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1996 (1)
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1992 (1)
1Author    Alexander BorstRequires cookie*
 Title    Periodic Current Injection (PCI) -A New Method to Image Steady-State Membrane Potential of Single Neurons in situ Using Extracellular Voltage-Sensitive Dyes  
 Abstract    A new method is described which allows to image the steady-state distribution of m em ­ brane potential of single neurons in situ. The method consists of staining the tissue with an extracellular voltage-sensitive dye (Di-4-ANEPPS) and impaling a single neuron with a microelectrode. After focusing the imaging system onto the cell a large series of images are taken with a C C D camera at the appropriate excitation wavelength of the voltage-sensitive dye while the neuron's membrane potential is shifted by a periodic current injection (PCI). Afterwards two groups of images are averaged separately: those images while the cell was at rest and those images while the cell was hyperpolarized. After subtraction of these averaged images, the resulting difference image shows only the membrane potential of the cell which was altered periodically. The success of the method is demonstrated on leech cells in intact ganglia. If applied to cells with a basically two-dimensional arborization pattern, the decrease of activity in the difference image in areas further away from the injection site should relate to a decrease in membrane potential according to the passive electrotonic properties of the cell under study. 
  Reference    Z. Naturforsch. 50c, 435—438 (1995); received March 21 1995 
  Published    1995 
  Keywords    Membrane Properties, Imaging, Optical Recording 
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 TEI-XML for    default:Reihe_C/50/ZNC-1995-50c-0435.pdf 
 Identifier    ZNC-1995-50c-0435 
 Volume    50 
2Author    Rainer KimmichRequires cookie*
 Title    Multidimensional NQR: Imaging and Exchange Spectroscopy  
 Abstract    In this context a "dimension" can be of a spatial or of a spectroscopic nature. In the last two decades, multidimensional nuclear magnetic resonance and imaging have proven to be most useful tools for the investigation of materials. It turned out that some of these measuring principles can be applied to zero-field NQR as well. The purpose of this presentation is to elucidate two-dimensional exchange spectroscopy and imaging procedures suitable for NQR and to outline potential applications. 
  Reference    Z. Naturforsch. 51a, 330—336 (1996); received January 22 1996 
  Published    1996 
  Keywords    NQR, imaging, 2D exchange spectroscopy, pressure, temperature 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0330.pdf 
 Identifier    ZNA-1996-51a-0330 
 Volume    51 
3Author    Rainer Kimmich, Eberhard Rommel, Peter Nickel, Daniel PusiolRequires cookie*
 Title    NQR Imaging  
 Abstract    A rotating-frame NQR imaging (ßNQRI) procedure based on pure NQR is reported. The tech-nique is suitable for powdery or crystalline solid materials containing quadrupole nuclei. The spatial information is encoded by gradients of the radio frequency amplitude of the excitation pulse. A special deconvolution procedure has been developed for the analysis of the spatial information encoded in the pseudo-FID of the NQR signal in the case of powder geometry. The technique is applicable to rotationally symmetric as well as to asymmetric electric field gradient tensors. The RF gradients are suitably produced by surface coils. The prominent advantage of surface-coil NQR is that objects larger than the coil diameter can be investigated. The imaging procedure then provides depth resolution in a range of the order of the coil radius. The technique is particularly suitable for the detection of gradients of physical parameters influencing the NQR line shift and of spatial distributions of the chemical composition. Examples are stress or temperature gradients. Two-dimensional images have been produced by rotating the sample step by step. For each orientation a profile across the sample is evaluated as the projection on the direction of the radio-frequency gradient. A projection-reconstruction formalism then permits the rendering of two-dimensional NQR images. 
  Reference    Z. Naturforsch. 47a, 361—366 (1992); received June 8 1991 
  Published    1992 
  Keywords    NQR, Imaging, Rotating-frame zeugmatography, Surface coil, Backprojection, Decon-volution 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0361.pdf 
 Identifier    ZNA-1992-47a-0361 
 Volume    47