Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Inducible, pharmacogenetic approaches to the study of learning and memory


Here we introduce a strategy in which pharmacology is used to induce the effects of recessive mutations. For example, mice heterozygous for a null mutation of the K-ras gene (K-ras+/−) show normal hippocampal mitogen-activated protein kinase (MAPK) activation, long-term potentiation (LTP) and contextual conditioning. However, a dose of a mitogen-activated/extracellular-signal-regulated kinase (MEK) inhibitor, ineffective in wild-type controls, blocks MAPK activation, LTP and contextual learning in K-ras+/− mutants. These indicate that K-Ras/MEK/MAPK signaling is critical in synaptic and behavioral plasticity. A subthreshold dose of NMDA receptor antagonists triggered a contextual learning deficit in mice heterozygous for a point mutation (T286A) in the αCaMKII gene, but not in K-ras+/− mutants, demonstrating the specificity of the synergistic interaction between the MEK inhibitor and the K-ras+/− mutation. This pharmacogenetic approach combines the high temporal specificity that pharmacological manipulations offer, with the molecular specificity of genetic disruptions.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: A subthreshold dose of a MEK inhibitor induces less MAPK activation in K-ras+/− mutants.
Figure 2: A subthreshold dose of a MEK inhibitor induces an LTP impairment in K-ras+/− mutants.
Figure 3: A subthreshold dose of a MEK inhibitor induces a contextual conditioning impairment in K-ras+/− mutants.
Figure 4: A subthreshold dose of an NMDA receptor antagonist does not induce a contextual conditioning impairment in K-ras+/− mutants.
Figure 5: Subthreshold doses of NMDA receptor antagonists induce a contextual conditioning impairment in αCaMKIIT286A heterozygotes, but not in K-ras+/− mutants.


  1. 1

    Steimer, W., Muller, B., Leucht, S. & Kissling, W. Pharmacogenetics: a new diagnostic tool in the management of antidepressive drug therapy. Clin. Chim. Acta 308, 33–41 (2001).

    CAS  Article  Google Scholar 

  2. 2

    McLeod, H. L. & Evans, W. E. Pharmacogenomics: unlocking the human genome for better drug therapy. Annu. Rev. Pharmacol. Toxicol. 41, 101–121 (2001).

    CAS  Article  Google Scholar 

  3. 3

    Brandon, E. P., Idzerda, R. L. & McKnight, G. S. Knockouts. Targeting the mouse genome: a compendium of knockouts (Part I). Curr. Biol. 5, 625–634 (1995).

    CAS  Article  Google Scholar 

  4. 4

    Brandon, E. P., Idzerda, R. L. & McKnight, G. S. Targeting the mouse genome: a compendium of knockouts (Part II). Curr. Biol. 5, 758–765 (1995).

    CAS  Article  Google Scholar 

  5. 5

    Silva, A. J., Smith, A. M. & Giese, K. P. Gene targeting and the biology of learning and memory. Annu. Rev. Genet. 31, 527–546 (1997).

    CAS  Article  Google Scholar 

  6. 6

    Chen, C. & Tonegawa, S. Molecular genetic analysis of synaptic plasticity, activity-dependent neural development, learning, and memory in the mammalian brain. Annu. Rev. Neurosci. 20, 157–184 (1997).

    CAS  Article  Google Scholar 

  7. 7

    Furth, P. A. et al. Temporal control of gene expression in transgenic mice by a tetracycline-responsive promoter. Proc. Natl. Acad. Sci. USA 91, 9302–9306 (1994).

    CAS  Article  Google Scholar 

  8. 8

    Ray, P. et al. Regulated overexpression of interleukin 11 in the lung. Use to dissociate development-dependent and -independent phenotypes. J. Clin. Invest. 100, 2501–2511 (1997).

    CAS  Article  Google Scholar 

  9. 9

    Derkinderen, P., Enslen, H. & Girault, J. A. The ERK/MAP-kinases cascade in the nervous system. Neuroreport 10, R24–34 (1999).

    CAS  PubMed  Google Scholar 

  10. 10

    Fukunaga, K. & Miyamoto, E. Role of MAP kinase in neurons. Mol. Neurobiol. 16, 79–95 (1998).

    CAS  Article  Google Scholar 

  11. 11

    Sweatt, J. D. The neuronal MAP kinase cascade: a biochemical signal integration system subserving synaptic plasticity and memory. J. Neurochem. 76, 1–10 (2001).

    CAS  Article  Google Scholar 

  12. 12

    Koera, K. et al. K-ras is essential for the development of the mouse embryo. Oncogene 15, 1151–1159 (1997).

    CAS  Article  Google Scholar 

  13. 13

    Johnson, L. et al. K-ras is an essential gene in the mouse with partial functional overlap with N-ras. (published erratum, Genes Dev. 11, 3277, 1997) Genes Dev. 11, 2468–2481 (1997).

