Mild Electric Shock Research Articles

Spider fear and covariation bias in children and adolescents

Covariation bias can be defined as phobic people's tendency to overestimate the association between fear-relevant stimuli and negative outcomes. The current article presents two studies that examined this type of cognitive bias in children and adolescents aged 8–16 years. Study 1 was concerned with a thought experiment during which youths ( N=150) were asked to imagine that they participated in an experiment during which they had to view a series of pictures showing spiders, guns, and flowers, that were occasionally followed by a negative outcome (i.e., a mild electric shock). Participants were asked to estimate the relation between each type of picture and the negative outcome. The results indicated that youths with higher levels of spider fear displayed a specific tendency to relate spider pictures to a negative outcome. In Study 2, youths ( N=220) actually participated in a computer game during which they were confronted with pictures of spiders, guns, and flowers, each of which was equally often followed by a negative (i.e., losing candy), positive (i.e., winning candy), or neutral outcome. After the game, participants had to estimate the relation between each type of picture and various outcomes. It was found that youths with higher levels of spider fear estimated more negative and less positive outcomes in relation to spider pictures. Taken together, these findings provide support for a fear-related covariation bias in youths. Further developmental analyses indicated that this type of cognitive bias seems to be more consistently present among adolescents than among children.

Changes in implicit associations do not occur simultaneously to Pavlovian conditioning of physiological anxiety responses

Previous research shows that an ‘angry face’ conditioned stimulus will elicit conditioned skin conductance responses (SCR) after a small number of trials pairing it with a mild electric shock. Such conditioning occurs even with masked presentations of the facial stimulus. Furthermore, the Implicit Association Test (IAT) has been demonstrated to be sensitive to the presence of information processing biases seen in specific phobias. We examined the ability of the IAT to detect changes in implicit associations that arise from pairing one facial image (CS+) with a mild electro-tactile stimulation whereas a second facial image (CS−) was presented alone. Participants ( N = 117) were assigned to one of four groups: a group that received no shocks with unmasked presentation of the facial images; a group that received no shocks with masked presentation; a group with shocks delivered simultaneously to the masked presentation of the CS+; and a group that received shocks simultaneous to unmasked CS+ presentation. Learning was assessed through both SCR and the IAT. Results showed that while it was possible to condition a SCR to the CS+, this learning was not detectable using the IAT. Implications of the discrepancies in the outcome measures are discussed.

The Role of Anxiety Sensitivity in Subjective and Physiological Responses to Social and Physical Stressors

This study examined the specificity of the relationship between anxiety sensitivity (AS), a measure of catastrophizing about arousal‐related sensations, and pain responses, by examining the effect of AS on responses to stressors of a physical and social nature. Healthy men and women (n = 129) between the ages of 18 and 25 years were recruited from the community to participate in a study examining subjective, cognitive and behavioural responses to different types of stressors. Participants were randomly assigned to one of 3 groups: (i) a neutral condition in which they sat quietly and read a popular magazine; (ii) a social stress condition in which they anticipated having to give a self‐disclosing speech; and (iii) a physical stress condition in which they were presented with 3 countdown to shock trials where a mild electrical shock was administered on the non‐dominant arm. Subjective ratings and physiological responses were recorded in anticipation of the stressor and immediately after stress exposure. Results indicated that AS was indirectly related to pain ratings via its effect on anticipatory anxiety ratings. AS was associated with anticipatory anxiety ratings, regardless of whether the stressor was of a physical or social nature. Furthermore, AS was not shown to be directly associated with exaggerated subjective or physiological reactions to the physical stressor. These results indicate that the role of AS in pain responses may be mediated through a global effect on anxiety, and limited to the anticipatory stage of the pain experience. If future studies yield similar findings in pain patients, then they would suggest that interventions for helping individuals high in AS should focus on catastrophic thinking in anticipation of stressors in general, rather than on pain‐specific stressors.

