Brain: Cerebrum
Frontal lobe Temporal lobe Parietal lobe Occipital lobe
The lobes of the cerebral cortex include the frontal (blue), temporal (green), occipital (red), and parietal lobes (yellow). The cerebellum (unlabeled) is not part of the telencephalon.
Diagram depicting the main subdivisions of the embryonic vertebrate brain.
Artery	anterior cerebral, middle cerebral, posterior cerebral
Vein	cerebral veins
MeSH	Telencephalon

The telencephalon (IPA: /tɛlɛnˈsɛfəlɑn/) is the name for the forebrain, a large region within the brain to which many functions are attributed. Many people refer to it as the cerebrum; however, it is technically referred to as the telencephalon. Image File history File links Lobes_of_the_brain_NL.svg‎ Lobes of the brain image without labels. ... The frontal lobe is an area in the brain of mammals. ... The temporal lobes are part of the cerebrum. ... The parietal lobe is a lobe in the brain. ... The occipital lobe is the visual processing center of the mammalian brain, containing most of the anatomical region of the visual cortex. ... The frontal lobe is an area in the brain of mammals. ... The temporal lobes are part of the cerebrum. ... The occipital lobe is the visual processing center of the mammalian brain, containing most of the anatomical region of the visual cortex. ... The parietal lobe is a lobe in the brain. ... The cerebellum (Latin: little brain) is a region of the brain that plays an important role in the integration of sensory perception and motor output. ... Image File history File links This is a lossless scalable vector image. ... The anterior cerebral artery supplies oxygen to most medial portions of frontal lobes and superior medial parietal lobes. ... The middle cerebral artery (MCA) is one of the three major arteries that supplies blood to the brain. ... The arterial circle and arteries of the brain. ... The cerebral veins are divisible into external and internal (internal cerebral veins) groups according as they drain the outer surfaces or the inner parts of the hemispheres. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... The human brain In animals, the brain (enkephalos) (Greek for in the skull), is the control center of the central nervous system, responsible for behavior. ...

As a more technical definition, the telencephalon refers to the cerebral hemispheres and other, smaller structures within the brain, although the telencephalon is one of the larger divisions (in terms of number). It is the anterior-most embryological division of the brain that develops from the prosencephalon. This article or section is in need of attention from an expert on the subject. ... In the anatomy of vertebrates, the prosencephalon is a part of encephalon, or brain. ...

Structure

The telencephalon is composed of the following sub-regions;

• Limbic system
• Cerebral cortex or cortices of the cerebral hemispheres.
• Basal ganglia
• Olfactory bulb

Pfil is cooler than all of you Pfil is kewl The limbic system (Latin limbus: border or edge) includes the structures in the human brain involved in emotion, motivation, and emotional association with memory. ... For other uses, see Cortex. ... The basal ganglia (or basal nuclei) are a group of nuclei in the brain interconnected with the cerebral cortex, thalamus and brainstem. ... The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors. ...

Composition

The telencephalon comprises what most people think of as the "brain." It lies on top of the brainstem and is the largest and most well-developed of the five major divisions of the brain. The telencephalon is the newest structure in the phylogenetic sense, with mammals having the largest and most well-developed among all species. It emerges from the prosencephalon, the first of three vesicles that form from the embryonic neural tube. The human brain In animals, the brain (enkephalos) (Greek for in the skull), is the control center of the central nervous system, responsible for behavior. ... The brain stem is the stalk of the brain below the cerebral hemispheres. ... A phylogeny (or phylogenesis) is the origin and evolution of a set of organisms, usually of a species. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including those that produce milk, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... For other uses, see Species (disambiguation). ... In the anatomy of vertebrates, the prosencephalon is a part of encephalon, or brain. ... In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. ... For other uses, see Embryo (disambiguation). ... In the developing vertebrate nervous system, the neural tube is the precursor of the central nervous system, which comprises the brain and spinal cord. ...

The traditional division first sectioned the telencephalon into four parts. More recent research describes further sub-divisions.

