Auditory nerve damage and tinnitus xtc,objective tinnitus definition uno,red bow earrings - For Begninners

The skin of the outer part of the external auditory canal has hairs and glands which produce wax and oils. In front the middle ear cavity connects with the Eustachian tube, which joins the back of the junction of the nose and throat. Because the prevalence of acoustic neuroma is low, and because the cost of MRI scans used in screening is very high, cost-analysis suggests that routine MRI scanning for asymmetrical hearing loss is not cost effective (Pan et al, 2015). Diagnosis of an acoustic usually requires either a physician with otologic expertise who can integrate together the entire picture, or an MRI with gadolinium. Clinicians often attempt to estimate the risk of an acoustic neuroma by looking at the pattern of hearing loss (see here for more about patterns). Hyperventilation induced nystagmus is a little known physical sign that may be far more specific for acoustic neuroma. It has recently been pointed out that some forms of acoustic neuromas have increased intralabyrinthine protein. As mentioned above -- acoustics can be diagnosed either by a medical doctor with otologic expertise who can integrate together the entire picture, or with an MRI scan with gadolinium of the brain. Audiogram of patient with large acoustic neuroma on left side, but (nearly) symmetrical hearing.
At this writing, we have ENG testing, Rotatory chair testing, VHIT testing, VEMP testing, and Posturography to choose from when we are attempting to diagnose dizzy patients. ENG is not a sufficient test by itself for acoustic neuroma because it is not specific, and also because there are far more other causes for caloric loss than acoustic neuromas.
Otoacoustic emissions are also considered a poor test for acoustic neuroma, although one would think that they would do as well as hearing testing. MRI scan of  brain (coronal) showing an acoustic neuroma (the white spot on the left side of the picture).
MRI scan of brain (axial with contrast) showing a largely intracanalicular acoustic neuroma on right side of brain (left side of scan). CT scans with IV contrast are poor tests for diagnosis of acoustic neuromas, as they have a high false negative rate (about 37%). A comparison between two scans of the same acoustic, the CT on the left and MRI on the right is shown above.
Axial image of patient with NF2 showing acoustic neuromas on both sides (Image courtesy of Dr. As CT and MRI scans become more commonly used, there are more acoustics being discovered accidentally -- serendipitously. If someone in such a situation proceeds with surgery or radiation treatment, it is certain that the surgery or radiation will create a vestibular imbalance as well deafness. According to Carlson et al (2015), about half of all patients are operated as soon as they are diagnosed, about 24% are radiated, and about 29% were observed.
According to Carlson et al (2015), about 29% of acoustics are initially treated with radiation. The author of this review does not favor high-dose gamma knife because of the possibility of radiation complications at 2 years and beyond. An interesting consequence of the lower-dose radiation protocol is that patients are now seen who do not have complete loss of hearing or vestibular function after radiation. Hyperventilation induced nystagmus for this situation beats towards the lesion (unlike vibration induced nystagmus which beats away from the lesion).
The translabyrinthine approach makes no attempt to preserve hearing, and does not open the skull. The middle fossa approach (not shown above), can theoretically preserve hearing, but like the retrosigmoid, the approach is intrinsically more dangerous as it involves retraction of the brain, and also more prone to complications.
Compared to radiosurgery, the primary advantage of conventional surgery is avoidance of late complications associated with radiation of neighboring structures. With respect to hearing preservation surgery, while of course this is certainly desirable, unfortunately the chance of hearing being preserved after acoustic neuroma surgery is slight.
At the author's clinical practice in Chicago Illinois, it is suggested that prospective operative candidates primarily consider safety and the probability of complications when considering surgery or gamma knife. Both surgery and gamma-knife methods of managing acoustic tumors seem reasonable at this writing, with the choice depending on individual factors. Imbalance and dizziness (almost all patients who have any vestibular function prior to surgery, will have worsening of balance after surgery). MRI scan from person who had acoustic neuroma removed via retrolab approach, and with refractory dizziness. Residual acoustic neuroma as well as cerebellar damage, in this patient who had surgery in the remote past.
One would not be likely to preserve hearing when the hearing is good, and the tumor is big. This is simple stuff -- balance deteriorates after acoustic surgery because the surgery damages or removes remaining function in the vestibular nerve (Levo et al, 2004; Tufarelli et al, 2007). At a recent meeting at the ANA (acoustic neuroma association), the author of this page participated in a 2-hour session and interviewed 8 patients who had persistent vertigo.
No standards exist regarding patient follow-up following complete acoustic neuroma resection.
Asthagiri AR, Vasquez RA, Butman JA, Wu T, Morgan K, Brewer CC, King K, Zalewski C, Kim HJ, Lonser RR.PLoS One. Tanbouzi Husseini S, Piccirillo E, Taibah A, Paties CT, Rizzoli R, Sanna M Malignancy in vestibular schwannoma after stereotactic radiotherapy: A case report and review of the literature. Markou K, Eimer S, Perret C, Huchet A, Goudakos J, Liguoro D, Franco-Vidal V, Maire JP, Darrouzet V.
Paresthesia symptoms include frequent drooling, biting of the lip or the inside of the cheek or the side of the tongue, and paralytic disfigurement or drooping of the lip.
Nerve damage can have long lasting affects on employment and the ability to work, can affect relationships, lead to problems eating, lead to depression, lead to insomnia, and lead to a reduction in mental energy, memory, and cognitive functions. It may also be possible for trigeminal nerve injuries to develop into trigeminal neuralgia.
The buccal nerve, mylohyoid nerve, glossopharyngeal nerve, nasopalatine nerve, and facial nerve have been damaged during wisdom teeth removal. It is possible that other neves could be damaged with wisdom teeth removal than the others previously mentioned above.
The international headache society states that injury or entrapment of peripheral branches of the trigeminal nerve other than the nasocilliary and supraoribital nerves may give rise to pain referred to the area innervated by the branch affected. The 6% number is probably much too high as meningiomas and pituitary tumors are underreported. A recent study suggested that the mechanism of hearing loss in NF2 is elevated intralabyrinthine protein rather than compression of the 8th nerve (Asthaqiri et al, 2012).
Because acoustic neuromas are very rare, and MRI's are very expensive, in our opinion -- all patients with a substantial risk of having an acoustic should be evaluated by a medical doctor with otologic expertise. Evaluation of HVIN requires more sophisticated equipment than is available in most offices.
One would expect that this would create timing differences between the ears without spontaneous nystagmus, and result in head-shaking nystagmus, without spontaneous or hyperventilation induced nystagmus. Because MRI's are so expensive, the most cost efficient method of diagnosis (at this writing - -in 2015), is to have all patients with unexplained asymmetrical hearing loss be evaluated by a medical doctor with otologic expertise.
