The Amazing Squishy Brain

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Further information: Development of the human brain Neurulation and neural crest cells Primary and secondary vesicle stages of development in the early embryo to the fifth week Brain of a human embryo in the sixth week of development

The brain splits that oxygen up between white and gray matter, with white matter getting just 6% and gray matter taking in a hearty 94%. Take that oxygen away and the brain will start to incur irreversible damage after only four to six minutes. 6. Brains use a hefty portion of the body’s energy The study of the anatomy of the brain is neuroanatomy, while the study of its function is neuroscience. Numerous techniques are used to study the brain. Specimens from other animals, which may be examined microscopically, have traditionally provided much information. Medical imaging technologies such as functional neuroimaging, and electroencephalography (EEG) recordings are important in studying the brain. The medical history of people with brain injury has provided insight into the function of each part of the brain. Neuroscience research has expanded considerably, and research is ongoing. The human brain is primarily composed of neurons, glial cells, neural stem cells, and blood vessels. Types of neuron include interneurons, pyramidal cells including Betz cells, motor neurons ( upper and lower motor neurons), and cerebellar Purkinje cells. Betz cells are the largest cells (by size of cell body) in the nervous system. [39] The adult human brain is estimated to contain 86±8 billion neurons, with a roughly equal number (85±10 billion) of non-neuronal cells. [40] Out of these neurons, 16 billion (19%) are located in the cerebral cortex, and 69 billion (80%) are in the cerebellum. [3] [40] The optic tract fibres reach the brain at the lateral geniculate nucleus, and travel through the optic radiation to reach the visual cortex. [88] This is largely due to the structure of the cerebellum, which is filled with a great number of tiny granule cells (a very small type of neuron) and is more tightly wrinkled than many other areas of the brain. 3. But the neocortex is the most massive part of the brain

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Netter, F. (2014). Atlas of Human Anatomy Including Student Consult Interactive Ancillaries and Guides (6thed.). Philadelphia, Penn.: W B Saunders Co. p.114. ISBN 978-1-4557-0418-7. Drachman, D. A. (2005). Do we have brain to spare? Neurology, 64(12). https://doi.org/10.1212/01.WNL.0000166914.38327.BB The Edwin Smith Papyrus, an ancient Egyptian medical treatise written in the 17th century BC, contains the earliest recorded reference to the brain. The hieroglyph for brain, occurring eight times in this papyrus, describes the symptoms, diagnosis, and prognosis of two traumatic injuries to the head. The papyrus mentions the external surface of the brain, the effects of injury (including seizures and aphasia), the meninges, and cerebrospinal fluid. [227] [228]

Vision is generated by light that hits the retina of the eye. Photoreceptors in the retina transduce the sensory stimulus of light into an electrical nerve signal that is sent to the visual cortex in the occipital lobe. Visual signals leave the retinas through the optic nerves. At any one time, there is about 150mL of cerebrospinal fluid – most within the subarachnoid space. It is constantly being regenerated and absorbed, and is replaced about once every 5–6 hours. [47] Rather than working with an actual chip, Jonas and Kording used a simulation, albeit one accurate enough to run classic games like Donkey Kong, Space Invaders, and Pitfall. That gave them experimental omniscience and omnipotence—they knew everything and could tweak anything. For example, they could disable each of the chip’s transistors one at a time. And by doing so, they found several that were essential for booting up all three games, and others that were essential for just one.The classic light bulb idea image might not be too far off. Even while sleeping, your brain can produce enough energy to power a 25-watt light bulb. Of course, if you have ever seen The Matrix you probably already knew that the human body is a powerful energy source (at least in sci-fi films). You brain creates enough electricity to power a light bulb. Take care of your brain to study better Other animals, including whales and elephants have larger brains than humans. However, when the brain-to-body mass ratio is taken into account, the human brain is almost twice as large as that of a bottlenose dolphin, and three times as large as that of a chimpanzee. However, a high ratio does not of itself demonstrate intelligence: very small animals have high ratios and the treeshrew has the largest quotient of any mammal. [218] In popular culture [ edit ] Phrenology summarised in an 1883 chart

