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bioRxiv · 10.64898/2026.05.18.725835

Primate Hippocampus Reveals Distinct Rules for Associative Synaptic Plasticity

Manakkadan, A.·Kumar, K.·Chong, Y. S.·Wong, L.-W.·Navakkode, S.·Wong, Y. P.·Soong, T. W.·Libedinsky, C.·Sajikumar, S.
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Abstract

Long-term potentiation (LTP) is a key cellular mechanism underlying learning and memory, but its conservation across species remains unclear. Using nonhuman primates (NHPs), we examined hippocampal synaptic plasticity at Schaffer collateral- CA1 synapses. Theta-burst stimulation (TBS) reliably induced LTP in NHPs, comparable to rodents. However, unlike rodents, TBS in NHPs readily engaged synaptic tagging and capture (STC), indicating a lower threshold for associative plasticity. This was accompanied by increased expression of plasticity-related proteins, including PKM{zeta} and BDNF, suggesting enhanced recruitment of protein synthesisdependent stabilization mechanisms. These findings reveal a species-specific divergence in the molecular regulation of persistent synaptic plasticity and identify an evolutionary specialization in mechanisms supporting associative memory. Together, our results highlight limitations of rodent models in fully capturing human-relevant memory processes and underscore the importance of primate systems for translational neuroscience.

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Manakkadan, A., Kumar, K., Chong, Y. S., Wong, L.-W., Navakkode, S., Wong, Y. P., Soong, T. W., Libedinsky, C., Sajikumar, S.. 2026-05-19. Primate Hippocampus Reveals Distinct Rules for Associative Synaptic Plasticity. https://doi.org/10.64898/2026.05.18.725835

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