FIG. 2.

Determining the core/belt boundary. A: distribution of band-pass noise/pure tone (BPN/PT) ratio obtained from the neurons' sustained responses [BPN/PT(s)] in the recording area. Data smoothed with a 2-dimensional Gaussian kernel, σ = 1.5. Black line shows the core/medial belt boundary. Belt areas are located medially and are predominantly red/yellow; core areas are located laterally and are predominantly blue/green. Location of units whose responses are shown in C and D is marked with white letters. B: direction, strength, and significance of BPN/PT(s) gradients. Correlation coefficient of the ratio values with spatial locations of units projected onto an axis that was rotated 360° in 5° steps is shown as a black line. The gradient direction angle is the angle at which maximum correlation was found, the strength is the maximum r value, and the P value is determined by comparison with correlations obtained from scrambled data (shades of gray). See methods for details. The outer circle of the plot denotes r = 0.4. C: example response of a belt unit, showing sustained activity to BPN stimuli. D: example response of a core unit, showing no sustained activity to BPN stimuli. Vertical lines show stimulus start and end. Peristimulus time histograms (PSTHs) binned with 20 ms.