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At least 19 recordsLinked to original sources
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↗
PubMed1977

Responses of crayfish muscle preparations to nerve stimulation with various patterns of impulse sequence. Effects of intermittent, intercalated and adaptational types of impulse sequence.

The present study was carried out with an attempt to see what effects would be produced by various patterns of impulse trains other than pulses of a definite frequency in nerve-muscle systems of the crayfish. Single axons of nerves of the opener, the slow closer and the fast closer of the crayfish claw were stimulated and the tension development of muscles were recorded. The impulse trains tested are as follows: (i) intermittent stimulation; e.g., paired (doublet) and triplet stimuli, (ii) the intercalated stimulation during stimulation by constant-frequency pulses and (iii) the adaptational type of stimulation, i.e. a train of pulses of which interval gradually increases as seen in the process of the adaptation in the sensory nerve. Results obtained are as follows. Intermittent doublet stimuli produced a greater tension than the monotonous stimulation of the same average frequency. Repetitive triplet or quadruplet stimuli caused further increments in the tension development. Intercalation of a stimulus during usual monotonous stimulation induced a catch-like effect on the tension. Intercalated triplet stimuli provoked a stronger catch action. With the adaptational type of stimulation, an initial rapid tension development occurred with a least latency and this was followed by a maintained tension. There are certain temporal configurations of stimuli which produced a greater tension or a more physiologically meaningful time course of tension development. This suggests the significance of nervous coding.

Animals↗
PubMed1976

[Impulse cytophotometry in neoplasm prevention. The behavior of normal vaginal smears in the impulse cytophotometric histogram].

Evaluation of histograms of normal cervical and vaginal smears, produced by ""rapid flow through'' cytophotometry. Normal cytological cervical and vaginal smears were examined for their appearance in histograms in order to find criteria for the classification of ""normal non-pathological'' cytological slides. Simultaneously, the reliability of the standardized method for preparation of vaginal and cervical smears was checked. The diagrams and data produced by the histograph were also coded on line and analyzed by a computer; thus obtaining an objective mathematical analysis and avoiding errors due to subjective visual analysis of the histograms. The objective interpretation of histograms of normal vaginal smears is an important step to the realisation of automatic pre-screening.

Computers↗
PubMed1977

[Effect of single impulses on cochlear microphone potentials of the guinea-pig cochlea].

The influence of highly intensive single impulses on the cochlea of guinea pig was studied in an acute experiment. Very short impulses of less than or equal to 0.1 ms duration were produced by a sparknoise generator. The cochlear microphonics (CM) to a test stimulus (sinus tone, 3150 Hz) were recorded from the round window and measured prior to, during, and following impulse treatment. During the impulse treatment, the greatest amplitude reduction of CM occurred after the first impulse, while the further impulses caused a decreasing reduction. At first the number of impulses was varied: 1, 3, and 5 impulses were applied at intervals of 15 s each, at an impulse sound level of 164 dB sound pressure level re. 0.002 mubar (SPL). After these impulse treatments, in all cases a continual decrease of CM amplitudes up to a constant end value without recovery was found within a 2-hrs period of observation. The height of the end value depends on the number of impulses applied. Subsequently, at an exposure to 5 impluses the impulse sound level was stepwise reduced (164, 153, 144, 139 and 133 dB SPL). Again, a characteristic decrease of CM amplitudes was observed during the 2-hrs period of observation. The height of the end value is now dependent on the impluse sound level. Impulses of 164, 153 and 144 dB SPL cause a strong decrease of CM while the effect of impulses of 139 and 133 dB SPL is distinctly lower.

Acoustic Stimulation↗
PubMed2026

Does impulsivity predict treatment outcomes in PTSD with borderline personality disorder features? Results from a randomized clinical trial.

