[Reflection of quantitative parameters of a series of nonreinforced heteromodal signals in cortical evoked potentials]. / Otrazhenie v korkovykh vyzvannykh potentsialakh kolichestvennykh parametrov riadov nepodkrepliaemykh signalov raznoi modal'nosti.

Systematic presentation to dogs of series, standard in number of sound, electro-cutaneous or visual stimuli, leads to a development of U-shaped dependence of cortical evoked potentials (EPs) on the stimulus position in the series. This indicates that in the dog's CNS an estimation is formed of the quantitative structure of the applied series, shaped in a similar way for stimuli of all of these modalities. Singling-out of the stimulus quantitative property results from a simple repetition of the series without any reinforcement, i.e. in the course of perceptual learning. Dependence of the EP on its position in the series appears earlier and with a greater stability in the projection of the stimulus modality than in cortical areas of other modalities. The dependence of the EP on signal position in a series of unimodal stimuli is relatively rapidly reproduced following a transition to similar series of other modalities. This suggests a possibility of transfer of the estimation of quantitative series structure from one modality analyser to another one.

[Evoked potentials of the dog sensomotor cortex following systematic application of series of electrocutaneous stimuli]. / Vyzvannye potentsialy sensomotornoi kory mozga sobak pri sistematicheskom primenenii riadov élektrokozhnykh razdrazhenii.

Standard 5-member series of weak electro-cutaneous stimulations of the fore-paw were applied in chronic experiments to two dogs with implanted cortical electrodes. The stimuli caused no apparent motor reactions and were not reinforced by any other type of stimulation. Evoked potentials (EP) in the sensorimotor cortex were gradually forming in the course of experiments in such a way that the amplitude of averaged EPs to the extreme stimuli of the series became larger than those to the middle ones. The elaborated U-shaped dependence of the averaged EP amplitudes in the sensorimotor cortex on the ordinal number of the electrical stimuli correlates with the same EP dependence observed in the auditory cortex of dogs in response to series of clicks. The described form of EP organization in response to the stimuli of one modality facilitates the elaboration of the same type of organization in response to the stimuli of an other modality.

[Responses of the auditory region of the dog cortex to paired clicks repeatedly presented in a standard series]. / Reaktsii slukhovoi oblasti kory sobak na parnye zvukovye shchelki, povtorno primeniaemye v standartnom riadu

A study was made of evoked potentials (EP) in the dog auditory cortex to systematically presented series of acoustic stimuli consisting of five pairs of clicks with a 150 to 300 msec interstimuli interval within the pair, for different dogs. As such series were presented, a dependence developed of amplitude characteristics of averaged EPs on the place of paired stimulation in the five-term series. The correlation of amplitudes inside each pair was likewise determined by the place of the pair in the series. The index of the EP amplitude recovery was smaller in the case of the first and fifth places of the pair in the series and greater in the middle places of the series. Reinforcement of the five-term series of paired clicks with electro-cutaneous stimulation of the paw and elaboration of a conditioned defensive reflex changed the established correlation of EP amplitudes. In the experiment the index of EP amplitude recovery depended on the signal significance of the presented click series.