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. Borrell, V (January 24, 2018). "How Cells Fold the Cerebral Cortex". The Journal of Neuroscience. 38 (4): 776–783. doi: 10.1523/JNEUROSCI.1106-17.2017. PMC 6596235. PMID 29367288. Each hemisphere is conventionally divided into four main lobes; the frontal lobe, parietal lobe, temporal lobe, and occipital lobe, named according to the skull bones that overlie them. [8] Each lobe is associated with one or two specialised functions though there is some functional overlap between them. [18] The surface of the brain is folded into ridges ( gyri) and grooves ( sulci), many of which are named, usually according to their position, such as the frontal gyrus of the frontal lobe or the central sulcus separating the central regions of the hemispheres. There are many small variations in the secondary and tertiary folds. [19] Cerebral atherosclerosis is atherosclerosis that affects the brain. It results from the build-up of plaques formed of cholesterol, in the large arteries of the brain, and can be mild to significant. When significant, arteries can become narrowed enough to reduce blood flow. It contributes to the development of dementia, and has protein similarities to those found in Alzheimer’s disease. [175] Brain death refers to an irreversible total loss of brain function. [200] [201] This is characterised by coma, loss of reflexes, and apnoea, [200] however, the declaration of brain death varies geographically and is not always accepted. [201] In some countries there is also a defined syndrome of brainstem death. [202] Declaration of brain death can have profound implications as the declaration, under the principle of medical futility, will be associated with the withdrawal of life support, [203] and as those with brain death often have organs suitable for organ donation. [201] [204] The process is often made more difficult by poor communication with patients' families. [205]

The cerebrum, brainstem, cerebellum, and spinal cord are covered by four [11] membranes called meninges. The membranes are the tough dura mater; the middle arachnoid mater and the more delicate inner pia mater. Between the arachnoid mater and the pia mater is the subarachnoid space and subarachnoid cisterns, which contain the cerebrospinal fluid. [12] The outermost membrane of the cerebral cortex is the basement membrane of the pia mater called the glia limitans and is an important part of the blood–brain barrier. [13] Daneman, R.; Zhou, L.; Kebede, A.A.; Barres, B.A. (November 25, 2010). "Pericytes are required for blood-brain barrier integrity during embryogenesis". Nature. 468 (7323): 562–6. Bibcode: 2010Natur.468..562D. doi: 10.1038/nature09513. PMC 3241506. PMID 20944625. 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 It’s unclear where this myth about the brain came from, but it’s certainly a pervasive one despite being almost entirely wrong. While there are certain times when only 10% of the brain is functioning (when we’re completely at rest, though not sleeping), generally every part of your brain will be used at some point throughout the day. The cerebellum is divided into an anterior lobe, a posterior lobe, and the flocculonodular lobe. [31] The anterior and posterior lobes are connected in the middle by the vermis. [32] Compared to the cerebral cortex, the cerebellum has a much thinner outer cortex that is narrowly furrowed into numerous curved transverse fissures. [32]Main article: History of neuroscience Early history [ edit ] Hieroglyph for the word "brain" ( c. 1700 BC) The left and right sides of the brain appear symmetrical, but they function asymmetrically. [113] For example, the counterpart of the left-hemisphere motor area controlling the right hand is the right-hemisphere area controlling the left hand. There are, however, several important exceptions, involving language and spatial cognition. The left frontal lobe is dominant for language. If a key language area in the left hemisphere is damaged, it can leave the victim unable to speak or understand, [113] whereas equivalent damage to the right hemisphere would cause only minor impairment to language skills. 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] a b Chen, X. (2012). Mechanical Self-Assembly: Science and Applications. Springer Science & Business Media. pp.188–189. ISBN 978-1-4614-4562-3. You will move to the head of the class at school after this trip through the senses, movement, memory, emotion, decision-making, and automatic functions of the brain. Fun activities and plenty of strange-but-true facts make this a toy and book you’ll revisit again and again.

a b Kolb, B.; Whishaw, I. (2009). Fundamentals of Human Neuropsychology. Macmillan. pp.73–75. ISBN 978-0-7167-9586-5. When they announced the BRAIN Initiative, I thought: Oh my god, the future is going to be here,” says Jonas. “But the problem is much harder than I thought it would be. Big data alone isn’t going to save us.” Frigeri, T.; Paglioli, E.; De Oliveira, E.; Rhoton Jr, A. L. (2015). "Microsurgical anatomy of the central lobe". Journal of Neurosurgery. 122 (3): 483–98. doi: 10.3171/2014.11.JNS14315. PMID 25555079. Møllgård, Kjeld; Beinlich, Felix R. M.; Kusk, Peter; Miyakoshi, Leo M.; Delle, Christine; Plá, Virginia; Hauglund, Natalie L.; Esmail, Tina; Rasmussen, Martin K.; Gomolka, Ryszard S.; Mori, Yuki; Nedergaard, Maiken (2023). "A mesothelium divides the subarachnoid space into functional compartments". Science. 379 (6627): 84–88. Bibcode: 2023Sci...379...84M. doi: 10.1126/science.adc8810. PMID 36603070. S2CID 255440992. Arsava, E. Y.; Arsava, E. M.; Oguz, K. K.; Topcuoglu, M. A. (2019). "Occipital petalia as a predictive imaging sign for transverse sinus dominance". Neurological Research. 41 (4): 306–311. doi: 10.1080/01616412.2018.1560643. PMID 30601110. S2CID 58546404.The tube flexes as it grows, forming the crescent-shaped cerebral hemispheres at the head. The cerebral hemispheres first appear on day 32. [69] Some of the most common ways our brains fail us is through inaccurately interpreting visual information. Take a look at this first image shown in this article. Do the colors in A and B look the same? They don’t, but they are. This is just one of the many ways our brains don’t quite get things right. 17. It doesn’t take long to lose consciousness Charles Sherrington published his influential 1906 work The Integrative Action of the Nervous System examining the function of reflexes, evolutionary development of the nervous system, functional specialisation of the brain, and layout and cellular function of the central nervous system. [245] In 1942 he coined the term enchanted loom as a metaphor for the brain. John Farquhar Fulton, founded the Journal of Neurophysiology and published the first comprehensive textbook on the physiology of the nervous system during 1938. [246] Neuroscience during the twentieth century began to be recognised as a distinct unified academic discipline, with David Rioch, Francis O. Schmitt, and Stephen Kuffler playing critical roles in establishing the field. [247] Rioch originated the integration of basic anatomical and physiological research with clinical psychiatry at the Walter Reed Army Institute of Research, starting in the 1950s. [248] During the same period, Schmitt established the Neuroscience Research Program, an inter-university and international organisation, bringing together biology, medicine, psychological and behavioural sciences. The word neuroscience itself arises from this program. [249] Molina, D. Kimberley; DiMaio, Vincent J. M. (2015). "Normal Organ Weights in Women". The American Journal of Forensic Medicine and Pathology. 36 (3): 182–187. doi: 10.1097/PAF.0000000000000175. ISSN 0195-7910. PMID 26108038. S2CID 25319215.