The use of auditory and visual information in the perception of stress in speech

Prior work on the acoustic correlates of the perception of psychological stress in speech has suffered from the problem of quantifying and verifying the extent to which a speaker was under stress during articulation. Two experiments were conducted to address this issue. First, stressed and unstressed speech samples were elicited from 78 speakers of American English. Stressed samples were recorded by having subjects read a standard passage while under the threat of the administration of mild electric shock. Both visual and audio recordings were collected. Stress was quantified in terms of four measures: two physiological (pulse rate and galvanic skin response) and two self-report scales. Sentences from the 16 speakers showing the largest differences between the stressed and unstressed conditions were then presented in a paired comparison task to 90 naive listeners, 30 each in three conditions: (1) audio-only presentation of the stimuli, (2) visual-only presentation of the stimuli, and (3) audiovisual presentation of the stimuli. The results indicate that individual listeners are sensitive to stress cues in speech in all three conditions.

Neuroticism-Anxiety, Impulsive-Sensation Seeking and autonomic responses to somatosensory stimuli

This study focused on autonomic responding in participants who scored high vs. low on the Neuroticism-Anxiety (N-Anx) and Impulsive-Sensation Seeking (Imp-SS) dimensions of the Zuckerman–Kuhlman Personality Questionnaire—Form III. Participants were presented with series of tones (standards, deviants and novels) and they received a mild electric shock (one, two or three pulses) at each 15th tone. Resting pre-stimulus skin conductance level (SCL) and heart rate (HR) level was recorded, as well as the skin conductance response (SCR) and (anticipatory) HR response to the electric stimuli. The autonomic measures differentiated between high- vs. low Imp-SS participants but failed to discriminate between high- vs. low N-Anx participants, with the exception that high N-Anx participants showed smaller SCRs on some trials compared to the low N-Anx participants. High Imp-SS had a lower pre-stimulus SCL and smaller SCRs to deviant stimuli compared to low Imp-SS participants. Additionally, their HR acceleration was smaller in anticipation of the first and the deviant tones whereas their deceleratory response was larger relative to the HR changes observed for the low Imp-SS participants. This pattern of findings was taken to suggest that high Imp-SS participants are more arousable and less prone to defensive reactions to novel or aversive stimulation.

Exercise is the primary factor associated with Hsp70 induction in muscle of treadmill running rats

The cytoprotective, inducible stress protein, Hsp70, increases in muscles of rodents subjected to strenuous treadmill running. Most treadmill running protocols employ negative reinforcement to encourage animals to exercise. As these stimuli may themselves activate stress responses, the present investigation was conducted to determine their contribution to the exercise-induced expression of Hsp70. Twenty-one male Sprague-Dawley rats were randomly divided into three equal groups including an exercise group (EX), which ran on a treadmill at 30 m min(-1) for 60 min; a stimulation group (STIM), which was not allowed to run, but was stimulated with compressed air and mild electric shock concurrently with their exercising cohort; and a control group (CON), which was housed in the treadmill room during the exercise period. Animals were killed 24 h post-experiment and hearts (H), soleii (SOL) and white gastrocnemii (WG) were harvested and analysed for Hsp70 content (mean% +/- SEM of standard). Significant increases in Hsp70 (as a % of standard) were noted in H and WG (H = 77.4 +/- 8.5; WG = 93.9 +/- 18.4) of EX but not in STIM (H = 32.5 +/- 4.6; WG = 32.0 +/- 3.4) or CON (H = 20.5 +/- 3.7; WG = 32.4 +/- 7.4). In SOL, Hsp70 expression in EX (126.7 +/- 6.2) was different from STIM (98.3 +/- 10.9) only. This occurred, despite the fact that all groups were exposed to a stressful environment and exhibited elevated (P < 0.001) temperatures (EX -41.2 +/- 0.1 degrees C > STIM -40.5 +/- 0.2 degrees C > CON -39.0 +/- 0.1 degrees C) indicative of a general stress response. These data suggest that exercise per se, rather than environmental conditions or noxious stimuli, are responsible for the induction of Hsp70 in rat muscle during treadmill running.

