The constant component f 0 of the image provides the average frequency during the test. The first harmonic f 1cos is a sine approximation of the one peak modulation. BIRB 796 The phase of the peak of the first harmonic indicates the preferred phase of neuronal discharge, 1. Finally, r is the remainder after the first two terms of the series. As a measure of periodical, tilt related PTN modulation, we used the peak to peak value of the first harmonic. All quantitative data are presented as the means. e. m. Statistical comparisons were made using Student,s t test, with the significance level set at P0. 05. Histological procedures At the termination of experiments, cats were deeply anaesthetized with pentobarbital sodium. Several reference lesions were made in the region of the motor cortex from which neurons were sampled.
Cats were then perfused with isotonic saline followed by a 10% formalin solution. Frozen brain sections of 50 m thickness were cut in the regions of recording and stimulating electrodes. The tissue was stained for Nissl substance with cresyl violet. Position of stimulation electrodes in the medullar pyramids was verified by PHA-680632 observation of electrode track gliosis. Positions of recording tracks in the motor cortex were estimated in relation to the reference lesions. Figure 1. Postural tests The cat was standing on two platforms, one under the forelimbs and one under the hindlimbs. The platforms were tilted in the frontal plane. The cat was continuously licking food from a feeder. A C, in phase tilts of the two platforms.
A, the body outline is shown for the horizontal position of the platforms. B and C, the body outline is shown for two positions of the platforms, horizontal and 15 degrees L, respectively. Postural corrections were characterized by measuring the lateral displacement of the upper point of the fore and hind parts of the trunk in relation to the corresponding platform. The normal component of the contact force produced by each limb was measured by means of a force plate. D, lifting the hindquarters. E, lifting the forequarters. F, antiphase tilt of the two platforms. G, lifting the hindquarters and one forelimb. H, lifting the forequarters and one hindlimb. Results Postural motor responses Postural motor responses in different tests were similar in the two cats and did not differ from those described in our previous paper.
When all limbs were standing, tilts of the platform evoked postural corrections, i. e. lateral displacements of the trunk in the direction opposite to tilt, with a peak to peak value of 6 8 cm. These corrective movements were caused by extension of the limbs on the sidemoving down, and flexion of the limbs on the opposite side. Due to postural corrections, cats maintained the dorsal side up 252 A. Karayannidou and others J Physiol 586. 1 orientation, and stabilized the head position against the feeder. When the two parts of the platform were tilted in antiphase, cats stabilized the dorsal side up orientation of both the forequarters and hindquarters. Correctivemovements in this testwere in antiphase relative to the corresponding platform, with the values similar to that in test 2F2H. When only two forelimbs or only two hindlimbs were standing on the platform, tilts of the platform evoked postu