Figure 6.

The sinusoidal field potentials during scratching propagate as a traveling wave. A, The traces indicated with electrodes 17–24 show averaged recordings of sinusoidal CDPs. MG and TA indicate the normalized, integrated, and rectified electroneurograms for the extensor medial gastrocnemius and flexor tibialis anterior nerves during scratching, respectively, for one cat. Each trace is the average of 95–200 normalized scratching cycles. Note that the peak of the negative component of the wave exhibits a phase gradient that occurs before and after the activation of the flexor TA nerve; in contrast, the peak of the positive component exhibits a phase gradient before the activation of the extensor MG nerve. The green and gray lines indicate the phase gradient in the sinusoidal-like CDPs. The blue and red circles show the points of intersection of the phase gradient lines and the vertical lines of the beginning for the flexor and extensor activity. B, Incidence of the negative or positive waves that immediately precedes the activation of flexor or extensor motoneurons, respectively, as is indicated by blue and red circles in Figure 6A versus the recording electrode (17–24). This graph was obtained from 18 cats for right scratching. C, D, The sinusoid-like cord dorsum potentials during scratching persist after the bilateral lesion of the ventral horn. C, Sinusoidal-like cord dorsum potentials and electroneurographic activity of the MG and TA nerves before the lesion of the ventral horn. The green and gray lines indicate the phase gradient in both conditions. D, The same as C but after the lesion of the ventral horn. Note that the sinusoidal potentials persist but the rhythmic activity in the nerves was abolished. E, F, Power spectra obtained from the sinusoidal cord dorsum potentials recorded with electrode 21. Au, Arbitrary units. G, Histological reconstruction of the lesions of the ventral horn in one cat. The sinusoidal CDP signals were refiltered at 1–70 Hz bandpass.