Editing Human brain (section)

{{Short description|Central organ of the human nervous system}}
{{Redirect|Brain tissue|brains in other animals|Brain}}
{{pp-pc}}
{{Good article}}
{{Use British English |date=April 2017}}
{{Use mdy dates|date=April 2019}}
{{Infobox anatomy
| Name       = Human brain
| Latin      = cerebrum
| Greek      = ἐγκέφαλος (enképhalos)<ref>{{cite encyclopedia |url=http://etymonline.com/index.php?allowed_in_frame=0&search=encephalo- |title=''Encephalo-'' Etymology |dictionary=[[Online Etymology Dictionary]] |access-date=October 24, 2015 |url-status=live |archive-url=https://web.archive.org/web/20171002022623/http://etymonline.com/index.php?allowed_in_frame=0&search=encephalo- |archive-date=October 2, 2017  }}</ref>
| Image      = Brain autopsy lateral view.jpg
| Caption    = The human brain, obtained after an [[autopsy]]
| Image2     = Skull and brain normal human.svg
| Caption2   = Human brain and skull
| Precursor  = [[Neural tube]]
| System     = [[Central nervous system]]
| Artery     = [[Internal carotid artery|Internal carotid arteries]], [[Vertebral artery|vertebral arteries]]
| Vein       = [[Internal jugular vein]], [[internal cerebral veins]];<br />external veins: ([[superior cerebral veins|superior]], [[middle cerebral veins|middle]], and [[inferior cerebral veins]]), [[basal vein]], and [[cerebellar veins]]
| Nerve      =
| Lymph      =
}}

The '''human brain''' is the central [[organ (anatomy)|organ]] of the [[nervous system]], and with the [[spinal cord]], comprises the [[central nervous system]]. It consists of the [[cerebrum]], the [[brainstem]] and the [[cerebellum]]. The brain controls most of the activities of the [[human body|body]], processing, integrating, and coordinating the information it receives from the [[sensory nervous system]]. The brain integrates sensory information and coordinates instructions sent to the rest of the body.

The cerebrum, the largest part of the human brain, consists of two [[cerebral hemisphere]]s. Each hemisphere has an inner core composed of [[white matter]], and an outer surface – the [[cerebral cortex]] – composed of [[grey matter]]. The cortex has an outer layer, the [[neocortex]], and an inner [[allocortex]]. The neocortex is made up of six [[Cerebral cortex#Layers of neocortex|neuronal layers]], while the allocortex has three or four. Each hemisphere is divided into four [[lobes of the brain|lobes]] – the [[frontal lobe|frontal]], [[parietal lobe|parietal]], [[temporal lobe|temporal]], and [[occipital lobe]]s. The frontal lobe is associated with [[executive functions]] including [[self-control]], [[planning]], [[reason]]ing, and [[abstraction|abstract thought]], while the [[occipital lobe]] is dedicated to vision. Within each lobe, cortical areas are associated with specific functions, such as the [[sensory cortex|sensory]], [[motor cortex|motor]], and [[Cerebral cortex#Association areas|association]] regions. Although the left and right hemispheres are broadly similar in shape and function, some functions are [[lateralization of brain function|associated with one side]], such as [[language]] in the left and [[spatial visualization ability|visual-spatial ability]] in the right. The hemispheres are connected by [[commissural fiber|commissural nerve tracts]], the largest being the [[corpus callosum]].

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 tract]]s called [[cerebellar peduncle]]s. Within the cerebrum is the [[ventricular system]], consisting of four interconnected [[Ventricular system#Structure|ventricles]] in which [[cerebrospinal fluid]] is produced and circulated. Underneath the cerebral cortex are several  structures, including the [[thalamus]], the [[epithalamus]], the [[pineal gland]], the [[hypothalamus]], the [[pituitary gland]], and the [[subthalamus]]; the [[limbic system|limbic structures]], including the [[Amygdala|amygdalae]] and the [[Hippocampus|hippocampi]], the [[claustrum]], the various [[Nucleus (neuroanatomy)|nuclei]] of the [[basal ganglia]], the [[basal forebrain]] structures, and three [[circumventricular organ]]s. Brain structures that are not on the midplane exist in pairs; for example, there are two hippocampi and two amygdalae. 

The [[Brain cell|cells of the brain]] include [[neuron]]s and supportive [[neuroglia|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 [[neurotransmitter]]s in response to [[action potential|nerve impulses]]. Neurons connect to form [[neural pathway]]s, [[neural circuit]]s, and elaborate [[large-scale brain networks|network systems]]. The whole circuitry is driven by the process of [[neurotransmission]].

The brain is protected by the [[Skull#Humans|skull]], suspended in [[cerebrospinal fluid]], and isolated from the [[circulatory system|bloodstream]] by the [[blood–brain barrier]]. However, the brain is still susceptible to [[brain damage|damage]], [[Central nervous system disease|disease]], and [[infection]]. Damage can be caused by [[closed head injury|trauma]], or a loss of blood supply known as a [[stroke]]. The brain is susceptible to [[neurodegeneration|degenerative disorders]], such as [[Parkinson's disease]], [[dementia]]s including [[Alzheimer's disease]], and [[multiple sclerosis]]. [[Psychiatric condition]]s, including [[schizophrenia]] and [[major depressive disorder|clinical depression]], are thought to be associated with brain dysfunctions. The brain can also be the site of [[brain tumors|tumours]], both [[benign tumour|benign]] and [[cancer|malignant]]; these mostly [[metastasis|originate from other sites in the body]].

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. [[Biological specimen|Specimens]] from other animals, which may be [[histology|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 damage|brain injury]] has provided insight into the function of each part of the brain. Neuroscience research has expanded considerably, and research is ongoing.

In culture, the [[philosophy of mind]] has for centuries attempted to address the question of the nature of [[consciousness]] and the [[mind–body problem]]. The [[pseudoscience]] of [[phrenology]] attempted to localise personality attributes to regions of the cortex in the 19th century. [[Brain transplant#In science fiction|In science fiction, brain transplants]] are imagined in tales such as the 1942 ''[[Donovan's Brain]]''.
{{TOC limit |3}}