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At least 19 recordsLinked to original sources

PubMed1980

An investigation of the effects of impulse noise exposure on man: impulse noise with a relatively low peak level.

The effects of impulse noise of a relatively low peak level were examined to develop damage risk criteria for impulse noise. Eight to 13 normal male students (age: 20-24 years) were exposed to impulse noise. Peak levels of impulse noise were 100 dB (S.P.L.) and 105 dB (S.P.L.), B-duration of impulse noise being 10 ms, 50 ms, and 100 ms, and the repetition rates of impulse noise were 3 per 1 s and 1 per 3 s. Exposure time was 8 h in all exposure conditions. Exposure conditions of long B-duration induced greater TTS2 than those of short B-duration (P less than 0.05). Impulse noise exposure at a high peak level induced slightly larger TTS2 than that at a low peak level. TTS2 increased proportionally to the logarithm of the amount of impulse noise. Exposure to impulse noise induced smaller TTS2 than that of steady-state noise of an equal energy level. In addition, exposure to large amounts of impulse noise induced slightly greater urinary 17 OHCS levels than small amounts of impulse noise, and exposure to impulse noise induced smaller urinary 17 OHCS levels than steady-state noise of an equal energy level (P less than 0.05). The decreasing effect of the acoustic reflex on the acoustic energy of impulse noise was considered to be the reason for the results obtained. This experiment supported the modified CHABA Limit of Damage Risk Criteria of impulse noise proposed by the US Environmental Protection Agency.

17-Hydroxycorticosteroids↗

PubMed2003

The spontaneously hypertensive-rat as an animal model of ADHD: evidence for impulsive and non-impulsive subpopulations.

Attention-deficit hyperactivity disorder (ADHD) is a neuropsychiatric syndrome, affecting human infants and adolescents. Two main behavioural features are reported: (1). impaired attention and (2). an impulsive-hyperactive behavioural trait. The latter has been studied in a series of experiments, using the spontaneously hypertensive-rat (SHR) strain (which is regarded as a validated animal model for ADHD) in operant tasks. Food-restricted SHRs and their Wistar-Kyoto (WKY) controls were tested during adolescence (i.e. post-natal days 30-45), in operant chambers provided with two nose-poking holes. Nose-poking in one hole (H1) resulted in the immediate delivery of a small amount of food, whereas nose-poking in the other hole (H5) delivered a larger amount of food after a delay, which was increased progressively each day (0-100 s). As expected, all animals showed a shift in preference from the large (H5) to the immediate (H1) reinforcer as the delay length increased. Impulsivity can be measured by the steepness of this preference-delay curve. The two strains differed in home-cage circadian activity, SHRs being more active than WKYs at several time-points. During the test for impulsivity, inter-individual differences were completely absent in the WKY strain, whereas a huge inter-individual variability was evident for SHRs. On the basis of the median value of average hole-preference, we found an 'impulsive' SHR subgroup, with a very quick shift towards the H1 hole, and a flat-slope ('non-impulsive') SHR subgroup, with little or no shift. The impulsive subpopulation also presented reduced noradrenaline levels in both cingulated and medial-frontal cortex, as well as reduced serotonin turnover in the latter. Also, cannabinoid CB1 receptor density resulted significantly lower in the prefrontal cortex of impulsive SHRs, when compared to both the non-impulsive subgroup and control WKYs. Interestingly, acute administration of a cannabinoid agonist (WIN 55,212, 2 mg/kg s.c.) normalized the impulsive behavioural profile, without any effect on WKY rats. Thus, two distinct subpopulations, differing for impulsive behaviour and specific neurochemical parameters, were evidenced within adolescent SHRs. These results support the notion that a reduced cortical density of cannabinoid CB1 receptors is associated with enhanced impulsivity. This behavioural trait can be positively modulated by administration of a cannabinoid agonist. Present results confirm and extend previous literature, indicating that adolescent SHRs represent a suitable animal model for the preclinical investigation of the early-onset ADHD syndrome.

