Bivariable Analysis of EEG Signals - Quantitative EEG Analysis Methods and Clinical Applications - page 113

c xy

1

0.8

0.6

0.4

0.2

0

− 0.2

− 2.5 − 2 − 1.5 − 1 − 0.5 0 0.5 1 1.5 2 2.5

(a)

c xy

1

0.8

0.6

0.4

0.2

0

− 0.2

− 2.5 − 2 − 1.5 − 1 − 0.5 0 0.5 1 1.5 2 2.5

(b)

c xy

1

0.8

0.6

0.4

0.2

0

− 0.2

− 2.5 − 2 − 1.5 − 1 − 0.5 0 0.5 1 1.5 2 2.5

(c)

Δ t (sec)

Figure 4.2 (a-c) Cross-correlation values for the three signals of Figure 4.1 as a function of the time
delay τ between both signals.

()
()

C ω

xy

()

Γ xy ω = (4.3)

()

C ω C ω

xx xx

is named the coherence function. As mentioned earlier, this measure is particularly
useful when synchronization is limited to some particular EEG frequency band (for
a review, see [12]). Note that without the segmentation of the data introduced to