Bioinspired figure-ground discrimination via visual motion smoothing
Fig 7
Stimulus-evoked responses at the single-unit level in the lobula network.
(A) Three classes of stimuli (upper row, with their names indicated) and the corresponding output of the ON+OFF EMD array (lower row). The ‘small obj.’ and the ‘bar’ had figures with sizes of 8.9° × 8.9° and 8.9° × 70°, respectively, and the luminance levels of their foreground and background were set as 0.25 and 0.75, respectively. The ‘wide-field’ square grating had a spatial wavelength of 17.8° and a Michelson contrast of 50%, and its luminance was periodically set as 0.25 and 0.75. All the stimuli had 70° x 180° visual fields and moved rightward at 33°/sec. (B) Stimulus-evoked membrane potentials in the six lobula modules with the names indicated beside each row. Only the response of the centrally located unit in each module is displayed. Dashed lines indicate the resting membrane potentials. (C) Effects of the bar height and speed on the depolarization extent of the Lm module. Only the data of the centrally located unit are displayed. Left panel: the peak of the evoked membrane potential versus the bar height. Right panel: the peak of the evoked membrane potential versus the bar speed. For all simulations, the synaptic weights of the projections from the EMD array to the postsynaptic lobula modules were set as αEMD→lo = 100.