BACKGROUND: Trauma-focused psychotherapies are first-line treatments for posttraumatic stress disorder (PTSD). However, a substantial proportion of clients do not respond adequately or drop out of therapy prematurely. This has sparked interest in identifying individual-level predictors of treatment outcomes, including improvement in PTSD severity and dropout. Impulsivity may be a predictor because it may interfere with key therapeutic processes, such as cognitive restructuring and emotional processing. Consequently, we present a hypothesis-driven secondary analysis of a 15-month randomized clinical trial comparing Dialectical Behavior Therapy for PTSD (DBT-PTSD) and Cognitive Processing Therapy (CPT) in women with childhood abuse-related PTSD and borderline personality disorder features to test whether impulsivity, assessed at baseline, predicts PTSD improvement and dropout. We further explore whether the dimensions of impulsivity (non-planning, attentional impulsivity, and motor impulsivity) differentially affect the outcomes in DBT-PTSD vs. CPT. METHODS: A total of 193 cis women with PTSD related to childhood abuse and borderline personality disorder features were assessed using the Clinician-Administered PTSD Scale (CAPS) and the Barratt Impulsiveness Scale (BIS-10). Separate probit models and general linear models were applied to predict dropout and pre-to-post changes in PTSD severity (ΔCAPS) from total impulsivity and subscale scores, i.e. non-planning, attentional and motor impulsivity. RESULTS: Overall, dropout rates were higher for participants with higher baseline impulsivity scores (p = 0.049), particularly for those with higher non-planning impulsivity (p = 0.012). In participants randomized to CPT improvement in PTSD symptom severity (ΔCAPS) was negatively related to baseline total impulsivity (p = 0.021). In participants randomized to DBT-PTSD this relation was not significant. CONCLUSIONS: The results suggest that impulsivity may predict treatment outcomes. Specifically, patients with elevated impulsivity may be less likely to respond adequately to CPT. If replicated, these findings have implications for personalization of treatment.

Humans↗
PubMed2026

Is impulsivity simply a failure of self-control? Evidence based on multi-omics analyses of genomics, metabolomics and brain imaging.

High impulsivity-a hallmark of various adverse life outcomes such as substance abuse, impulsive buying, violence, and crime-has typically been considered as a failure of self-control. However, is impulsivity simply a failure of self-control? To address this issue, we employed multi-omics combined with brain imaging approach in a large-scale sample (Nbrain imaging=1524, Ngenomics=835, Nmetabolomics=946) to elucidate the relationship between impulsivity and self-control. Mendelian randomization showed a bidirectional association between impulsivity and self-control, suggesting that they influenced each other. Partial least squares analysis highlighted that self-control primarily implicates the frontal lobe regions (e.g., superior frontal gyrus), whereas impulsivity involves the amygdala, insula, and basal ganglia. The cerebellum, superior frontal gyrus, and middle frontal gyrus were identified as shared areas in impulsivity and self-control. Furthermore, gene-based association analysis identified heterochromatin protein 1 binding protein 3 as specifically related to impulsivity, while pathway enrichment analysis demonstrated that arginine and proline metabolism was a common metabolic pathway associated with both impulsivity and self-control. Overall findings demonstrate that impulsivity and self-control involve both shared and distinct brain regions, genetic and metabolic foundations. The brain imaging results suggest that impulsivity is related not only to self-control-related processes but also to the motivation to pursue rewards. Together, this large-scale integrative study firstly provides a side-by-side map of genomic, metabolic, and limbic-network signatures of impulsivity distinct from self-control, offering a foundation for mechanism-driven biomarker and intervention research in maladaptive impulsivity.

Impulsive Behavior↗
PubMed2024

Longitudinal characterization of impulsivity phenotypes boosts signal for genomic correlates and heritability.

Genomic correlates of impulsivity have been identified in several genome-wide association studies (GWAS) using cross-sectional designs, but no studies have investigated the molecular genetic correlates of impulsivity phenotypes using longitudinally constructed traits. In 3860 unrelated European participants in the Avon Longitudinal Study of Parents and Children (ALSPAC), we constructed longitudinal phenotypes for delay discounting and impulsive personality traits (as measured by the UPPS-P impulsive behavior scales) via assessment at ages 24, 26, and 28. We conducted GWASs of impulsivity using both cross-sectional and longitudinal phenotypes, estimated heritability and their phenotypic and genetic correlations, and evaluated their association with recently-developed polygenic risk scores (PRSs) for the impulsivity indicators themselves and also related psychiatric conditions. Latent growth curve modeling revealed a stable intercept over time for all impulsivity phenotypes. High genetic correlation of cross-sectional measures over time suggested a stable genetic component for delay discounting (rg = 0.53-0.99) and sensation seeking (rg = 0.99). Heritability estimates of the stable longitudinal phenotypes substantively improved as compared to their cross-sectional counterparts, revealing a significant SNP-heritability for delay discounting (0.22; p = 0.03) and sensation seeking (0.35; p = 0.0007). Consistent with previous reports, GWAS and gene-based analyses revealed associations between specific longitudinal impulsivity indicators and CADM2 and NCAM1 genes. The PRSs for the impulsivity indicators and disorders related to self-regulation were also significantly associated with longitudinal impulsivity traits. Finally, we validated the associations between longitudinal impulsivity phenotypes and their PRSs in an independent 13-wave longitudinal study (n = 1019) and the benefit of longitudinal phenotypes in simulation studies. In this first longitudinal genetic study of impulsivity traits, the results revealed stable genomic correlates of delay discounting and sensation seeking over time and further validated the utility of recently-developed PRSs, both in relation to the observed traits and in connecting them to psychiatric disorders. More generally, these findings support using latent intercepts as novel longitudinal phenotypes to boost signal for heritability and genomic correlates of mechanisms contributing to psychiatric disease liability.

