Figure 9.
Difference between the power at negative and positive wavenumbers for the peak response flicker frequencies (f = 3,7 8,11,12, and 13 Hz). Differences were averaged across 9 subjects. For each frequency the difference in wavenumber spectrum Ψ(f, −k) − Ψ(f, + k) is shown at each wavenumber k by a point. Filled circles indicates a positive difference (posterior to anterior traveling waves) and open circles indicate a negative difference (anterior to posterior traveling waves). The size of each circle is proportional to the SNR difference. To emphasize robust differences larger than additive effects of broadband noise, any difference of magnitude less than 4.0 (in SNR units) was represented by a point. For example, the left superior (LS) array indicates anterior to posterior traveling 11 Hz waves of relatively long wavelengths. By contrast, this same array indicates 12 Hz posterior to anterior waves in roughly the same wave length range (10–15 cm).