Because hearing asymmetry is mainly due to other conditions than acoustic neuromas, other pieces of information need to be integrated to make the clinical diagnosis of acoustic neuroma. This example shows that symmetrical hearing testing does not always exclude the diagnosis of an acoustic neuroma. Because this is terribly expensive (to screen everyone with hearing impairment of any type), mistakes are sometimes made. In our clinical context in Chicago, this technique is rarely relevant as the more sensitive test for acoustics (MRI) is so common. We have diagnosed a few acoustics by noting that ENG function is lost but hearing is relatively preserved. VHIT testing is probably also less sensitive than caloric testing but it depends on the tumor size. As OAE's are generated by the cochlea, and acoustics involve the 8th nerve, which is further in, the lack of sensitivity may be due to this anatomical specificity. Chiarovano et al (2015) reported that cervical VEMPs were abnormal in 65% of patients with acoustic neuroma. Parenthetically, it is puzzling that an old technology like MRI should keep increasing in cost every year.
The best protocol MRI protocol is generally a T1 with contrast (gadolinium) of the IAC, in a closed MRI with the highest resolution available (3T is the best right now -- in 2015). If a person has a pacemaker or other metallic device, then they may have to have a CT scan with contrast instead of an MRI. Once again, one looks for enhancement (lighting up of the tumor with contrast, and no lighting up without contrast). False negative errors mainly occur in persons with very small tumors, or very bad scans (such as a scan done in a low-field unit, such as an open MRI, without contrast).
Metastatic tumors usually grow rapidly -- hearing goes down quickly, and often the facial nerve is involved with a Bells palsy, over a few weeks time. For example, a person who has a migraine headache, might get an MRI which reveals an acoustic neuroma. It is not very likely that a previously silent acoustic neuroma, will suddenly manifest itself at the same time as another problem - -such as a minor head injury or migraine. This will eventually occur anyway, but treatment of a tumor that is not growing will speed up the process. Billing for this procedure is amazingly high, so this is not something that be generally used without health insurance.
They are damaged, they are scarred, but it is just not the nature of radiation to completely obliterate tumors. However, low dose gamma knife is looking much better and there are certainly many times when it is the best option. In some cases this can be very annoying as it may result in nerve irritability symptoms such as hyperventilation induced nystagmus.
This is a reasonable consideration which, in our opinion, makes conventional surgery advantageous when the patient is a reasonable surgical risk.
If one has serviceable hearing, and there is no other danger of waiting (such as needing a bigger operation), one might reasonably simply wait until hearing becomes unserviceable before proceeding with surgery or radiation.
El-Kashlan et al (1998) reported that dizziness from unoperated acoustic neuroma's is generally mild as damage progresses slowly and is handled with compensation.
On the right side of the picture (left side of head), there is a black area where there was damage to the cerebellum, presumably associated with the surgery. This type of injury will most likely be accompanied by permanent imbalance due to the combination of a cerebellar injury and loss of inner ear function on the left. There is clear cerebellar damage on the left side of the cerebellum (right side of picture). Keep in mind also that audiograms are somewhat subjective, there is such a thing as a placebo response, and reported results may sometimes mainly be wishful thinking. The middle fossa approach has more risk to one's brain and other aspects than other approaches.
Tufarelli and associated reported that 10% of 459 patients judged their imbalance as disabling, and 73% felt that they had at least moderate oscillopsia (trouble seeing with head moving). 2 years), balance generally returns to near normal, but persons who have other deficits such as visual disturbances (e.g. As a general rule, patients who had vertigo 2 years following surgery, had had a mixture of a cerebellar injury and total vestibular loss, associated with a difficult surgery (usually for a 4cm + tumor). The timing and prognosis of this vertigo depends on the reason and associated damage to the cerebellum (if any). This probably reflects the fact that migraine is an extremely common health condition that worsens with any type of head pain.
The Changing Landscape of Vestibular Schwannoma Management in the United States-A Shift Toward Conservatism.
The role of cervical and ocular vestibular evoked myogenic potentials in the assessment of patients with vestibular schwannomas. The Solid Component of Radiographically Non-Growing, Post-Radiated Vestibular Schwannoma Retains Proliferative Capacity: Implications for Patient Counseling. Unique case of malignant transformation of a vestibular schwannoma after fractionated radiotherapy.
Cost analysis of vestibular schwannoma screening with contrast-enhanced magnetic resonance imaging in patients with asymmetrical hearing loss.
Gamma knife radiosurgery for acoustic neuromas performed by a neurotologist: early experiences and outcomes.
The sense of taste, the facility of speech (as in slurred speech), and the sensory pleasure of kissing are diminished. The attacks are said to feel like stabbing electric shocks or shooting pain that becomes intractable.
There is evidence that the use of lingual nerve retraction can increase the risk of mylohyoid nerve damage.
The higher prevalence figures do not correspond to our clinical experience in our practice in Chicago, or the findings of others. While we doubt that this is always the case, we have also invoked this cause in patients with tiny tumors such as intralabyrinthine schwannomas, driven by MRI findings. In other words, patients with unexplained stable asymmetrical hearing loss should generally all be evaluated by a physician with otologic expertise. One might also expect abnormalities in OAE's as auditory efferents enter the cochlear area via the inferior division of the nerve.
Usually this integration process is done by a medical doctor with otologic expertise, and not by allied health persons such as audiologists. While this is really a decision for health care economists, it seems to us that occasional errors are overall permissible, when one considers what is best for the population at large. Nevertheless, this method might have utility in contexts where MRI's are difficult to access. Caloric, VEMP, perhaps VHIT), do better than those that test both sides at the same time (rotatory chair, posturography). As in the more common condition of Meniere's disease, hearing loss precedes vestibular impairment, the opposite pattern is suggestive of a tumor (especially an intralabyrinthine schwannoma). Or someone who experienced an auto accident, might get an MRI which reveals an acoustic neuroma. Rather, it is commonly the case that the person will have one of the common causes of dizziness, and just happen to also have a silent acoustic.
For this reason, extreme caution is suggested -- in our opinion, except for very large tumors, it is best to have objective evidence -- i.e.
Because of this observation, some surgeons simply recommend taking out the entire 8th nerve when most convenient as this approach makes tumor recurrence very unlikely. This is probably a consequence of using a treatment methodology that works more slowly than surgery. In persons with this sign, one can either wait for it to go away (this may take several years), try a medication that reduces nerve irritability, or reconsider surgical treatment. A detailed discussion of dizziness, vertigo and imbalance, pre and post surgery can be found in this lecture handout.
If damage to this branch is to occur it can cause additional problems.All sensory information from the face is sent to the trigeminal nerve nucleus.
