Intermediate-term memory

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Intermediate-term memory (ITM) is a stage of memory distinct from sensory memory, working memory/short-term memory, and long-term memory.[1][2] While sensory memory persists for several milliseconds, working memory persists for up to thirty seconds, and long-term memory persists from thirty minutes to the end of an individual's life, intermediate-term memory persists for about two to three hours.[3] This overlap in the durations of these memory processes indicates that they occur simultaneously, rather than sequentially. Indeed, intermediate-term facilitation can be produced in the absence of long-term facilitation.[4] However, the boundaries between these forms of memory are not clear-cut, and they can vary depending on the task.[5] Intermediate-term memory is thought to be supported by the parahippocampal cortex.[6]

In 1993, Rosenzweig and colleagues demonstrated that, in rats conditioned to avoid an aversive stimulus, percent avoidance of the stimulus (and, by implication, memory of the aversive nature of the stimulus) reached relative minima at one minute, fifteen minutes, and sixty minutes.[7] These dips were theorized to correspond to the time points in which the rats switched from working memory to intermediate-term memory, from intermediate-term memory to the early phase of long-term memory, and from the early phase of long-term memory to the late phase of long-term memory, respectively—thus demonstrating the presence of a form of memory that exists between working memory and long-term memory, which they referred to as "intermediate-term memory".

Though the idea of intermediate-term memory has existed since the 1990s, Sutton et al. introduced a novel theory for the neural correlates underlying intermediate-term memory in Aplysia in 2001, where they described it as the primary behavioral manifestation of intermediate-term facilitation.[8]


In 2001, Sutton and colleagues proposed that intermediate-term memory possesses the following three characteristics:

  • It declines completely before the onset of long-term memory[8]

Comparison with short-term/working memory[edit]

Main article: Working memory

Unlike short-term memory and working memory, intermediate-term memory requires changes in translation to occur in order to function.

Comparison with long-term memory[edit]

Main article: Long-term memory

While ITM requires only changes in translation, induction of long-term memory requires changes in transcription as well.[11] The change from short-term memory to long-term memory is thought to dependent on CREB, which regulates transcription, but because ITM does not involve a change in transcription, it is thought to be independent of CREB activity.[3] According to the definition of ITM proposed by Sutton et al. in 2001, it disappears completely before long-term memory is induced.[8]


  1. ^ Grimes, M. T.; Smith, M.; Li, X.; Darby-King, A.; Harley, C. W.; McLean, J. H. (2011). "Mammalian intermediate-term memory: New findings in neonate rat". Neurobiology of Learning and Memory 95 (3): 385–391. doi:10.1016/j.nlm.2011.01.012. PMID 21296674. 
  2. ^ Sutton, M. A.; Carew, T. J. (2002). "Behavioral, Cellular, and Molecular Analysis of Memory in Aplysia I: Intermediate-Term Memory". Integrative and Comparative Biology 42 (4): 725–735. doi:10.1093/icb/42.4.725. PMID 21708769. 
  3. ^ a b Lukowiak, K.; Adatia, N.; Krygier, D.; Syed, N. (2000). "Operant conditioning in Lymnaea: Evidence for intermediate- and long-term memory". Learning & memory (Cold Spring Harbor, N.Y.) 7 (3): 140–150. doi:10.1101/lm.7.3.140. PMC 311329. PMID 10837503. 
  4. ^ Mauelshagen, J.; Sherff, C. M.; Carew, T. J. (1998). "Differential induction of long-term synaptic facilitation by spaced and massed applications of serotonin at sensory neuron synapses of Aplysia californica". Learning & memory (Cold Spring Harbor, N.Y.) 5 (3): 246–256. PMC 313806. PMID 10454368. 
  5. ^ Raymond P. Kesner and Joe L. Martinez, Jr. (eds) (2007). Neurobiology of Learning and Memory, 2nd edition. Nikki Levy, Academic Press. p. 284. ISBN 9780123725400. 
  6. ^ Eichenbaum, H.; Otto, T.; Cohen, N. J. (2010). "Two functional components of the hippocampal memory system". Behavioral and Brain Sciences 17 (3): 449. doi:10.1017/S0140525X00035391. 
  7. ^ Rosenzweig, M. R.; Bennett, E. L.; Colombo, P. J.; Lee, D. W.; Serrano, P. A. (1993). "Short-term, intermediate-term, and long-term memories". Behavioural Brain Research 57 (2): 193–198. doi:10.1016/0166-4328(93)90135-D. PMID 8117424. 
  8. ^ a b c d e Sutton, M. A.; Masters, S. E.; Bagnall, M. W.; Carew, T. J. (2001). "Molecular Mechanisms Underlying a Unique Intermediate Phase of Memory in Aplysia". Neuron 31 (1): 143–154. doi:10.1016/S0896-6273(01)00342-7. PMID 11498057. 
  9. ^ Parvez, K.; Stewart, O.; Sangha, S.; Lukowiak, K. (2005). "Boosting intermediate-term into long-term memory". Journal of Experimental Biology 208 (8): 1525–1536. doi:10.1242/jeb.01545. PMID 15802676. 
  10. ^ Sutton, M. A.; Bagnall, M. W.; Sharma, S. K.; Shobe, J.; Carew, T. J. (2004). "Intermediate-Term Memory for Site-Specific Sensitization in Aplysia is Maintained by Persistent Activation of Protein Kinase C". Journal of Neuroscience 24 (14): 3600–3609. doi:10.1523/JNEUROSCI.1134-03.2004. PMID 15071108. 
  11. ^ Braun, M. H.; Lukowiak, K. (2011). "Intermediate and long-term memory are different at the neuronal level in Lymnaea stagnalis (L.)". Neurobiology of Learning and Memory 96 (2): 403–416. doi:10.1016/j.nlm.2011.06.016. PMID 21757019.