Editing Memory transfer (section)

{{short description|Historically proposed biological process}}
'''Memory transfer''' was a biological process proposed by [[James V. McConnell]] and others in the 1960s. Memory transfer proposes a chemical basis for [[memory]] termed '''memory [[RNA]]''' which can be [[Heredity|passed down]] through flesh instead of an intact nervous system. Since RNA encodes information<ref name="Reckoning"/> and living cells produce and modify RNA in reaction to external events, it might also be used in [[neuron]]s to record stimuli.<ref name="Kentridge">{{cite web |author=Bob Kentridge |title=Investigations of the cellular bases of memory |url=http://www.dur.ac.uk/robert.kentridge/bpp2mem1.html |access-date=2011-03-03 |publisher=[[University of Durham]] |archive-url=https://web.archive.org/web/20121015043719/http://www.dur.ac.uk/robert.kentridge/bpp2mem1.html |archive-date=2012-10-15 }}</ref><ref>{{Cite web|url=https://www.scientificamerican.com/article/memory-transferred-between-snails-challenging-standard-theory-of-how-the-brain-remembers/|title=Memory Transferred between Snails, Challenging Standard Theory of How the Brain Remembers|last=McFarling, STAT|first=Usha Lee|website=Scientific American|language=en|access-date=2019-03-10}}</ref><ref>{{Cite news|url=https://www.bbc.com/news/science-environment-44111476|title='Memory transplant' achieved in snails|last=Dave|first=Shivani|date=2018-05-14|access-date=2019-03-10|language=en-GB}}</ref> This was proposed as an explanation for the results of McConnell's experiments in which [[planarian]]s retained memory of [[Learning|acquired information]] after [[Planarian#Regeneration|regeneration]].

In McConnell's experiments, he [[Classical conditioning|classically conditioned]] planarians to contract their bodies upon exposure to light by pairing it with an electric shock.<ref name="POLCT"/><ref name="TMTA">{{Cite web|url=https://www.apa.org/monitor/2010/06/memory-transfer|access-date=2021-02-05|website=www.apa.org|title=The memory-transfer episode}}</ref> The planarians retained this acquired information after being sliced and [[Planarian#Regeneration|regenerated]], even after multiple slicings to produce a planarian where none of the original trained planarian was present.<ref name="TMTA"/> The same held true after the planarians were ground up and fed to untrained [[cannibalistic]] planarians, usually ''[[Dugesia dorotocephala]]''.<ref name="TMTA"/><ref>{{Cite encyclopedia |first=James |last=McConnell |title=The Modern Search for the Engram |date=1965 |editor=McConnell |encyclopedia=A Manual of Psychological Experimentation on Planarians |publisher=[[The Worm Runner's Digest]] |pages=5, 7 |url=https://ase.tufts.edu/biology/labs/levin/resources/documents/PlanarianManual.pdf |archive-url=https://web.archive.org/web/20120418133845/https://ase.tufts.edu/biology/labs/levin/resources/documents/PlanarianManual.pdf |archive-date=2012-04-18 |via=Tufts University}}</ref> As the nervous system was fragmented but the nucleic acids were not, this seemed to indicate the existence of memory RNA.<ref name="TMTA"/> Some further experiments seem to support the original findings in that some memories may be stored outside the brain,<ref name="Reckoning"/><ref>{{cite news|last1=Duhaime-Ross|first1=Arielle|title=Flatworms Recall Familiar Environs, Even after Losing Their Heads|url=http://www.scientificamerican.com/article/flatworms-recall-familiar-environs-even-after-losing-their-heads/|access-date=18 March 2015|work=[[Scientific American]]|date=17 September 2013}}</ref><ref name="Shomrat2013">{{cite journal |vauthors=Shomrat T, Levin M|title=An automated training paradigm reveals long-term memory in planaria and its persistence through head regeneration |journal=The Journal of Experimental Biology |volume=216 |issue=20|pages=3799–3810 |date=2013-07-02 |pmid=23821717 |doi=10.1242/jeb.087809|doi-access=free }}</ref>
but McConnell's experiments proved to be largely [[irreproducible]] and it was later suggested that only sensitization was transferred,<ref name="POLCT">{{cite web|url=http://uwf.edu/wmikulas/Webpage/concept/chaptertwo.htm|title=Physiology of Learning|author=William L. Mikulas|access-date=2011-03-03|publisher=[[University of West Florida]]|archive-url=https://web.archive.org/web/20171127051125/http://uwf.edu/wmikulas/Webpage/concept/chaptertwo.htm|archive-date=2017-11-27}}</ref> or that no transfer occurred and the effect was due to [[stress hormones]] in the donor or [[pheromone]] trails left on dirty lab glass.<ref name="Kentridge"/> Memory transfer through memory RNA is not currently a well-accepted explanation for the planarian behavior.<ref name="TMTA"/>