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bioRxiv · 10.1101/2025.06.10.658878

Problem-solving without a cortex: inferior lobe drives goal-directed object manipulation in cichlid fish

Estienne, P.·Page, G.·Poon, G.·Larrat, B.·Durier, T.·Dufresne, A.·Ciobanu, L.·Yamamoto, K.
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Abstract

Goal-directed object manipulation and problem-solving, which are necessary to evolve tool use behaviors, have long been linked to the expansion of the telencephalon in mammals and birds. Here, we show that goal-directed object manipulation in cichlid fish is driven by a non-telencephalic brain structure, the inferior lobe. Using manganese-enhanced MRI (MEMRI) on an ultra-high field 17.2 Tesla MRI system, we show that the inferior lobe is activated during a puzzle-box opening task. Furthermore, magnetic resonance (MR)-guided High Intensity Focused Ultrasound (HIFU) lesions profoundly impair fine motor coordination during this task without affecting general locomotion or motivation. These results reveal that cortex-like cognitive functions can arise from non-telencephalic brain structures in teleosts. With no homolog in tetrapods, the inferior lobe is a critical hub for flexible behavior in teleost fish. Our findings highlight the existence of alternative neural architectures for the emergence of complex cognition.

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Estienne, P., Page, G., Poon, G., Larrat, B., Durier, T., Dufresne, A., Ciobanu, L., Yamamoto, K.. 2025-06-15. Problem-solving without a cortex: inferior lobe drives goal-directed object manipulation in cichlid fish. https://doi.org/10.1101/2025.06.10.658878

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