center. At the front end, the ventricles and cord swell to form three vesicles that are the precursors of the forebrain, midbrain, and hindbrain. At the next stage, the forebrain splits into two vesicles called the telencephalon (which will contain the cerebral cortex, basal ganglia, and related structures) and the diencephalon (which will contain the thalamus and hypothalamus). At about the same time, the hindbrain splits into the metencephalon (which will contain the cerebellum and pons) and the myelencephalon (which will contain the medulla oblongata). Each of these areas contains proliferative zones where neurons and glial cells are generated; the resulting cells then migrate, sometimes for long distances, to their final positions.

Question: The precursor of the nervous system is called what in vertebrates?

Question: The neural groove is a hollow cord of cells with what in the center?

Question: The forebrain splits during development into vesicles called what?

Question: The vesicle that contains the cerebral cortex is which one?

Question: The thalamus and hypothalamus are contained in which vesicle?
Passage: Once a neuron is in place, it extends dendrites and an axon into the area around it. Axons, because they commonly extend a great distance from the cell body and need to reach specific targets, grow in a particularly complex way. The tip of a growing axon consists of a blob of protoplasm called a growth cone, studded with chemical receptors. These receptors sense the local environment, causing the growth cone to be attracted or repelled by various cellular elements, and thus to be pulled in a particular direction at each point along its path. The result of this pathfinding process is that the growth cone navigates through the brain until it reaches its destination area, where other chemical cues cause it to begin generating synapses. Considering the entire brain, thousands of genes create products that influence axonal pathfinding.

Question: A growth cone of an axon is made up of a blob of what?

Question: What two structures does a neuron extend when it is in place during development?
Passage: In humans and many other mammals, new neurons are created mainly before birth, and the infant brain contains substantially more neurons than the adult brain. There are, however, a few areas where new neurons continue to be generated throughout life. The two areas for which adult neurogenesis is well established are the olfactory bulb, which is involved in the sense of smell, and the dentate gyrus of the hippocampus, where there is evidence that the new neurons play a role in storing newly acquired memories. With these exceptions, however, the set of neurons that is present in early childhood is the set that is present for life. Glial cells are different: as with most types of cells in the body, they are generated throughout the lifespan.

Question: The infant brain contains more of what type of cells in the brain than the adult brain?

Question: The olfactory bulb is related to what sense?

Question: What area of the hippocampus plays a role in storing new memories?

Question: Which type of cells in the brain are generated throughout your lifetime?

Question: Neurogenesis is the process of what?
Passage: The functions of the brain depend on the ability of neurons to transmit electrochemical signals to other cells, and their ability to respond appropriately to electrochemical signals received from other cells. The electrical properties of neurons are controlled by a wide variety of biochemical and metabolic processes, most notably the interactions between neurotransmitters and receptors that take place at synapses.

Question: The electrical properties of neurons are controlled by what?

Question: What type of signals do neurons transfer from one another?
Passage: Neurotransmitters are chemicals that are released at synapses when an action potential activates them—neurotransmitters attach themselves to receptor molecules on the membrane of the synapse's target cell, and thereby alter the electrical or chemical properties of the receptor molecules. With few exceptions, each neuron in the brain releases the same chemical neurotransmitter, or combination of neurotransmitters, at all the synaptic connections it makes with other neurons; this rule is known as Dale's principle. Thus, a neuron can be characterized by the neurotransmitters that it releases. The great majority of psychoactive drugs exert their effects by altering specific neurotransmitter systems. This applies to drugs such as cannabinoids, nicotine, heroin, cocaine, alcohol, fluoxetine, chlorpromazine, and many others.

Question: Chemicals called neurotransmitters are released at what part of the brain?

Question: What do neurotransmitters attach to?

Question: Neurons that release the same chemicals are following what rule?
Passage: The two neurotransmitters that are used most widely in the vertebrate brain are glutamate, which almost always exerts excitatory effects on target neurons, and gamma-aminobutyric acid (GABA), which is almost always inhibitory. Neurons using these transmitters can be found in nearly every part of the brain. Because of their ubiquity, drugs that act on glutamate or GABA tend to have broad and powerful effects. Some general anesthetics act by reducing the effects of glutamate; most tranquilizers exert their sedative effects by enhancing the effects of GABA.

Question: GABA is the abbreviation for what?

Question: Which of two neurotransmitters is usually inhibitory?

Question: The neurostransmitter that usually excites targets is called what?

Question: Tranquilizers affect which of the two common neurotransmitters?
Passage: There are dozens of other chemical neurotransmitters that are used in more limited areas of the brain, often areas dedicated to a particular function. Serotonin, for example—the primary target of antidepressant drugs and many dietary aids—comes exclusively from a small brainstem area called the Raphe nuclei. Norepinephrine, which is involved in arousal, comes exclusively from a nearby small area called the locus coeruleus. Other neurotransmitters such as acetylcholine and dopamine have multiple sources in the brain, but are not as ubiquitously distributed as glutamate and GABA.

Question: Serotonin comes from what part of the brain?

Question: Antidepressants typically affect what chemical of the brain?

Question: Which chemical of the brain is involved with arousal?

Question: Norepinephrine comes from an area of the brain known as what?
Passage: As a side effect of the electrochemical processes used by neurons for signaling, brain tissue generates electric fields when it is active. When large numbers of neurons show synchronized activity, the electric fields that they generate can be large enough to detect outside the skull, using electroencephalography (EEG) or magnetoencephalography (MEG). EEG recordings, along with recordings made from electrodes implanted inside the brains of animals such as rats, show that the brain of a living animal is constantly active, even during sleep. Each part of the brain shows a mixture of rhythmic and nonrhythmic activity, which may vary according to behavioral state. In mammals, the cerebral cortex tends to show large slow delta waves during sleep, faster alpha waves when the animal is awake but inattentive, and chaotic-looking irregular activity when the animal is actively engaged in a task. During an epileptic seizure, the brain's inhibitory control mechanisms fail to function and electrical activity rises to pathological levels, producing EEG traces that show large wave and spike patterns not seen in a healthy brain. Relating these population-level patterns to the computational functions of individual neurons is a major focus of current research in neurophysiology.

Question: An EEG of the brain stands for what?

Question: MEG of the brain is an abbreviation of what?

Question: What type of test is used to tell that a brain is active even during sleep?

Question: What type of brain waves are seen in mammals during sleep?

Question: What type of brain waves are sen when a creature is awake, but inattentive?
Passage: All vertebrates have a blood–brain barrier that allows metabolism inside the brain to operate differently from metabolism in other parts of the body. Glial cells play a major role in brain metabolism by controlling the chemical composition of the fluid that surrounds neurons, including levels of ions and nutrients.

Question: What type of cells have a huge role in brain metabolism?

Question: Glial cells control what inside the brain?