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You can find the current article at its original source at http://www.theguardian.com/science/neurophilosophy/2014/jun/09/sleep-dendritic-spines-memory
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| Version 1 | Version 2 |
|---|---|
| Sleep may help memories form by promoting new synapses | Sleep may help memories form by promoting new synapses |
| (35 minutes later) | |
| If you’ve just learnt something | |
| new and want to improve your chances of remembering it, you’d do well to sleep | new and want to improve your chances of remembering it, you’d do well to sleep |
| on it. Whether you’re learning to play a musical instrument or revising for exams, a good night’s sleep afterwards – or even just a power nap – | on it. Whether you’re learning to play a musical instrument or revising for exams, a good night’s sleep afterwards – or even just a power nap – |
| will aid long-term storage of the new memories and make it more likely they'll stick. | will aid long-term storage of the new memories and make it more likely they'll stick. |
| We know that learning and | We know that learning and |
| memory involve the modification of synapses, the connections between nerve | memory involve the modification of synapses, the connections between nerve |
| cells, but it wasn’t entirely clear how sleep aids memory consolidation. New | cells, but it wasn’t entirely clear how sleep aids memory consolidation. New |
| research published in the journal Science | research published in the journal Science |
| seems to suggest that it does so by promoting the formation of new synapses and then stabilizing them. | seems to suggest that it does so by promoting the formation of new synapses and then stabilizing them. |
| Wenbiao Gan | Wenbiao Gan |
| of the Langone Medical Center at New York University and his colleagues trained | of the Langone Medical Center at New York University and his colleagues trained |
| mice to run backwards or forwards on a rotating rod, then left some of them to | mice to run backwards or forwards on a rotating rod, then left some of them to |
| sleep while keeping the rest awake, using confocal and two-photon microscopy to | sleep while keeping the rest awake, using confocal and two-photon microscopy to |
| monitor the motor cortex, which is involved in controlling movement, through ‘windows’ | monitor the motor cortex, which is involved in controlling movement, through ‘windows’ |
| scraped into animals’ skulls. | scraped into animals’ skulls. |
| Learning induced the | Learning induced the |
| formation of new dendritic spines, the tiny, bulbous protuberances on the | formation of new dendritic spines, the tiny, bulbous protuberances on the |
| branches of neurons, which come into close contact with the nerve terminals | branches of neurons, which come into close contact with the nerve terminals |
| of other cells to form synapses, the junctions at which the cells can | of other cells to form synapses, the junctions at which the cells can |
| communicate with each other. Each task produced a unique pattern of new spines | communicate with each other. Each task produced a unique pattern of new spines |
| on the branches of the same motor cortex neurons, but only in the mice that | on the branches of the same motor cortex neurons, but only in the mice that |
| were left to sleep after the training. | were left to sleep after the training. |
| “We found that about 5% of spines | “We found that about 5% of spines |
| in the motor cortex were formed anew in response to the learning task over 8-24 | in the motor cortex were formed anew in response to the learning task over 8-24 |
| hours,” says Gan, “and our previous | hours,” says Gan, “and our previous |
| studies show that a fraction of these rapidly formed new spines – about | studies show that a fraction of these rapidly formed new spines – about |
| 10% - are maintained over the subsequent weeks to months." The | 10% - are maintained over the subsequent weeks to months." The |
| experiments also showed that the same neurons that were activated during | experiments also showed that the same neurons that were activated during |
| learning of the task were reactivated during sleep, and this apparently | learning of the task were reactivated during sleep, and this apparently |
| stablized the newly-formed spines, because no new spines were seen when reactivation was blocked with a drug. | stablized the newly-formed spines, because no new spines were seen when reactivation was blocked with a drug. |
| The researchers did not re-test learning behaviour after blocking spine formation, however, or determine whether the new spines actually paired up | The researchers did not re-test learning behaviour after blocking spine formation, however, or determine whether the new spines actually paired up |
| with nerve terminals to form functioning synapses. Even if they did form synapses, it’s | with nerve terminals to form functioning synapses. Even if they did form synapses, it’s |
| not clear that such a small number of them could contribute to information | not clear that such a small number of them could contribute to information |
| processing, so more work is needed to confirm that the new spines that sprout during sleep are indeed involved in memory. | processing, so more work is needed to confirm that the new spines that sprout during sleep are indeed involved in memory. |
| Reference: | Reference: |
| Yang, G., et al. (2014). Sleep promotes branch-specific formation of | Yang, G., et al. (2014). Sleep promotes branch-specific formation of |
| dendritic spines after learning. Science, | dendritic spines after learning. Science, |
| 344: 1173-1178. DOI: 10.1126/science.1249098 | 344: 1173-1178. DOI: 10.1126/science.1249098 |