The four-plates test: Anxiolytic or analgesic paradigm?

The four-plates test (FPT) is an animal model of anxiety in which the exploration of the novel surroundings is suppressed by the delivery of a mild electric foot shock. The anti-nociceptive system has been reported to be activated by a variety of stressful stimuli such as footshock. The present study was thus designed to compare effects of drugs in the FPT and in the hot-plate test (an animal model of pain), in order to disambiguate the drug-induced anti-punishment effects obtained in the FPT from alterations in pain sensitivity. Various compounds, known to be implicated in anxiety states as well as nociception, have been studied. Although morphine induced a strong anti-nociceptive effect, it did not modify the number of shocks received in the FPT. Alprazolam and diazepam induced an anxiolytic-like effect in the FPT, at doses that did not induce any effect in the hot-plate test. The antidepressants previously reported anxiogenic (desipramine, maprotiline) in the FPT were found to be analgesic at the same doses. Milnacipran, venlafaxine and paroxetine did not modify the pain threshold, whereas they have previously been shown to induce anxiolytic-like effects in the FPT. The dopaminergic antidepressant agent nomifensine was without effect on both tests. Our results suggest that the reported drug-induced anti-punishment effects in the FPT are not related to modifications of pain threshold but to a pure anxiolytic-like effect.

Influence of Subjective Intoxication, Breath Alcohol Concentration, and Expectancies on the Alcohol‐Aggression Relation

The purpose of this study was to investigate the influence of subjective intoxication, alcohol-aggression expectancies, and breath alcohol concentration (BrAC) on intoxicated aggression in men and women while controlling for dispositional aggressivity. Subjects were 328 (163 men and 165 women) healthy social drinkers between 21 and 35 years of age. Following the consumption of either an alcohol or an active placebo beverage, subjects were tested on a modified version of the Taylor Aggression Paradigm in which mild electric shocks were received from, and administered to, a fictitious opponent during a competitive task. Levels of subjective intoxication and BrAC were measured immediately before subjects began the aggression task. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. Subjective intoxication ratings were not related to aggressive behavior for either men or women. Alcohol-aggression expectancies were related to aggression for men, but this effect was rendered nonsignificant when controlling for dispositional aggressivity, which in turn, was significantly related to the dependent variables for both men and women. Finally, BrAC was also related to aggression above and beyond the effects of dispositional aggressivity, yet only for men. Taken as a whole, this study suggests that intoxicated aggression is primarily the result of alcohol's pharmacological properties in conjunction with an aggressive disposition.

The effect of past-year heavy drinking on alcohol-related aggression.

The primary goal of this study was to determine the moderating effect of a history of heavy episodic drinking on the alcohol-aggression relation in men and women. Participants were 310 (152 men and 158 women) healthy social drinkers between 21 and 35 years of age. Drinking history was operationalized as participants' average number of alcoholic drinks consumed per drinking occasion during the past year. Following the consumption of either an alcohol or a placebo beverage, participants were tested on a modified version of the Taylor Aggression Paradigm in which mild electric shocks were received from, and administered to, a fictitious opponent during a competitive task. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. Alcohol increased aggression only among highly provoked men who reported a history of heavy episodic drinking. A history of high-frequency drinking did not moderate the alcohol-aggression relation. These findings highlight the importance of considering a history of heavy episodic drinking in the prediction of intoxicated aggression.

Behavioral Assessment of Hearing in Mice—Conditioned Suppression

The method of conditioned suppression described in this unit involves training a thirsty mouse to make steady contact with a waterspout in order to receive a slow, but steady trickle of water and then pairing a sound with mild electric shock delivered through the spout. The mouse quickly learns to avoid the shock by breaking contact with the spout whenever it detects the sound. This suppression of drinking is then used to indicate that the animal detected the sound. Because it is a cognitively simple procedure, conditioned suppression can be used to determine the ability of brain-damaged and genetically altered as well as normal animals to detect and discriminate sounds.

