J. theor. Biol. (1975) 49, 245-247
Lt~rrer.
TO THE
EDITOR
On the Perception of Information in CNS Memory Mechanism The discussion initiated by Mikhaltsev (1972) makes it necessary to clarify one of the points of the suggested concept. It was mentioned in the article that " . . . the engram consolidation process is understood as an unconditional and immediate result of the perception of information". This suggestion caused some opposition. The basis of the objections is that not all the information perceived is stored. One of the arguments was that it would "waste" the storage capacity of the memory. Others emphasized that relatively little is stored in memory, as compared to how much is forgotten ('Y. D. Zuckerbrot, F. O. Schmitt, pets. comm.). I assume that the origin of the objections lies in the understanding of the term perception. I want to call attention to the principal difference between the volume of the information perceived by a biological system and the volume of the information which is presented to it or available for perception at the moment. I assume that in the CNS there is a mechanism which filters out of the whole volume of the available information a very small portion which becomes the perceived one. What is the physiology of the mechanism and what experimental evidence can be given for the validity of this statement ? The physiological substantiation of the existence of such a mechanism can be traced back to the works of Sherrington (1911) who disclosed the reciprocal innervation for anatomical antagonists and to the discovery of Ukhtomsky (1923) of the principle of "the dominant", as a dynamic constellation of innervated areas in the nervous system which optimize the reaction to the acting stimuli. This was understood as a mechanism which provides a proper choice of the most important stimulus out of all available ones at the moment. It would be vital for the survival of lower animals or for much more complicated reasons in the case of man, to make a proper reaction to this stimulus. Later, the physics of the dominant was investigated by Rusinov (1953) who reported the behavioural responses to low-level transcortieal polarization. In the international neuroscience literature such terms as "the dominant"-understood as a general physiological principle, or "the dominant focus"M understood as the correlated physiological phenomenon, are used rather
246
I.E.
MIKHALTSEV
rarely (though sometimes they are still in use--e.g. John, 1967). Mostly these terms describing the physiological state of the system are substituted by definition of the physical consequence of such a physiological state-localized "steady potential shifts (or gradients)". The works of Morrell (1963), Rowland (1967), Nielson (1968) and others show that steady potential shifts form a mechanism which prepares the CNS for the acceptance of novel information. Additional confirmation of the role of the steady potential shifts in the process of perception of information is found in a comprehensive review of Rowland (1968) as well as some results of a broad discussion on the problem of slow electrical phenomena in the CNS (Adey, 1969). The final contribution to the list might be the monograph of Rusinov (1969) who summarized important facts concerning the effect of slow potential changes in CNS on the behaviour of an animal. These experimental results may be regarded as good evidence in support of the validity of the statement that the dominant, or its physical correlate-the dynamics of the steady potential shifts in the cortex, is the mechanism which controls the volume of information perceived by the system out of the whole volume of information available at the moment. This physiological mect/anism is assumed to be equivalent to a narrow filter in the information domain; the action of such a falter prevents the overloading effect of memory. Though this analogy seems favorable for proper understanding of the described phenomenon I want to warn the reader against the temptation to broaden the analogy beyond the limits of its illustratory value. An attempt to apply the well developed filter-problems mathematics to the case should fail because of the dramatic difference between the physics of filtering (or resonance) process and the biological background of the discussed mechanism. I wish to thank my colleagues whose friendly remarks triggered the formulation of the foregoing comments which might be of some use to the experimenters involved "in the search of the engram". Institute of Oceanology, Academy of Sciences of U.S.S.R., Moscow, 109387, U.S.S.R.
IGOR E. MIKr~LTSEV
(Received 7 November 1973, and in revised form 2 July 1974)
REFERENCES ADEY,W. R. (1969). Neurosciences Res. Prog. Bull. 7, 1. JOHN,E. R. (1967). Mechanisms of Memory, p. 182. New York: Academic Press. MORaELL,F. (1963). In Information Storage and Neural Control (W. Fields & W. Abbot, eds) p. 189, Springfield, Iil.: Thomas. Mmm~rs~v, I. E. (1972). J. theor. Biol. 37~ 587.
LETTER TO THE EDITOR
247
Nt~t~N, H. C. (1968). ExpL Neurol. 20, 3. ROWLAND, V. (1967). In The Neurosciences. A Study Program, p. 482. New York: Rockefeller University. ROWLAND, V. (1968). In Progress in Physiological Psychology (E. Stellar & J. Sprague, eds). New York: Academic Press. RusINov, V. S. (1953). In Communications at XIXInt. Physiol. Congr., Montreal. Rus~ov, V. S. (1969). Dominanta. Moscow: Meditsina. SH~RRrNGTON, C. S. (1911). The Integrative Action o f the Nervous System. London. UKnTOMSKY,A. A. (1923). In Collected Works, vol. 1, p. 163. Leningrad: Gosizdat.
