Veränderungen von Spontanaktivität und Reizantwort retinaler und geniculärer Neurone der Katze bei fraktionierter Injektion von Pentobarbital-Na (Nembutal)

✍ Scribed by R. Schmidt; O. D. Creutzfeldt

• Publisher: Springer
• Year: 1968
• Tongue: English
• Weight: 954 KB
• Volume: 300
• Category: Article
• ISSN: 0031-6768
• DOI: 10.1007/bf00362545

✦ Synopsis

~:~. SCHiVIIDT und O. D. CREUTZFELDT Abteilung fiir Neurophysiologie des 5{ax-Planck-Instituts ffir Psychiatrie, Miinchen Eingegangen am 28. Dezember 1967 Changes o~ Spontaneous and Evoked Activity o/ Single Neurones o/ the Retina and Lateral Geniculate Body o/ the Cat Induced by Fractionated

Injection o/ Pentobarbital-Na (NembutaO Summary. 1. Changes of the spontaneous and evoked activity of optic tract and radiation fibers of cats after fractionated injections of Pentobarbital-Na (Nembutal) were investigated. Every 5 rain 5 mg Nembutal were injected intravenously and the mean discharge rate, the interval and post-stimulus histograms were taken.

2. The over-all activity of most retinal neurones increased after injections between 5 and 30 mg Nembutal. Only in experiments with an initially low discharge rate a decrease was observed from the beginning. Beyond 30 rag, the activity of all ncurones was depressed. After each injection, a multiphasic sequence of activity changes was seen, with initial activation, secondary strong depression, and slow recovery into a steady state. Postgeniculate neurones did not show an initial increase of activity.

3. Retinal ganglion cells showed characteristic changes of their discharge pattern at a medium anaesthetic dosis, with grouped discharges and multimodal interval distributions. The short intervals of 4--5 msec were extremely constant in all experiments and were independant from the dosis. The longer intervals (15 to 35 msec and multiples) were more variable and dosis dependant. The observed interval distributions are explained by the sub-and supranormal phases of retinal ganglion cells (delayed depolarization and polarizing after-potential).

4. The reaction to punctiform light stimuli into the center of the receptive field showed a stronger decrease of the tonic steady state than of the initial phasic reactions. With decreasing steady-state-activation of omcenter-neurones a phasic off-activation became apparent, which was already present before anaesthesia but indiscriminable from the steady-state discharge. Off-center neurones only showed a slight decrease of the off-reaction. The reactions of geniculate neurones were depressed stronger than those of retinal cells.

5. The importance of peripheral and general membrane mechanisms for the action of anaesthetic drugs is emphasized.