Figure 5. Low or high contrast primers increase probe contrast sensitivity.
(A) Either a low or high contrast primer is presented before varying contrast probes (contrast sensitivity function). These either continue the path trajectory or jump to a distant location. (B) Example data traces of responses to either low (grey) or high (black) contrast primers that are presented before a series of varying contrast probes (light, medium and dark blue) (C) CSTMD1’s sensitivity to varying contrast probes exhibits a sigmoidal function (grey), with the dashed line indicating a detection threshold above spontaneous levels. Following either a nearby low contrast (pink) or high contrast (red) primer, contrast sensitivity is substantially increased (n = 9 dragonflies, p<0.0001). A distant primer (yellow) does not elicit facilitation, even though spiking activity during low and high contrast primers (final 100 ms) is significantly different (inset, n = 9 dragonflies, p=0.02). (D) In response to an excitatory stimulus (e.g. high contrast stimulation), the underlying membrane potential is hyperpolarized, a form of motion-after-effect (MAE). (E) The hyperpolarizing motion-after-effect is related to the strength (e.g. target contrast) of the stimulus.