Humans↗
PubMed1979

Effects of nerve impulses on threshold of frog sciatic nerve fibres.

1. The firing thresholds of single myelinated fibres of frog sciatic nerves were monitored as a function of impulse activity in the fibre. The threshold was given by the number of coulombs in current pulses that excited a particular fibre half the time when delivered to the whole nerve. Threshold was tracked by a device that incrementally decreased the number of coulombs in the current pulse whenever the fibre responded and increased the pulse if it did not respond. 2. There was a pattern to the after-oscillations of threshold following activity. The fibres were briefly refractory, transiently superexcitable for about 1-1.5 sec and then entered a phase of raised threshold or 'depression' that lasted for many minutes. 3. Activity produced little change in the threshold curve during the refractory period. Strong depressions following prolonged activity prevented the threshold from returning to the base-line level within the time associated with the refractory period for the same fibre at rest. 4. After an impulse, superexcitability reached a maximum within 7-20 msec. This peak was larger as the number of impulses in a preceding burst increased and as the intervals between the impulses became briefer. Each successive impulse of a burst contributed less to the growth of superexcitability, and after the burst had 6-10 impulses additional impulses contributed nothing. 5. The depression phase was marked by the interaction between build-up, which depended on the activity rate, and recovery, which required as long as an hour or more for the threshold to be completely restored to resting level. These two mechanisms, one causing build-up and the other recovery, led to formation of dynamic equilibria. The threshold level at equilibrium increased monotonically with the activity rate. 6. The processes associated with superexcitability interact with those producing depression. In active fibres showing raised thresholds, impulses are followed by a relative superexcitability that persists for at least as long as an absolute superexcitability (with threshold below the resting level) can be measured in the same fibre at rest. 7. The duration of the superexcitable phase interpreted as a relative change in excitability was roughly the same regardless of the level of depression. 8. The magnitude of the oscillation in threshold was give to ten times larger than the grey region (the range of stimuli for which response is probabilistic). It is concluded that at regions of low conduction safety such as axonal branches, where weak forces can influence whether an impulse will pass, such pronounced and long-lasting after-effects of firing can be expected to modulate conduction of nerve impulses.

Action Potentials↗
PubMed1977

The effects of calcium ions on the binomial parameters that control acetylcholine release during trains of nerve impulses at amphibian neuromuscular synapses.

1. A study has been made of the effects of changing the external calcium concentration [Ca](o) on the binomial parameters p and n that control the average quantal content (m) of the end-plate potential (e.p.p.) during trains of nerve impulses at synapses in amphibian striated muscle.2. In high external calcium concentrations (0.4 mM </= [Ca](o) < 1.0 mM) the increase in m of a test impulse following a conditioning impulse at different intervals (< 100 msec) was due to an increase in the number of quanta available for release, n; the increase in m of successive e.p.p.s in a short high frequency train was primarily due to an increase in n.3. In high external calcium concentrations (1.0 mM </= [Ca](o) < 10 mM) there was a decrease in m of a test impulse following a short high frequency conditioning train (4-5 impulses, 20-100 Hz) at different intervals (200 msec < 5 sec) and this was due to a decrease in the number of quanta available for release, n; in a long high frequency train (20 impulses, 20-100 Hz) there was an increase in m for the first few successive e.p.p.s followed by a depression of m which eventually reached a steady state and these changes in m were due to changes in n; the higher the frequency the greater was the depression in n during the steady-state period.4. In high calcium concentrations, the steady-state m reached in the first 20 impulses during continual stimulation at high frequency gave way to a decline in m over several minutes until a new depressed steady-state value of m was reached and this was maintained during the longest periods of stimulation (30 min); this decline in m was primarily due to a decline in the number of quanta available for release.5. These changes in the number of quanta available for release during trains of impulses are predicted in terms of a hypothesis in which facilitation is due to the accumulation of a residual calcium-receptor complex in the nerve terminal that determines the fraction of a pool of quanta which contributes to n, and depression is due to a decrease in the number of quanta in this pool.

