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PubMed2003

A psychometrically derived impulsive trait related to a polymorphism in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) in a Japanese nonclinical population: assessment by the Barratt impulsiveness scale (BIS).

Although a number of studies have shown that human impulsive traits are associated with indices of central serotonin function, few researchers have investigated the relationship between a polymorphism in the serotonin transporter gene-linked region (5-HTTLPR) and a psychometrically derived impulsive trait. We determined the 5-HTTLPR polymorphism in 123 employed Japanese male adults using the polymerase chain reaction. The distribution of allelic frequency was determined and also investigated the relationship of the 5-HTTLPR polymorphism to a impulsive trait as measured by the Barratt Impulsiveness Scale, 11th version (BIS-11). The distribution of allelic frequency was found to be almost identical to that previously reported in Japanese (the frequency for the long (L)/L, L/short (S), and S/S genotypes was: 3, 28, and 68%, respectively). In a comparison between the genotype groups, the S/S genotype group significantly higher scored for the total BIS-11 and the subscale attentional impulsiveness than the L/S + L/L genotype group. These findings suggest that individuals with a homozygous S-allele may be more impulsive than those with the other genotype.

Carrier Proteins↗
PubMed2004

Reward drive and rash impulsiveness as dimensions of impulsivity: implications for substance misuse.

One of the primary personality dimensions or traits that has consistently been linked to substance abuse is impulsivity. However, impulsivity is not a homogenous construct and although many of the measures of impulsivity are correlated, the most recent review of published factor analytic studies has proposed two independent dimensions of impulsivity: reward sensitivity, reflecting one of the primary dimension of J. A. Gray's personality theory, and rash impulsiveness. These two facets of impulsivity derived from the field of personality research parallel recent developments in the neurosciences where changes in the incentive value of rewarding substances has been linked to alterations in neural substrates involved in reward seeking and with a diminished capacity to inhibit behavior due to chronic drug exposure. In this paper, we propose a model that integrates the findings from research into individual differences with recent models of neural substrates implicated in the development of substance misuse.

Brain↗
PubMed1994

Impulsivity and time of day: is rate of change in arousal a function of impulsivity?

Impulsivity has been interpreted as a stable mediator of rate of change in arousal states. To test this hypothesis, 129 Ss differing in impulsivity were given placebo or caffeine at 9:00 a.m. or 7:30 p.m. Recognition memory was tested for the last 20 items from 2 lists of 24 items and 2 lists of 80 items. Scores from this paradigm reflect sustained attention and are thus sensitive to changes in arousal. A 4-way interaction among impulsivity, time of day, drug, and prior stimuli (p < .05) indicated that for those given placebo, recognition memory for long and late lists was poorer the higher the impulsivity in the morning; this pattern reversed in the evening. Caffeine reduced recognition errors. These results indicate that impulsivity is not a stable predictor of rate of change in arousal states. Instead, susceptibility to attentional lapses is mediated by impulsivity-related phase differences in diurnal arousal rhythms.

Arousal↗
PubMedDate not supplied

Impulsive personality traits in male pedophiles versus healthy controls: is pedophilia an impulsive-aggressive disorder?

Pedophilia is characterized by sexual attraction to prepubescent children. Despite the extensive literature documenting the pervasive and pernicious effects of childhood sexual abuse, there is surprisingly little psychiatric literature on pedophilia and its etiology remains enigmatic. In recent years, the psychiatric literature on the phenomenology, neurobiology, and treatment of impulsive-aggressive disorders has grown significantly. As some investigators have conceptualized pedophilia as an impulsive-aggressive disorder, it is of interest whether recent advances in the study of impulsive-aggressive disorders might shed light on pathological mechanisms underlying pedophilia. In the following study, 20 male subjects with a DSM-IV diagnosis of pedophilia, heterosexual type were recruited from an outpatient facility for sexual offenders and compared to 24 demographically similar control subjects. Groups were compared on three personality instruments--the Millon Clinical Multiaxial Inventory-II (MCMI-II), the Temperament and Character Inventory (TCI), and the Dimensional Assessment of Personality Impairment-Questionnaire (DAPI-Q)--to assess for select impairment in impulsive-aggressive personality traits. Pedophiles showed severe and pervasive personality impairment relative to controls. Although there was evidence of impulsivity, the findings do not suggest a predominance of impulsive-aggressive traits, and in fact provide evidence of inhibition, passive-aggression, and harm avoidance. The notion of "compulsive-aggression" in pedophilia is proposed.

