Embodied cognition in miniature brains and bodies of marine zooplankton

EMBO Members’ Meeting
October 25-27, 2023

Gáspár Jékely

Centre for Organismal Studies, Heidelberg University

The ‘brain’

Ciliated zooplankton larvae

Platynereis dumerilii

• breeding culture, full life-cycle
• embryos daily, year round
• genome sequence
• microinjection, transgenesis
• neuron-specific promoters and antibodies
• knock-out lines
• neuronal connectome
• whole-body neuronal activity imaging
• whole-animal pharmacology by bath application 😎

Whole-body vEM reconstruction of a 3d Platynereis larva

.

Phototaxis

Helical swimming, sensing and turning are tightly linked

Whole-body coordination of cilia

Whole-body coordination of cilia

Whole-body coordination during startle

Coordinated arrest of all cilia

No arrest in polycystin receptor mutant

Startle recruits body-wide circuits and effectors

Pressure response in Platynereis larvae

Pressure response is graded

Pressure is sensed by photoreceptors with ramified cilia

cPRC - ciliated Photoreceptor Cells

UV response in Platynereis larvae

Circuitry of ciliary photoreceptors

Mathematical modelling of the circuit

Up or down?

‘front-wheel drive’ head cilia fast

‘rear-wheel drive’ head cilia slow

Conclusions

• whole-organism approach is needed to understand how effectors are coordinated

  
  

• many behaviours and circuit mechanisms only make sense in a whole-body (embodied) context

  
  

• need to study the body to understand the brain

  
  

• small animals have great potential to reveal how nervous systems control behaviour

Acknowledgements

• Emelie Brodrick
• Sanja Jasek
• Adam Johnstone
• Luis A. Bezares-Calderón
• Kei Jokura
• Alexandra Kerbl
• Emily Savage
• Simone Wolters