Animals↗

PubMed2005

Interactions between serotonin and dopamine in the control of impulsive choice in rats: therapeutic implications for impulse control disorders.

Forebrain serotonergic lesions attenuate the ability of d-amphetamine to decrease impulsivity in a delay-discounting paradigm, potentially through interactions between the serotonin (5-HT) and dopamine (DA) systems. Nucleus accumbens (NAC) lesions increase impulsivity, but the extent to which accumbal DA is involved in regulating impulsive choice is unknown. In the current study, the effects of intra-accumbal infusions of 6-hydroxydopamine (6-OHDA) on impulsive choice were evaluated, in combination with d-amphetamine and serotonergic drugs, in order to investigate the importance of 5-HT : DA interactions in the control of impulsive behavior. Following training on a delay-discounting task, animals received intra-NAC 6-OHDA or sham surgery. Postoperatively, subjects received systemic injections of d-amphetamine (0, 0.3, 1.0, 1.5 mg/kg) and the 5-HT(1A) receptor agonist 8-OH-DPAT (0, 0.1, 0.3, 1.0 mg/kg). Intra-NAC 6-OHDA, which reduced local DA and NA levels by 70-75%, had no effect on delay-discounting, but transiently potentiated the d-amphetamine-induced decrease in impulsive choice. 8-OH-DPAT (1.0 mg/kg) increased impulsivity in sham-operated controls, an effect which was blocked by the 5-HT(1A) receptor antagonist WAY 100635. However, 8-OH-DPAT had no effect on impulsivity in 6-OHDA NAC lesioned rats. 8-OH-DPAT (0.3 mg/kg), which did not itself alter task performance, blocked the effect of d-amphetamine in sham-operated controls, while WAY 100635 augmented the effect of amphetamine in all subjects. In an additional experiment, intracerebroventricular administration of the selective serotonergic toxin 5,7-dihydroxytryptamine, which decreased forebrain 5-HT levels by 85-90%, did not block 8-OH-DPAT's ability to increase impulsive choice. These data suggest a significant role for 5-HT : DA interactions within the NAC in the control of impulsivity, and in the mechanism by which amphetamine decreases impulsive choice.

5,7-Dihydroxytryptamine↗

PubMed1977

Impulse dependent adaptation in Helix pomatia neurones: effect of the impulse on the firing pattern.

In neurones of the ventral ganglion of Helix pomatia an adaptation type is demonstrated where the impulses contribute to the adaptation, as if a slowly changing outward current were associated to every impulse. The current appears to be accumulated from impulse to impulse and the accumulated current to decrease towards zero in the interval between the impulses. This type of adaptation is called impulse dependent. A method to distinguish between impulse dependent adaptation and impulse independent adaptation is described. Typical adaptation curves for the impulse dependent adaptation are shown. With a strong adaptation there is a linear relation between the steady state frequency and the applied stimulus. When stimuli of short duration are applied repetitively, neurones with impulse dependent adaptation respond with spikes on an increasing fraction of the stimuli as the stimulus strength is increased. A simplified model of the adaptation is proposed, and the firing pattern of the cells is compared with that of the model. In this way numerical values of the model parameters have been estimated.

Action Potentials↗

PubMed2000

Multi-impulsivity of Japanese patients with eating disorders: primary and secondary impulsivity.

Several studies have noted that multi-impulsive bulimia nervosa tends to be refractory to treatment. However, it is not known whether these impulsivities are an expression of more fundamental psychopathology or simply the consequence of chaotic eating behaviors. Studies of the temporal relationship between the onset of eating disorder and the occurrence of impulsive behaviors will facilitate a better understanding of these issues. Subjects consisted of 60 patients with anorexia nervosa restricting type (AN-R), 62 patients with anorexia nervosa binge-eating/purging type (AN-BP), 114 patients with bulimia nervosa purging type (BN) and 66 control subjects. Impulsive behaviors and childhood traumatic experiences were assessed by self-report questionnaire. Multi-impulsivity (defined by at least three of the following: heavy regular alcohol drinking; suicide attempt; self-mutilation; repeated shoplifting of items other than food; sexual relationships with persons not well known to the subject) was found in 2% of AN-R, 11% of AN-BP, 18% of BN and 2% of control subjects. Eighty percent of BN patients with multi-impulsivity had a history of suicide attempts or self-mutilation history prior to the onset of bulimia nervosa. In BN patients, there tended to be a relationship between childhood parental loss or borderline personality disorder and multi-impulsivity. In conclusion, primary impulsivity (chronological prior occurrence of impulsive behaviors) does exist even in a very different culture, although the number of patients of this type is very limited.

