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Biomedical subjects

I N Tveritskaya

Publications and source records attributed to I N Tveritskaya.

7 recordsLinked to original sources
PubMed1979

Hippocampal evoked potentials and EEG changes during classical conditioning in the rat.

Hippocampal evoked potentials (EPs) and EEG responses were studied in rats, using a classical conditioning paradigm (water, US), with a spatially discontiguous CS-US arrangement in order to separate the CS and goal-related responses. In early training, when the orienting score was high, the tone CS, instead of eliciting a definite EP, usually reset hippocampal theta activity in phase, i.e. theta rhythm became time-locked to CS. With further training, orienting activity (ORI) decreased to the preconditioning level, and this was associated with the recurrence of short-latency and high voltage hippocampal EPs, similar to those observed during habituation. This high voltage EP predicted that the animal would not orient any more towards CS. This correlation was confirmed by behavioural (satiation, shock US) and by pharmacological (scopolamine HBr, 2 mg/kg) treatments, all of which reduced the ORI score. Hippocampal EEGs also showed characteristic changes during conditioning. ORI towards CS was accompanied by higher frequency spectral peaks (9 c/sec) than response to US (7--8 c/sec). This correlation was seen both across sessions and within trials. We conclude that the above changes are related to orienting, attentional factors rather than to movement-related variables.

Animals↗
PubMed1979

Auto-shaping or orienting?

Four experiments were carried out to study the development of the orienting response (OR) under different experimental conditions in the cat and rat. In Experiment I and II (cat) and Experiment IV (rat) classical CS-US pairing was used (with food, shock and water reinforcers, respectively). In Experiment III (cat) an instrumental pedal press response was brought under the control of a discriminative signal. In all four experiments the auditory CS was spatially discontiguous with reinforcement in order t o separate CS directed orienting responses from US related activities. Exposure to CS signalling food or water caused the animals to orient to it throughout conditioning (up to 700 trials) and this overt responding was absent if CS predicted aversive reinforcers. OR was consistently followed by goal (US) directed anticipatory activities. It is proposed that the CS directed auto-shaped response ("sign-tracking") is identical with the conditional orienting response, and that the spatio-temporal patterning of behaviors is influenced both by CS and US.

Animals↗
PubMed1974

"Counting" of clicks, as reflected in amplitude of potentials evoked in auditory cortex of the dog.

In eight dogs with chronically implanted electrodes click-evoked potentials were recorded in the ectosylvian and suprasylvian gyri. During daily sessions clicks were presented in several short trains with a steady interclick interval of 1 s and not followed by any unconditional stimulus. The largest amplitudes resulted from the first and last clicks in the series so that curves plotted for each series assumed a U-shape. Changing the intensity or interclick interval disrupted this pattern.

Acoustic Stimulation↗
PubMedDate not supplied

Cortical multineuronal activity in dogs with defensive instrumental conditioned reflex.

For the first time in dogs with semi-microelectrodes chronically implanted in the motor and somatosensory region of the cortex, background multineuronal activity (MNA) was recorded over the long term followed by an amplitudinal discrimination from the MNA of impulse series presumably belonging to cells of large, medium, and small size was performed. The presence of close synergistic functional connections, particularly significant during the avoidance conditioned reflex and its extinction, was established by determining the correlation coefficient (CC) between the impulse flows of these neurons. In trained animals the highest CC values were observed between neurons with a small and medium spike amplitude. The network properties of identified neurons were studied by constructing histograms of cross interval relationships. The connections established were of primarily a unilateral, excitatory character.

Animals↗
PubMedDate not supplied

Is the electrical activity of the brain always electrical? (The factors forming the potential of the metallic electrode during its direct contact with the brain).

This article is devoted to an analysis of the factors forming slow changes in the potential of a metallic electrode coming into direct contact with living tissue. Data are presented in this paper according to which, the electrochemical activity of the tissue also participates, in addition to electrical activity, in the formation of the electrode potential. The article is in the nature of a discussion.

Amplifiers, Electronic↗