Anastasi, M. and Bellomonte, L. and Brai, M. and Lauricella, M. (1994) Aspetti temporali dell'elettroretinogramma (ERG) umano. Accademia Peloritana dei Pericolanti Classe FF.MM.NN., LXXII (Supplement 1). pp. 309-319.
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The retina is a highly compiex nervous tissue containing two stages of synaptic layers and at least five types of cells. The electrical response of the retina, recorded by the electrorctinogram (ERG), reflects the complexity of the anatomicai connection in the retina.
When a flash of light fails on the retina, the ERG records the change of the retinai potential from the resting potentiai generated at the junction between the photoreceptors and the pigment epithelium. It consists of various components which arise in different layers of the retina.
We analyse the temporal aspects of three components of the seven recordable eiectricai potentials evoked by a flash of light: the a- and b-waves, and the OPs.
The a-wave is generated along a radial path from the cell body of the photoreceptors into the membrane of the outer segments and is an important component of the clinical ERG as a measure of photoreceptos activity. The a-wave consists of several components arising from cones and rods.
The b-wave originates, probabiy, in Muller cells which reflect extracellular current spread due to potassium concentration changes caused by the depolarising activity and is expression of post-synaptic summed neuronal activities and thus is an important measure. The b-wave implicit time is a good indicator of receptor sensitivity and hence it correlates with the Naka-Rushton parameters.
The osciiiatory potentials (OPs) of the electroretinograrn (ERG) are small waves superimposed on the b-wave of the ERG. It seems that their generators are probably located at inner plexiform layer and can reflect the activity of inhibitory feedback circuits strictly dependent on the retinal circulation. For this reason the OPs have a considerable clinical interest even if until now there is a great deal of disagreement about their measurement and analysis. The OP analysis in the frequency domain gives a measurement of the energy content and of the dominating frequency. The OPs were analysed in time and frequency domain by Fourier Transform after spectrum filtering. The amplitudes, the delays, the
dominant frequencies and the correlation coefficients were calculated.
The analyses were carried out in normal eyes and in eyes affected by different selected pathologies.
|Subjects:||M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Fisiche, Matematiche e Naturali > 1994 > Supplemento 1 parte 1|
M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Medico-Biologiche > 1994 > Supplemento 1 parte 1
M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Scienze Giuridiche, Economiche e Politiche > 1994 > Supplemento 1 parte 1
M.U.S. - Miscellanea > Atti Accademia Peloritana > Classe di Lettere, Filosofia e belle Arti > 1994 > Supplemento 1 parte 1
|Depositing User:||Mr Nunzio Femminò|
|Date Deposited:||02 Apr 2014 16:28|
|Last Modified:||02 Apr 2014 16:28|
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