Adult↗

PubMed1997

[Impulsiveness and impulse control. On the psychological and psychopathological conceptualization].

Impulsiveness and impaired impulse control are connected with an increasing number of psychic disorders. While impulsiveness presents an enduring, pervasive predisposition of personality, the DSM-IV category of "impulse control disorder not elsewhere classified" is operationalized by specific dysfunctional behaviors. So far, the construction of impulsiveness has really not been sufficiently clarified. What does it means and how can one describes it. Different means of conceptualization are presented from a psychological and psychopathological point of view. Their critical review leads to the hypothesis that impulsiveness subsumes a specific quality of drive, on the one hand, which is closely related to a person's temperament and control mechanisms on the other. Drive and impulse control represent enduring traits that act on all levels of personality function, including behavior, cognitive processing and affect regulation. Finally, a model of impulsiveness is suggested that reflects the close interactions among drive, affect and cognition in the regulation of behavior.

Disruptive, Impulse Control, and Conduct Disorders↗

PubMed1998

Impulse-control disorders in alcoholics are related to sensation seeking and not to impulsivity.

Impulse-control disorders (ICD) include intermittent explosive disorder, kleptomania, trichotillomania, pyromania and pathological gambling. Several studies have suggested that the incidence of pathological gambling and impulsive violent behavior is substantially higher in alcohol-dependent patients than in the general population. The association between ICD and alcoholism, as well as personality characteristics such as sensation seeking and impulsivity, has never been systematically studied. The present study compared the levels of impulsivity and sensation seeking in age- and sex-matched groups of alcohol-dependent patients with concomitant ICD (ICD+, n = 30), alcohol-dependent patients without ICD (ICD-; n = 30) and control subjects (n = 30). All the alcohol-dependent patients (ICD+ and ICD-) were hospitalized for alcohol detoxification. Diagnoses of ICD were based on DSM-IV criteria and the Minnesota Impulsive Disorders Interview. All patients completed the Zuckerman Sensation-Seeking Scale (SSS) and the Barratt Impulsiveness Rating Scale (BIS). Mean scores on the SSS general factor, the SSS disinhibition subscale, and the SSS experience-seeking scale were significantly higher in ICD+ patients than in either ICD- patients or control subjects. By contrast, total scores and subscale scores on the BIS showed no significant differences among the three groups. Thus, it appears that measures of sensation seeking, rather than impulsivity, are relevant in distinguishing between alcohol-dependent patients with and without concomitant impulse control disorders.

Adult↗

PubMed1993

Impulsivity and dyscontrol in bulimia nervosa: is impulsivity an independent phenomenon or a marker of severity?

Fifty-eight normal-weight DSM-III-R bulimia nervosa patients were compared with 27 normal controls on measures of bulimia nervosa, depression, impulsivity, obsessionality and impulse control (dyscontrol) behaviours. Patients scored higher than controls on all these measures. Almost half the patient cohort met Lacey's multi-impulsive bulimia criteria. When bulimic symptoms were controlled for in an analysis of covariance, multi-impulsive bulimics did not score significantly differently to non-impulsive bulimics on psychometric measures of impulsivity, obsessionality and depression. The concept of impulsivity is critically reviewed and newer concepts linking obsessionality and impulsivity are explored.

Adult↗

PubMed1998

Impulsive corporal punishment by mothers and antisocial behavior and impulsiveness of children.

