Facilitating

Facilitation is a term from neurophysiology and describes the phenomenon that repeated excitation of certain nerve tracts increases the effectiveness of stimuli of the same strength or that this nerve tract can be stimulated by weaker stimuli (see also: summation and long-term potentiation ).

Concept history

The development of the neurophysiological concept of facilitation - as well as inhibition and summation - is attributed to the Austrian physiologist Sigmund Exner , who in 1894 published his draft for a physiological explanation of psychological phenomena . In 1875 Exner became professor at the Physiological Institute in Vienna - and from 1891 its head as successor to Ernst Brücke - where Sigmund Freud also received his doctorate in 1881 . The term can also be found in his unpublished draft of a psychology (1895), which contains thoughts on possible brain-physiological foundations of memory.

Spatial and temporal facilitation

When considering a single nerve cell, a distinction is made between spatial and temporal orientation. “Spatial facilitation” is defined as the simultaneous effect of stimuli on spatially different afferents , i.e. different synapses of a nerve cell. “Timing” is understood to mean a relatively rapid succession, approximately every 4 ms, of so-called repetitive individual stimuli to one and the same affinity of a synapse. These stimuli thus take place within the decaying course of the exciting postsynaptic potentials ( EPSP ). A subliminal single stimulus does not cause depolarization of the nerve cell. In the case of a resulting facilitation, however, a corresponding nerve cell is depolarized. This is understandable because of the model concept of a summation of subliminal individual stimuli taken individually.

More complex uses of the term

As a neurophysiological concept, facilitation is also used in the consideration of complex phenomena from brain research , psychophysics , behavioral physiology and social psychology .

Long-term potentiation ( neuroanatomy and neurophysiology ): Long-term potentiation (LTP = long-term potentiation) is a temporal facilitating assumption of learning effects of a nerve cell. However, this learning effect only comes about through a previous spatial facilitation with the participation of several input axons or several afferents. This u. U. to a change in the synapse weights .

Priming (psychology): A stimulus can have a positive or negative effect on the processing of a subsequent stimulus if the first stimulus activates certain memory contents.

Facilitating ( learning theory ): Frequent repetition facilitates certain memory contents, i.e. H. neural correlates of mental representations are linked ( associated ) with one another through frequent simultaneous activation . Facilitating effects can be viewed as neurophysiological precursors of a thought or memory.

Web links

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References and comments

↑ Exner introduces the concept of facilitation in Chapter II. Basic physiological phenomena under 3. The central inhibition and facilitating the concept of facilitating as follows: “Just as an excitation in the central nervous system can weaken or completely inhibit the process of another excitation, excitations can also promote the process others work by, as it were, clearing the way. That's why I called this phenomenon 'facilitation'. "Then he presents the effect of facilitation when two individually ineffective weak stimuli interact - as" paw stimulus "and" bark stimulus "in a rabbit - and explains:" You can of course also without bringing the two effective stimuli below their threshold. If both of them are already active individually, the effect of the facilitation is shown in the intensification of the twitching. The example given would be analogous to the case in which a state of irritation in the cerebral cortex, i.e. conscious attention to the processes on the paw, favors the course of the associated spinal cord processes (the reflex twitching in a needle prick is stronger if we are anxiously attentive to the sting watch); however, the facilitation can also be demonstrated in reverse for the case that first the paw stimulation and then the cortex stimulation occurs. ”(Sigmund Exner: Draft for a physiological explanation of psychological phenomena. 1st part. F. Deuticke, Leipzig and Vienna 1894, p . 76f. Online here ).

↑ Freud first introduces the hypothetical distinction between two classes of neurons: “There are therefore permeable (non-resisting and non-retentive) neurons that are used for perception, and impermeable (with resistance and quantity (Qη) restrained) neurons that Carriers of memory, probably therefore of psychic processes in general. So from now on I want to call the former system of neurons Φ, the latter Ψ. ”He then makes the assumption:“ Ψ-neurons [...] are constantly changed by the course of excitation. With the addition of the contact barrier theory: your contact barriers get into a constantly changing state. And since psychological experience shows that there is over-learning on the basis of memory, this change must consist in the contact barriers becoming more conductive, less impermeable, i.e. more similar to those of the Φ-system. We want to call this state of the contact barriers the degree of facilitation. Then one can say: The memory is represented by the pathways between the Ψ neurons. ”(In: Gesammelte Werke, supplementary volume, texts from the years 1885 to 1938, Frankfurt / M. 1987, p. 308; quoted from Sigmund Freud , “Draft of a Psychology” , here p. 7).

^ Schmidt, Robert F. (Ed.): Outline of Neurophysiology . Springer, Berlin ³ 1979, ISBN 3-540-07827-4 , pages 110-113.

↑ Spitzer, Manfred : Spirit in the net , models for learning, thinking and acting. Spektrum Akademischer Verlag Heidelberg 1996, ISBN 3-8274-0109-7 . Page 44 ff.

[1] Exner introduces the concept of facilitation in Chapter II. Basic physiological phenomena under 3. The central inhibition and facilitating the concept of facilitating as follows: “Just as an excitation in the central nervous system can weaken or completely inhibit the process of another excitation, excitations can also promote the process others work by, as it were, clearing the way. That's why I called this phenomenon 'facilitation'. "Then he presents the effect of facilitation when two individually ineffective weak stimuli interact - as" paw stimulus "and" bark stimulus "in a rabbit - and explains:" You can of course also without bringing the two effective stimuli below their threshold. If both of them are already active individually, the effect of the facilitation is shown in the intensification of the twitching. The example given would be analogous to the case in which a state of irritation in the cerebral cortex, i.e. conscious attention to the processes on the paw, favors the course of the associated spinal cord processes (the reflex twitching in a needle prick is stronger if we are anxiously attentive to the sting watch); however, the facilitation can also be demonstrated in reverse for the case that first the paw stimulation and then the cortex stimulation occurs. ”(Sigmund Exner: Draft for a physiological explanation of psychological phenomena. 1st part. F. Deuticke, Leipzig and Vienna 1894, p . 76f. Online here ).

[2] Freud first introduces the hypothetical distinction between two classes of neurons: “There are therefore permeable (non-resisting and non-retentive) neurons that are used for perception, and impermeable (with resistance and quantity (Qη) restrained) neurons that Carriers of memory, probably therefore of psychic processes in general. So from now on I want to call the former system of neurons Φ, the latter Ψ. ”He then makes the assumption:“ Ψ-neurons [...] are constantly changed by the course of excitation. With the addition of the contact barrier theory: your contact barriers get into a constantly changing state. And since psychological experience shows that there is over-learning on the basis of memory, this change must consist in the contact barriers becoming more conductive, less impermeable, i.e. more similar to those of the Φ-system. We want to call this state of the contact barriers the degree of facilitation. Then one can say: The memory is represented by the pathways between the Ψ neurons. ”(In: Gesammelte Werke, supplementary volume, texts from the years 1885 to 1938, Frankfurt / M. 1987, p. 308; quoted from Sigmund Freud , “Draft of a Psychology” , here p. 7).

[3] Schmidt, Robert F. (Ed.): Outline of Neurophysiology . Springer, Berlin ³ 1979, ISBN 3-540-07827-4 , pages 110-113.

[GIN-4] Spitzer, Manfred : Spirit in the net , models for learning, thinking and acting. Spektrum Akademischer Verlag Heidelberg 1996, ISBN 3-8274-0109-7 . Page 44 ff.