Pacemakers, Synchronization, and Epilepsy

  • M. Verzeano


Few words in the vocabulary of neurophysiology have been more misused than “synchronization”. This term originated in the mid-thirties, when it was believed that brain waves were generated by the synchronous discharge and the summation of action potentials produced by cortical neurons. A few years later (Renshaw et al. 1940; Li and Jasper 1953) it was shown that synchronous discharge of neurons could not be found, and could not be related to the development of brain waves. In the mid-fifties (Verzeano and Calma 1954; Verzeano 1955, 1956) it was shown that the neuronal discharge which accompanies the development of periodic gross waves, in the cortex and in the thalamus, is sequential rather than synchronous, i.e., several groups of neurons discharge in a regular sequence in relation to each gross wave. Around the same epoch, new hypotheses were presented involving graded potentials, synaptic and dendritic, which would not have to occur synchronously in order to summate and generate brain waves. From that time on, the term “synchronization” was reserved for the development, in the electroencephalogram or the electrocorticogram, of rhythmic waves such as those which occur in the alpha rhythm or in sleep spindles. It is still used in this sense at the present time, even though there is sufficient evidence to indicate that nothing is truly synchronous in any aspect of brain wave development. However, since, so far, neurophysiologists and electroencephalographers have not agreed on a better term, “synchronization” will be used in this article to denote the development of rhythmic waves, wherever they may occur, in cortical or subcortical structures.


