Engram
Engram (from the Greek en , "in", and gramma , "inscription") is a general name for a physiological trace that a stimulus leaves behind as a permanent structural change in the brain . The total of all engrams - billions of them - make up the memory .
According to Richard Semon (1904), an engram is an experience impression that leaves a memory trail and is therefore an element of memory. This conception presupposes the property of the organic substance to retain memory traces longer.
Karl Lashley undertook extensive but unsuccessful research to locate engrams in the brain. However, he only looked in the cortex (cerebral cortex) of the brain. Richard F. Thompson , however, looked for engrams in the cerebellum (cerebellum).
Donald O. Hebb , the founder of all physiological memory theories, confirmed the observations of his predecessors in his studies of memory content in 1949. He spoke of the theory of the ground paths. An engram can therefore be illustrated with Aristotle through the image that a signet ring presses in wax.
As we understand it today, engrams are to be found in the excitation lines . The idea that individual or several locally delimitable neurons each store an engram is outdated (keyword: grandmother neuron ).
Synapses (points of contact between two nerve cells for chemical or electrical signal transmission) are changed (strengthened, newly formed or dissolved) through frequent use, prolonged non-use or coincidence . This changes the lines of excitation and so changes the engrams.
In every action and situation, the brain uses engrams.
See also
literature
- Karl Lashley: In search of the engram. In: Symposia of the Society for Experimental Biology 4, 1950, pp. 454-482.