Individual attacks affect one side of the face at a time, last several seconds or longer, and repeats up to hundreds of times throughout the day. The occipital nerve is located in the neck and could be damaged if the patient is not placed properly in the dental chair when having their teeth taken out. Thus nerve damage to the lingual and alveolar nerves (among others) is a cause of headache. This conclusion needs to be tempered by other clinical information - -someone with a progressive asymmetrical sensorineural hearing reduction would (in our opinion) be far more likely to have an acoustic than someone with a static or improving asymmetry. Genetic testing for NF1 and NF2 is available commercially, for example, from Athena Diagnostics. 13 Gy) are presently advised because of the much lower risk of facial weakness and numbness (Wackym et al, 2004). Long term hearing preservation is very rare in persons with stereotactic radiotherapy (6.7% according to Lin et al, 2005). As a general rule, patients who have lost both inner ear function (from the acoustic), and substantial cerebellar function (from the surgery or acoustic), will have an enduring loss of balance. Cochlear implants stimulate the part of the ear prior to the wiring - -they affect the microphone. Organic causes include damage to the brain, through trauma or disease, or use of certain (generally sedative) drugs. The mandibular nerve has many branches which consist of nerves implicated in taking out wisdom teeth. Of course this statistic actually reports the number of acoustics diagnosed, not the number that might be found through a prospective study. Because of the high sensitivity but low specificity, routine use of a very expensive diagnostic test such as a gad-MRI of the IAC's in all persons with asymmetrical hearing is not always justified. Should someone be suggesting an invasive procedure, a second opinion is well worth obtaining. Thus, one would expect that a cochlear implant would generally be ineffective in someone whose cochlear nerve has already been damaged by a tumor. Pan et al (2015) reported that the estimated screening cost per patient for those who benefitted from surgery or radiation was $147,030 while the US compensation for unilateral hearing loss is $44,888.
It is apparent from the figure on the right that these nerves are clearly beneath the lower teeth and thus can be damaged when removing one of the lower wisdom teeth.

Those suffering from severe paresthesia may be driven to near hysteria by a loss of sensory functions that affects all aspects of their lives. As we have a symptomatic population that presumably would be more likely to have acoustics than individuals with no hearing or dizziness symptoms, this implies that the prevalence in the general population is probably much lower than 1%. The mesencephalic nucleus receives proprioceptor and mechanoreceptor fibers from the jaws and teeth. Of course, this does not really answer the question as to the number of persons with hearing asymmetry that have AN. They perform a primary role in the processing and memory of emotional reactions, the amygdalae are considered part of the limbic system.
The inferior alveolar nerve supplies sensation to the lower teeth on the right or left half of the dental arch, as well as sense of touch to the right or left half of the chin and lower lip. Therefore damage to the mandibular nerve can cause pain, not regulate temperature properly, and feel numb.
The amygdalae send impulses to the hypothalamus for important activation of the sympathetic nervous system, to the thalamic reticular nucleus for increased reflexes, to the nuclei of the trigeminal nerve and facial nerve for facial expressions of fear, and to the ventral tegmental area, locus coeruleus, and laterodorsal tegmental nucleus for activation of dopamine, norepinephrine and epinephrine. Following any learning event, the long-term memory for the event is not instantaneously formed. Rather, information regarding the event is slowly assimilated into long-term storage over time (the duration of long-term memory storage can be life-long), a process referred to as memory consolidation, until it reaches a relatively permanent state.Anterior commissure - The Anterior Commissure (precommissure) is a bundle of white fibers, connecting the two cerebral hemispheres across the middle line, and placed in front of the columns of the fornix. On a sagittal section, it is oval in shape, having a long vertical diameter that measures about 5 mm. Its fibers can be traced laterally and backwards on either side beneath the corpus striatum into the substance of the temporal lobe. It serves in this way to connect the two temporal lobes, but it also contains decussating fibers from the olfactory tracts, and is a part of the neospinothalamic tract for pain. The anterior commissure also serves to connect the two amygdala.Astrocyte - Astrocytes (also known collectively as astroglia) are characteristic star-shaped glial cells in the brain and spinal cord. They perform many functions, including biochemical support of endothelial cells which form the blood-brain barrier, the provision of nutrients to the nervous tissue, and a principal role in the repair and scarring process in the brain.Axon - An axon or nerve fiber is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma.
Axons are in effect the primary transmission lines of the nervous system, and as bundles they help make up nerves.
Individual axons are microscopic in diameter (typically about 1um across), but may be up to multiple feet long.
In vertebrates, only the axons of many neurons are sheathed in myelin, which is formed by either of two types of glial cells: Schwann cells ensheathing peripheral neurons and oligodendrocytes insulating those of the central nervous system.
Along myelinated nerve fibers, gaps in the sheath known as nodes of Ranvier occur at evenly-spaced intervals, enabling an especially rapid mode of electrical impulse propagation called saltation. The demyelination of axons is what causes the multitude of neurological symptoms found in the disease Multiple Sclerosis. The axons of some neurons branch to form axon collaterals, that can be divided into a number of smaller branches called telodendria.
Along these the bifurcated impulse travels simultaneously to signal more than one other cell.Basal ganglia - The basal ganglia (or basal nuclei) are a group of nuclei in the brain interconnected with the cerebral cortex, thalamus and brainstem. Mammalian basal ganglia are associated with a variety of functions: motor control, cognition, emotions, and learning. Functionally, the basal ganglia consist of a series of circuits, such as skeletomotor, limbic and occulomotor circuits. Betz cells send their axons down to the spinal cord where in humans they synapse directly with anterior horn cells, which in turn synapse directly with their target muscles. While Betz cells have one apical dendrite typical to pyramidal neurons, they have more primary dendritic shafts, and these do not leave the soma only at basal angles but rather branch out from almost any point asymmetrically.Brain Cells - A generic term for the neurons and glial cells.
Other cells in the brain include epithelial cells that make up the lining of the blood vessels.Brain Stem - The brain stem is the lower part of the brain, adjoining and structurally continuous with the spinal cord. The brain stem provides the main motor and sensory innervation to the face and neck via the cranial nerves. The nerve connections of the motor and sensory systems to the rest of the body also pass through the brain stem. This includes the corticospinal tract(motor), the posterior column-medial lemniscus pathway (fine touch, vibration sensation and proprioception) and the spinothalamic tract(pain, temperature, itch and crude touch). The brain stem also plays an important role in the regulation of cardiac and respiratory function. It also regulates the central nervous system, and is pivotal in maintaining consciousness and regulating the sleep cycle.Brain tumor - Any intracranial tumor created by abnormal and uncontrolled cell division, normally either in the brain itself (neurons, glial cells (astrocytes, oligodendrocytes, ependymal cells), lymphatic tissue, blood vessels), in the cranial nerves (myelin-producing Schwann cells), in the brain envelopes (meninges), skull, pituitary and pineal gland, or spread from cancers primarily located in other organs (metastatic tumors). It is a subdivision of the cytoarchitecturally defined occipital region of cerebral cortex.
