Memory transfer was a biological process proposed by
James V. McConnell
James V. McConnell (October 26, 1925 – April 9, 1990) was an American biologist and Comparative psychology, animal psychologist. He is most known for his research on learning and memory transfer in planarians conducted in the 1950s and 1960 ...
and others in the 1960s. Memory transfer proposes a chemical basis for
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembe ...
termed memory
RNA
Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...
which can be
passed down through flesh instead of an intact nervous system. Since RNA encodes information
and living cells produce and modify RNA in reaction to external events, it might also be used in
neuron
A neuron (American English), neurone (British English), or nerve cell, is an membrane potential#Cell excitability, excitable cell (biology), cell that fires electric signals called action potentials across a neural network (biology), neural net ...
s to record stimuli.
This was proposed as an explanation for the results of McConnell's experiments in which
planarian
Planarians (triclads) are free-living flatworms of the class Turbellaria, order Tricladida, which includes hundreds of species, found in freshwater, marine, and terrestrial habitats.pp 3., "Planarians (the popular name for the group as a whole ...
s retained memory of
acquired information after
regeneration
Regeneration may refer to:
Science and technology
* Regeneration (biology), the ability to recreate lost or damaged cells, tissues, organs and limbs
* Regeneration (ecology), the ability of ecosystems to regenerate biomass, using photosynthesis
...
.
In McConnell's experiments, he
classically conditioned planarians to contract their bodies upon exposure to light by pairing it with an electric shock.
The planarians retained this acquired information after being sliced and
regenerated, even after multiple slicings to produce a planarian where none of the original trained planarian was present.
The same held true after the planarians were ground up and fed to untrained
cannibalistic
Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is also well documente ...
planarians, usually ''
Dugesia dorotocephala''.
As the nervous system was fragmented but the nucleic acids were not, this seemed to indicate the existence of memory RNA.
Some further experiments seem to support the original findings in that some memories may be stored outside the brain,
but McConnell's experiments proved to be largely
irreproducible and it was later suggested that only sensitization was transferred,
or that no transfer occurred and the effect was due to
stress hormones
Stress hormones are secreted by endocrine glands to modify one's internal environment during times of stress. By performing various functions such as mobilizing energy sources, increasing heart rate, and downregulating metabolic processes which ...
in the donor or
pheromone
A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
trails left on dirty lab glass.
Memory transfer through memory RNA is not currently a well-accepted explanation for the planarian behavior.
See also
*
Scotophobin
References
RNA
Molecular neuroscience
Memory
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