This study tested the hypothesis that corporal punishment (CP), such as spanking or slapping a child for purposes of correcting misbehavior, is associated with antisocial behavior (ASB) and impulsiveness by the child. The data were obtained through interviews with a probability sample of 933 mothers of children age 2-14 in two small American cities. Analyses of variance found that the more CP experienced by the child, the greater the tendency for the child to engage in ASB and to act impulsively. These relationships hold even after controlling for family socioeconomic status, the age and sex of the child, nurturance by the mother, and the level of noncorporal interventions by the mother. There were also significant interaction effects of CP with impulsiveness by the mother. When CP was carried out impulsively, it was most strongly related to child impulsiveness and ASB; when CP was done when the mother was under control, the relationship to child behavior problems was reduced but still present. In view of the fact that there is a high risk of losing control when engaged in CP, even by parents who are not usually impulsive, and the fact that impulsive CP is so strongly associated with child behavior problems, the results of this study suggest that CP is an important risk factor for children developing a pattern of impulsive and antisocial behavior which, in turn, may contribute to the level of violence and other crime in society.

Adolescent↗

PubMed1998

Ethanol induces impulsive-like responding in a delay-of-reward operant choice procedure: impulsivity predicts autoshaping.

Autoshaping conditioned responses (CRs) are reflexive and targeted motor responses expressed as a result of experience with reward. To evaluate the hypothesis that autoshaping may be a form of impulsive responding, within-subjects correlations between performance on autoshaping and impulsivity tasks were assessed in 15 Long-Evans hooded rats. Autoshaping procedures [insertion of retractable lever conditioned stimulus (CS) followed by the response-independent delivery of food (US)] were followed by testing for impulsive-like responding in a two-choice lever-press operant delay-of-reward procedure (immediate small food reward versus delayed large food reward). Delay-of-reward functions revealed two distinct subject populations. Subjects in the Sensitive group (n=7) were more impulsive-like, increasing immediate reward choices at longer delays for large reward, while those in the Insensitive group (n=8) responded predominantly on only one lever. During the prior autoshaping phase, the Sensitive group had performed more autoshaping CRs, and correlations revealed that impulsive subjects acquired the autoshaping CR in fewer trials. In the Sensitive group, acute injections of ethanol (0, 0.25, 0.50, 1.00, 1.50 g/kg) given immediately before delay-of-reward sessions yielded an inverted U-shaped dose-response curve with increased impulsivity induced by the 0.25, 0.50, and 1.00 g/kg doses of ethanol, while choice strategy of the Insensitive group was not influenced by ethanol dose. Ethanol induced impulsive-like responding only in rats that were flexible in their response strategy (Sensitive group), and this group also performed more autoshaping CRs. Data support the hypothesis that autoshaping and impulsivity are linked.

Animals↗

PubMed2004

Fractionating impulsivity: contrasting effects of central 5-HT depletion on different measures of impulsive behavior.

Reducing levels of 5-HT in the central nervous system has been associated with increases in impulsive behavior. However, the impulsivity construct describes a wide range of behaviors, including the inability to withhold a response, intolerance to delay of reward and perseveration of a nonrewarded response. Although these behaviors are generally studied using instrumental paradigms, impulsivity may also be reflected in simple Pavlovian tasks such as autoshaping and conditioned activity. This experiment aimed to characterize further the effects of central 5-HT depletion and to investigate whether different behavioral measures of impulsivity are inter-related, thus validating the construct. Rats received intracerebroventricular (ICV) infusions of vehicle (n=10) or the serotonergic neurotoxin 5,7-dihydroxytryptamine (n=12) which depleted forebrain 5-HT levels by about 90%. Lesioned animals showed significant increases in the speed and number of responses made in autoshaping, increased premature responding on a simple visual attentional task, enhanced expression of locomotor activity conditioned to food presentation, yet no change in impulsive choice was observed, as measured by a delay-discounting paradigm. Significant positive correlations were found between responses made in autoshaping and the level of conditioned activity, indicating a possible common basis for these behaviors, yet no correlations were found between other behavioral measures. These data strengthen and extend the hypothesis that 5-HT depletion increases certain types of impulsive responding. However, not all measures of impulsivity appear to be uniformly affected by 5-HT depletion, or correlate with each other, supporting the suggestion that impulsivity is not a unitary construct.