In the human it is located in parts of the cuneus, the lingual gyrus and the lateral occipital gyrus of the occipital lobe. Cytoarchitecturally it is bounded on one side by the striate area 17, from which it is distinguished by absence of a band of Gennari, and on the other by the peristriate area 19.Brodmann area 19 - Part of the occipital lobe cortex in the human brain. In normally-sighted humans, extrastriate cortex is a visual association area, with feature-extracting, shape recognition, attentional, and multimodal integrating functions.Brodmann area 20 - Part of the temporal cortex in the human brain.
The region encompasses most of the ventral temporal cortex, a region believed to play a part in high-level visual processing and recognition memory. This area is also known as inferior temporal area 20, and it refers to a subdivision of the cytoarchitecturally defined temporal region of cerebral cortex. Cytoarchitecturally it is bounded medially by the ectorhinal area 36, laterally by the middle temporal area 21, rostrally by the temporopolar area 38 and caudally by the occipitotemporal area 37.Brodmann area 21 - BA21, is part of the temporal cortex in the human brain. The region encompasses most of the lateral temporal cortex, a region believed to play a part in auditory processing and language. It is a subdivision of the cytoarchitecturally defined hippocampal region of the human cerebral cortex. It and the entorhinal area 28 together constitute approximately the entorhinal area.Brodmann area 37 - This area is known as occipitotemporal area 37 (H).
It is located primarily in the caudal portions of the fusiform gyrus and inferior temporal gyrus on the mediobasal and lateral surfaces at the caudal extreme of the temporal lobe.
Cytoarchitecturally it is bounded caudally by the peristriate Brodmann area 19, rostrally by the inferior temporal area 20 and middle temporal area 21 and dorsally on the lateral aspect of the hemisphere by the angular area 39.Brodmann area 39 - Part of the parietalcortex in the human brain.
BA39 encompasses the angular gyrus, lying near to the junction of temporal, occipital and parietal lobes. It corresponds to the angular gyrus surrounding the caudal tip of the superior temporal sulcus. Cytoarchitecturally it is bounded rostrally by the supramarginal area 40 (H), dorsally and caudally by the peristriate area 19, and ventrally by the occipitotemporal area 37.Brodmann area 40 - BA40, is part of the parietal cortex in the human brain. The inferior part of BA40 is in the area of the supramarginal gyrus, which lies at the posterior end of the lateral fissure, in the inferior lateral part of the parietal lobe. It is bounded approximately by the intraparietal sulcus, the inferior postcentral sulcus, the posterior subcentral sulcus and the lateral sulcus. Cytoarchitecturally it is bounded caudally by the angular area 39 (H), rostrally and dorsally by the caudal postcentral area 2, and ventrally by the subcentral area 43 and the superior temporal area 22.Calcarine fissure - The calcarine fissure (or calcarine sulcus) is an anatomical landmark located at the very caudal end of the medial surface of the brain. The calcarine sulcus begins near the occipital pole in two converging rami and runs forward to a point a little below the splenium of the corpus callosum, where it is joined at an acute angle by the medial part of the parietooccipital fissure.
The anterior part of this fissure gives rise to the prominence of the calcar avis in the posterior cornu of the lateral ventricle.Caudate nucleus - The caudate nucleus is a nucleus located within the basal ganglia of the brains of many animal species. The caudate, originally thought to primarily be involved with control of voluntary movement, is now known to be an important part of the brain's learning and memory system. Individually, they resemble a C-shape structure with a wider head at the front, tapering to a body and a tail.Central sulcus - The central sulcus is a fold in the cerebral cortex of brains in vertebrates.
The central sulcus is a prominent landmark of the brain, separating the parietal lobe from the frontal lobe and the primary motor cortex from the primary somatosensory cortex.Cerebellum - The cerebellum is a region of the brain that plays an important role in the integration of sensory perception, coordination and motor control. In order to coordinate motor control, there are many neural pathways linking the cerebellum with the cerebral motor cortex (which sends information to the muscles causing them to move) and the spinocerebellar tract (which provides proprioceptive feedback on the position of the body in space). There are three layers to the cerebellar cortex; from outer to inner layer, these are the molecular, Purkinje, and granular layers. The cerebellum is located in the inferior posterior portion of the head (the hindbrain), directly dorsal to the pons, and inferior to the occipital lobe. Because of its large number of tiny granule cells, the cerebellum contains more than 50% of all neurons in the brain, but it only takes up 10% of total brain volume. The cerebellum receives nearly 200 million input fibers; in contrast, the optic nerve is composed of a mere one million fibers. The cerebellum is divided into two large hemispheres, much like the cerebrum, and contains ten smaller lobules. Each of these hemispheres has an outer layer of grey matter called the cerebral cortex that is supported by an inner layer of white matter.
The hemispheres are linked by the corpus callosum, a very large bundle of nerve fibers, and also by other smaller commissures, including the anterior commissure, posterior commissure, and hippocampal commissure. These commissures transfer information between the two hemispheres to coordinate localized functions.Cerebrum (also called the cerebral cortex or just the cortex) - The telencephalon, cerebrum, or forebrain is the most anterior or, especially in humans, most dorsal region of the vertebrate central nervous system. The dorsal telencephalon, or pallium, develops into the cerebral cortex, and the ventral telencephalon, or subpallium, becomes the basal ganglia. 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. These functions originate within the primary motor cortex and other frontal lobe motor areas where actions are planned. Upper motor neurons in the primary motor cortex send their axons 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.Cerebrospinal Fluid - Liquor cerebrospinalis, is a clear bodily fluid that occupies the subarachnoid space and the ventricular system around and inside the brain.
The CSF occupies the space between the arachnoid mater (the middle layer of the brain cover, meninges) and the pia mater (the layer of the meninges closest to the brain). It constitutes the content of all intra-cerebral (inside the brain, cerebrum) ventricles, cisterns and sulci (singular sulcus), as well as the central canal of the spinal cord. It is an approximately isotonic solution and acts as a "cushion" or buffer for the cortex, providing also a basic mechanical and immunological protection to the brain inside the skull. Since the brain can only contain from 135-150 ml, large amounts are drained primarily into the blood through arachnoid granulations in the superior sagittal sinus. This continuous flow into the venous system dilutes the concentration of larger, lipoinsoluble molecules penetrating the brain and CSF.Cerebral peduncle - The cerebral peduncle, by most classifications, is everything in the mesencephalon except the tectum.