Acetylcholine↗
PubMed1975

Vestibular nystagmus and teleost oculomotor neurons: functions of electrotonic coupling and dendritic impulse initiation.

1. Nystagmus in the horizontal plane is evoked in fish by mechanical stimulation of the ampulla of the horizontal semicircular canal or by electrical stimulation of the nerve from this canal. The movements are conjugate and the slow phase is away from the side of stimulation. 2. Medial rectus motoneurons were recorded from intracellularly, during nystagmus. During the slow phase (induced by ipsilateral stimulation), impulses arise abruptly from the base line and appear to arise at a distance from the cell body. During the fast phase (evoked by contralateral stimulation), impulses appear to arise from large PSPs that must be generated at or near the cell body. 3. In the curarized fish, stimulation of the nerve from the contralateral horizontal canal evokes spikes that arise from large EPSPs and that are blocked relatively easily by hyperpolarizing currents. Stimulation of the nerve from the ipsilateral horizontal canal evokes spikes that arise abruptly from the base line and that are much more difficult to block by hyperpolarizing currents. Little if any underlying PSP is observed when these impulses are delayed or blocked. Thus impulses evoked by stimulation of contralateral and ipsilateral side are initiated near to and far from the cell soma, respectively. 4. If impulses evoked by contralateral stimulation fail to excite the cell body due to injury, antidromic spikes are not occluded. Thus contralateral stimulation initiates impulses in the dendrites. 5. Cell bodies of neighboring motoneurons are coupled electrotonically, and graded antidromic stimulation evokes graded depolarizing potentials which result from electrotonic spread of spike activity from adjacent neurons. These depolarizing potentials are adequate to excite the cells in the presence of a background EPSP evoked by contralateral canal stimulation. In this manner coupling tends to synchronize cells during the fast phase of the nystagmus. 6. Antidromic responses of neighboring cells fail to interact with dendritic inputs to a particular cell, although indirect evidence indicates antidromic spikes invade the impulse-initiating regions in the dendrites. Thus coupling between dendrites is negligible and dendritic inputs can mediate the smoothly graded movements of the slow nystagmic phase. Coupling between somata is too weak to cause significant interaction between dendritically evoked impulses (unless the cell bodies are depolarized by EPSPs). 7. Rhythmic firing can be recorded in a single presynaptic fiber corresponding to either the slow or the fast phase of nystagmus, but not to both. Oculomotor neurons appear to be "relay cells" that, during the fast phase of the nystagmus receive a synchronized synaptic input which is initiated in a higher level command nucleus.

Animals↗
PubMed1979

[Structure and correlation of "fast" and "slow" background impulse activity of visual cortex neurons].

Background and optically modified impulse activity of neurons in visual cortex of unanaesthetized rabbits was analyzed. By means of joint interval histograms it was shown that neurons can be distinguished by the ratio of burts (intervals to 15-40 ms) and extraburst activity and by the shape of transition from one from of activity to another. The extraburst activity comprises 63% of impulses and its ratio to bursts of 2 or 3 and more impulses was 27:3:1. Burts impulse distribution showed a relative stability of timing pattern within bursts and small number of burst impulses (2.4 on the average). Bursts of 3 and more impulses (3.6 on the average) are not rhythmical and 79% of them contained long intervals (18.6 +/- 2.4 ms) before the shortest one (7.9 +/- 0.9 ms). Optical stimulation resulted in bursts containing core impulses, shorter intervals and beginning with the shortest interval in most neurons. This may testify to the increase of the EPSP steepness and amplitude. 20% of cortical neurons showed background bursts containing more impulses and shorter intervals in comparison with evoked bursts.

Animals↗
PubMed1977

Efficacy of monophasic electrical impulses with steep leading and trailing edges in cardiac defibrillation.

Experiments on dogs were performed to investigate the efficacy of various defibrillation impulse waveforms. The results showed that the decisive factors for the effectiveness of the defibrillation impulse of certain shape are its relationship to the carciac tissue accomodation and the duration of the suprathreshold current flow. For cardiac defibrillation the most convenient impulse is therefore the impulse with the highest rate of rise of the leading edge as well as the trailing edge. The amplitude of the rear trailing edge of the defibrillation impulse should be either equal or higher than the amplitude of the front leading edge. That means that rectangular or trapezoidal impulses with an ascending slope may be most conveniently used for cardiac defibrillation. The biologically optimal duration of the trapezoidal impulse with an ascending slope proved to range from 7 to 14 msec. The authors emphasize the inevitability of additional characteristics of the defibrillation impulse by its peak current and total energy contents.