5,7-Dihydroxytryptamine↗

PubMed2005

Lesions to the subthalamic nucleus decrease impulsive choice but impair autoshaping in rats: the importance of the basal ganglia in Pavlovian conditioning and impulse control.

Although the subthalamic nucleus (STN) is involved in regulating motor function, and inactivation of this structure relieves the motor symptoms in Parkinsonian patients, recent data indicate that corticosubthalamic connections are involved in both the regulation of attention and the ability to withhold from responding. Considerable evidence suggests that the neural circuitry underlying such behavioural disinhibition or impulsive action can be at least partially dissociated from that implicated in impulsive decision-making and it has been suggested that the tendency to choose impulsively is related to the ability to form and use Pavlovian associations. To explore these hypotheses further, STN-lesioned rats were tested on the delay-discounting model of impulsive choice, where impulsivity is defined as the selection of a small immediate over a larger delayed reward, as well as in a rodent autoshaping paradigm. In contrast to previous reports of increased impulsive action, STN lesions decreased impulsive choice but dramatically impaired the acquisition of the autoshaping response. When the STN was lesioned after the establishment of autoshaping behaviour, lesioned subjects were more sensitive to the omission of reward, indicative of a reduction in the use of Pavlovian associations to control autoshaping performance. These results emphasize the importance of the STN in permitting conditioned stimulus-unconditioned stimulus associations to regulate goal-seeking, a function which may relate to the alterations in impulsive choice observed in the delay-discounting task. These data bear a striking similarity to those observed after lesions of the orbitofrontal cortex and are suggestive of an important role for corticosubthalamic connections in complex cognitive behaviour.

Animals↗

PubMed1993

Neurobiology of impulsivity and the impulse control disorders.

Clinical impulsivity has been characterized in both dimensional and categorical terms. Whereas DSM-III-R classifies personality disorders characterized by impulsivity and impulse control disorders as discrete entities, impulsive symptoms and traits can also be conceived in terms of an underlying behavioral dimension. The authors review research on impulsivity and the impulse control disorders from a biological perspective. In particular, they critically review evidence that the serotonin neurotransmitter system mediates symptoms and traits of impulsive personality disorders and the impulse control disorders.

Adult↗

PubMed2003

Impulsiveness, impulsive aggression, personality disorder, and spousal violence.

Impulsiveness has become a key concept in thinking about the determinants of violence and aggression. In this study of spouse abusers, the relationship between impulsiveness, impulsive aggression, and physical violence is confirmed. Impulsiveness and impulsive aggression have significant correlations with physical aggression. Impulsiveness and impulsive aggression are also correlated with measures of Borderline Personality Disorder and Antisocial Personality Disorder. In addition, the measures of Borderline and Antisocial Personality Disorder (PD) are significantly correlated with physical aggression. The violent and non-violent groups differed on impulsive aggression and on Borderline Personality Disorder. A partial replication of Tweed and Dutton's findings (1998) revealed sub-groups of high- and low-violence men. The high-violence group was very different from the low-violent and the non-violent groups. The high-violence group had higher pathology scores on all clinical scales, except Mania, of the Personality Assessment Inventory. These findings have implications for violence prediction and for treatment of violent men.

Adult↗

PubMed2005

Alcohol expectancies, conduct disorder and early-onset alcoholism: negative alcohol expectancies are associated with less drinking in non-impulsive versus impulsive subjects.