Adolescent↗
PubMed2006

Subthalamic nucleus lesions increase impulsive action and decrease impulsive choice - mediation by enhanced incentive motivation?

The subthalamic nucleus (STN) is traditionally thought of as part of a system involved in motor control but recent evidence suggests that it may also play a role in other psychological processes. Here we examined the effects of STN lesions on two measures of impulsivity and found that STN lesions increased 'impulsive action' (produced behavioral disinhibition), as measured by performance on a differential reinforcement of low rates of responding task, but decreased 'impulsive choice' (impulsive decision making), as measured by a delay discounting task. In addition, amphetamine and food restriction increased 'impulsive action' and decreased 'impulsive choice' to a greater extent in STN-lesioned animals than in sham controls. We speculate that these apparently discrepant effects may be because STN lesions enhance the incentive salience assigned to rewards. These findings suggest that the STN may serve as a novel target for the treatment of psychological disorders characterized by deficits in behavioral control, such as drug addiction and attention deficit hyperactivity disorder.

Amphetamine↗
PubMed2004

The relationship between impulsivity, aggression, and impulsive-aggression in borderline personality disorder: an empirical analysis of self-report measures.

Impulsivity has been repeatedly identified as a key construct in BPD; however, its precise definition seems to vary especially regarding the overlap with aggression. The term impulsive-aggression , also generally seen as central to an understanding of BPD, seems to address itself to the interface between the two, but has itself been used inconsistently in the literature, sometimes having reference to a unitary phenotypic dimension, and at other times suggesting some combination of distinct traits. This study examined the relationship between multiple measures of impulsivity, aggression, and impulsive-aggression in a BPD sample ( N = 92) in order to clarify the relationship between these measured constructs in this clinical population. Results show little relationship between measures of aggression and impulsivity in BPD, with measures of impulsive-aggression correlating strongly with measures of aggression only. Implications of the present results for future research and clinical work with BPD are discussed.

Adolescent↗
PubMed1999

[Electronystagmography of sudden head impulses (head-only impulsive rotational testing, head thrust test, head impulse test)].

The basis of the head-thrust test is when a head thrust is done in the horizontal plane, the ipsilateral semicircular canal is the only which gets the gaze stabilization, being the other HSC completely inhibited. In this paper are investigated the ENG records according the test and analyzed the main parameters obtained. As conclusion we admit that the main parameters are the compensating ocular movements amplitude and their latencies.

Adult↗
PubMed1991

[Problem of evaluation of impulse noise by the impulse-background criterion].

The article narrates on the study of the impulse-background index evaluated as the difference between the levels measured with a phonemeter at the 'impulse' ('I') and 'slow' ('S') temporal characteristics and within the noise impulses' amplitude-temporal parameters. It was established that delta L was the function of both the amplitude and the impulse duration. If the impulse duration was commensurable with the constant 'S',--delta L was regularly less than 7 dBa irrespective of the actual 'impulse-background' correlation. Expositions of the noises with equal delta L and different amplitude-temporal characteristics were performed with a group of volunteers and resulted in different biologic effects. It was suggested that the delta L evaluation technique proposed by the existing hygienic standards was inadequate and needed reconsideration.

Acoustic Stimulation↗
PubMed2002

A dimensional impulsive-aggressive phenotype is associated with the A218C polymorphism of the tryptophan hydroxylase gene: a pilot study in well-characterized impulsive inpatients.

Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the biosynthesis of serotonin, and association and linkage studies of its variants in suicidal and impulsive-aggressive behavior have brought conflicting results. This pilot study was designed to investigate whether TPH A218C genotypes could be associated with impulsive behavioral tendencies (IBTs) in consecutively admitted nonpsychotic nonorganic inpatients. Patients (20 females and 34 males; age, 38.8 +/- 11.8) did not differ from healthy nonimpulsive controls (16 females and 11 males; age, 35.2 +/- 10.2) regarding TPH genotypes, but in the patients, the number of IBT was related to the presence of the 218C allele. It was concluded that impulsive-aggressive behavior may be associated with the TPH genotype in well-characterized impulsive patients and that the present results stress the importance of considering impulsiveness-aggressiveness in studies investigating the relationship between suicidal behavior and TPH genotypes.

Adult↗
PubMed2004

Assessment of behavioral and cognitive impulsivity: development and validation of the Lifetime History of Impulsive Behaviors Interview.

The construction and initial psychometric evaluation of an interview assessment of clinically significant impulsivity (Lifetime History of Impulsive Behaviors; LHIB) is presented. Personality-disordered and control subjects participated by completing self-report measures of depression, anxiety and social desirability, along with self-report and laboratory analogue measures of impulsivity, and finally the LHIB. The LHIB demonstrated good to excellent internal consistency and test-retest reliability. Supporting concurrent construct validity, scores on the LHIB correlated with other self-report measures of impulsivity. Diagnostic group differences were obtained and the LHIB evidenced concurrent validity in its ability to classify subjects by scores. No relationship was obtained between the LHIB and laboratory analogue measures. While evidence of discriminant validity was mixed, these data suggest that the LHIB may be a useful instrument for the assessment of impulsive behavior.

Adult↗
PubMed1992

Failure of parasystolic impulses to appear on schedule. Exit block due to concealed conduction of sinus impulses.

A 45-year-old patient free of any heart disease was admitted to the hospital with an electrocardiographic pattern of ventricular parasystole. The parasystolic rhythm was relatively fast, such that several consecutive ectopic complexes manifested. A later tracing reflected only isolated parasystolic complexes with long and fixed coupling intervals. The interectopic intervals, however, were once more in multiple of the parasystolic cycle as directly measured during the phases of undisturbed parasystolic rhythm. In the latter tracing, several scheduled parasystolic impulses did not yield a response, despite calculation suggesting that these impulses occurred outside the refractory period. In other words, an exit block was present. Analysis of the tracing suggests that the exit block was caused by concealed penetration of the sinus impulses into the ectopic-ventricular junction. That is, any sinus impulse penetrates into the junction and renders it refractory, in such a way that only parasystolic impulses that are relatively late within the sinus cycle may be conducted to the surrounding myocardium and result in a parasystolic complex.

Cardiac Complexes, Premature↗
PubMed1983

Impulse and moment of impulse in the leg joints by impact from kicking.

In a previous paper we have given a theoretical analysis of the impulsive motion of the leg, modeled as a double pendulum. This analysis made it possible to estimate the impulsive reactions in the knee joint as a function of the measured initial and final velocities of the leg, when an impact was given to the lower leg, e.g., by means of a kick. This estimation was made under the assumption that no impulsive moments occur in the hip and the knee joints, i.e., that no muscles were stretched during the time of impact. In the present paper it is shown how such impulsive moments, should they occur, can be determined by means of an additional measurement, i.e., of the velocity of the ball after the impact. The results from a series of experiments are reported, showing that such impulsive moments in the joints occur in an appreciable number of the kicks, especially in the hip joint, indicating that muscles, acting on this joint, are prestressed during the impact.

Adult↗
PubMed1987

The effect of impulse intensity and the number of impulses on hearing and cochlear pathology in the chinchilla.

Forty-one chinchillas, divided into seven groups, were exposed to 1, 10, or 100 noise impulses (one every 3s) having peak intensities of 131, 135, 139, or 147 dB. Hearing thresholds were measured in each animal before and after exposure using an avoidance conditioning procedure; a surface preparation of the cochlear sensory epithelia was performed approximately 90 days after exposure. There was generally an orderly relation between the amount of permanent threshold shift and the severity of exposure, and a general agreement between averaged histological data and the audiometric data. For the impulses used in this study, there is a range of intensities which is bounded on the high side by the intensity which just produces injury with single impulse exposures and bounded on the low side by a critical intensity below which the injury potential drops precipitously with a reduction of impulse intensity. This region is only about 10-15 dB wide for the exposure conditions of this experiment. Within this region, the threshold of injury is a constant total energy; i.e., 10-dB change of intensity implies a tenfold change in the number of impulses for threshold injury. Detailed relations between temporary and permanent threshold shift, cochlear pathology, and exposure variables are discussed, as are the implications of these data to the development of exposure criteria.

