Abstract
A neuron model with the ability of learning has been examined by means of mathematical and statistical methods. By use of the established anatomical concepts the main features of the model can be described as follows.
The synapses are randomly distributed on the dendrites in a way that can be described by poisson processes. The afferent connections to the synapses are also random.
The input signals are divided into excitatory, inhibitory and unspecified signals. The latter, whose detailed action is not specified, may involve excitatory as well as inhibitory action on the cell. Signals are described in terms of impulse frequencies.
Learning takes place through facilitation of excitatory synapses. The condition for facilitation is the occurrence of simultaneous presynaptic and postsynaptic activity. The synaptical changes occurring during repeated learning are superimposed. Inhibitory synapses are capable of influencing learning by blocking the dendritic transmission.
It is shown that, under certain conditions, a collection of model cells is able to work as an associative memory. This means that a pattern of output signals that once occurred through the combined action of the excitatory, the inhibitory, and the unspecified signals may later be recalled by applying just the two former signal patterns. It is shown that excitatory and inhibitory signals are similar in their ability to evoke associations.
However there is also a difference between excitation and inhibition due to the fact that the pattern of inhibitory signals is subject to a non-linear transformation. This implies that great similarity is required between the inhibitory pattern once present during learning and the inhibitory pattern that is fed in later in order to obtain an associative recall. This phenomenon is called pattern separation and is supposed to be of importance when discriminating between patterns.
Similar content being viewed by others
References
Andersen,P., Eccles,J.C., Løyning,Y.: Location of postsynaptic inhibitory synapses on hippocampal pyramids. J. Neurophysiol. 27, 592–607 (1964).
Andersen,P., Holmqvist,B., Voorhoeve,P. E.: Excitatory synapses on hippocampal apical dendrites activated by entorhinal stimulation. Acta physiol. scand. 66, 461–472 (1966).
Bliss, T.V. P., Lømo, T.: Plasticity in monosynaptic cortical pathway. J. Physiol. (Lond.) 207, 61 P (1970).
Bliss,T. V. P., Gardner-Medwin,A.R.: Long-lasting increases of synaptic influence in the unanaesthetized hippocampus. J. Physiol. (Lond.) 216, 32–33P (1971).
Curtis,D.R., Eccles,J.C.: Synaptic action during and after repetitive stimulation. J. Physiol. (Lond.) 150, 374–398 (1960).
Eccles,J.C.: The neurophysiological basis of mind. Oxford: Oxford University Press 1953.
Eccles,J.C.: The inhibitory pathways of the central nervous system. Liverpool: Liverpool University Press 1969.
Gnedenko,B.V., Kovalenko,I. N.: Vvedenie v teoriyu massovogo obsluzhivaniya. Moskva: Izdatel'stvo “Nauka” 1966. English translation: Introduction to queueing theory. Jerusalem: Israel Program for Scientific Translations 1968.
Hebb,D. O.: The organization of behavior. New York: John Wiley 1949.
Hydén,H., Egyhazi,E.: Changes in RNA content and base composition in cortical neurons of rats in a learning experiment involving transfer of handedness. Proc. nat. Acad. Sci. (Wash.) 52, 1030–1035 (1964).
Lahley,K.S.: Brain mechanisms and intelligence. Chicago: University of Chicago Press 1929.
Llinas,R., Nicholson,C.: Electrophysiological properties of dendrites and somata in alligator purkinje cells. J. Neurophysiol. 34, 532–551 (1971).
Lloyd,D.P.C.: Post-tetanic potentiation of responce in monosynaptic reflex pathways of the spinal cord. J. gen. Physiol. 33, 147–170 (1949).
Marr,D.: A theory of cerebellar cortex. J. Physiol. (Lond.) 202, 437–470 (1969).
Rashewsky,N.: Mathematical Biophysics. Chicago: University of Chicago Press 1938.
Steinbuch,K.: Die Lernmatrix. Kybernetik 1, 36–45 (1961).
Willshaw,D. J., Buneman,O. P., Longuet-Higgins,H.C.: Non holographic associative memory. Nature (Lond.) 222, 960–962 (1969).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Wigström, H. A neuron model with learning capability and its relation to mechanisms of association. Kybernetik 12, 204–215 (1973). https://doi.org/10.1007/BF00270573
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00270573