    CAS  Article  Google Scholar 

  14. 14

    Roberson, E. D. et al. The mitogen-activated protein kinase cascade couples PKA and PKC to cAMP response element binding protein phosphorylation in area CA1 of hippocampus. J. Neurosci. 19, 4337–4348 (1999).

    CAS  Article  Google Scholar 

  15. 15

    Atkins, C. M., Selcher, J. C., Petraitis, J., Trzaskos, J. & Sweatt, J. The MAPK cascade is required for mammalian associative learning. Nat. Neurosci. 1, 602–609 (1998).

    CAS  Article  Google Scholar 

  16. 16

    Selcher, J. C., Atkins, C. M., Trzaskos, J. M., Paylor, R. & Sweatt, J. D. A necessity for MAP kinase activation in mammalian spatial learning. Learn. Mem. 6, 478–490 (1999).

    CAS  Article  Google Scholar 

  17. 17

    English, J. D. & Sweatt, J. D. A requirement for the mitogen-activated protein kinase cascade in hippocampal long term potentiation. J. Biol. Chem. 272, 19103–19106 (1997).

    CAS  Article  Google Scholar 

  18. 18

    Ebinu, J. O. et al. RasGRP, a Ras guanyl nucleotide- releasing protein with calcium- and diacylglycerol-binding motifs. Science 280, 1082–1086 (1998).

    CAS  Article  Google Scholar 

  19. 19

    Tognon, C. E. et al. Regulation of RasGRP via a phorbol ester-responsive C1 domain. Mol. Cell Biol. 18, 6995–7008 (1998).

    CAS  Article  Google Scholar 

  20. 20

    English, J. D. & Sweatt, J. D. Activation of p42 mitogen-activated protein kinase in hippocampal long term potentiation. J. Biol. Chem. 271, 24329–24332 (1996).

    CAS  Article  Google Scholar 

  21. 21

    Frankland, P. W., Cestari, V., Filipkowski, R. K., McDonald, R. J. & Silva, A. J. The dorsal hippocampus is essential for context discrimination but not for contextual conditioning. Behav. Neurosci. 112, 863–874 (1998).

    CAS  Article  Google Scholar 

  22. 22

    Fanselow, M. S. Contextual fear, gestalt memories, and the hippocampus. Behav. Brain Res. 110, 73–81 (2000).

    CAS  Article  Google Scholar 

  23. 23

    Rampon, C. et al. Enrichment induces structural changes and recovery from nonspatial memory deficits in CA1 NMDAR1-knockout mice. Nat. Neurosci. 3, 238–244 (2000).

    CAS  Article  Google Scholar 

  24. 24

    Shimizu, E., Tang, Y. P., Rampon, C. & Tsien, J. Z. NMDA receptor-dependent synaptic reinforcement as a crucial process for memory consolidation. Science 290, 1170–1174 (2000).

    CAS  Article  Google Scholar 

  25. 25

    Fanselow, M. S. Factors governing one-trial contextual conditioning. Anim. Learn. Behav. 18, 264–270 (1990).

    Article  Google Scholar 

  26. 26

    Phillips, R. G. & LeDoux, J. E. Differential contribution of amygdala and hippocampus to cued and contextual fear conditioning. Behav. Neurosci. 106, 274–285 (1992).

    CAS  Article  Google Scholar 

  27. 27

    Schafe, G. E., Nadel, N. V., Sullivan, G. M., Harris, A. & LeDoux, J. E. Memory consolidation for contextual and auditory fear conditioning is dependent on protein synthesis, PKA, and MAP kinase. Learn. Mem. 6, 97–110 (1999).

    CAS  PubMed  PubMed Central  Google Scholar 

  28. 28

    Husi, H., Ward, M. A., Choudhary, J. S., Blackstock, W. P. & Grant, S. G. Proteomic analysis of NMDA receptor-adhesion protein signaling complexes. Nat. Neurosci. 3, 661–669 (2000).

    CAS  Article  Google Scholar 

  29. 29

    Kennedy, M. B. Signal-processing machines at the postsynaptic density. Science 290, 750–754 (2000).

    CAS  Article  Google Scholar 

  30. 30

    Leonard, A. S., Lim, I. A., Hemsworth, D. E., Horne, M. C. & Hell, J. W. Calcium/calmodulin-dependent protein kinase II is associated with the N-methyl-d-aspartate receptor. Proc. Natl. Acad. Sci. USA 96, 3239–3244 (1999).

    CAS  Article  Google Scholar 

  31. 31

    Silva, A. J. & Giese, K. P. in Neurobiology of Learning and Memory (eds. Martinez, J. & Kesner, R.) 89–142 (Academic, San Diego, California, 1998).

    Book  Google Scholar 

  32. 32

    Lisman, J. The CaM kinase II hypothesis for the storage of synaptic memory. Trends Neurosci. 17, 406–412 (1994).

