Speaker
Description
Molecular components of cells must communicate with each other through physical mechanisms that necessarily consume energy [1]; for example, ion channels communicate electrically, by modulating ionic currents which are sensed as resulting charge accumulation at the membrane by distant voltage gated channels. I will first argue in general that powering such communication must incur large costs to overcome thermal fluctuations, likely dominating the information processing energy budget of cells. I will then report on progress towards understanding the energetic requirements of running a specific sensory system – neurons in the pit organ of certain snakes which sense tiny changes in temperature. In this system, individual thermally sensitive ion channels are molecular thermometers, whose opening is triggered by a roughly 1K change in temperature. However, individual neurons can respond reliably to mK temperature changes, 1000 fold smaller. I will briefly explain our model for how this signal amplification and information integration works mechanistically [2], requiring individual channels to communicate with each other electrically. While some of the details of this system are specific to the task of high-precision thermometry, others are likely general, and we seek design principles for the scale of single-channel currents, the sensitivity of voltage-gated channels, and the density of typical voltage-gated channels in neurons.
[1] SJ Bryant, BB Machta. Physical constraints in intracellular signaling: the cost of sending a bit. PRL, 2023
[2] I Graf, B Machta. A bifurcation integrates information from many noisy ion channels. arXiv:2305.05647, 2023
