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Animal Cognition

, Volume 20, Issue 2, pp 215–220 | Cite as

A test of the reward-value hypothesis

  • Alexandra E. Smith
  • Stefan J. Dalecki
  • Jonathon D. Crystal
Original Paper

Abstract

Rats retain source memory (memory for the origin of information) over a retention interval of at least 1 week, whereas their spatial working memory (radial maze locations) decays within approximately 1 day. We have argued that different forgetting functions dissociate memory systems. However, the two tasks, in our previous work, used different reward values. The source memory task used multiple pellets of a preferred food flavor (chocolate), whereas the spatial working memory task provided access to a single pellet of standard chow-flavored food at each location. Thus, according to the reward-value hypothesis, enhanced performance in the source memory task stems from enhanced encoding/memory of a preferred reward. We tested the reward-value hypothesis by using a standard 8-arm radial maze task to compare spatial working memory accuracy of rats rewarded with either multiple chocolate or chow pellets at each location using a between-subjects design. The reward-value hypothesis predicts superior accuracy for high-valued rewards. We documented equivalent spatial memory accuracy for high- and low-value rewards. Importantly, a 24-h retention interval produced equivalent spatial working memory accuracy for both flavors. These data are inconsistent with the reward-value hypothesis and suggest that reward value does not explain our earlier findings that source memory survives unusually long retention intervals.

Keywords

Reward value Source memory Spatial memory Episodic memory Rats 

Notes

Acknowledgments

This work was supported by National Institute of Mental Health R01MH098985 and National Institute on Aging R21AG044530 to JDC and the support of a Neuroscience Fellowship and the Harlan Scholars Program to AES.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted. This article does not contain any studies with human participants performed by any of the authors.

