Cerebrum 487841 225558148 2008-07-14T08:43:14Z Cst17 6898026 Reverted edits by [[Special:Contributions/125.60.241.8|125.60.241.8]] to last version by JAnDbot (using [[WP:HG|Huggle]]) {{Infobox Brain| Name = {{Telencephalon}} | Latin = | GraySubject = | GrayPage = | Map = Cerebrum map| MapPos = | MapCaption = The lobes of the cerebral cortex include the [[frontal lobe|frontal]] (blue), [[temporal lobe|temporal]] (green), [[occipital lobe|occipital]] (red), and [[parietal lobe]]s (yellow). The [[cerebellum]] (unlabeled) is not part of the telencephalon. | Image2 = EmbryonicBrain.svg | Caption2 = Diagram depicting the main subdivisions of the embryonic vertebrate brain. | IsPartOf = | Components = | Artery = [[anterior cerebral artery|anterior cerebral]], [[middle cerebral artery|middle cerebral]], [[posterior cerebral artery|posterior cerebral]] | Vein = [[cerebral veins]] | BrainInfoType = | BrainInfoNumber = | MeshName = Telencephalon | MeshNumber = A08.186.21.730.885 | DorlandsPre = | DorlandsSuf = | }} The '''telencephalon''' ({{pronEng|tɛlɛnˈsɛfəlɒn}}), '''cerebrum''', or '''forebrain''' is the most [[anterior]] or, especially in humans, most [[dorsal]] region of the [[vertebrate]] [[central nervous system]]. "Telencephalon" refers to the embryonic structure, from which the mature "cerebrum" develops. The [[dorsal]] telencephalon, or [[pallium]], develops into the [[cerebral cortex]], and the [[ventral]] telencephalon, or [[subpallium]], becomes the [[basal ganglia]]. The cerebrum is also divided into symmetric left and right cerebral hemispheres. == Development == During vertebrate embryonic development, the [[prosencephalon]], the most anterior of three [[Vesicle (Biology)|vesicle]]s that form from the [[embryo]]nic [[neural tube]], is further subdivided into the telencephalon and [[diencephalon]]. The telencephalon then forms two lateral telencephalic vesicles which develop into the left and right cerebral hemispheres. == Structure == The cerebrum is composed of the following sub-regions: * [[Cerebral cortex]], or cortices of the cerebral hemispheres * [[Basal ganglia]], or basal nuclei (also often called the striatum) * [[Olfactory bulb]] == Composition == The cerebrum comprises what most people think of as the "[[brain]]." It lies in front or on top of the [[brainstem]] and in humans is the largest and most well-developed of the five major divisions of the brain. The cerebrum is the newest structure in the [[phylogenetic]] sense, with [[mammal]]s having the largest and most well-developed among all [[species]]. In larger mammals, the cerebral cortex is folded into many gyri and sulci, which has allowed the cortex to expand in surface area without taking up much greater volume. '''See also''' [[Cerebral Cortex]]. In [[human]]s, the cerebrum surrounds older parts of the brain. Limbic, olfactory, and motor systems project fibers from the cerebrum to the [[brainstem]] and [[spinal cord]]. [[Cognition|Cognitive]] and [[volition (psychology)|volitive]] systems project fibers from the cerebrum to the [[thalamus]] and to specific regions of the [[midbrain]]. The neural networks of the cerebrum facilitate complex behaviors such as social interactions, learning, [[working memory]], and in humans, speech and [[language]]. == Functions == '''Note''': As the cerebrum is a gross division with many subdivisions and sub-regions, it is important to state that this section lists the functions that the cerebrum ''as a whole'' serves. See main articles on [[cerebral cortex]] and [[basal ganglia]] for more information. === Movement === The cerebrum directs the conscious or volitional motor functions of the body. These functions originate within the [[primary motor cortex]] and other frontal lobe motor areas where actions are planned. [[Upper motor neuron]]s in the primary motor cortex send their [[axon]]s to the brainstem and spinal cord to [[synapse]] on the [[lower motor neurons]], which innervate the muscles. Damage to motor areas of cortex can lead to certain types of [[motor neuron disease]]. This kind of damage results in loss of muscular power and precision rather than total [[paralysis]]. === Sensory Processing === The primary sensory areas of the [[cerebral cortex]] receive and process visual, auditory, [[somatosensory]], [[gustatory]], and [[olfactory]] information. Together with association cortical areas, these brain regions synthesize sensory information into our perceptions of the world around us. === Olfaction === {{Main|Olfaction}} The [[olfactory bulb]] in most vertebrates is the most anterior portion of the cerebrum, and makes up a relatively large proportion of the telencephalon. However, in humans, this part of the brain is much smaller, and lies underneath the frontal lobe. The olfactory sensory system is unique in the sense that neurons in the olfactory bulb send their axons directly to the [[piriform cortex|olfactory cortex]], rather than to the [[thalamus]] first. Damage to the olfactory bulb results in a loss of the sense of smell. === Language and communication === {{Main|Language}} [[Speech communication|Speech]] and language are mainly attributed to parts of the cerebral cortex. Motor portions of language are attributed to [[Broca's area]] within the frontal lobe. Speech comprehension is attributed to [[Wernicke's area]], at the temporal-parietal lobe junction. These two regions are interconnected by a large white matter tract, the [[arcuate fasciculus]]. Damage to the Broca's area results in [[expressive aphasia]] (non-fluent aphasia) while damage to Wernicke's area results in [[receptive aphasia]] (also called fluent aphasia). === Learning and Memory === {{Main|Memory}} Explicit or declarative (factual) memory formation is attributed to the [[hippocampus]] and associated regions of the medial temporal lobe. This association was originally described after a patient known as [[HM (patient)|HM]] had both his hippocampuses (left and right) surgically removed to treat severe epilepsy. After surgery, HM had [[anterograde amnesia]], or the inability to form new memories. This condition is also portrayed in the film ''[[Memento (film)|Memento]]'', in which the protagonist has to take pictures of people he has met in order to be able to remember what to do in the days following his accident. Implicit or procedural memory, such as complex motor behaviors, involve the basal ganglia. Therefore, == Cell regeneration == === Xenopus laevis === ==== Larval stage ==== In a study of the telencephalon conducted in [[Hokkaido University]] on [[African clawed frog]]s (''xenopus laevis''){{ref|Yoshino}}, it was discovered that, during [[larva]]l stages, the telencephalon was able to regenerate around half of the anterior portion (otherwise known as '''partially truncated'''), after a reconstruction of a would-be accident, or malformation of features. The regeneration and active proliferation of cells within the clawed frog is quite remarkable, regenerated cells being almost functionally identical to the ones originally found in the brain after birth, despite the lack of brain matter for a sustained period of time. This kind of regeneration depends on ependymal layer cells covering the cerebral lateral ventricles, within a short period before, or within the initial stage of wound-healing. This is observed within the stages of healing within larvae of the clawed frog. ==== Developed stage ==== The regeneration within the developed stage of the clawed frog is different from that in the larval stage. Because the cells adhere to one another, they are unable to form an entity that can cover the cerebral lateral ventricles. Thus, the telencephalon remains truncated and the loss of function becomes permanent. ==== Effects of abnormality ==== After removing over half of the telencephalon in the developed stage of the clawed frog, the lack of functions within the animal was apparent, manifesting with obvious difficulties in movement, [[nonverbal communication]] between other species, as well as other difficulties thought to be similar to those seen in humans. This kind of regeneration is still relatively unknown in regard to regeneration within larval stages, similar to the human [[fetus|fetal stage]]. == References == #{{note|Levi-Oppenheim}} Levi-Montalcini, R. (1949) Proliferation, differentiation and degeneration in the spinal ganglia of the chick embryo under normal and experimental conditions. Pages 450 - 502 #{{note|Yoshino}} Yoshino J, Tochinai S. Successful reconstitution of the non-regenerating adult telencephalon by cell transplantation in Xenopus laevis. ''Dev Growth Differ.'' 2004;46(6):523–34. PMID 15610142 #{{note|Yaginuma}} Yaginuma, H., Tomita, M., Takashita, N., McKay, S., Cardwell, C., Yin, Q.- Aminobuytric acid immunoreactivity within the human cerebral cortex. Pages 481 - 500 #{{note|Haydar}} Haydar, T. F, Kuan, C., Y., Flavell, R. A. & Rakic, P. (1999) The role of cell death in regulating the size and shape of the mammalian forebrain. Pages 621 - 626 == See also== * [[List of regions in the human brain]] * [[Cerebral cortex]] * [[Basal ganglia]] ==External links== *[http://www.rahulgladwin.com/blog/2006/06/cerebrum-higher-integrative-functions.html Cerebrum Medical Notes on rahulgladwin.com] {{Prosencephalon}} [[Category:Neuroanatomy]] [[Category:Cerebrum]] [[Category:Central nervous system]] [[Category:Cranial nerves]] [[Category:Developmental biology]] [[ar:مخ]] [[cs:Koncový mozek]] [[da:Storhjerne]] [[de:Telencephalon]] [[es:Telencéfalo]] [[eo:Grandcerbo]] [[fa:مخ]] [[fr:Télencéphale]] [[ko:대뇌]] [[he:המוח הגדול]] [[lt:Galinės smegenys]] [[nl:Grote hersenen]] [[ja:大脳]] [[no:Telencephalon]] [[pl:Kresomózgowie]] [[ru:Конечный мозг]] [[simple:Cerebrum]] [[sv:Storhjärna]] [[th:ซีรีบรัม]]