By this definition, the cerebral peduncles are also known as the basis pedunculi, while the large ventral bundle of efferent fibers is referred to as the crus cerebri or the pes pedunculi There are numerous nerve tracts located within this section of the brainstem. Of note, in the cerebral peduncular loop fibers from motor areas of the brain project to the cerebral peduncle and then project to various thalamic nuclei.Choroid Plexus - The choroid plexus is the area on the ventricles of the brain where cerebrospinal fluid (CSF) is produced by modified ependymal cells. Choroid plexus is present in all components of the ventricular system except for the cerebral aqueduct and the occipital and frontal horns of the lateral ventricles. It follows up along this boundary, continuous with the inferior of the body of the lateral ventricles. It passes into the interventricular foramen, and is present at the top of the third ventricle. Through the medulla, one projection bifurcates, and projects to the contralateral the superior olivary complex (SOC) via the trapezoid body, whilst the other half shoots to the ipsilateral SOC.Corpora quadrigemina - In the brain, the corpora quadrigemina are the four colliculi - two inferior, two superior - located on the tectum the dorsal aspect of the midbrain.
The corpora quadrigemina are reflex centers involving vision and hearing.Corpus Callosum - The corpus callosum is a structure of the mammalian brain in the longitudinal fissure that connects the left and right cerebral hemispheres. It is the largest white matter structure in the brain, consisting of 200-250 million contralateral axonal projections. Much of the inter-hemispheric communication in the brain is conducted across the corpus callosum. There are disputed claims about the difference of the size of the human corpus callosum in men and women and the relationship of any such differences to gender differences in human behaviour and cognition.Corticospinal tract - (Pyramidal tract) is a massive collection of axons that travel between the cerebral cortex of the brain and the spinal cord. It actually consists of two separate tracts in the spinal cord: the lateral corticospinal tract and the anterior corticospinal tract. An understanding of these tracts leads to an understanding of why for the most part, one side of the body is controlled by the opposite side of the brain. The corticobulbar tract carries signals that control motor neurons located in cranial nerve brain nuclei rather than motor neurons located in the spinal cord.Cingulate Cortex - The cingulate cortex is a part of the brain situated in the medial aspect of the cortex. It is extended from the corpus callosum below to the cingulate sulcus above, at least anteriorly. It partially wraps around the corpus callosum and is limited above by the cingulate sulcus.
The cingulate gyrus receives inputs from the anterior nucleus of the thalamus and the neocortex, as well as from somatosensory areas of the cerebral cortex.
It functions as an integral part of the limbic system, which is involved with emotion formation and processing, learning, and memory.
A comatose person cannot be awakened, fails to respond normally to pain or light, does not have sleep-wake cycles, and does not take voluntary actions. Coma may result from a variety of conditions, including intoxication, metabolic abnormalities, central nervous system diseases, acute neurologic injuries such as stroke, and hypoxia. A coma may also result from head trauma caused by mechanisms such as falls or car accidents.
It may also be deliberately induced by pharmaceutical agents in order to preserve higher brain function following another form of brain trauma, or to save the patient from extreme pain during healing of injuries or diseases.
The underlying cause of coma is bilateral damage to the Reticular formation of the midbrain, which is important in regulating sleep.Consciousness - Defined loosely as a constellation of attributes of mind such as subjectivity, self-awareness, sentience, and the ability to perceive a relationship between oneself and one's environment. The study of brain states of non-linguistic primates, in particular the macaques, has been used extensively by scientists and philosophers in their quest for the neural correlates of the contents of consciousness. From lateral to medial, the four deep cerebellar nuclei are the dentate, emboliform, globose, and fastigial. These nuclei receive inhibitory (GABAergic) inputs from Purkinje cells in the cerebellar cortex and excitatory (glutamatergic) inputs from mossy fiber and climbing fiber pathways. One exception is that fibers from the flocculonodular lobe synapse directly on vestibular nuclei without first passing through the deep cerebellar nuclei. The vestibular nuclei in the brainstem are analogous structures to the deep nuclei, since they receive both mossy fiber and Purkinje cell inputs. In general, each pair of deep nuclei is associated with a corresponding region of cerebellar surface anatomy.Dendrites - The branched projections of a neuron that act to conduct the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project.
Electrical stimulation is transmitted onto dendrites by upstream neurons via synapses which are located at various points throughout the dendritic arbor. Dendrites play a critical role in integrating these synaptic inputs and in determining the extent to which action potentials are produced by the neuron. Recent research has also found that dendrites can support action potentials and release neurotransmitters.
This property was originally believed to be specific to axons.Dentate gyrus - Part of the hippocampal formation.
It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult humans, (other sites include the olfactory bulb and cerebellum).
It is the largest of the four deep cerebellar nuclei, the others being the fastigial nucleus and the interposed nucleus (globose and emboliform nuclei combined). It therefore receives its afferents from the premotor cortex and the supplementary motor cortex (via the pontocerebellar system).Dopamine - A hormone and neurotransmitter occurring in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this phenethylamine functions as a neurotransmitter, activating the five types of dopamine receptors - D1, D2, D3, D4 and D5, and their variants. The EC forms the main input to the hippocampus and is responsible for the pre-processing (familiarity) of the input signals. In the reflex nictitating membrane response of classical trace conditioning, the association of impulses from the eye and the ear occurs in the entorhinal cortex. The EC-hippocampus system plays an important role in memory consolidation and memory optimization in sleep. Entorhinal cortex is one of the first areas to be affected in Alzheimer's DiseaseEpithalamus - The epithalamus is a dorsal posterior segment of the diencephalon (a segment in the middle of the brain also containing the hypothalamus and the thalamus) which includes the habenula, the stria medullaris and the pineal body. The epithalamus comprises the trigonum habenulae, the pineal body, and the posterior commissure.Extrastriate cortex - The extrastriate cortex is the region of the occipital cortex of the mammalian brain located next to the striate cortex (which is also known as the primary visual cortex).
In terms of Brodmann areas, the extrastriate cortex comprises Brodmann area 18 and Brodmann area 19, while the striate cortex comprises Brodmann area 17. Neurons in the extrastriate cortex generally respond to visual stimuli within their receptive fields. These responses are modulated by extraretinal effects, like attention, working memory, and reward expectation.Falx cerebri - Also known as the cerebral falx, so named from its sickle-like form, is a strong, arched fold of dura mater which descends vertically in the longitudinal fissure between the cerebral hemispheres. It is narrow in front, where it is attached to the crista galli of the ethmoid; and broad behind, where it is connected with the upper surface of the tentorium cerebelli.
Its upper margin is convex, and attached to the inner surface of the skull in the middle line, as far back as the internal occipital protuberance; it contains the superior sagittal sinus. It is separated from the parietal lobe by the primary motor cortex, which controls voluntary movements of specific body parts associated with the precentral gyrus.The frontal lobe contains most of the dopamine-sensitive neurons in the cerebral cortex.