Lt~rrer.
TO THE
EDITOR
On the Perception of Information in CNS Memory Mechanism The discussion initiated by Mikhaltsev (1972) makes it necessary to clarify one of the points of the suggested concept. It was mentioned in the article that " . . . the engram consolidation process is understood as an unconditional and immediate result of the perception of information". This suggestion caused some opposition. The basis of the objections is that not all the information perceived is stored. One of the arguments was that it would "waste" the storage capacity of the memory. Others emphasized that relatively little is stored in memory, as compared to how much is forgotten ('Y. D. Zuckerbrot, F. O. Schmitt, pets. comm.). I assume that the origin of the objections lies in the understanding of the term perception. I want to call attention to the principal difference between the volume of the information perceived by a biological system and the volume of the information which is presented to it or available for perception at the moment. I assume that in the CNS there is a mechanism which filters out of the whole volume of the available information a very small portion which becomes the perceived one. What is the physiology of the mechanism and what experimental evidence can be given for the validity of this statement ? The physiological substantiation of the existence of such a mechanism can be traced back to the works of Sherrington (1911) who disclosed the reciprocal innervation for anatomical antagonists and to the discovery of Ukhtomsky (1923) of the principle of "the dominant", as a dynamic constellation of innervated areas in the nervous system which optimize the reaction to the acting stimuli. This was understood as a mechanism which provides a proper choice of the most important stimulus out of all available ones at the moment. It would be vital for the survival of lower animals or for much more complicated reasons in the case of man, to make a proper reaction to this stimulus. Later, the physics of the dominant was investigated by Rusinov (1953) who reported the behavioural responses to low-level transcortieal polarization. In the international neuroscience literature such terms as "the dominant"-understood as a general physiological principle, or "the dominant focus"M understood as the correlated physiological phenomenon, are used rather
246
I.E.
MIKHALTSEV
rarely (though sometimes they are still in use--e.g. John, 1967). Mostly these terms describing the physiological state of the system are substituted by definition of the physical consequence of such a physiological state-localized "steady potential shifts (or gradients)". The works of Morrell (1963), Rowland (1967), Nielson (1968) and others show that steady potential shifts form a mechanism which prepares the CNS for the acceptance of novel information. Additional confirmation of the role of the steady potential shifts in the process of perception of information is found in a comprehensive review of Rowland (1968) as well as some results of a broad discussion on the problem of slow electrical phenomena in the CNS (Adey, 1969). The final contribution to the list might be the monograph of Rusinov (1969) who summarized important facts concerning the effect of slow potential changes in CNS on the behaviour of an animal. These experimental results may be regarded as good evidence in support of the validity of the statement that the dominant, or its physical correlate-the dynamics of the steady potential shifts in the cortex, is the mechanism which controls the volume of information perceived by the system out of the whole volume of information available at the moment. This physiological mect/anism is assumed to be equivalent to a narrow filter in the information domain; the action of such a falter prevents the overloading effect of memory. Though this analogy seems favorable for proper understanding of the described phenomenon I want to warn the reader against the temptation to broaden the analogy beyond the limits of its illustratory value. An attempt to apply the well developed filter-problems mathematics to the case should fail because of the dramatic difference between the physics of filtering (or resonance) process and the biological background of the discussed mechanism. I wish to thank my colleagues whose friendly remarks triggered the formulation of the foregoing comments which might be of some use to the experimenters involved "in the search of the engram". Institute of Oceanology, Academy of Sciences of U.S.S.R., Moscow, 109387, U.S.S.R.
IGOR E. MIKr~LTSEV
(Received 7 November 1973, and in revised form 2 July 1974)
REFERENCES ADEY,W. R. (1969). Neurosciences Res. Prog. Bull. 7, 1. JOHN,E. R. (1967). Mechanisms of Memory, p. 182. New York: Academic Press. MORaELL,F. (1963). In Information Storage and Neural Control (W. Fields & W. Abbot, eds) p. 189, Springfield, Iil.: Thomas. Mmm~rs~v, I. E. (1972). J. theor. Biol. 37~ 587.
LETTER TO THE EDITOR
247
Nt~t~N, H. C. (1968). ExpL Neurol. 20, 3. ROWLAND, V. (1967). In The Neurosciences. A Study Program, p. 482. New York: Rockefeller University. ROWLAND, V. (1968). In Progress in Physiological Psychology (E. Stellar & J. Sprague, eds). New York: Academic Press. RusINov, V. S. (1953). In Communications at XIXInt. Physiol. Congr., Montreal. Rus~ov, V. S. (1969). Dominanta. Moscow: Meditsina. SH~RRrNGTON, C. S. (1911). The Integrative Action o f the Nervous System. London. UKnTOMSKY,A. A. (1923). In Collected Works, vol. 1, p. 163. Leningrad: Gosizdat.