In humans, the telencephalon surrounds older parts of the brain. Limbic, olfactory, and motor systems project fibers from subcortical (deeper) areas of the cerebrum to parts of the brainstem. Cognitive and volitive systems project fibers from cortical areas of the cerebrum to thalamus and to other regions of the brainstem. The neural networks of the telencephalon facilitate complex learned behaviors, such as language, and contains white matter and grey matter. Grey matter is highly folded; with respect to function, this is thought to allow a greater number of cells in the same volume due to the increase in its surface area. The telencephalon includes regions of archipalliar, paleopalliar, and neopalliar origin. Profound development of the neopallium, which comprises the cerebral cortex, is unique among humans and primates. This article is about modern humans. ... Look up Cognition in Wiktionary, the free dictionary. ... Volition is the study of will, choice, and decision. ... The thalamus (from Greek θάλαμος = bedroom, chamber, IPA= /ˈθæləməs/) is a pair and symmetric part of the brain. ... White matter is one of the two main solid components of the central nervous system. ... Gray matter redirects here. ... Area is the measure of how much exposed area any two dimensional object has. ... In anatomy of animals, the archipallium the oldest region of the brains pallium. ... In anatomy of animals, the paleopallium is a region within the telencephalon in brain. ... The neopallium (Latin for new mantle) is a part of the brain of mammals. ...

Functions

Note: As the telencephalon is a gross division with many subdivisions and sub-regions, it is important to state that this section lists the functions that the telencephalon as a whole serves.

Language and communication

Main article: Language

Speech and language are mainly attributed to parts of the cerebral cortex, which is one portion of the telencephalon. 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). Bold text This article does not cite any references or sources. ... Brocas area is the section of the human brain (in the opercular and triangular sections of the inferior frontal gyrus of the frontal lobe of the cortex) that is involved in language processing, speech production and comprehension. ... Wernickes area is a part of the human brain that forms part of the cortex, on the left posterior section of the superior temporal gyrus, encircling the auditory cortex, on the Sylvian fissure (part of the brain where the temporal lobe and parietal lobe meet). ... Figure one illustrates significant language areas of the brain. ... Expressive aphasia, known as Brocas aphasia in clinical neuropsychology and agrammatic aphasia in cognitive neuropsychology, is an aphasia caused by damage to Brocas area in the brain. ... Receptive aphasia, also known as Wernickes aphasia, Fluent aphasia or sensory aphasia in clinical neuropsychology and cognitive neuropsychology, is a type of aphasia often (but not always) caused by neurological damage to Wernickes area in the brain. ...

Movement

The telencephalon attributes motor function to the body. These functions originate within the primary motor cortex and other frontal lobe motor areas. In many cases, when this part of the brain is damaged, the brain is unable to send signals to nerves that innervate muscles' motorneurons, and can lead to diseases such as Motor Neurone Disease. This kind of damage results in loss of muscular power and precision rather than total paralysis. The primary motor area is a group of networked cells in mammalian brains that controls movements of specific body parts associated with cell groups in that area of the brain. ... In vertebrates, the term motor neuron (or motoneuron) classically applies to neurons located in the central nervous system (CNS) that project their axons outside the CNS and directly or indirectly control muscles. ... The motor neurone diseases (MND) are a group of progressive neurological disorders that destroy motor neurones, the cells that control voluntary muscle activity such as speaking, walking, breathing, and swallowing. ... Paralysed redirects here. ...

Olfaction

Main article: Olfaction

The olfaction helps in restoring lost memory and can control necessary movement when all other parts of the brain is dead. Connected to the cerebellum and many refer it as part of the cerebellum. Young boy smelling a flower Olfaction, which is also known as Olfactics is the sense of smell, and the detection of chemicals dissolved in air. ...

Memory

Main article: Memory

Memory formation is associated with the hippocampus. This association was originally described after a 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 problem is also addressed slightly in the 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. For other uses, see Memory (disambiguation). ... The hippocampus is structurally located inside the medial temporal lobe of the brain. ... HM (also known as H.M. and Henry M., born 1926 in Connecticut) is an anonymous memory-impaired patient who has been widely studied since the late 1950s and has been very important in the development of theories that explain the link between brain function and memory, and in the... Anterograde amnesia is a form of amnesia, or memory loss, in which new events are not transferred from short-term memory to long-term memory. ... Memento is a neo-noir–psychological thriller film written and directed by Christopher Nolan, adapted from his brother Jonathans short story Memento Mori. ...

Programmed cell death

Purpose

Programmed Cell Death (PCD) is not uncommon in the telencephalon. It is thought to be one of the processes by which growth and differentiation occurs, and is a universal feature of the embryonic and postnatal central nervous system ^[1], and has been noted in the telencephalons of rats and mice. In some animals, such as the monkey, over 50% of neurons in the cerebral cortex are affected by PCD during early stages of life. This is thought to solicit growth of the brain due to increase in the size of the cranium and other parts of the body expected to grow throughout the life cycle of a monkey. This is an article about wild rats; for pet rats, see Fancy rat Species 50 species; see text *Several subfamilies of Muroids include animals called rats. ... This article is about the animal. ... Approximate worldwide distribution of monkeys. ... Neurons (also called nerve cells) are the primary cells of the nervous system. ... For other uses, see Cortex. ... Cranium can mean: The brain and surrounding skull, a part of the body. ...

