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  • cerebral
  • The most common cause of cortical blindness is ischemia ( oxygen deprivation ) to the occipital lobes caused by blockage to one or both of the posterior cerebral arteries. (wikipedia.org)
  • plasticity
  • The current experimental studies of my group (Experimental Cortical Plasticity) are concerned with the cellular mechanisms of the modulatory action of transcranial magnetic stimulation (TMS). (ruhr-uni-bochum.de)
  • On one hand, we study the effects of rTMS on sensory processing itself and the relationship to changes in cortical protein expression, on the other hand, we further test how rTMS can modulate plasticity of the sensory system. (ruhr-uni-bochum.de)
  • Merzenich and William Jenkins (1990) initiated studies relating sensory experience, without pathological perturbation, to cortically observed plasticity in the primate somatosensory system, with the finding that sensory sites activated in an attended operant behavior increase in their cortical representation. (wikipedia.org)
  • However, the rodent studies were poorly focused on the behavioral end, and Ron Frostig and Daniel Polley (1999, 2004) identified behavioral manipulations as causing a substantial impact on the cortical plasticity in that system. (wikipedia.org)
  • Merzenich and DT Blake (2002, 2005, 2006) went on to use cortical implants to study the evolution of plasticity in both the somatosensory and auditory systems. (wikipedia.org)
  • brain
  • NVI and its three subtypes-cortical blindness, cortical visual impairment, and delayed visual maturation -must be distinguished from ocular visual impairment in terms of their different causes and structural foci, the brain and the eye respectively. (wikipedia.org)
  • Because the first problems are perceived as eye problems, cortical brain dysfunction initially may not be considered as a cause. (alz.org)
  • Layer V gives rise to all of the principal cortical efferent projections to basal ganglia, brain stem and spinal cord. (lonza.com)
  • A cortical minicolumn is a vertical column through the cortical layers of the brain. (wikipedia.org)
  • The goal of a cortical implant and neuroprosthetic in general is "to replace neural circuitry in the brain that no longer functions appropriately. (wikipedia.org)
  • There are two ways that cortical implants can interface with the brain, either intracortically (direct) or epicortically (indirect). (wikipedia.org)
  • A cortical homunculus is a distorted representation of the human body, based on a neurological "map" of the areas and proportions of the human brain dedicated to processing motor functions, or sensory functions, for different parts of the body. (wikipedia.org)
  • Cortical deafness is most often cause by stroke, but can also result from brain injury or birth defects. (wikipedia.org)
  • Cortical remapping in the somatosensory system happens when there has been a decrease in sensory input to the brain due to deafferentation or amputation, as well as a sensory input increase to an area of the brain. (wikipedia.org)
  • Every part of the body is connected to a corresponding area in the brain which creates a cortical map. (wikipedia.org)
  • The part of the brain that is in charge of the amputated limb or neuronal change will be dominated by adjacent cortical regions that are still receiving input, thus creating a remapped area. (wikipedia.org)
  • Wilder Penfield, a neurosurgeon, was one of the first to map the cortical maps of the human brain. (wikipedia.org)
  • To better understand this phenomenon in the brain, they used micro-electrodes to micromap the monkey's cortical map of its hand. (wikipedia.org)
  • They concluded if a cortical map was able to "normalize" itself when stimulated with an irregular input that the adult brain must be plastic. (wikipedia.org)
  • thalamus
  • After the initial establishment of areal identity, axons from the developing thalamus arrive at their correct cortical areal destination through the process of axon guidance and begin to form synapses. (wikipedia.org)
  • polyspermy
  • Cortical granules are regulatory secretory organelles (ranging from 0.2 um to 0.6 um in diameter) found within oocytes and are most associated with polyspermy prevention after the event of fertilization. (wikipedia.org)
  • In addition to modifying the oocyte's extracellular matrix and establishing a block to polyspermy, the exocytosis of cortical granules may also contribute towards protection and support of the developing embryo during preimplantation. (wikipedia.org)
  • The cortical reaction is a process initiated during fertilization by the release of cortical granules from the egg, which prevents polyspermy, the fusion of multiple sperm with one egg. (wikipedia.org)
  • In contrast to the fast block of polyspermy which immediately but temporarily blocks additional sperm from fertilizing the egg, the cortical reaction gradually establishes a permanent barrier to sperm entry and functions as the main part of the slow block of polyspermy in many animals. (wikipedia.org)
  • Neural
  • A typical cortical implant is an implantable multielectrode array, which is a small device through which a neural signal can be received or transmitted. (wikipedia.org)
  • mammals
  • Cortical granules are found among all mammals, many vertebrates, and some invertebrates. (wikipedia.org)
  • Although various mammals have been studied, mice represent the best studied animal models for understanding the cortical reaction in mammals. (wikipedia.org)
  • neuronal
  • When something happens to disrupt the cortical maps such as an amputation or a change in neuronal characteristics, the map is no longer relevant. (wikipedia.org)
  • mammalian
  • It has been shown in both mammalian and non-mammalian animal models that cortical granule migration depends on cytoskeleton processes, particularly microfilament activity. (wikipedia.org)
  • secretory
  • The cortical reaction within the egg is analogous to the acrosomal reaction within the sperm, where the acrosome, a specialized secretory vesicle that is homologous to cortical granules, is fused with the plasma membrane of the sperm cell to release its contents which degrade the egg's tough coating and allow the sperm to bind to and fuse with the egg. (wikipedia.org)
  • depends
  • The prognosis of a patient with acquired cortical blindness depends largely on the original cause of the blindness. (wikipedia.org)
  • Visual performance depends importantly on the amount of cortical tissue devoted to the task. (wikipedia.org)
  • projections
  • For example, sensory information from the foot projects to one cortical site and the projections from the hand target in another site. (wikipedia.org)
  • areas
  • TMS allows non-invasively the activation of superficially located cortical areas. (ruhr-uni-bochum.de)
  • These layers are most developed in motor cortical areas. (lonza.com)
  • Today the field supports the idea of a 'protomap', which is a molecular pre-pattern of the cortical areas during early embryonic stages. (wikipedia.org)
  • However, more recent research has suggested that there may be two different cortical areas for the genitals, possibly differentiated by one dealing with erogenous stimulation and the other dealing with non-erogenous stimulation. (wikipedia.org)
  • areas of the body adjacent to one another would likely be adjacent on the cortical maps. (wikipedia.org)
  • functions
  • Therefore, one diagnostic test for cortical blindness is to first objectively verify the optic nerves and the non-cortical functions of the eyes are functioning normally. (wikipedia.org)
  • However, the variation of visual performance across the visual field differs widely between different functions (pattern recognition, motion perception, etc.), and cortical magnification is only one factor amongst others that determine visual performance. (wikipedia.org)
  • Once the cortical granules complete their functions, the oocyte does not replenish them. (wikipedia.org)
  • stimulation
  • Repetitive stimulation (rTMS) on the other hand has a sustained modulatory action on cortical excitability, offering a potential therapeutic use. (ruhr-uni-bochum.de)
  • Early work to restore vision through cortical stimulation began in 1970 with the work of Brindley and Dobelle. (wikipedia.org)
  • More recent models, such as the "Utah" Electrode Array use deeper cortical stimulation that would hypothetically provide higher resolution images with less power needed, thus causing less damage. (wikipedia.org)
  • Genetic
  • It has been impossible to find a canonical microcircuit that corresponds to the cortical column, and no genetic mechanism has been deciphered that designates how to construct a column. (wikipedia.org)
  • proteins
  • The cortical granules contain proteases that clip perivitelline tether proteins, peroxidases that harden the vitelline envelope, and glycosaminoglycans that attract water into the perivitelline space, causing it to expand and form the hyaline layer. (wikipedia.org)
  • The released cortical granule proteins exert a colloid osmotic pressure causing water to enter the space between the plasma membrane and the vitelline layer, and the vitelline layer expands away from the egg surface. (wikipedia.org)
  • reaction
  • This exocytosis of cortical granules is known as the cortical reaction. (wikipedia.org)
  • In most animals, the extracellular matrix present around the egg is the vitelline envelope which becomes the fertilization membrane following the cortical reaction. (wikipedia.org)
  • Although highly conserved across the animal kingdom, the cortical reaction shows great diversity between species. (wikipedia.org)
  • Therefore, the cortical reaction prevents polyspermic fertilization, a lethal event. (wikipedia.org)
  • Epilepsy
  • It is estimated that up to 40% of children with drug-resistant epilepsy have a cortical malformation. (springer.com)
  • However, the physiopathological mechanisms relating cortical malformations to epilepsy remain elusive. (springer.com)
  • sensory
  • In some cases, cortical representations can increase two to threefold in 1-2 days at the time at which a new sensory motor behavior is first acquired, and changes are largely finished within at most a few weeks. (wikipedia.org)
  • however
  • However, cortical visual prostheses are important to people who have a completed damaged retina, optic nerve or lateral geniculate body, as they are one of the only ways they would be able to have their vision restored, so further developments will need to be sought out. (wikipedia.org)
  • However, it has been observed in rodents that some cortical granules are rearranged leaving a space amidst the remaining cortical granules. (wikipedia.org)
  • neurological
  • Neurological and cognitive testing help to distinguish between total cortical deafness and auditory agnosia, resulting in the inability to perceive words, music, or specific environmental sounds. (wikipedia.org)
  • visual
  • In most cases, the complete loss of vision is not permanent and the patient may recover some of their vision ( cortical visual impairment ). (wikipedia.org)
  • Cortical blindness can be associated with visual hallucinations , denial of visual loss ( Anton-Babinski syndrome ), and the ability to perceive moving but not static objects. (wikipedia.org)
  • The development of cortical blindness into the milder cortical visual impairment is a more likely outcome. (wikipedia.org)
  • For quantitative purposes, the cortical magnification factor is normally expressed in millimeters of cortical surface per degree of visual angle. (wikipedia.org)
  • The inverse of M (i.e. degrees visual angle per millimeter cortical tissue) increases linearly with eccentricity in the visual field. (wikipedia.org)
  • Consequently, visual performance variations across the visual field can often be equalized by enlarging stimuli depending on their location in the visual field by a factor that compensates for cortical magnification, which is referred to as M scaling (M=magnification). (wikipedia.org)
  • phenomenon
  • Rarely, a patient with acquired cortical blindness may have little or no insight that they have lost vision, a phenomenon known as Anton-Babinski syndrome . (wikipedia.org)
  • fertilization
  • Following fertilization, a signaling pathway induces the cortical granules to fuse with the oocyte's cell membrane and release their contents into the oocyte's extracellular matrix. (wikipedia.org)
  • Additionally, some pre-fertilization cortical granule exocytotic events occur in the cell's cleavage furrow simultaneously with polar body formation. (wikipedia.org)
  • An assortment of hypotheses exist concerning the biological function of CGFDs and pre-fertilization cortical granule exocytosis. (wikipedia.org)