Pharmacological evaluation of the stress-induced social avoidance model of anxiety

We have shown earlier that mild electric shocks induce a lasting social avoidance in male rats. Here we investigated whether shock-induced social avoidance can be developed into a laboratory model of stress-induced anxiety. The putative new model would assess sub-chronic, stress-induced anxiety (as opposed to tests based on natural fear) in a heterologous context (as opposed to classical fear conditioning). A single exposure to mild electric shocks induced a robust social avoidance that lasted more than 5 days. Low doses of chlordiazepoxide (0.5, 1 mg/kg), diazepam (0.5, 1, 5 mg/kg), buspirone (0.3, 1 mg/kg), and fluoxetine (1, 3, 5 mg/kg) abolished this effect, whereas the anxiogenic compound m-chlorophenylpiperazine (0.5–3 mg/kg) induced social avoidance in unshocked rats. These effects were produced at doses that did not affect locomotion in the open field. Haloperidol (0.05, 0.1, 1, 5 mg/kg) influenced social avoidance at sedative doses only. The sensitivity of the model to anxiolytic agents was compromised at high (sedating) doses. Taken conjointly, these data show that shock-induced social avoidance can be used to assess the anxiolytic potential of compounds. In addition to predictive validity, the model appears to show construct and face validity as well: stress is among the etiological factors of, whereas social avoidance simulates the social deficits seen in, a variety of anxiety disorders. The model may be used to study the effects of anxiolytics on sub-chronic states of stress-induced anxiety.

"So I can't blame the booze?": Dispositional aggressivity negates the moderating effects of expectancies on alcohol-related aggression.

The purpose of this study was to determine the effects of alcohol expectancies on intoxicated aggression in men and women while controlling for dispositional aggressivity. Subjects were 328 (163 men and 165 women) healthy social drinkers between 21 and 35 years of age. Alcohol expectancies were measured using items from a variety of validated self-report inventories. Following the consumption of either an alcohol or a placebo beverage, subjects were tested on a modified version of the Taylor Aggression Paradigm, in which mild electric shocks were received from and administered to a fictitious opponent during a competitive task. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. On their own, alcohol expectancies played a limited role in impacting aggressive behavior. Specifically, alcohol expectancies were significantly related to aggression for men who received the placebo beverage under low provocation and for men who received alcohol under high provocation. A significant main effect of alcohol expectancies was also detected. However, all of these effects were rendered nonsignificant when controlling for dispositional aggressivity. It is important to note that the main effect for beverage group remained significant after controlling for dispositional aggressivity. Taken as a whole, this pattern of findings suggests that intoxicated aggression is primarily the result of alcohol's pharmacological properties in conjunction with an aggressive personality.

Differential effects of past-year stimulant and sedative drug use on alcohol-related aggression

The goals of this study were to determine the effects of past-year stimulant and sedative drug use on alcohol-related aggression and to examine whether the relation between stimulant drug use and intoxicated aggression is better accounted for by behavioral disinhibition. Participants were 330 healthy social drinkers (164 men and 166 women) between 21 and 35 years of age. Past-year stimulant and sedative use and behavioral disinhibition were assessed via self-report questionnaires. Following the consumption of either an alcohol or a placebo beverage, participants were tested on a modified version of the Taylor Aggression Paradigm [Taylor, S. (1967). Aggressive behavior and physiological arousal as a function of provocation and the tendency to inhibit aggression. Journal of Personality, 35, 297–310] in which mild electric shocks were received from, and administered to, a fictitious opponent. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. Results indicated that alcohol significantly strengthened the relation between stimulant drug use and aggression, but only among men. Behavioral disinhibition did not account for this effect. Regardless of past-year drug use, alcohol did not facilitate aggression among women. The present findings suggest that stimulant drug use may be a risk factor for intoxicated aggression for men. However, the underlying mechanisms accounting for this effect remain unclear.