AIMS: Research suggests that positive alcohol expectancies promote excessive alcohol use while negative alcohol expectancies discourage excessive alcohol use. Evidence suggests that disinhibitory characteristics, such as conduct disorder and impulsivity, are associated with a general neglect of long-term negative outcomes. This study assessed whether negative expectancies would be associated more strongly with lower levels of alcohol use for low- compared with high-impulsive individuals. DESIGN: Positive and negative alcohol expectancies, alcohol use and impulsivity were assessed in a sample of 99 young adults with alcohol dependence (AD) and conduct disorder (CD), 77 with AD and no CD and 124 controls. FINDINGS: AD/CD subjects had higher proximal (same day) and distal (next day) negative alcohol expectancies, even though they drank more alcohol, compared with AD-alone and control subjects. Distal negative expectancies were associated more strongly with lower levels of drinking for low-impulsive compared with high-impulsive subjects. Proximal negative expectancies were associated more strongly with higher alcohol consumption for high- versus low-impulsive subjects. CONCLUSIONS: Impulsivity and conduct disorder may be important factors in determining how much distal negative alcohol expectancies may discourage excessive alcohol consumption.

Adolescent↗

PubMed1986

Impulse characteristics in rapid movement: implications for impulse-variability models.

Three untested assumptions of the impulse-variability model were examined in two experiments utilizing rapid, uni-planar limb movements. Experiment 1 varied movement distance (A) and movement time (MT) in a rapid-timing paradigm where the subject moved a lever through a certain distance in a certain time. Experiment 2 varied A in a reversal response where the S made a rapid elbow flexion and extension in a given MT. Displacement recordings were made on every trial. KR (knowledge of results) about MT was given after every trial. The results can be summarized as follows: (a) As predicted by the model, variations in impulse size and velocity were directly related to the impulses size; (b) There was no correlation between the accelerative and decelerative impulse durations recorded during the reversal response supporting the notion that the impulses might be independent; (c) Negative correlations (-.20 to -.50) were demonstrated between peak acceleration and impulse duration for both experiments, counter to the predictions of the model; and (d) Counter to the predictions of the model, timing error (VEt) increased as A decreased for rapid-timing responses. When the correlational results are taken into account, the model has the capacity to account for curvilinear relationships between relative timing error and movement speed. Overall, the results suggest that the impulse variability model requires some restructuring before it can be considered a viable model for the control of rapid limb movements.

Journal Article↗

PubMed2002

Relative rates of growth of annoyance of impulsive and non-impulsive noises.

Twenty-nine people judged the relative annoyance of five variable level signals and 29 impulsive and non-impulsive fixed-level signals in an adaptive paired comparison study. Signals were presented for judgment as heard indoors in a facility capable of accurately reproducing the very low-frequency content of sonic booms. When the annoyance of sonic booms unaccompanied by rattle was compared with that of sounds containing more higher-frequency energy (an aircraft flyover and an octave band of noise centered at 1 kHz), the relative rate of growth of annoyance, as expressed in C-weighted SEL units, was nearly 2:1. In other words, to maintain subjective equality of annoyance, each increase in level of sonic booms had to be matched by nearly twice the increase in level of an aircraft flyover or an octave band of noise centered at 1 kHz. Relative rates of growth of annoyance of sonic booms accompanied by rattle and of non-impulsive sounds, including both low- (63-Hz octave band of noise) and high-frequency energy (1-kHz octave band of noise and an aircraft flyover), were closer to 1:1. Relative rates of growth of annoyance for sonic booms unaccompanied by rattle and low-frequency sounds (63 Hz) were also about 1:1. These differences in relative rates of growth of annoyance of impulsive and non-impulsive sounds are as plausibly attributed to their relative low-frequency content as to impulsiveness per se. It may therefore be more useful for some purposes to express the annoyance of impulsive signals and other environmental noises containing substantial low-frequency energy in terms of effective (duration-corrected) loudness level rather than commonplace ASEL or CSEL.

Aircraft↗

PubMedDate not supplied

[Comparative study of nerve stimulation factors by a single rectangular impulse and a series of rectangular impulses].

The experiments were performed on the sciatic nerve of Rana temporaria. A single rectangular electric impulse and a series of rectangular microsecond impulses were used for stimulation. The threshold amplitude of a single impulse and the average voltage in series of impulses were compared. It was experimentally shown that application of a series of impulses as a stimulus necessitated less values of stimulation near the threshold. There was no significant difference between the average voltage in a series of impulses and the amplitude of a single rectangular impulse in stimulation far up the threshold.

Animals↗