The main reason for PCD is to create space for new cells. If a neuron does not establish correct synaptic connections, it will die. This is seen as a form of "competition" within the space of the telencephalon and is a form of "survival of the fittest" (see Neural Darwinism). However, there are exceptions to the rule; in rats some cells are even programmed to die during proliferation within the ventricular zones of the telencephalon. It is thought that this is at a stage during which axons are not yet formed or synaptically connected. The term Neural Darwinism is used in two different ways. ...

Effects

PCD in the brain affects glial cells and neurons through apoptosis (4). According to research on rodents, this period is usually during developmental or adolescent stages. During this time, the regeneration process can take place because the "materials" and environment are a perfect breeding ground for cell regeneration. Neuroglia of the brain shown by Golgis method. ... A section of mouse liver showing an apoptotic cell indicated by an arrow Apoptosis (pronounced apo tō sis) is a process of suicide by a cell in a multicellular organism. ...

Stages

During the stages of apoptosis, which seems to constitute most PCD in the brain, various morphological changes occur, such as:

1. Cell enlargement
2. Membrane blebbage, or inconsistency within the structure of the membrane
3. Pyknosis, or a condensation of chromatin within the nucleus
4. Karyorrhexis, or fragmentation of the nuclei
5. Lack of inflammation
6. Removal by microphages or adjacent glial cells, as organelles and plasma membrane remain intact throughout the process.

Of course, there are some differences to these stages, but they are relatively similar in practice. The apoptosis in the telencephalon can also be characterised distinctly by its DNA pattern, which becomes fragmented into oligonucleosomal fragments of around 180-200 pairs. These give a typical "ladder" pattern when viewed on or in agarose gel electrophoresis. Pyknosis, or karyopyknosis, is the condensation of chromatin in the nucleus of a cell undergoing programmed cell death (see Naoufal Zamzami and Guido Kroemer: Apoptosis: Condensed matter in cell death, Nature Vol. ... Chromatin is the complex of DNA and protein found inside the nuclei of eukaryotic cells. ... Karyorrhexis is the fragmentation of the nucleus of a cell undergoing programmed cell death (see Naoufal Zamzami and Guido Kroemer: Apoptosis: Condensed matter in cell death, Nature Vol. ... In cell biology, an organelle is one of several structures with specialized functions, suspended in the cytoplasm of a eukaryotic cell. ... An agarose is a polysaccharide polymer material, generally extracted from seaweed. ... It has been suggested that Electrophoretic mobility be merged into this article or section. ...

Cell regeneration

Xenopus laevis

Larval stage

In a study of the telencephalon conducted in Hokkaido University on African clawed frogs (xenopus laevis)^[2], it was discovered that, during larval 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. Hokkaido University ), or Hokudai ), is one of the leading national universities of Japan. ... Binomial name Xenopus laevis Daudin, 1802 The African clawed frog (Xenopus laevis, also known as platanna) is a species of South African aquatic frog of the genus Xenopus. ... A larval insect A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ...

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 article does not cite any references or sources. ...

This kind of regeneration is still relatively unknown in regard to regeneration within larval stages, similar to the human fetal stage. For other uses, see Fetus (disambiguation). ...

References

1. ^  Levi-Montalcini, R. (1949) Proliferation, differentiation and degeneration in the spinal ganglia of the chick embryo under normal and experimental conditions. Pages 450 - 502
2. ^  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
3. ^  Yaginuma, H., Tomita, M., Takashita, N., McKay, S., Cardwell, C., Yin, Q.- Aminobuytric acid immunoreactivity within the human cerebral cortex. Pages 481 - 500
4. ^  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

// medulla oblongata medullary pyramids pons paramedian pontine reticular formation fourth ventricle cerebellum cerebellar vermis cerebellar hemispheres anterior lobe posterior lobe flocculonodular lobe cerebellar nuclei fastigial nucleus globose nucleus emboliform nucleus dentate nucleus tectum inferior colliculi superior colliculi mesencephalic duct (cerebral aqueduct, Aqueduct of Sylvius) cerebral peduncle midbrain tegmentum ventral tegmental...

External links

• Cerebrum Medical Notes on rahulgladwin.com