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. 2000 Dec 19;97(26):14748–14753. doi: 10.1073/pnas.97.26.14748

Figure 2.

Figure 2

(a) Cross-correlation between supragranular layers of area 17 and infragranular layers of area 7 in the middle-frequency range (4–20 Hz, Left) during presentation of the go (red line) and no-go (blue line) stimuli. The star indicates a significant cross-correlation during go trials (P < 0.05, n = 75). The respective cross-correlation functions in the high-frequency range are shown (Right). (b) In one cat, stimuli for go and no-go trials were reversed (icons to the right). The cross-correlation of neuronal activity in area 17 and area 7 is shown for either stimulus. The star indicates a significant cross-correlation during go trials. (c) As measure for an enhancement of cross-correlation, the ratio of cross-correlation amplitudes during go and no-go trials is introduced. It is averaged over all electrode pairs (cat P). Black bars, ratio during the relevant second stimulus; and gray bars, ratio during the preparatory first stimulus. A significant enhancement of cross-correlation (i.e., a ratio > 1) is found with a maximum at alpha frequency; this difference between go and no-go cross-correlation was significant (P < 0.05) in a paired Wilcoxon test. (d) Comparison is shown of cross-correlation during stimulus presentation in correctly performed go trials and incorrectly performed trials (average over all electrodes of area 17 and 7, cat L). The star indicates a significant difference in the θ-frequency range between correct and incorrect trials (P < 0.05, paired Wilcoxon test). The small difference seen in the γ range did not reach significance. The inlet shows the subdivision into intraareal and interareal interaction, demonstrating that a substantial increase is accounted for by the interareal interactions. (e) Electrode-pairs where cross-correlation differed significantly (P < 0.05) between go and no-go stimuli are depicted with respect to their position in the different cortical layers (cat P). Solid lines, increased cross-correlation during go stimuli; and dashed lines, decreased cross-correlation during go stimuli. The different frequency ranges are indicated by color.