Repeated Stress Suppresses Interferon-.GAMMA. Production by Murine Intestinal Intraepithelial Lymphocytes

Intestinal intraepithelial lymphocytes (IEL), one of the major effector components in the mucosal immune system, are phenotypically and functionally distinct from thymic and peripheral T cells. To investigate the effect of repeated stress on the number and function of IEL, we exposed male C3H/HeN mice to mild electric foot shock for 30 min/day for 5 consecutive days. Immediately after the final foot shock stress, the blood, spleen, thymus and small intestine of each of the mice were obtained. As a functional measure, we evaluated interferon (IFN)- gamma production by IEL, since IFN-gamma is a key immunomodulating cytokine in mucosal immune responses. Serum corticosterone level was elevated immediately after foot shock stress. There were no significant changes in the number of whole IEL and CD3+ IEL subsets after the stress. In contrast, the stress led to a significant decrease in the total number of thymocytes, particularly the reduction in the number of CD4+CD8+ thymocytes. Thymocytes expressed the highest level of intracellular glucocorticoid receptor (GR), followed by splenocytes and IEL. The foot shock stress induced a marked suppression of IFN-gamma production by IEL, when stimulated with immobilized anti-CD3 monoclonal antibody. Furthermore, corticosterone suppressed the IFN-gamma production by cultured IEL, which was prevented by Mifepristone (RU486), a GR antagonist. In summary, repeated foot shock stress did not alter the numbers of IEL and CD3+ IEL subsets, but suppressed IFN-gamma production by IEL, which was probably mediated by the elevated corticosterone. We therefore propose that stress influences host defense by suppressing the production of IFN-gamma in IEL.

Executive Functioning and Alcohol-Related Aggression.

The primary goal of this investigation was to determine whether executive functioning (EF) would moderate the alcohol-aggression relation. Participants were 310 (152 men and 158 women) healthy social drinkers between 21 and 35 years of age. EF as well as non-EF skills were measured with 13 validated neuropsychological tests. Following the consumption of either an alcoholic or a placebo beverage, participants were tested on a modified version of the Taylor Aggression Paradigm (S. Taylor, 1967), in which mild electric shocks were received from, and administered to, a fictitious opponent. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent. EF was negatively related to aggressive behavior for men, regardless of beverage group, even when controlling for non-EF skills. Furthermore, alcohol increased aggression only for men with lower EF scores. Finally, the mere belief that alcohol was consumed suppressed aggression for women but not for men.

Difficult temperament, acute alcohol intoxication, and aggressive behavior

The purpose of this study was to investigate the influence of a difficult temperament on alcohol-related aggression in men and women. Subjects were 330 (164 men and 166 women) healthy social drinkers between 21 and 35 years of age. Temperament was measured using the dimensions of temperament survey—revised (DOTS-R). Following the consumption of either an alcohol or a placebo beverage, subjects were tested on a modified version of the Taylor aggression paradigm in which mild electric shocks were received from, and administered to, a fictitious opponent during a competitive task. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. Of all the variables, provocation was the strongest elicitor of aggression. Overall, a difficult temperament was positively related to the aggression for all subjects. The finding of greatest importance was that alcohol only increased aggression for men with a difficult temperament. The results highlight the fact that alcohol consumption does not increase aggression in all persons and in all situations. An important goal for future research is to identify which individual difference and which contextual factors are most important in determining who will, and who will not, behave in an aggressive manner when intoxicated.

The moderating effects of dispositional empathy on alcohol-related aggression in men and women.