While they’re not a part of your brain proper, your eyeballs are actually an extension of your brain. If someone were to try to remove your brain, your eyeballs would come with it. Cerebrospinal fluid is a clear, colourless transcellular fluid that circulates around the brain in the subarachnoid space, in the ventricular system, and in the central canal of the spinal cord. It also fills some gaps in the subarachnoid space, known as subarachnoid cisterns. [47] The four ventricles, two lateral, a third, and a fourth ventricle, all contain a choroid plexus that produces cerebrospinal fluid. [48] The third ventricle lies in the midline and is connected to the lateral ventricles. [47] A single duct, the cerebral aqueduct between the pons and the cerebellum, connects the third ventricle to the fourth ventricle. [49] Three separate openings, the middle and two lateral apertures, drain the cerebrospinal fluid from the fourth ventricle to the cisterna magna, one of the major cisterns. From here, cerebrospinal fluid circulates around the brain and spinal cord in the subarachnoid space, between the arachnoid mater and pia mater. [47] One is obliged to admit that perception and what depends upon it is inexplicable on mechanical principles, that is, by figures and motions. In imagining that there is a machine whose construction would enable it to think, to sense, and to have perception, one could conceive it enlarged while retaining the same proportions, so that one could enter into it, just like into a windmill. Supposing this, one should, when visiting within it, find only parts pushing one another, and never anything by which to explain a perception. The cortex is mapped by divisions into about fifty different functional areas known as Brodmann's areas. These areas are distinctly different when seen under a microscope. [21] The cortex is divided into two main functional areas – a motor cortex and a sensory cortex. [22] The primary motor cortex, which sends axons down to motor neurons in the brainstem and spinal cord, occupies the rear portion of the frontal lobe, directly in front of the somatosensory area. The primary sensory areas receive signals from the sensory nerves and tracts by way of relay nuclei in the thalamus. Primary sensory areas include the visual cortex of the occipital lobe, the auditory cortex in parts of the temporal lobe and insular cortex, and the somatosensory cortex in the parietal lobe. The remaining parts of the cortex are called the association areas. These areas receive input from the sensory areas and lower parts of the brain and are involved in the complex cognitive processes of perception, thought, and decision-making. [23] The main functions of the frontal lobe are to control attention, abstract thinking, behaviour, problem-solving tasks, and physical reactions and personality. [24] [25] The occipital lobe is the smallest lobe; its main functions are visual reception, visual-spatial processing, movement, and colour recognition. [24] [25] There is a smaller occipital lobule in the lobe known as the cuneus. The temporal lobe controls auditory and visual memories, language, and some hearing and speech. [24] Cortical folds and white matter in horizontal bisection of headThe sense of smell is generated by receptor cells in the epithelium of the olfactory mucosa in the nasal cavity. This information passes via the olfactory nerve which goes into the skull through a relatively permeable part. This nerve transmits to the neural circuitry of the olfactory bulb from where information is passed to the olfactory cortex. [90] [91] Taste is generated from receptors on the tongue and passed along the facial and glossopharyngeal nerves into the solitary nucleus in the brainstem. Some taste information is also passed from the pharynx into this area via the vagus nerve. Information is then passed from here through the thalamus into the gustatory cortex. [92] Regulation [ edit ] The adult human brain weighs on average about 1.2–1.4kg (2.6–3.1lb) which is about 2% of the total body weight, [2] [3] with a volume of around 1260 cm 3 in men and 1130cm 3 in women. [4] There is substantial individual variation, [4] with the standard reference range for men being 1,180–1,620g (2.60–3.57lb) [5] and for women 1,030–1,400g (2.27–3.09lb). [6] The frontal lobe is involved in reasoning, motor control, emotion, and language. It contains the motor cortex, which is involved in planning and coordinating movement; the prefrontal cortex, which is responsible for higher-level cognitive functioning; and Broca’s area, which is essential for language production. [79] The motor system of the brain is responsible for the generation and control of movement. [80] Generated movements pass from the brain through nerves to motor neurons in the body, which control the action of muscles. The corticospinal tract carries movements from the brain, through the spinal cord, to the torso and limbs. [81] The cranial nerves carry movements related to the eyes, mouth and face. Each cell in your brain is connected to a large number of other cells, usually somewhere in the 7,000 range. When you consider that there are roughly 100 billion cells in the brain, that’s a whole lot of connections. 22. Size doesn’t necessarily matter when it comes to brains Main articles: Cognition and Mind The skull of Phineas Gage, with the path of the iron rod that passed through it without killing him, but altering his cognition. The case helped to convince people that mental functions were localised in the brain. [208]