Animals↗
PubMed1978

Ectopic generation of impulses and cross-talk in spinal nerve roots of "dystrophic" mice.

In "dystrophic" mice, many spinal root axons are bare and closely apposed to one another in midroot. The direction of nerve impulse traffic in lubosacral spinal nerve roots was determined by biphasic recording of spontaneous activity. In normal mice, impulse traffic in dorsal and ventral roots is directed toward and away from the spinal cord, respectively. However, in spinal root fibers of dystrophic mice, impulses also originate in midroot and are propagated toward both the spinal cord and the periphery. Impulses originate in midroot as single isolated events, in bursts at frequencies of up to 100 Hz, or as continuous activity persisting for several minutes in single fibers. Ectopically arising activity in some single fibers is consistently associated with transmission of an impulse in another fiber past the site of origin of the ectopically arising impulse. Thus impulses arise in the spinal root axons of dystrophic mice both spontaneously and as a result of cross-talk between single fibers.

Animals↗
PubMed1976

Noradrenaline synthesis and utilization: control by nerve impulse flow under normal conditions and after treatment with alpha-adrenoreceptor blocking agents.

The changes in the synthesis and utilization or noradrenaline cranial and caudal to an acute section of the rat spinal cord have been used to investigate the importance of nerve impulses for these processes. 1. Cranial to a lesion of the spinal cord, the alpha-methyltyrosine-induced disappearance of noradrenaline was accelerated by the alpha-adrenoreceptor blocking agents yohimbine (10 mg/kg), piperoxan (60 mg/kg) and tolazoline (50 mg/kg). In the absence of nerve impulses caudal to a lesion of the spinal cord, this disappearance was decelerated as compared to that cranial to the lesion and it was not influenced by the three alpha-adrenoreceptor blocking agents. 2. The nialamide-induced accumulation of normetanephrine in the whole brain was increased by phenoxybenzamine (20 mg/kg) and yohimbine whereas it was decreased by the alpha-adrenoreceptor stimulating agent clonidine (0.1 mg/kg). The effect of clonidine was completely antagonized by yohimbine, but not by phenoxybenzamine, giving further evidence for the view that clonidine and yohimbine have a stronger effect than phenoxybenzamine on the alpha-adrenoreceptors regulating the release of noradrenaline induced by nerve impluses. 3. The accumulation of Dopa after decarboxylase inhibition cranial to a lesion of the spinal cord was accelerated by yohimbine, piperoxan and tolazoline, but not significantly affected by phenoxybenzamine and haloperidol (10 mg/kg). In the absence of nerve impulses caudal to a lesion of the spinal cord, the popa accumulation was decelerated as compared to that cranial to the lesion and it was not influenced by the former three alpha--adrenoreceptor blocking agents as well as by clonidine. 4. The results show that the synthesis and the utilization noradrenaline normally, as well as the accelerations of these processes by alpha-adrenoreceptor blocking agents, are dependent on nerve impulses. The stimulation of the synthesis and utilization of noradrenaline by nerve impulses might by influenced via the activity of teh alpha-adrenoreceptors located either on the nerve terminals or on the cell bodies or on both parts of the noradrenergic neurones. In the absence of nerve impulses, a receptor-mediated feedback mechanism similar to that described for the synthesis of dopamine does not appear to regulate the synthesis of noradrenaline.

Adrenergic alpha-Antagonists↗
PubMed1978

Growth function for human response to large-amplitude impulse noise.

The U. S. Environmental Protection Agency has proposed the use of C-weighted day/night level for the assessment of impulse noise such as the noise resulting from sonic boom, blast noise (artillery, armor, demolition, etc.) and other large-amplitude impulse sources. One remaining question pertaining to the use of C-weighting has been the growth function for human response to impulse noise. This question arises because work by Kryter and by Young using peak values and/or small amplitudes exhibited growth functions of 6--7dB for a doubling of annoyance, while the growth function for human response to common sources (planes, vehicles, etc.) increases by about 10 dB for a doubling of annoyance. Kyter's and Young's data are reanalyzed herein by using C-weighting and by including only large-amplitude data. This reanalysis results in a growth function for human response to impulse noise which increases by about 10 dB for a doubling of annoyance. This equality of growth function between common A-weighted noise and C-weighted impulse noise further supports the use of C-weighted day/night level for assessment of sonic boom, blast noise, or other large-amplitude impulse noises having similar spectral content.

Humans↗