Although the human brain represents only 2% of the body weight, it receives 15% of the cardiac output, 20% of total body oxygen consumption, and 25% of total body glucose utilization. [138] The brain mostly uses glucose for energy, and deprivation of glucose, as can happen in hypoglycemia, can result in loss of consciousness. [139] The energy consumption of the brain does not vary greatly over time, but active regions of the cortex consume somewhat more energy than inactive regions, which forms the basis for the functional neuroimaging methods of PET and fMRI. [140] These techniques provide a three-dimensional image of metabolic activity. [141] A preliminary study showed that brain metabolic requirements in humans peak at about five years old. [142] Some treatments for stroke are time-critical. These include clot dissolution or surgical removal of a clot for ischaemic strokes, and decompression for haemorrhagic strokes. [195] [196] As stroke is time critical, [197] hospitals and even pre-hospital care of stroke involves expedited investigations – usually a CT scan to investigate for a haemorrhagic stroke and a CT or MR angiogram to evaluate arteries that supply the brain. [194] MRI scans, not as widely available, may be able to demonstrate the affected area of the brain more accurately, particularly with ischaemic stroke. [194] The sensory nervous system is involved with the reception and processing of sensory information. This information is received through the cranial nerves, through tracts in the spinal cord, and directly at centres of the brain exposed to the blood. [85] The brain also receives and interprets information from the special senses of vision, smell, hearing, and taste. Mixed motor and sensory signals are also integrated. [85] This is because the eyes are hardwired by nerve fibers to the occipital lobe, a part of the brain responsible for sight information. If your brain is a computer, your eyes work like a mouse or keyboard that is inputting information directly into that system. 16. Your brain is pretty smart, but can make mistakes

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 The cerebrum is connected by the brainstem to the spinal cord. The brainstem consists of the midbrain, the pons, and the medulla oblongata. The cerebellum is connected to the brainstem by three pairs of nerve tracts called cerebellar peduncles. Within the cerebrum is the ventricular system, consisting of four interconnected ventricles in which cerebrospinal fluid is produced and circulated. Underneath the cerebral cortex are several important structures, including the thalamus, the epithalamus, the pineal gland, the hypothalamus, the pituitary gland, and the subthalamus; the limbic structures, including the amygdalae and the hippocampi, the claustrum, the various nuclei of the basal ganglia, the basal forebrain structures, and the three circumventricular organs. Brain structures that are not on the midplane exist in pairs, so there are for example two hippocampi and two amygdalae. The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses. Neurons connect to form neural pathways, neural circuits, and elaborate network systems. The whole circuitry is driven by the process of neurotransmission. a b Ribas, G. C. (2010). "The cerebral sulci and gyri". Neurosurgical Focus. 28 (2): 7. doi: 10.3171/2009.11.FOCUS09245. PMID 20121437. The human brain has many properties that are common to all vertebrate brains. [256] Many of its features are common to all mammalian brains, [257] most notably a six-layered cerebral cortex and a set of associated structures, [258] including the hippocampus and amygdala. [259] The cortex is proportionally larger in humans than in many other mammals. [260] Humans have more association cortex, sensory and motor parts than smaller mammals such as the rat and the cat. [261] 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]

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.The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head. Brain scientists have doing something similar for centuries, either by studying people with localized brain damage or by temporarily shutting down specific brain regions. Through such studies, they’ve labelled different areas as memory centers or language centers or emotional centers. But Jonas and Kording’s work shows why such inferences can be deceptive. They didn’t find “Donkey Kong transistors” or “Space Invaders transistors”; instead, they found components that carry out basic processes that just so happen to be important for those particular games. Thomas Willis is considered a second pioneer in the study of neurology and brain science. He wrote Cerebri Anatome ( Latin: Anatomy of the brain) [c] in 1664, followed by Cerebral Pathology in 1667. In these he described the structure of the cerebellum, the ventricles, the cerebral hemispheres, the brainstem, and the cranial nerves, studied its blood supply; and proposed functions associated with different areas of the brain. [233] The circle of Willis was named after his investigations into the blood supply of the brain, and he was the first to use the word "neurology." [238] Willis removed the brain from the body when examining it, and rejected the commonly held view that the cortex only consisted of blood vessels, and the view of the last two millennia that the cortex was only incidentally important. [233]