References

  1. Babb SJ, Crystal JD (2005) Discrimination of what, when, and where: implications for episodic-like memory in rats. Learn Motiv 36:177–189CrossRefGoogle Scholar
  2. Babb SJ, Crystal JD (2006a) Discrimination of what, when, and where is not based on time of day. Learn Behav 34:124–130CrossRefPubMedGoogle Scholar
  3. Babb SJ, Crystal JD (2006b) Episodic-like memory in the rat. Curr Biol 16:1317–1321CrossRefPubMedGoogle Scholar
  4. Beatty WW, Shavalia DA (1980) Spatial memory in rats: time course of working memory and effect of anesthetics. Behav Neural Biol 28:454–462CrossRefPubMedGoogle Scholar
  5. Clayton NS, Dickinson A (1998) Episodic-like memory during cache recovery by scrub jays. Nature 395(6699):272–274CrossRefPubMedGoogle Scholar
  6. Clayton NS, Yu KS, Dickinson A (2001) Scrub jays (Aphelocoma coerulescens) form integrated memories of the multiple features of caching episodes. J Exp Psychol Anim Behav Process 27(1):17–29CrossRefPubMedGoogle Scholar
  7. Cohen J (1988) Statistical power analysis for the behavioral sciences, 2nd edn. Lawrence Erlbaum Associates, HillsdaleGoogle Scholar
  8. Cohen J, Pardy S, Solway H, Graham H (2003) Chunking versus foraging search patterns by rats in the hierarchically baited radial maze. Anim Cogn 6(2):93–104CrossRefPubMedGoogle Scholar
  9. Crystal JD (2016) Animal models of source memory. J Exp Anal Behav 105(1):56–67. doi: 10.1002/jeab.173 CrossRefPubMedGoogle Scholar
  10. Crystal JD, Alford WT (2014) Validation of a rodent model of source memory. Biol Lett 10(3):20140064. doi: 10.1098/rsbl.2014.0064 CrossRefPubMedPubMedCentralGoogle Scholar
  11. Crystal JD, Babb SJ (2008) Spatial memory in rats after 25 hours. Learn Motiv 39(4):278–284CrossRefPubMedPubMedCentralGoogle Scholar
  12. Crystal JD, Smith AE (2014) Binding of episodic memories in the rat. Curr Biol 24(24):2957–2961. doi: 10.1016/j.cub.2014.10.074 CrossRefPubMedPubMedCentralGoogle Scholar
  13. Crystal JD, Alford WT, Zhou W, Hohmann AG (2013) Source memory in the rat. Curr Biol 23(5):387–391. doi: 10.1016/j.cub.2013.01.023 CrossRefPubMedPubMedCentralGoogle Scholar
  14. Flaherty CF, Riley EP, Spear NE (1973) Effects of sucrose concentration and goal units on runway behavior in the rat. Learn Motiv 4(2):163–175CrossRefGoogle Scholar
  15. Flaherty CF, Ciszewski WA, Kaplan PS (1979) Retention of taste quality following brief exposure to sucrose. Chem Sens Flavor 4(1):73–78. doi: 10.1093/chemse/4.1.73 CrossRefGoogle Scholar
  16. Gaffan EA, Davies J (1981) The role of exploration in win-shift and win-stay performance on a radial maze. Learn Motiv 12(3):282–299. doi: 10.1016/0023-9690(81)90010-2 CrossRefGoogle Scholar
  17. Gallistel CR (2009) The importance of proving the null. Psychol Rev 116(2):439–453. doi: 10.1037/a0015251 CrossRefPubMedPubMedCentralGoogle Scholar
  18. Hasselmo ME, Eichenbaum H (2005) Hippocampal mechanisms for the context-dependent retrieval of episodes. Neural Netw 18(9):1172–1190. doi: 10.1016/j.neunet.2005.08.007 CrossRefPubMedPubMedCentralGoogle Scholar
  19. Hoffman ML, Beran MJ, Washburn DA (2009) Memory for “what”, “where”, and “when” information in rhesus monkeys (Macaca mulatta). J Exp Psychol Anim Behav Process 35(2):143–152CrossRefPubMedPubMedCentralGoogle Scholar
  20. Johnson MK (2005) The relation between source memory and episodic memory: comment on Siedlecki et al. (2005). Psychol Aging 20(3):529–531. doi: 10.1037/0882-7974.20.3.529 CrossRefPubMedGoogle Scholar
  21. Johnson MK, Hashtroudi S, Lindsay DS (1993) Source monitoring. Psychol Bull 114(1):3–28CrossRefPubMedGoogle Scholar
  22. Martin-Ordas G, Haun D, Colmenares F, Call J (2010) Keeping track of time: evidence for episodic-like memory in great apes. Anim Cogn 13(2):331–340. doi: 10.1007/s10071-009-0282-4 CrossRefPubMedGoogle Scholar
  23. Martin-Ordas G, Berntsen D, Call J (2013) Memory for distant past events in chimpanzees and orangutans. Curr Biol 23(15):1438–1441CrossRefPubMedGoogle Scholar
  24. Olton DS, Samuelson RJ (1976) Remembrance of places passed—spatial memory in rats. J Exp Psychol Anim B 2(2):97–116. doi: 10.1037/0097-7403.2.2.97 CrossRefGoogle Scholar
  25. Panoz-Brown DE, Corbin HE, Dalecki SJ, Gentry M, Brotheridge S, Sluka CM, Wu J-E, Crystal JD (2016) Rats remember items in context using episodic memory. Curr Biol. doi: 10.1016/j.cub.2016.08.023 PubMedGoogle Scholar
  26. Rouder J, Speckman P, Sun D, Morey R, Iverson G (2009) Bayesian t tests for accepting and rejecting the null hypothesis. Psychonom Bull Rev 16(2):225–237. doi: 10.3758/pbr.16.2.225 CrossRefGoogle Scholar
  27. Smith AE, Xu Z, Lai YY, Kulkarni PM, Thakur GA, Hohmann AG, Crystal JD (2016) Source memory in rats is impaired by an NMDA receptor antagonist but not by PSD95-nNOS protein-protein interaction inhibitors. Behav Brain Res 305:23–29. doi: 10.1016/j.bbr.2016.02.021 CrossRefPubMedGoogle Scholar
  28. Timberlake W, White W (1990) Winning isn’t everything: rats need only food deprivation and not food reward to efficiently traverse a radial arm maze. Learn Motiv 21(2):153–163CrossRefGoogle Scholar
  29. Tulving E (1983) Elements of episodic memory. Oxford University Press, New YorkGoogle Scholar
  30. Wright AA (2013) Episodic memory: a rat model of source memory. Curr Biol 23(5):R198–R200. doi: 10.1016/j.cub.2013.01.055 CrossRefPubMedGoogle Scholar
  31. Zhou W, Crystal JD (2009) Evidence for remembering when events occurred in a rodent model of episodic memory. Proc Natl Acad Sci USA 106(23):9525–9529. doi: 10.1073/pnas.0904360106 CrossRefPubMedPubMedCentralGoogle Scholar
  32. Zhou W, Crystal JD (2011) Validation of a rodent model of episodic memory. Anim Cogn 14(3):325–340. doi: 10.1007/s10071-010-0367-0 CrossRefPubMedGoogle Scholar
  33. Zhou W, Hohmann AG, Crystal JD (2012) Rats answer an unexpected question after incidental encoding. Curr Biol 22(12):1149–1153. doi: 10.1016/j.cub.2012.04.040 CrossRefPubMedPubMedCentralGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Alexandra E. Smith
    • 1
  • Stefan J. Dalecki
    • 1
  • Jonathon D. Crystal
    • 1
  1. 1.Department of Psychological and Brain SciencesIndiana UniversityBloomingtonUSA

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