Seeing the Heat

Science Signaling  14 Jun 2011:
Vol. 4, Issue 177, pp. ec167
DOI: 10.1126/scisignal.4177ec167

Dim-light vision requires a visual system that has high sensitivity to light but a low probability of thermal activation. Nevertheless, thermal pigment noise does occur. Luo et al. used single-cell recordings to measure photoisomerization activation energies and noise rates for diverse rod and cone pigments. A quantitative relation was observed between a pigment's photoactivation energy and its peak absorption wavelength. A statistical-mechanical analysis using this relation and modeling thermal activation was able to predict pigment noise rates.

D.-G. Luo, W. W. S. Yue, P. Ala-Laurila, K.-W. Yau, Activation of visual pigments by light and heat. Science 332, 1307–1312 (2011). [Abstract] [Full Text]