    CAS  Article  Google Scholar 

  33. 33

    Fukunaga, K., Soderling, T. R. & Miyamoto, E. Activation of Ca2+/calmodulin-dependent protein kinase II and protein kinase C by glutamate in cultured rat hippocampal neurons. J. Biol. Chem. 267, 22527–22533 (1992).

    CAS  PubMed  Google Scholar 

  34. 34

    Ouyang, Y., Kantor, D., Harris, K. M., Schuman, E. M. & Kennedy, M. B. Visualization of the distribution of autophosphorylated calcium/calmodulin-dependent protein kinase II after tetanic stimulation in the CA1 area of the hippocampus. J. Neurosci. 17, 5416–5427 (1997).

    CAS  Article  Google Scholar 

  35. 35

    Hanson, P. I. & Schulman, H. Neuronal Ca2+/calmodulin-dependent protein kinases. Annu. Rev. Biochem. 61, 559–601 (1992).

    CAS  Article  Google Scholar 

  36. 36

    Giese, K. P., Fedorov, N. B., Filipkowski, R. K. & Silva, A. J. Autophosphorylation at Thr286 of the α calcium-calmodulin kinase II in LTP and learning. Science 279, 870–873 (1998).

    CAS  Article  Google Scholar 

  37. 37

    Berman, D. E. & Dudai, Y. Memory extinction, learning anew, and learning the new: dissociations in the molecular machinery of learning in cortex. Science 291, 2417–2419 (2001).

    CAS  Article  Google Scholar 

  38. 38

    Manabe, T. et al. Regulation of long-term potentiation by H-Ras through NMDA receptor phosphorylation. J. Neurosci. 20, 2504–2511 (2000).

    CAS  Article  Google Scholar 

  39. 39

    Farnsworth, C. L. et al. Calcium activation of Ras mediated by neuronal exchange factor Ras-GRF. Nature 376, 524–527 (1995).

    CAS  Article  Google Scholar 

  40. 40

    Giese, K. et. al. Hippocampus-dependent learning and memory is impaired in mice lacking the Ras-guanine-nucleotide releasing factor 1 (RAS-GRF1). Neuropharmacology 41, 791–800 (2001).

    CAS  Article  Google Scholar 

  41. 41

    Brambilla, R. et al. A role for the Ras signalling pathway in synaptic transmission and long- term memory. Nature 390, 281–286 (1997).

    CAS  Article  Google Scholar 

  42. 42

    Kim, J. H., Liao, D., Lau, L. F. & Huganir, R. L. SynGAP: a synaptic RasGAP that associates with the PSD-95/SAP90 protein family. Neuron 20, 683–691 (1998).

    CAS  Article  Google Scholar 

  43. 43

    Chen, H. J., Rojas-Soto, M., Oguni, A. & Kennedy, M. B. A synaptic Ras-GTPase activating protein (p135 SynGAP) inhibited by CaM kinase II. Neuron 20, 895–904 (1998).

    CAS  Article  Google Scholar 

  44. 44

    Barria, A., Muller, D., Derkach, V., Griffith, L. C. & Soderling, T. R. Regulatory phosphorylation of AMPA-type glutamate receptors by CaMK-II during long-term potentiation. Science 276, 2042–2045 (1997).

    CAS  Article  Google Scholar 

  45. 45

    Tan, S. E. & Liang, K. C. Spatial learning alters hippocampal calcium/calmodulin-dependent protein kinase II activity in rats. Brain Res. 711, 234–240 (1996).

    CAS  Article  Google Scholar 

  46. 46

    Cammarota, M., Bernabeu, R., Levi De Stein, M., Izquierdo, I. & Medina, J. H. Learning-specific, time-dependent increases in hippocampal Ca2+/calmodulin-dependent protein kinase II activity and AMPA GluR1 subunit immunoreactivity. Eur. J. Neurosci. 10, 2669–2676 (1998).

    CAS  Article  Google Scholar 

  47. 47

    Anagnostaras, S. G., Josselyn, S. A., Frankland, P. W. & Silva, A. J. Computer-assisted behavioral assessment of Pavlovian fear conditioning in mice. Learn. Mem. 7, 58–72 (2000).

    CAS  Article  Google Scholar 

Download references


We thank S.A. Josselyn, N.B. Fedorov and K.P. Giese for discussions, and R. Chen and M. Lacuesta for help with genotyping. We also thank J.M. Trzaskos (DuPont Pharmaceuticals Research Laboratories) and T. Jacks (Department of Biology, MIT) for donating SL327 and K-ras+/− mutants, respectively. This work was funded by grants from the McKnight Foundation, Merck Foundation and the NIH (P01HD33098 and AG13622) to A.J.S. M.O. was partially supported by a research fellowship from the Uehara Memorial Foundation for Life Sciences.

Author information



Corresponding author

Correspondence to Alcino J. Silva.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Ohno, M., Frankland, P., Chen, A. et al. Inducible, pharmacogenetic approaches to the study of learning and memory. Nat Neurosci 4, 1238–1243 (2001).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing