Figure 6.
CTS model parameters and summary metrics. A, CTS model parameter estimates. The estimated parameter σ is smaller for later (∼0.003, hV4-IPS), compared with earlier visual areas (∼0.3, V1–V3ab), indicating that the temporal sum in the later visual areas deviates more from the linear sum. The time constant τ is short in V1–V3, compared with most of the later visual areas. B, CTS parameter recovery. The precision with which parameters can be fit depends on the noise level in the data and the specific parameter values. We simulated data using the median τ and σ from V1, V3ab, and LO, and the noise levels estimated from these areas. The analysis shows that, under these conditions, τ (x-axes) is specified most precisely in V1 and least precisely in V3ab; the opposite pattern is found for σ (y-axes). C, Summary metrics. Two summary metrics of the CTS model reveal a pattern across ROIs. Rdouble is the ratio of the predicted response to a 200 ms pulse divided by twice the response to a 100 ms pulse. Rdouble is <1 for all ROIs, indicating subadditivity, and decreases along the visual hierarchy (V1–V3, ∼0.67, LO-IPS, <0.6). TISI is the length of ISI required for the response to two 100 ms pulses to approach the linear prediction. TISI is short in the earlier areas (V1–V3, ∼100 ms) compared with most of the later areas. Figure made from the script trf_mkFigure6.m.