Parameters in LIP simulation
| Parameter | Value | Justification |
|---|---|---|
| MT, baseline firing rate | 8 spikes/s | Britten et al., 1993 |
| MT, firing rate to 0% coherence | 20 spikes/s | Britten et al., 1993 |
| MT, latency | 100 ms | Britten et al., 1993 |
| MT, gain on preferred direction | 0.36 spikes/s/%coh | Match to psychophysical data on no-pulse trials |
| MT, gain on null direction | −0.18 spikes/s/%coh | Match to psychophysical data on no-pulse trials |
| Magnitude of interneuronal correlation | r = 0.21 | Bair et al., 2001 |
| Timescale of interneural correlation | width of CCG at half-height = 9 ms | Bair et al., 2001 |
| LIP, gain on MT signal | 5.6 | Match to LIP responses on no-pulse trials |
| LIP, baseline firing rate | 48 spikes/s | Match to LIP responses on no-pulse trials |
| LIP, latency | 125 ms | Match to LIP responses on no-pulse trials |
| Spike rate smoothing, MT | τ = 20 ms | Mazurek et al., 2003; for explanation, see Materials and Methods |
| Spike rate smoothing, LIP | τ = 100 ms | Mazurek et al., 2003; for explanation, see Materials and Methods |
| Height of decision bound | 68 spikes/s | Match to psychophysical data on no-pulse trials |
| Effective pulse strength | 10% motion coherence | Match to pulse effect on psychophysical data |
| Postdecision time | Mean = 150 ms | Match to psychophysical data on no-pulse trials |
The table shows parameter settings for a simulated bounded integrator used to generate predictions in Figures 9 and 10. The “Justification” column indicates the source of data that was used to set the parameter. For simulation and analysis of a model perfect integrator, see Materials and Methods. For comparison of LIP activity with perfect integration to a decision bound for additional information, see Results. %coh, Percentage coherence; CCG, cross-correlogram. Format follows that for Mazurek et al. (2003).