Neuronal Activity Neuronal Network Thalamic Nucleus Neuronal Discharge Brain Wave 
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  1. Adrian, E. D.: Afferent discharges to the cerebral cortex from peripheral sense organs. J. Physiol. 100, 159–191 (1941).PubMedGoogle Scholar
  2. Andersen, P., and S. A. Andersson: Physiological basis of the alpha rhythm. New York: Appleton-Century-Crofts. 1968.Google Scholar
  3. Andersen, P., and J. C. Eccles: Inhibitory phasing of neuronal discharge. Nature 196, 645–647 (1962).PubMedCrossRefGoogle Scholar
  4. Andersen, P., and T. A. Sears: The role of inhibition in the phasing of spontaneous thalamo-cortical discharge. J. Physiol. 173, 459–480 (1964).PubMedGoogle Scholar
  5. Babb, T. L., M. Babb, J. H. Mahnke, and M. Verzeano: The action of cholinergic agents on the electrical activity of the non-specific nuclei of the thalamus. Int. J. Neurol. (in press, 1972).Google Scholar
  6. Creutzfeldt, O. D., S. Watanabe, and H. D. Lux: Relations between EEG phenomena and potentials of single cortical cells. I. Evoked responses after thalamic and epicortical stimulation. Electroenceph. clin. Neurophysiol. 20, 1–18 (1966 a).CrossRefGoogle Scholar
  7. Creutzfeldt, O. D., S. Watanabe, and H. D. Lux: Relations between EEG phenomena and potentials of single cortical cells. II. Spontaneous and convulsoid activity. Electroenceph. clin. Neurophysiol. 20,19–37 (1966 b).CrossRefGoogle Scholar
  8. Doty, R. W., and D. S. Kimura: Oscillatory potentials in the visual system of cats and monkeys. J. Physiol. 168, 205–218 (1963).PubMedGoogle Scholar
  9. Frigyesi, T. L.: Intracellular studies of neurons in the thalamic reticular nucleus during caudate, capsular and thalamic stimulation. Fed. Proc. 30, 324 (1971).Google Scholar
  10. Doty, R. W., and R. Schwartz: Reciprocal innervation of ventrolateral and medial thalamic neurons by corticothalamic pathways. In: Frigyesi, T. L., E. Rinvik, and M. D. Yahr (eds.), Corticothalamic Projections and Sensorimotor Activities. New York: Raven Press. (In press, 1972.)Google Scholar
  11. Fuxe, K., T. Hökfelt, and U. Ungerstedt: Morphological and functional aspects of central monoamine neurons. Int. Rev. Neurobiol. 13, 93–126 (1970).CrossRefGoogle Scholar
  12. Hanbery, J., and H. H. Jasper: Independence of diffuse thalamo-cortical pro-jection system shown by specific nuclear destruction. J. Neurophysiol. 16, 252–271 (1953).PubMedGoogle Scholar
  13. Jasper, H. H.: Functional properties of the thalamic reticular system. In: Adrian, E. D., F. Bremer, and H. H. Jasper (eds.), Brain Mechanisms and Consciousness, pp. 374–401. Springfield: Charles C. Thomas. 1954.Google Scholar
  14. Jouvet, M.: Biogenic amines and the states of sleep. Science 163, 32–41 (1969).PubMedCrossRefGoogle Scholar
  15. Laufer, M., and M. Verzeano: Periodic activity in the visual system of the cat. Vision Research 7, 215–229 (1967).PubMedCrossRefGoogle Scholar
  16. Li, C. L., and H. H. Jasper: Microelectrode studies of the electrical activity of the cerebral cortex in the cat. J. Physiol. 121, 117–140 (1953).PubMedGoogle Scholar
  17. Lynch, G., and S. Moscow: Personal Communication (1971).Google Scholar
  18. Mescherskii, R. M.: The vectorgraphical characteristic of spontaneous rabbit brain cortex activity. Sechenov Physiological Journal of the USSR (English Translation) 47, 419–426 (1961).Google Scholar
  19. Morison, R. S., and D. L. Bassett: Electrical activity of the thalamus and basal ganglia in decorticate cats. J. Neurophysiol. 8, 309–314 (1945).Google Scholar
  20. Morison, R. S., and E. W. Dempsey: A study of thalamo-cortical relations. Amer. J. Physiol. 135, 281–292 (1942).Google Scholar
  21. Moruzzi, G., and H. W. Magoun: Brain stem reticular formation and activation of the EEG. Electroenceph. clin. Neurophysiol. 1, 455–473 (1949).Google Scholar
  22. Negishi, K., M. C. Bravo, and M. Verzeano: The action of convulsants on neuronal and gross wave activity in the thalamus and in the cortex. Electroenceph. clin. Neurophysiol. Suppl. 24, 90–96 (1963).Google Scholar
  23. Negishi, K., E. S. Lu, and M. Verzeano: Neuronal activity in the lateral geniculate body and the nucleus reticularis of the thalamus. Vision Research 1, 343–353 (1962).CrossRefGoogle Scholar
  24. Olivier, A., A. Parent, and L. J. Poirier: Identification of the thalamic nuclei on the basis of their cholinesterase content in the monkey. J. Anat. 106, 37–50 (1970).PubMedGoogle Scholar
  25. Petsche, H., and P. Rappelsberger: Influence of cortical incisions upon synchronization pattern and travelling waves. Electroenceph. clin. Neurophysiol. 28, 592–600 (1970).Google Scholar
  26. Petsche, H., and J. Sterc: The significance of the cortex for the travelling phenomenon of brain waves. Electroenceph. clin. Neurophysiol. 25, 11–22 (1968).Google Scholar
  27. Purpura, D. P.: Nature of electrocortical potentials and synaptic organizations in cerebral and cerebellar cortex. Int. Rev. Neurobiol. 1, 47–163 (1959).PubMedCrossRefGoogle Scholar
  28. Purpura, D. P., and R. J. Shofer: Cortical intracellular potentials during augmenting and recruiting responses. I. Effects of injected hyperpolarizing currents on evoked membrane potential changes. J. Neurophysiol. 27, 117–132 (1964).PubMedGoogle Scholar
  29. Renshaw, B., A. Forbes, and B. R. Morison: Activity of isocortex and hippo-campus: Electrical studies with micro-electrodes. J. Neurophysiol. 3, 74–105 (1940).Google Scholar
  30. Scheibel, M. E., and A. B. Scheibel: Patterns of organization in specific and nonspecific thalamic fields. In: Purpura, D. P., and M. D. Yahr (eds.), The Thalamus, pp. 13–46. New York: Columbia University Press. 1966.Google Scholar
  31. Shuts, C. C. D., and P. R. Lewis: The ascending cholinergic reticular system: neocortical, olfactory and subcortical projections. Brain 90, 497–520 (1967).CrossRefGoogle Scholar
  32. Starzl, T. E., C. W. Taylor, and H. W. Magoun: Ascending conduction in reticular activating system, with special reference to the diencephalon. J. Neurophysiol. 41, 461–477 (1951).Google Scholar
  33. Verzeano, M.: Sequential activity of cerebral neurons. Arch. Internat. Physiol. Biochim. 63, 458–476 (1955).CrossRefGoogle Scholar
  34. Verzeano, M.: Activity of cerebral neurons in the transition from wakefulness to sleep. Science 124, 366–367 (1956).PubMedCrossRefGoogle Scholar
  35. Verzeano, M.: The synchronization of brain waves. Acta Neurol. Latinoamer. 9, 297–307 (1963).Google Scholar
  36. Verzeano, M.: Evoked responses and network dynamics. In: Whalen, R. E., R. F. Thompson, M. Verzeano, and N. M. Weinberger (eds.), The Neural Control of Behavior, pp. 27–54. New York: Academic Press. 1970.Google Scholar
  37. Verzeano, M., and I. Calma: Unit-activity in spindle bursts. J. Neurophysiol. 17, 417–428 (1954).PubMedGoogle Scholar
  38. Verzeano, M., R. Dill, G. Navarro, and E. Vallecalle: The action of metrazol on spon- taneous and evoked activity. Physiol and Behay. 5,1099–1102 (1970 b).CrossRefGoogle Scholar
  39. Verzeano, M., M. Laufer, Phyllis Spear et Sharon Mcdonald: L’activité des reseaux neuroniques dans le thalamus du singe. Actualités Neurophysiologiques 6, 223–252 (1965).PubMedGoogle Scholar
  40. Verzeano, M., and S. Mcdonald: The activity of neuronal networks in the thalamus of the monkey. In: Pribram, K., and D. E. Broadbent (eds.), Biology of Memory, pp. 239–271. New York: Academic Press. 1970 a.Google Scholar
  41. Verzeano, M., and J. H. Mahnke: In Press.Google Scholar
  42. Verzeano, M., and K. Negishi: Neuronal activity and states of consciousness. Proc. Int. Cong. Physiol. Buenos Aires. August 1959.Google Scholar
  43. Verzeano, M., and K. Negishi: Neuronal activity in wakefulness and in sleep. In: Wolstenholme G. E. W., and M. O’connor (eds.), The Nature of Sleep, pp. 108–130. ( Ciba Symposium.) London: Churchill. 1961.Google Scholar

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© Springer-Verlag/Wien 1972

Authors and Affiliations

  • M. Verzeano
    • 1
  1. 1.Department of PsychobiologyUniversity of CaliforniaIrvineUSA

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