Range Of Shock Intensities Research Articles

Ethograms reveal a fear conditioned visual cue to organize diverse behaviors.

Recognizing and responding to threat cues is essential to survival. In rats, freezing is the most common behavior measured. Previously we demonstrated a threat cue can organize diverse behaviors (Chu et al., 2024). However, the experimental design of Chu et al. (2024) was complex and the findings descriptive. Here, we gave female and male Long Evans rats simple paired or unpaired presentations of a light and foot shock (8 total) in a conditioned suppression setting, using a range of shock intensities (0.15, 0.25, 0.35 or 0.5 mA). We found that conditioned suppression was only observed at higher foot shock intensities (0.35 mA and 0.5 mA). We constructed comprehensive, temporal ethograms by scoring 22,272 frames of behavior for 12 mutually exclusive behavior categories in 200 ms intervals around cue presentation. A 0.5 mA and 0.35 mA shock-paired visual cue suppressed reward seeking, rearing and scaling, as well as light-directed rearing and light-directed scaling. The shock-paired visual paired cue further elicited locomotion and freezing. Linear discriminant analyses showed that ethogram data could accurately classify rats into paired and unpaired groups. Considering the complete ethogram data produced superior classification than considering subsets of behaviors. The results demonstrate diverse threat-elicited behaviors - in a simple Pavlovian fear conditioning design - containing sufficient information to distinguish the fear learning status of individual rats.

Decreased Measures of Experimental Anxiety in Rats Bred for High Alcohol Preference

A prevalent notion holds that acute anti-anxiety actions of ethanol are important for the reinforcing properties of this drug, and might predispose individuals with pre-existing anxiety disorders for developing ethanol dependence. This notion remains controversial, and human studies have yielded conflicting results. Ethanol dependence is likely a heterogenous disorder, and the discrepancies might be explained by a different relationship between anxiety and alcohol reinforcement in different subtypes of alcoholism. Recent results in experimental animals suggest that antianxiety actions of ethanol are important reinforcers of voluntary ethanol consumption in heterogeneous rats. Here, we examined whether the relationship is different in the AA line of rats bred for high voluntary ethanol intake. Behavior was studied in two established animal models of anxiety, a punished drinking conflict test, and the elevated plus maze. In the conflict test, the AA line displayed a markedly disinhibited behavior over a range of shock intensities, compared both with their counterpart, the ANA line, and with regular Wistar rats. On the plus maze, both AA and Wistar rats showed lower measures of experimental anxiety than ANA subjects. The phenotype of the animals was confirmed using a two-bottle free choice alcohol drinking procedure. The disinhibited behavior and spontaneous ethanol preference of the AA line differs from what has been found in heterogeneous rats, and displays similarities to genetically transmitted type II alcoholism according to the nomenclature of Cloninger.

Relative aversion thresholds for shock in infant mice.

Using a spatial-preference technique, we tested separate groups of mice, 5, 7, 9, 11, 13, and 15 days of age, for escape and avoidance of a range of shock intensities administered from AC contant current and fixed impedance shock sources. With intensities ranging from 0 to .2 mA and 0 to 70 V for the respective sources, near asymptotic escape and avoidance were obtained at .1 mA and at 50 V for ages tested. Although few differences in the relative aversiveness of particular shock intensities were noted across ages with each source, the fixed impedance source produced more consistent avoidance than did the constant source. The findings suggest that the motivational properties of shock remain relatively constant throughout the early development of the mouse and that the technique employed in this study should prove useful in assessing possible age-related alterations in sensitivity to shock as a result of physiological or pharmacological manipulations.

Social setting: influence on the physiological response to electric shock in the rat.

A significant fall in tail blood pressure occurs in paired rats after shock-induced aggression. Pressure returns to baseline levels within 4 hours after fighting. Conversely, single rats subjected to jump threshold measurements or to shocks identical to those used in the aggression paradigm show significant elevations in tail blood pressure. The size of the pressure increase in rats shocked alone appears dependent on the intensity of the shocks, while the pressure fall in rats shocked in pairs occurs over a broad range of shock intensities.

PUNISHMENT: THE INTERACTIVE EFFECTS OF DELAY AND INTENSITY OF SHOCK1

A discrete-trial punishment procedure, with rats, was used to examine how delay-of-shock intervals of 0 to 28 sec and shock intensity interact to decrease the frequency and increase the latency of a positively reinforced response. For delay-of-shock intervals of 0, 7, 14, and 28 sec, there was a range of shock intensities, for some subjects, over which the punishing effect of shock was an increasing, monotonic function of shock intensity. For other subjects this transition was abrupt. Functions relating response frequency and latency measures to shock intensity were displaced toward higher values on the shock intensity axis with an increase in delay-of-shock interval. The effects of "gradual" and "abrupt" introduction to "severe" shock, as well as re-exposure to previously used shock intensities, were examined under both the immediate and delay-of-shock conditions. With delay-of-shock intervals of 7, 14, or 28 sec, shock intensities of approximately 0.50 milliamperes or greater were necessary to decrease substantially the number and increase the latency of the lever-pressing response. For the immediate punishment group this intensity was approximately 0.20 ma. These facts were related to Annau and Kamin's (1961) conditioned emotional response experiment in which a shock intensity of 0.49 ma or greater was required to suppress the rate of a positively reinforced response.