Dopamine tends to limit and select sensory information arriving from the thalamus to the fore-brain. The executive functions of the frontal lobes involve the ability to recognize future consequences resulting from current actions, to choose between good and bad actions (or better and best), override and suppress unacceptable social responses, and determine similarities and differences between things or events. Psychological tests that measure frontal lobe function include Finger tapping, Wisconsin Card Sorting Task, and measures of verbal and figural fluency.Glial cell - Glial cells, commonly called neuroglia or simply glia are non-neuronal cells that provide support and nutrition, maintain homeostasis, form myelin, and participate in signal transmission in the nervous system.
In the human brain, glia are estimated to outnumber neurons by about 10 to 1.Glial cells provide support and protection for neurons, the other main type of cell in the nervous system. The four main functions of glial cells are to surround neurons and hold them in place, to supply nutrients and oxygen to neurons, to insulate one neuron from another, and to destroy pathogens and remove dead neurons. They also modulate neurotransmission.Globus pallidus - A sub-cortical structure of the brain.
In this system, it is a major constituent of the basal ganglia core, which consists of the striatum and its direct targets: globus pallidus and substantia nigra. It is generally surrounded by one or more sulci.Hippocampus - Part of the forebrain, located in the medial temporal lobe.

It belongs to the limbic system and plays major roles in short term memory and spatial navigation.
In Alzheimer's disease the hippocampus is one of the first regions of the brain to suffer damage; memory problems and disorientation appear among the first symptoms. Damage to the hippocampus can also result from oxygen starvation (anoxia), encephalitis, or mesial temporal lobe epilepsy. People with extensive hippocampal damage may experience amnesia, that is, inability to form or retain new memories. Psychologists and neuroscientists generally agree that the hippocampus has an important role in the formation of new memories about experienced events.Hypothalamus - The hypothalamus links the nervous system to the endocrine system via the pituitary gland (hypophysis). The hypothalamus co-ordinates many hormonal and behavioural circadian rhythms, complex patterns of neuroendocrine outputs, complex homeostatic mechanisms, and many important behaviours.
The hypothalamus contains neurons that react strongly to steroids and glucocorticoids - (the steroid hormones of the adrenal gland, released in response to ACTH). It also contains specialised glucose-sensitive neurons (in the arcuate nucleus and ventromedial hypothalamus), which are important for appetite. The inferior colliculus lies caudal to its counterpart - the superior colliculus - above the trochlear nerve, and at the base of the projection of the medial geniculate nucleus (MGN) and the lateral geniculate nucleus (LGN).The inferior colliculus is the principal midbrain nucleus of the auditory pathway and receives input from several more peripheral brainstem nuclei in the auditory pathway, as well as inputs from the auditory cortex.
It lies deep to the brain's lateral surface, within the lateral sulcus which separates the temporal lobe and inferior parietal cortex.
These overlying cortical areas are known as opercula (meaning "lids"), and parts of the frontal, temporal and parietal lobes form opercula over the insula. The insular cortex, in particular its most anterior portion, is considered a limbic-related cortex.
The insula has increasingly become the focus of attention for its role in body representation and subjective emotional experience. The limbic system, or Paleomammalian brain is a term for a set of brain structures including the hippocampus and amygdala and anterior thalamic nuclei and a limbic cortex that support a variety of functions including emotion, behavior and long term memory. The structures of the brain described by the limbic system are closely associated with the olfactory structures.
The limbic system operates by influencing the endocrine system and the autonomic nervous system. It is highly interconnected with the nucleus accumbens, the brain's pleasure center, which plays a role in sexual arousal and the "high" derived from certain recreational drugs. These procedures often result in major personality changes and possible mental disabilities.
Lobotomies were used in the 20th century to treat a wide range of severe mental illnesses, including schizophrenia, clinical depression, and various anxiety disorders. The procedure has since been characterized "as one of the most barbaric mistakes ever perpetrated by mainstream medicine".Lower motor neuron - Lower motor neurons (LMNs) are the motor neurons connecting the brainstem and spinal cord to muscle fibers, bringing the nerve impulses from the upper motor neurons out to the muscles. A lower motor neuron's axon travels through a foramen and terminates on an effector (muscle).Magnocellular neurosecretory cell - large cells within the supraoptic nucleus and paraventricular nucleus of the hypothalamus. They are also found in smaller numbers in accessory cell groups between these two nuclei, the largest one being the nucleus circularis. There are two types of magnocellular neurosecretory cells, oxytocin-producing cells and vasopressin-producing cells, but a small number can produce both hormones.
These cells are neuroendocrine neurons, they are electrically excitable, and generate action potentials in response to afferent stimulation.Medial longitudinal fissure - The great longitudinal fissure (or longitudinal cerebral fissure, or longitudinal fissure, or interhemispheric fissure) is the deep groove which separates the two hemispheres of the vertebrate brain. The falx cerebri, a dural brain covering, lies within the medial longitudinal fissure.Medulla Oblongata - The medulla oblongata is the lower portion of the brainstem. The cardiac center is the part of the medulla oblongata responsible for controlling the heart rate.Meninges - The meninges (singular meninx) is the system of membranes which envelops the central nervous system. The meninges consist of three layers: the dura mater, the arachnoid mater, and the pia mater. The primary function of the meninges and of the cerebrospinal fluid is to protect the central nervous system.Mesencephalon - the mesencephalon (or midbrain) comprises the tectum (or corpora quadrigemini), tegmentum, the ventricular mesocoelia (or "iter"), and the cerebral peduncles, as well as several nuclei and fasciculi. Caudally the mesencephalon adjoins the pons (metencephalon) and rostrally it adjoins the diencephalon (Thalamus, hypothalamus, et al).
During development, the mesencephalon forms from the middle of three vesicles that arise from the neural tube to generate the brain. In mature human brains, the mesencephalon becomes the least differentiated, from both its developmental form and within its own structure, among the three vesicles. Its substantia nigra is closely associated with motor system pathways of the basal ganglia.Midbrain - The mesencephalon (or midbrain) comprises the tectum (or corpora quadrigemini), tegmentum, the ventricular mesocoelia (or "iter"), and the cerebral peduncles, as well as several nuclei and fasciculi. Caudally the mesencephalon adjoins the pons (metencephalon) and rostrally it adjoins the diencephalon.Midbrain tectum - The tectum is a region of the brain, specifically the dorsal part of the mesencephalon (midbrain).
It is derived in embryonic development from the alar plate of the neural tube.Motor cortex - Regions of the cerebral cortex involved in the planning, control, and execution of voluntary motor functions. The main consequence of a myelin layer is an increase in the speed at which impulses propagate along the myelinated fiber.
