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 (Q(10) of 2.6). The corresponding sensory transducer-spike encoding processes have a weaker temperature dependence (Q(10) 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 (Q(10) of 5), while receptor potential onset latency (Q(10) of 1.4) and optic nerve spike conduction velocity (Q(10) 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 (Q(10) of 2.4) and broad interspike interval distribution compared to the thermal sensitivity (Q(10) of 1.4) and narrow spike interval spectrum of the response of a single unit within the bursting group.