Figure 5
An integrate-and-fire neuron model explains multisensory enhancement of C-start behavior. (a) Model Diagram. Functions representing visual (upper left) or auditory (lower left) input converge onto the Mauthner cell model (central panel). Output variables measured are membrane potential and spike time when threshold is reached. (b) Response probability as a function of stimulus intensity for unisensory trials. Six auditory (bi) or visual (bii) intensities were fitted so that response probability matched behavioral results for non-freezing animals (n = 1200). (c) C-start probability for multisensory trials. Numbers in white represent the relative difference with the experimental response probability, calculated as (p(mod) − p(exp))/(p(mod) + p(exp)) (cf., Fig. 4a). (d) ICs as a function of sound intensity and colored by visual intensity (di) or as function of visual intensity and colored by auditory intensity (dii). As in behavioral experiments, the model shows enhanced multisensory integration during the MSI period and inverse effectiveness for auditory intensity, although not for visual intensity. (e) Modelled ICs during the UV period as a function of sound intensity and colored by visual intensity (ei) or as a function of visual intensity colored by auditory intensity (eii) (horizontal jitter applied to ease visualization). The dashed horizontal line represents no integration.