The author investigated the influence of dispositional empathy on alcohol-related aggression in men and women. Participants were 204 (111 men, 93 women) healthy social drinkers, 21-35 years old. Dispositional empathy was measured with the Interpersonal Reactivity Index. Following the consumption of either an alcoholic or a placebo beverage, participants were tested on a modified version of the Taylor Aggression Paradigm in which mild electric shocks were received from, and administered to, a fictitious opponent during a competitive task. Alcohol increased aggression for persons (particularly men) with lower, as opposed to higher, levels of empathy. Men with lower empathy levels exhibited the most aggression followed by men with higher empathy levels. Women displayed the least aggression regardless of their empathy levels.

Dynamics of local changes and oscillations in energy metabolism in the rabbit cerebral cortex during the formation of a conditioned defensive reflex.

Brain energy metabolism associated with different functional states and different types of human and animal activity is accompanied by dynamic changes in the degree of linkage between glycolysis and oxidalive phosphorylation in different cell compartments. These processes are reflected in the redox state of brain tissue and can be recorded potentiometrically as changes in the redox state potential (E) of brain tissue. Studies of E in the cortex of rabbits using implanted platinum electrodes showed that during the acquisition of a conditioned defensive reflex using a combination of a light and a mild electric shock to one of the rabbit's ears, conical E showed oscillations with periods of several seconds after 5-15 combinations. This number of combinations started to be accompanied by generalized changes in E in the cortex, which, at 20-100 combinations, could be either an increase or a decrease in E. As the number of combinations increased, increases in E were gradually replaced by decreases. By 200-400 combinations, occillations in E disappeared and the episodes of decreased E accompanying combinations acquired a stable local character. These results suggest that there is a change in the balance of the major sources of brain tissue energy supply during the formation and stabilization of a conditioned defensive reflex: at the initial stages of acquisition of the conditioned reflex a number of conical points have an energy supply dominated by tissue respiration, while the main energy source for brain function during performance of the acquired conditioned defensive reflex is glycolysis.

Irritability, acute alcohol consumption and aggressive behavior in men and women

The purpose of this study was to investigate the influence of irritability on alcohol-related aggression in men and women. Subjects were 204 (111 men and 93 women) healthy social drinkers between 21 and 35 years of age. Irritability was measured using the Caprara Irritability Scale. Following the consumption of either an alcohol or a placebo beverage, subjects were tested on a modified version of the Taylor Aggression Paradigm in which mild electric shocks were received from, and administered to, a fictitious opponent during a competitive task. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. Of all the variables, provocation was the strongest elicitor of aggression. Overall, irritability was positively related to aggression for all subjects. The finding of greatest importance was that alcohol increased aggression for persons with higher, as opposed to lower, levels of irritability. However, this pattern of results was only evident for men. The results highlight the fact that alcohol consumption does not increase aggression in all persons and in all situations. An important goal for future research is to identify which individual differences and which contextual factors are most important in determining who will, and who will not, behave in an aggressive manner when intoxicated.

The Influence of Trait Anger on the Alcohol-Aggression Relation in Men and Women

Background The purpose of this study was to investigate the influence of trait anger on alcohol-related aggression in men and women. Methods Subjects were 204 healthy social drinkers (111 men and 93 women) between 21 and 35 years of age. Trait anger was measured using the Spielberger Trait Anger Scale. After the consumption of either an alcohol or a placebo beverage, subjects were tested on a modified version of the Taylor Aggression Paradigm in which mild electric shocks were received from and administered to a fictitious opponent during a competitive task. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. Results Of all of the variables, provocation was the strongest elicitor of aggression. Overall, anger was positively related to aggression for all subjects. However, the central finding of this study was that alcohol was more likely to increase aggression for persons, particularly men, with higher, as opposed to lower, levels of trait anger. Conclusions The results show that alcohol consumption does not increase aggression for all persons and in all situations. A continuing goal for future research in this area is to identify which individual difference and which contextual factors are most important in determining who will and who will not behave in an aggressive manner when intoxicated.