Along unmyelinated fibers, impulses move continuously as waves, but, in myelinated fibers, they hop or "propagate by saltation." Myelin increases resistance across the cell membrane by a factor of 5,000 and decreases capacitance by a factor of 50. When a peripheral fiber is severed, the myelin sheath provides a track along which regrowth can occur.
Unmyelinated fibers and myelinated axons of the mammalian central nervous system do not regenerate.Neocortex - The neocortex is part of the cerebral cortex (along with the archicortex and paleocortex, which are cortical parts of the limbic system). It is involved in higher functions such as sensory perception, generation of motor commands, spatial reasoning, conscious thought and, in humans, language. Other names for the neocortex include neopallium ("new mantel") and isocortex ("equal rind"). With 100 billion cells, each with 1,000 to 10,000 synapses, the neocortex makes roughly 100 trillion connections and contains 300 million feet of wiring packed with other tissue into a one-and-a-half-quart volume in the brain. The neocortex consists of the grey matter, or neuronal cell bodies and unmyelinated fibers, surrounding the deeper white matter (myelinated axons) in the cerebrum.Neurons - Responsive cells in the nervous system that process and transmit information by chemical signals within the neuron. They are the core components of the brain, the vertebrate spinal cord, the invertebrate ventral nerve cord, and the peripheral nerves. Neurons respond to stimulus and communicate the presence of that stimuli to the central nervous system, which processes that information and sends responses to other parts of the body for action.
Neurons exist in a number of different shapes and sizes and can be classified by their morphology and function.* Motor neurons that control muscle contractions have a cell body on one end, a long axon in the middle and dendrites on the other end. They carry signals from the central nervous system to the outer parts (muscles, skin, glands) of your body.* Sensory neurons have dendrites on both ends, connected by a long axon with a cell body in the middle.
Neurons expressing certain types of neurotransmitters sometimes form distinct systems, where activation of the system affects large volumes of the brain, called volume transmission. The major neurotransmitter systems are the noradrenaline (norepinephrine) system, the dopamine system, the serotonin system and the cholinergic system.Nucleus accumbens - Also known as the accumbens nucleus or as the nucleus accumbens septi, is a collection of neurons within the forebrain.
It is thought to play an important role in reward, laughter, pleasure, addiction, fear, and the placebo effect.
The principal neuronal cell type found in the nucleus accumbens is the medium spiny neuron.
The neurotransmitter produced by these neurons is gamma-aminobutyric acid (GABA), one of the main inhibitory neurotransmitters of the central nervous system.
These neurons are also the main projection or output neurons of the nucleus accumbens.Occipital Lobe - The occipital lobe is the visual processing center of the brain containing most of the anatomical region of the visual cortex.
Located in the rearmost portion of the skull, the occipital lobes are part of the forebrain structure. The lobes rest on the tentorium cerebelli, a process of dura mater that separates the cerebrum from the cerebellum. They are structurally isolated in their respective cerebral hemispheres by the separation of the cerebral fissure. The front edge of the occipitalseveral lateral occipital gyri, which are separated by lateral occipital sulcus. The occipital aspects along the inside face of each hemisphere are divided by the calcarine sulcus. Above the medial, Y-shaped sulcus lies the cuneus, and the area below the sulcus is the lingual gyrus.
Retinal sensors convey stimuli through the optic tracts to the lateral geniculate bodies, where optic radiations continue to the visual cortex.
Each visual cortex receives raw sensory information from the outside half of the retina on the same side of the head and from the inside half of the retina on the other side of the head.Parahippocampal gyrus - The parahippocampal gyrus (or hippocampal gyrus) is a grey matter cortical region of the brain that surrounds the hippocampus.
The term parahippocampal cortex is used to refer to an area that encompasses both the posterior portion of the parahippocampal gyrus and the medial portion of the fusiform gyrus.Parietal Lobe - A lobe in the brain. It is positioned above (superior to) the occipital lobe and behind (posterior to) the frontal lobe. The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. The parietal lobe plays important roles in integrating sensory information from various parts of the body, knowledge of numbers and their relations, and in the manipulation of objects.
Gerstmann's syndrome is associated with lesion to the dominant (usually left) parietal lobe. The syndrome of hemispatial neglect is usually associated with large deficits of attention of the non-dominant hemisphere.Pars Compacta - The pars compacta contains neurons which, in humans, are coloured black by the pigment neuromelanin that increases with age.
This pigmentation is visible as a distinctive black stripe in brain sections and is the origin of the name given to this area. The neurons have particularly long and thick dendrites.Pars Reticulata - The pars reticulata is a portion of the substantia nigra. They are smaller and thinner than the dopaminergic neurons and conversely identical and morphologically similar to the pallidal neurons.
They make connections with the dopamine neurons of the pars compacta whose long dendrites plunge deeply in the pars reticulata.
The neurons of the pars reticulata and lateralis produce the neurotransmitter gamma-aminobutyric acid (GABA).Perirhinal cortex - A cortical region in the medial temporal lobe that is made up of Brodmann areas 35 and 36.
It receives highly-processed sensory information from all sensory regions, and is generally accepted to be an important region for memory. It is bordered caudally by postrhinal cortex or parahippocampal cortex (homologous regions in rodents and primates, respectively) and ventrally and medially by entorhinal cortex.Periaqueductal gray - Midbrain grey matter that is located around the cerebral aqueduct within the midbrain.
The ascending pain and temperature fibers of the spinothalamic tract also send information to the PAG via the spinomesencephalic tract.
The spinomesencephalic tract is so-named because the fibers originate in the spine and terminate in the mesencephalon, another name for the midbrain, which is the part of the brain in which the PAG resides.Pineal gland - The pineal gland (also called the pineal body, epiphysis cerebri, or epiphysis) is a small endocrine gland in the vertebrate brain. It is shaped like a tiny pine cone, and is located near the center of the brain, between the two hemispheres, tucked in a groove where the two rounded thalamic bodies join.Pons - A structure located on the brain stem. It is cranial to the medulla oblongata, caudal to the midbrain, and ventral to the cerebellum. Its fibers acquire their medullary sheaths early, but their connections have not been definitely determined.
Most of them have their origin in a nucleus, the nucleus of the posterior commissure (nucleus of Darkschewitsch), which lies in the central gray substance of the upper end of the cerebral aqueduct, in front of the nucleus of the oculomotor nerve.Postcentral gyrus - The lateral postcentral gyrus is a prominent structure in the parietal lobe of the human brain.
Although initially defined to be roughly the same as Brodmann areas 3, 1 and 2, more recent work by Kaas has suggested that for homogeny with other sensory fields only area 3 should be referred to as "primary somatosensory cortex", as it received the bulk of the thalamocortical projection from the sensory input fields.Premotor cortex - An area of motor cortex in the frontal lobe of the brain.
It extends 3mm in front of the Primary motor cortex near the Sylvian fissure before narrowing to approximately 1mm near the Medial longitudinal fissure, where it has the prefrontal cortex. M1 contains large neurons known as Betz cells which send long axons down the spinal cord to synapse onto alpha motor neurons which connect to the muscles. Pre-motor areas are involved in planning actions (in concert with the basal ganglia) and refining movements based upon sensory input (this requires the cerebellum).Putamen - The putamen is a structure in the middle of the brain which, together with the caudate nucleus, forms the dorsal striatum. The putamen is a portion of the basal ganglia that forms the outermost part of the lenticular nucleus.
The motor and somatosensory cortices, the intralaminar nuclei of the thalamus, and the substantia nigra project to the putamen.
The putamen projects to premotor and supplementary motor areas of cortex via the globus pallidus and thalamus.Receptors - In biochemistry, a receptor is a protein molecule, embedded in either the plasma membrane or cytoplasm of a cell, to which a mobile signaling (or "signal") molecule may attach. In the brain they sense the environment (chemicals, light, sound, touch) and encode this information into electrochemical messages that are transmitted by sensory neurons.Red Nucleus - The red nucleus is a structure in the rostral midbrain involved in motor coordination.
It is essential for governing some of the basic functions of higher organisms, and is one of the oldest portions of the brain. The reticular formation is an important regulator in the autonomic nervous system for such processes as respiration rate, heart rate and gastrointestinal activity. It also plays an important role in sleep and consciousness as well as modulation of pain.Spinal cord - The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. The spinal cord is a long, thin, tubular bundle of nerves that is an extension of the central nervous system from the brain and is enclosed in and protected by the bony vertebral column.
The dorsal striatum forms a continuous and large mass, topographically separated by the internal capsule into the caudate nucleus medially, the putamen laterally and the fundus below, linking the two preceding ventrally; but a single entity. It is built up of 4 neuronal types.Stria medullaris - Also known as stria medullaris thalami, is a fiber bundle containing efferent fibers from the septal nuclei, lateral preoptico-hypothalmic region, and anterior thalamic nuclei to the habenula.
It forms a horizontal ridge on the medial surface of the thalamus.Substantia Nigra - The substantia nigra or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and an accessory to the basal ganglia system. The nucleus is situated at the base of the brain, adjacent to the optic chiasm, and, in humans, it contains about 3,000 neurons.Superior colliculus - The superior colliculus is a paired structure that is part of the brain's tectal area. The two superior colliculi sit below the thalamus and surround the pineal gland in the mesencephalon of vertebrate brains. It comprises the caudal aspect of the midbrain, posterior to the periaqueductal gray and immediately superior to the inferior colliculus.
In humans, the superior colliculus (SC) is involved in the generation of saccadic (fast) eye movements and eye-head coordination.Synapses - Chemical synapses allow neurons to form interconnected circuits within the central nervous system. They provide the means through which the nervous system connects to and controls the other systems of the body, for example the specialized synapse between a motor neuron and a muscle cell is called a neuromuscular junction. The adult human brain has been estimated to contain from 1014 to 5 Times 1014 (100-500 trillion) synapses.Tegmentum - The tegmentum is a general area within the brainstem. It is located between the ventricular system and distinctive basal or ventral structures at each level. It is a multisynaptic network of neurons that is involved in many unconscious homeostatic and reflexive pathways.Temporal lobe - Parts of the cerebrum that are involved in speech, memory, and hearing. The temporal lobe is involved in auditory processing and is home to the primary auditory cortex.
The thalamus is generally believed to act as a translator for which various "prethalamic" inputs are processed into a form readable by the cerebral cortex.
The thalamus is believed to both process and relay sensory information selectively to various parts of the cerebral cortex, as one thalamic point may reach one or several regions in the cortex.
Thalamic nuclei have strong reciprocal connections with the cerebral cortex, forming thalamo-cortico-thalamic circuits that are believed to be involved with consciousness. The thalamus plays a major role in regulating arousal, the level of awareness, and activity. Damage to the thalamus can lead to permanent coma.Upper motor neuron - Upper motor neurons are motor neurons that originate in motor region of the cerebral cortex or the brain stem and carry motor information down to the final common pathway, that is, any motor neurons that are not directly responsible for stimulating the target muscle. The main effector neurons for voluntary movement lie within layer V of the primary motor cortex and are called Betz cells. The cell bodies of these neurons are some of the largest in the brain, approaching nearly 100um in diameter. These neurons connect the brain to the appropriate level in the spinal cord, from which point nerve signals continue to the muscles by means of the lower motor neurons.
The neurotransmitter glutamate transmits the nerve impulses from upper to lower motor neurons where it is detected by glutamatergic receptors.Ventricles - The ventricular system is a set of structures in the brain continuous with the central canal of the spinal cord. There are four cerebral ventricles: the paired lateral ventricles, and midline the third and fourth ventricles.
The two lateral ventricles, located within the cerebrum, are relatively large and C-shaped, roughly wrapping around the dorsal aspects of the basal ganglia.
It is in the lateral ventricles of the embryo that the successive generation of neurons gives rise to the 6-layered structure of the neocortex, constructed from the inside out during development. Each lateral ventricle extends into the frontal, temporal and occipital lobes via the frontal (anterior), temporal (inferior), and occipital (posterior) horns, respectively. The lateral ventricles both communicate via the interventricular foramina with the third ventricle, found centrally within the diencephalon. The third ventricle communicates via the cerebral aqueduct, located within the midbrain, with the fourth ventricle, found within the hindbrain.
The three foramina to the subarachnoid space are found here, permitting cerebrospinal fluid produced in the ventricles to surround the brainstem, cerebellum, and cerebral cortex. The fourth ventricle is also continuous with the central canal, allowing CSF to bathe the inside surface of the spinal cord as well.Visual cortex - The term visual cortex refers to the primary visual cortex (also known as striate cortex or V1) and extrastriate visual cortical areas such as V2, V3, V4, and V5.
In all mammals studied, it is located in the posterior pole of the occipital cortex (the occipital cortex is responsible for processing visual stimuli). It is highly specialized for processing information about static and moving objects and is excellent in pattern recognition.Wernicke's Area - Part of the human cerebrum that forms part of the cortex, on the 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).
For most people, it is located in the left hemisphere, as the left hemisphere is specialized for language skills. Occlusion of the middle cerebral artery in a stroke can affect the proper functioning of this area.White Matter - One of the three main solid components of the central nervous system.
White matter is composed of bundles of myelinated nerve cell processes (or axons), which connect various gray matter areas (the locations of nerve cell bodies) of the brain to each other, and carry nerve impulses between neurons.

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