Animals↗
PubMed2000

Impulsivity and AMPA receptors: aniracetam ameliorates impulsive behavior induced by a blockade of AMPA receptors in rats.

The study aimed to ascertain the involvement of central AMPA receptors in impulsive behaviors of aged rats and to examine the effects of aniracetam. Premature response in the two-lever choice reaction task was assessed as an index of impulsivity. Intracerebroventricular injection of 2, 3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX), an AMPA receptor antagonist, dose-dependently (10.1-1009 ng/rat) increased only premature response without altering responding speed and choice accuracy 30 min after the injection. Aniracetam (30 mg/kg p.o.), a positive allosteric modulator of AMPA receptors, or AMPA (55.9 ng/rat, co-injected with NBQX) completely restored the NBQX-induced increase in impulsivity. These results indicate that AMPA receptors are tonically involved in the regulation of impulsivity.

Animals↗
PubMed1996

Impulsivity and negative priming: evidence for diminished cognitive inhibition in impulsive children.

This study addresses the relationship between impulsivity and lack of inhibition. Inhibition was measured both by the interference score and by the negative priming effect in a Stroop colour-word paradigm. The negative priming effect in this paradigm is defined by slower naming of a target colour if this colour was the distractor in the immediately preceding trial. For the study, a total of 210 school children were selected. These were children rated high or low by their teachers for either social or cognitive impulsivity. A reduced negative priming effect showed up with social type but not with cognitive type impulsive children. No differences were found regarding the Stroop interference score. The divergence between negative priming and interference as a measure of inhibition was discussed. Overall, the findings corroborate the distinction between a cognitive and a social dimension of impulsivity.

Attention↗
PubMed1975

Disorders of impulse conduction and impulse formation caused by hyperkalemia in man.

In eight patients we have demonstrated manifold types of impairment of impulse conduction produced by hyperkalemia. These abnormalities of impulse conduction occurred either simultaneously or in sequence, and were located in the atria, in the A-V junction, in the fascicular distribution of the ventricular conduction system, or in the free ventricular walls. In association with the abnormalities of conduction, abnormal impulse formation was also frequently observed as manifested by acceleration of normal pacemakers or the emergence of ectopic pacemakers. In one patient hyperkalemia produced alteration in sinus and A-V junctional impulse formation which overshadowed conduction disorders. In all of the eight cases the hyperkalemia was considered to be noniatrogenic. Hyperkalemia appears to potentiate subclinical conduction abnormalities, especially in the His-Purkinje system. However, the presence of pre-existent intraventricular conduction defects such as a bifascicular block does not exclude the possibility that the site of an A-V conduction delay during hyperkalemia can be in the A-V node, as demonstrated by His bundle recording in one instance after development of second-degree (type I) A-V block.

Adolescent↗
PubMed1993

Method for distinguishing between drug action on impulse propagation versus impulse generation.

Systemic or regional application of local anaesthetics or tetrodotoxin eliminate repetitive impulse discharge, but do they do so by blocking impulse propagation or by suppressing impulse initiation? A method is described for making this distinction based on differences in the pattern of discharge change during the onset of the block. Suppression of conductances involved in downstream impulse propagation produces integer multiplication of the fundamental interspike interval (interspike interval (ISI) doubling, tripling, etc.) In contrast, progressive block of conductances responsible for either the creation of the generator potential, or for its encoding into a spike train, causes a smooth increase in the rhythmic ISI. These two patterns of block, predicted on the basis of fundamental principles and numerical simulations, were verified in in vivo single-axon recordings.

Action Potentials↗