Tópico: Decapitated Worms Regrow Heads, Keep Old Memories

[Feliperj]

Ola Pessoal,

Não bastassem as experiências com salamandras e ratos de labortório evidenciando o caráter holográfico do processamento cerebral, agora mais essa : 

http://newswatch.nationalgeographic.com/2013/07/16/decapitated-worms-regrow-heads-keep-old-memories/

Não sei se vou falar uma grande besteira, mas assumindo que a memória está associada a padrões de ligação entre celulas nervosas, o caso não é somente de memória estar gravada no corpo e ser passada para o novo cérebro: é a memória do corpo direcionar a formação do novo órgão, de modo que tenha o mesmo padrão de ligações neurais que o cérebro anterior, ou seja, funcionar como uma espécie de "código genético". SINISTRO!!!

Abs
Felipe

[Buckaroo Banzai]

Provavelmente não é nada com "código genético", mas, se houver algo minimamente parecido com o descrito, seria só influência do restante do sistema nervoso no novo cérebro, do mesmo tipo que ocorre entre células nervosas fora de instâncias de decapitação e regeneração. Mas provavelmente é isso e uma combinação ou papel preponderante de química do organismo, presente nele, e lançada no ambiente, meio como fazem as formigas.

Aquatic flatworms use chemical cues from injured conspecifics to
assess predation risk and to associate risk with novel cues
BRIAN D. WISENDEN & MELISSA C. MILLARD
Biology Department, Minnesota State University Moorhead
(Received 23 October 2000; initial acceptance 7 December 2000;
final acceptance 20 March 2001; MS. number: A8914)
A growing number of aquatic organisms have been shown to display antipredator behaviour in response
to injury-released chemical cues from conspecifics. Here, we demonstrate a clear antipredator response in
the form of avoidance behaviour by a free-living flatworm Dugesia dorotocephala to chemical cues from
injured conspecifics. This is the first demonstration of a chemical alarm cue in a platyhelminth. In a
second experiment, we exposed planaria to combined cues of sunfish odour and planaria alarm cue, or
sunfish odour alone. Planaria avoided the sunfish+alarm cue but did not avoid the sunfish odour,
indicating no prior aversion to sunfish odour. When these same planaria were subsequently retested
2 days later with sunfish odour only, planaria that had previously received sunfish odour+alarm cue
avoided the cue but planaria that had previously received sunfish odour alone did not. These data
indicate that planaria learned to recognize sunfish odour as an indicator of danger based on a single
simultaneous exposure to conspecific alarm cue and the novel cue. This is the first demonstration of this
phenomenon in a platyhelminth and the simplest nervous system known to be capable of learned risk
association.
 2

http://web.mnstate.edu/wisenden/reprint%20pdfs/2001%20planaria%20An%20Beh%2062%20761-766.pdf

[Feliperj]

Provavelmente não é nada com "código genético", mas, se houver algo minimamente parecido com o descrito, seria só influência do restante do sistema nervoso no novo cérebro, do mesmo tipo que ocorre entre células nervosas fora de instâncias de decapitação e regeneração. Mas provavelmente é isso e uma combinação ou papel preponderante de química do organismo, presente nele, e lançada no ambiente, meio como fazem as formigas.

Aquatic flatworms use chemical cues from injured conspecifics to
assess predation risk and to associate risk with novel cues
BRIAN D. WISENDEN & MELISSA C. MILLARD
Biology Department, Minnesota State University Moorhead
(Received 23 October 2000; initial acceptance 7 December 2000;
final acceptance 20 March 2001; MS. number: A8914)
A growing number of aquatic organisms have been shown to display antipredator behaviour in response
to injury-released chemical cues from conspecifics. Here, we demonstrate a clear antipredator response in
the form of avoidance behaviour by a free-living flatworm Dugesia dorotocephala to chemical cues from
injured conspecifics. This is the first demonstration of a chemical alarm cue in a platyhelminth. In a
second experiment, we exposed planaria to combined cues of sunfish odour and planaria alarm cue, or
sunfish odour alone. Planaria avoided the sunfish+alarm cue but did not avoid the sunfish odour,
indicating no prior aversion to sunfish odour. When these same planaria were subsequently retested
2 days later with sunfish odour only, planaria that had previously received sunfish odour+alarm cue
avoided the cue but planaria that had previously received sunfish odour alone did not. These data
indicate that planaria learned to recognize sunfish odour as an indicator of danger based on a single
simultaneous exposure to conspecific alarm cue and the novel cue. This is the first demonstration of this
phenomenon in a platyhelminth and the simplest nervous system known to be capable of learned risk
association.
 2

http://web.mnstate.edu/wisenden/reprint%20pdfs/2001%20planaria%20An%20Beh%2062%20761-766.pdf

Ola Buck,

São fenômeno bem diferentes; e acho que o que vc colocou não ajuda a explicar como um corpo sem cérebro consegue reconstruir o órgão e as conexões anteriores. Creio que o mais esperado era que o novo cérebro fosse "zerado", parecido com o que ela tinha ao nascer.

Abs
Felipe

[Buckaroo Banzai]

O problema é que simplesmente não se sabe se o novo cérebro tem as conexões anteriores, apenas se observa o mesmo comportamento, que provavelmente pode ser induzido por algo mais trivial, como esses mecanismos.

http://en.wikipedia.org/wiki/Planarian#Biochemical_memory_experiments

Biochemical memory experiments[edit]

Main article: Memory RNA
In 1955, Robert Thompson and James V. McConnell conditioned planarian flatworms by pairing a bright light with an electric shock. After repeating this several times they took away the electric shock, and only exposed them to the bright light. The flatworms would react to the bright light as if they had been shocked. Thompson and McConnell found that if they cut the worm in two, and allowed both worms to regenerate each half would develop the light-shock reaction. In 1962, McConnell repeated the experiment, but instead of cutting the trained flatworms in two he ground them into small pieces and fed them to other flatworms. He reported that the flatworms learned to associate the bright light with a shock much faster than flatworms who had not been fed trained worms.
This experiment intended to show that memory could be transferred chemically. The experiment was repeated with mice, fish, and rats, but it always failed to produce the same results. The perceived explanation was that rather than memory being transferred to the other animals, it was the hormones in the ingested ground animals that changed the behavior.[15] McConnell believed that this was evidence of a chemical basis for memory, which he identified as memory RNA. McConnell's results are now attributed to observer bias.[16][17] No blinded experiment has ever reproduced his results of 'maze-running'. Subsequent explanations of maze-running enhancements associated with cannibalism of trained planarian worms were that the untrained flatworms were only following tracks left on the dirty glassware rather than absorbing the memory of their fodder.