Yasmine Meroz: Plant Tropisms: A Window on Memory and Computation in Distributed Systems

Plants solve complex navigational problems, continuously negotiating their unstructured and changing environment. They strategically redirect their growth to optimize photosynthesis in response to fluctuating light sources, while minimizing mechanical strains. While they have no brain or neural system, they can sense their environment, process sensory information, and plan strategic growth movements. Since plants are decentralized systems, underlying computational processes must be distributed; emergent properties of the tissue. We show that plants are capable of integration sensory information over space and time: (i) plants represent spatial information about light distributions as vectors, and respond to a non-linear vectorial sum. (ii) we find that plants integrate sensory information over time, summing and subtracting stimuli over different timescales, effectively representing a band-pass filter, or 2^nd order motor control function. Finally, we discuss how such sensory information is encoded and processed microscopically.