Two types of evoked potentials are recorded in the tectum mesencephali in response to electrical stimulation of the forebrain surface of the turtleEmys orbicularis. The results of a layer-by-layer analysis show that evoked potentials of type I in response to stimulation of the hippocampal and piriform cortex are generated outside the tectum. Evoked potentials of type II, consisting of two surface-negative components, are recorded in the tectum in response to stimulation of the rostro-central surface of the forebrain. The first component appeared after a latent period of 20 msec and lasted 40–60 msec; the second component appeared after 80–100 msec and lasted 100–300 msec. Layer-by-layer and pharmacological analysis showed that the first component of the type II evoked potential is generated in the tegmental structures of the mesencephalon, whereas the second (long-latency) is generated in the tectum. The tectal origin of the second component is confirmed by its interaction with the tectal response to photic stimulation or to electrical stimulation of the optic nerve, evidence that these evoked potentials are generated by common structures. The efferent pathway from the dorsal cortex to the primary visual center is unilateral and has features of polysynaptic projections (long latent period, low lability).
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M. M. Akulina, "Electrophysiological investigation of thalamo-telencephalic relations in the turtle," Zh. Évolyuts. Biokhim. i Fiziol.,7, 543 (1971).
M. G. Belekhova and M. M. Akulina, "The tecto-thalamo-telencephalic system of the turtle," Neirofiziologiya,2, 296 (1970).
T. M. Zagorul'ko, M. G. Belekhova, and N. P. Veselkin, "Features of evoked responses of the turtle cerebral cortex (to photic stimuli)," in: Functional Organization of the Nervous System [in Russian], Nauka, Leningrad (1965), pp. 73–83.
T. M. Zagorul'ko, "Functional connections of the general cortex and visual center of the tectum mesencephali of the turtle," Zh. Évolyuts. Biokhim. i Fiziol.,3, 342 (1967).
S. B. Isabekova, "Influence of the forebrain cortex on unit activity of the turtle mesencephalon," Abstracts of Proceedings of a Junior Scientific Conference of the A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR [in Russian], Moscow (1968), pp. 18, 19.
O. A. Karamyan, "Mesencephalo-cortical connections in reptiles," Dokl. Akad. Nauk SSSR,160, 479 (1965).
A. I. Karamyan, The Functional Evolution of the Vertebrate Brain [in Russian], Nauka, Leningrad (1970).
A. I. Karamyan, T. M. Zagorul'ko, M. G. Belekhova, and N. P. Veselkin, "Morpho-functional features of cortico-subcortical relations in premammalian vertebrates," in: Cortical Regulation of Subcortical Activity of the Brain [in Russian], Metsniereba, Tbilisi (1968), pp. 96–114.
A. I. Karamyan, M. G. Belekhova and T. M. Zagorul'ko, "A new conception of the evolution of two divisions of the certebrate visual system: retino-geniculo-cortical and retino-tecto-thalamo-cortical," Zh. Évolyuts. Biokhim. i Fiziol.,8, 166 (1972).
P. Z. Mazurskaya and G. D. Smirnov, "Functional aspects of projections of exteroceptors in the dorsal cortex of the turtle forebrain," Zh. Évolyuts. Biokhim. i Fiziol.,1, 442 (1965).
P. Z. Mazurskaya and G. D. Smirnov, "Some characteristics of the visual projections of the turtle forebrain," Dokl. Akad. Nauk SSSR,167, 1414 (1966).
Yu. B. Manteifel', "Interaction between evoked potentials of the frog tectum mesencephali," Dokl. Akad. Nauk SSSR,168, 712 (1966).
K. V. A. Kappers and G. C. Huber, The Comparative Anatomy of the Nervous System, Macmillan, New York (1936).
H. I. Northcutt, "Architectonic research of the telencephalon ofIguana iguana," J. Comp. Neurol.,130, 109 (1967).
W. M. Shanklin, "The central nervous system ofChameleon vulgaris," Acta. Zool.,11, 425 (1930).
A. N. Severtsov Institute of Evolutionary Morphology and Ecology of Animals, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 6, No. 2, pp. 127–134, March–April, 1974.
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Isabekova, S.B. Electrophysiological analysis of cortico-tectal connections in the turtle. Neurophysiology 6, 97–103 (1974). https://doi.org/10.1007/BF01062744
- Electrical Stimulation
- Optic Nerve
- Latent Period
- Common Structure
- Analysis Show