Figure 8. SF-STMDs are facilitated by a primer that moves toward the receptive field.
(A) Primers move either toward (red) or away (yellow) from the classical receptive field (RF), preceding a probe target within the RF (mean, n = 13 dragonflies). (B) Outside the receptive field, primer responses do not significantly differ from spontaneous activity. Primers that move towards the receptive field increase probe responses by over 40% (p=0.0004, n = 13 dragonflies). (C) Individual STMDs, with either small or large receptive fields, exhibit varying degrees of facilitation (blue). Mean facilitation (black) increase responses by over 40% in small-field (n = 13 dragonflies), 80% in large-field STMDs (n = 11 dragonflies) and 50% in CSTMD1 (data not shown). (D) Six small-field STMD receptive fields (RF) are predominantly fronto-dorsal and exhibit variation in overall size and spatial locations. Contour lines represent 25 spikes/s. The SF-STMD with light purple contours is the same neuron in E, with inputs in the binocular region of the dragonfly’s right visual field, whilst input dendrites are in the left hemisphere (E) An SF-STMD’s axon traverses the brain, potentially underlying transfer of local predictive gain modulation.