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    Comparison of Fiber Diameter Distributions Deduced by Modeling Compound Action Potentials Recorded by Extracellular and Suction Techniques
    (TAYLOR & FRANCIS LTD, 2002) Dalkılıç, Nizamettin; Pehlivan, Ferit
    In this study, the extracellular and suction techniques, used widely to record compound action Potentials (CAP), were compared in respect to their ability to deduce fiber diameter distribution (FDD). Fiber. diameter distribution derived by applying the deconvolution model to CAP depends not only on the modeling but also on the recording techniques. The FDDs determined by these two techniques were compared with that predicted by histological means. In our model study, a waveform for single fiber action potential (SFAP) was defined as f(t) = Asin(t/tau(01)) . exp(-t/tau(02)) where the parameters tau(1) and tau(2) were taken from the literature and given for the SFAP of each fiber diameter between d = 3-22 mum, and A Was chosen to normalize the amplitude of SFAP to 1. We substituted the measured CAPs into our model and calculated the histograms related with the fiber diameter distribution of the sciatic nerve trunk. We sail, that the FDD as predicted from the CAP, recorded by the extracellular techniques, coincides better with that of the histologically determined FDD than that predicted by suction techniques.
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    Conduction velocity distribution: Early diagnostic tool for peripheral neuropathies
    (TAYLOR & FRANCIS LTD, 2007) Kiziltan, Erhan; Dalkilic, Nizamettin; Guney, Figen Bayramoglu; Pehlivan, Ferit
    In order to get early information on the functional state of smaller myelinated fibers this article investigated the applicability of conduction velocity distribution on compound action potential recorded in experimentally demyelinated frog sciatic nerve. Conduction velocity distribution histograms were estimated by using the mathematical model the authors enhanced. The results suggest that by using appropriate conduction velocity distribution model the diagnosis time in demyelinating neuropathy may be shortened at least three times as compared with conventional conduction velocity assessment. Therefore, it may be concluded that a well-defined model designed for the estimation of the conduction velocity distribution may be used as a diagnostic tool for the early phase of peripheral demyelinating neuropathies.
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    A Correction Procedure for the Volume Conductor Effect in the Compound Action Potential Recorded From Isolated Nerve Trunk
    (Taylor & Francis Ltd, 2002) Dalkılıç, Nizamettin; Pehlivan, Ferit
    The shape and magnitude of the compound action potential (CAP), which is the linear summation of the single fiber action potentials, depend strongly on the recording conditions. Volume conductor effect should be eliminated or corrected in order to get reliable information about the functional state of the nerve trunk. In the case of nronophasic extracellular recordings, the integral of CAP recorded extracellularly tends to decrease with the distance, because the extracellular resistance between the stimulating and recording electrodes changes. To compensate for this effect, we took into account the spatial deviation of the integral of CAP versus distance and defined a spatial correcting factor, g(x). By applying g(x) to all CAPS, we get corrected CAP (cCAP) data for further evaluations. It is well known that the slope of the maximum derivative of CAP versus distance curve would be a measure of conduction velocity distribution for the fast conducting nerves in a nerve trunk. The slopes of these curves for extracellular and suction techniques on the same nerves are compared; we concluded that the difference between the two techniques was not important for the correction procedure on extracellular records.
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    Does Collagenase Affect the Electrophysiological Parameters of Nerve Trunk?
    (PHARMACEUTICAL SOC JAPAN, 2003) Dalkilic, Nizamettin; Kiziltan, Erhan; Pehlivan, Ferit; Kose, Kenan
    Collegenase is widely used in the process of teasing a nerve in order to perform single fiber action potential (SFAP) recordings. In this study, the effects of collagenase on nerve conduction parameters were investigated. To accomplish this, normal compound action potentials (nCAPs) were recorded from isolated frog sciatic nerve at various distances using the suction technique. Then, the same nerve was treated with collagenased Ringer's solution (3.5 mg/ml, Sigma Type XI) for 90 minutes and action potentials (cCAPs) were recorded again. Numerical analysis of these records was performed and the results were compared. Using the nCAP and cCAP recordings, the conduction velocity distributions (CVD) of the individual nerve trunks were determined by a method that we have previously described. Statistical results indicated significant differences (p<0.05) between the nCAP and cCAP CVD data. From these findings it is concluded that, when used for teasing the nerve fibers, collagenase may affect the nerve trunk conduction parameters. Specifically, a significant amount of decrease has been observed in conduction velocities of myelinated fibers having diameters smaller than 8 mum.
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    Sexual dependency of rat sciatic nerve fiber conduction velocity distributions
    (TAYLOR & FRANCIS LTD, 2007) Ayaz, Murat; Kiziltan, Erhan; Tuncer, Seckin; Dalkilic, Nizamettin; Demirel, Ilhami; Bariskaner, Hulagu; Pehlivan, Ferit
    Gender differences, either with the structural or through with hormones, dictate how the corresponding organ or organ system responses to physiological signals. Current study aims to investigate gender dependent differences in conduction related parameters of rat sciatic nerve. Compound action potentials ( CAP) were recorded via suction electrode whereas the conduction velocity distributions (CVD) were performed using the method known as collision technique in the literature. Studied CAP parameters, namely conduction velocities ( CV), area of the CAPs and time required to reach the maximum depolarization (TP) have been found significantly different for female and male rats. Detailed analyses have shown that sex dependent differences were more remarkable in the right leg responses of female and male rats. Additionally, CVDs indicate that the number of fibers having CVs between 5-30 m/s is much more in male right sciatic nerve trunk when compared to age matched female rats. The present study, for the first time clearly shows that shift in the contribution of nerve fibers to lower CVs is the main causal of the sex dependent differences seen in rat sciatic nerve fibers.