Thermal Sensitivity of Lateral Inhibition in Limulus Eye

Abstract

The effectiveness of lateral inhibition, measured as spike response decrement in a test ommatidium, produced by activity in a group of neighboring ommatidia, decreases as temperature decreases (Q10 of 2.6). The corresponding sensory transducer-spike encoding processes have a weaker temperature dependence (Q10 of 1.6). Relative synaptic delay, the time difference between the latency of inhibition onset and the latency of test receptor excitation, has a strong temperature dependence (Q10 of 5), while receptor potential onset latency (Q10 of 1.4) and optic nerve spike conduction velocity (Q10 of 1.7), two factors inherent in relative synaptic delay, are less temperature sensitive. Oscillations of optic nerve spike response ("bursting") may be produced by thermal adjustment of temperature-sensitive parameters of the lateral inhibitory network in the retina. Burst interval has a strong temperature dependence (Q10 of 2.4) and broad interspike interval distribution compared to the thermal sensitivity (Q10 of 1.4) and narrow spike interval spectrum of the response of a single unit within the bursting group.