article published yes Renée S. Koolschijn author Prakriti Parthasarathy author Michael Browning author Xenia Przygodda author Liliana P. Capitão author William T. Clarke author Tim P Vogels author CB6FF8D2-008F-11EA-8E08-2637E66974250000-0003-3295-6181 Jill X. O’Reilly author Helen C. Barron author TiVo department The mammalian brain organises knowledge about entities in the world and relationships between them using cognitive maps. When forming a cognitive map, there is a necessary trade-off between extending the map to make novel inferences, and storing a veridical copy of past experience. However, the neural mechanisms that control this trade-off remain unknown. Using a cross-scale approach that combines a pharmacological intervention in humans with neural network modelling, we show that the neuromodulator noradrenaline elicits a significant ‘spread of association’ across hippocampal cognitive maps. This neural spread of association can be explained by changes in synaptic plasticity that predict overgeneralisation in behaviour. Thus, elevated noradrenaline during learning increases the ‘smoothing kernel’ for plasticity across the cognitive map, allowing disparate memories to become linked and distorted. https://research-explorer.ista.ac.at/download/21895/21905/2026_NatureComm_Koolschijn.pdf application/pdfno https://creativecommons.org/licenses/by/4.0/ Springer Nature2026 eng 2041-1723 4183218610.1038/s41467-026-70659-x 17 Koolschijn, Renée S., Prakriti Parthasarathy, Michael Browning, Xenia Przygodda, Liliana P. Capitão, William T. Clarke, Tim P Vogels, Jill X. O’Reilly, and Helen C. Barron. “Noradrenaline Causes a Spread of Association in the Hippocampal Cognitive Map.” <i>Nature Communications</i>. Springer Nature, 2026. <a href="https://doi.org/10.1038/s41467-026-70659-x">https://doi.org/10.1038/s41467-026-70659-x</a>. Koolschijn RS, Parthasarathy P, Browning M, et al. Noradrenaline causes a spread of association in the hippocampal cognitive map. <i>Nature Communications</i>. 2026;17. doi:<a href="https://doi.org/10.1038/s41467-026-70659-x">10.1038/s41467-026-70659-x</a> Koolschijn RS, Parthasarathy P, Browning M, Przygodda X, Capitão LP, Clarke WT, Vogels TP, O’Reilly JX, Barron HC. 2026. Noradrenaline causes a spread of association in the hippocampal cognitive map. Nature Communications. 17, 3961. Koolschijn, R. S., Parthasarathy, P., Browning, M., Przygodda, X., Capitão, L. P., Clarke, W. T., … Barron, H. C. (2026). Noradrenaline causes a spread of association in the hippocampal cognitive map. <i>Nature Communications</i>. Springer Nature. <a href="https://doi.org/10.1038/s41467-026-70659-x">https://doi.org/10.1038/s41467-026-70659-x</a> R. S. Koolschijn <i>et al.</i>, “Noradrenaline causes a spread of association in the hippocampal cognitive map,” <i>Nature Communications</i>, vol. 17. Springer Nature, 2026. R.S. Koolschijn, P. Parthasarathy, M. Browning, X. Przygodda, L.P. Capitão, W.T. Clarke, T.P. Vogels, J.X. O’Reilly, H.C. Barron, Nature Communications 17 (2026). Koolschijn, Renée S., et al. “Noradrenaline Causes a Spread of Association in the Hippocampal Cognitive Map.” <i>Nature Communications</i>, vol. 17, 3961, Springer Nature, 2026, doi:<a href="https://doi.org/10.1038/s41467-026-70659-x">10.1038/s41467-026-70659-x</a>. 218952026-05-20T14:30:37Z2026-05-21T07:05:01Z