Neural Elements (neural + element)

Distribution by Scientific Domains


Selected Abstracts


Clinical application of neurotrophic factors: the potential for primary auditory neuron protection

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 9 2005
Lisa N. Gillespie
Abstract Sensorineural hearing loss, as a result of damage to or destruction of the sensory epithelia within the cochlea, is a common cause of deafness. The subsequent degeneration of the neural elements within the inner ear may impinge upon the efficacy of the cochlear implant. Experimental studies have demonstrated that neurotrophic factors can prevent this degeneration in animal models of deafness, and can even provide functional benefits. Neurotrophic factor therapy may therefore provide similar protective effects in humans, resulting in improved speech perception outcomes among cochlear implant patients. There are, however, numerous issues pertaining to delivery techniques and treatment regimes that need to be addressed prior to any clinical application. This review considers these issues in view of the potential therapeutic application of neurotrophic factors within the auditory system. [source]


Saccadic eye movements evoked by microstimulation of striate cortex

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2003
Edward J. Tehovnik
Abstract Experiments were performed to assess the excitability of neural elements activated while inducing saccadic eye movements electrically from different cortical layers of striate cortex (area V1) in rhesus monkeys. Excitability was assessed by measuring current thresholds, saccadic latencies, chronaxies, and the effectiveness of anode-first vs. cathode-first pulses. Minimum current thresholds for the evocation of saccades (i.e. less than 5 µA) were observed when the deepest layers of V1 were stimulated. The shortest saccadic latencies were also observed at these depths. The shortest latency at 10 times the threshold current was 49 ms on average. The chronaxies of the elements mediating saccades were less in deep V1 (i.e. 0.17 ms) than in superficial V1 (i.e. 0.23 ms). Anode-first pulses were more effective at evoking saccades from superficial V1, whereas cathode-first pulses were more effective at evoking saccades from deep V1. These results indicate that the excitability properties of superficial and deep V1 are distinct for the generation of saccades. Moreover, the excitability of elements mediating saccades in V1 of monkeys is comparable to that of elements mediating phosphenes in human V1. [source]


Bilateral symmetric organization of neural elements in the visual system of a coelenterate, Tripedalia cystophora (Cubozoa)

THE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2005
Linda Parkefelt
Abstract Cubozoans differ from other cnidarians by their body architecture and nervous system structure. In the medusa stage they possess the most advanced visual system within the phylum, located in sophisticated sensory structures, rhopalia. The rhopalium is a club-shaped structure with paired pit-shaped pigment cup eyes, paired slit-shaped pigment cup eyes, and two complex camera-type eyes: one small upper lens eye and one large lower lens eye. The medusa carries four rhopalia and visual processing and locomotor rhythm generation takes place in the rhopalia. We show here a bilaterally symmetric organization of neurons, with commissures connecting the two sides, in the rhopalium of the cubozoan Tripedalia cystophora. The fortuitous observation that a subset of neurons is strongly immunoreactive for a PCNA (proliferating cell nuclear antigen)-like epitope allowed us to analyze the organization of these neurons in detail. Distinct PCNA-immunoreactive (PCNA-ir) nuclei form six bilateral pairs that are associated with the slit eyes, pit eyes, upper lens eye, and the posterior wall of the rhopalium. Three commissures connect the clusters of the two sides and all clusters in the rhopalium have connections to the area around the base of the stalk. This neuronal system provides an anatomical substrate for integration of visual signals from the different eyes. J. Comp. Neurol. 492:251,262, 2005. © 2005 Wiley-Liss, Inc. [source]


Potential Structures That Could Be Confused With a Nonrecurrent Inferior Laryngeal Nerve: An Anatomic Study,

THE LARYNGOSCOPE, Issue 1 2008
Eva Maranillo MD
Abstract Objectives: Study and detailed description of the large connections between the normally recurrent inferior laryngeal nerve (RILN) and the sympathetic trunk (ST) because these may be mistaken for a nonrecurrent inferior laryngeal nerve (NRILN). Study Design: Morphologic study of adult human necks. Methods: The necks of 144 human, adult, embalmed cadavers were examined (68 males, 76 females). They had been partially dissected by Cambridge preclinical medical students and then further dissected by the authors using magnification. The RILN, the ST, and their branches were identified and dissected. A total of 277 RILNs and STs (137 rights, 140 lefts) were observed. Results: A communicating branch (CB) with a similar diameter to the RILN occurred between the ST and the RILN in 48 of the 277 (17.3%) dissections, 24 from the 137 (17.5%) right dissections, and 24 from the 140 (17%) left dissections. In 12 cases, the CB was bilateral. The CB arose from the superior cervical sympathetic ganglion in 3 of the 48 (6.25%) cases, from the middle ganglion in 10 (21%) cases, from the stellate ganglion in 3 (6.25%) cases, and from the ST in 32 (66.6%) cases. One (0.36%) NRILN associated with a right retro-esophageal subclavian artery (arteria lusoria) was found. Conclusions: 1) The CB between the RILN and the ST may have a diameter and course similar to an NRILN and may be confused with it. 2) The occurrence of the CB is greater than the occurrence referred to in previous studies. 3) The occurrence of the CB is similar by side and sex. 4) The CB may arise at different levels from the cervical ST and ganglia and end in the thyroid area. 5) Other neural elements may also be confused with an RILN, such as the cardiac nerves and the collateral branches from an NRILN to the trachea and esophagus. [source]


Multichannel Cochlear Implants: Relation of Histopathology to Performance,

THE LARYNGOSCOPE, Issue 8 2006
Jose N. Fayad MD
Abstract Objectives: To determine the relationship of surviving neural elements to auditory function in multichannel cochlear implant temporal bones. Study Design: Case series of all 14 existing multichannel cochlear implants in our temporal bone collection. Methods: Devices included Nucleus 22 (n = 11), Nucleus 24 (n = 1), Ineraid (n = 1), and Clarion (n = 1). Morphologic evaluation of structural elements including spiral ligament, stria vascularis, hair cells, peripheral processes, and spiral ganglion cells was performed. Clinical performance data were obtained from patient charts. For eight patients, nonimplanted contralateral temporal bones were available and paired comparisons were made. Results: Despite frequent absence of hair cells and peripheral processes, all bones had at least some remaining spiral ganglion cells. Percent of normal remaining structures were unrelated to auditory performance with the implant for any of the structural elements. Ganglion cell count in segment III showed significant negative correlations to speech discrimination scores for words and sentences (Rhos = ,.687 and ,.661, P , .03 and .04) as did segment IV and total ganglion cell count with word score (Rhos = ,.632 and ,.638; P , .05). Spiral ganglion cell survival did not differ between implanted and nonimplanted ears, with the exception of segment I, which had fewer cells in the implanted ear (P , .028). Conclusions: Performance variability of cochlear implants cannot be explained on the basis of cochlear neuronal survival. Although hair cells and peripheral processes were frequently absent or greatly diminished from normal, all subjects had at least some spiral ganglion cells. And, in this series, there was an inverse relationship between survival of ganglion cells and performance. [source]