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Psychophysiology Feb 2018During threat of shock, the startle reflex is potentiated, suggesting modulation by defensive mobilization. To determine whether startle potentiation is specific to...
During threat of shock, the startle reflex is potentiated, suggesting modulation by defensive mobilization. To determine whether startle potentiation is specific to aversive anticipation, startle reflexes were measured in the context of either aversive or appetitive anticipation in a between-subject study. Participants wore a device on the wrist that could deliver electrical shock (n = 49), or vibrotactile stimulation indicating monetary reward (n = 48). Cues signaling "threat" or "safe" periods were presented alone, or accompanied by presentation of affective and neutral pictures on half of the trials. Results indicated that the startle reflex was significantly potentiated when anticipating either shock or reward, compared to safe periods, both when no picture was presented, as well as during picture viewing. The difference between threat and safety in both reflex magnitude and skin conductance changes was larger for those anticipating shock, suggesting that the aversive context was more motivationally engaging. The pattern of reflex modulation as a function of picture valence varied under threat and safety, but was identical in the shock and reward groups, consistent with a hypothesis that anticipation of either aversive or appetitive events prompts heightened perceptual vigilance, potentiating the acoustic startle reflex.
Topics: Anticipation, Psychological; Anxiety; Electric Stimulation; Electromyography; Emotions; Female; Galvanic Skin Response; Humans; Male; Photic Stimulation; Reflex, Startle; Reward
PubMed: 28881032
DOI: 10.1111/psyp.12989 -
Scientific Reports Jan 2021Zebrafish is an established animal model for the reproduction and study of neurobiological pathogenesis of human neurological conditions. The 'startle reflex' in...
Zebrafish is an established animal model for the reproduction and study of neurobiological pathogenesis of human neurological conditions. The 'startle reflex' in zebrafish larvae is an evolutionarily preserved defence response, manifesting as a quick body-bend in reaction to sudden sensory stimuli. Changes in startle reflex habituation characterise several neuropsychiatric disorders and hence represent an informative index of neurophysiological health. This study aimed at establishing a simple and reliable experimental protocol for the quantification of startle reflex response and habituation. The fish were stimulated with 20 repeated pulses of specific vibratory frequency, acoustic intensity/power, light-intensity and interstimulus-interval, in three separate studies. The cumulative distance travelled, namely the sum of the distance travelled (mm) during all 20 stimuli, was computed as a group-level description for all the experimental conditions in each study. Additionally, by the use of bootstrapping, the data was fitted to a model of habituation with a first-order exponential representing the decay of locomotor distance travelled over repeated stimulation. Our results suggest that startle habituation is a stereotypic first-order process with a decay constant ranging from 1 to 2 stimuli. Habituation memory lasts no more than 5 min, as manifested by the locomotor activity recovering to baseline levels. We further observed significant effects of vibratory frequency, acoustic intensity/power and interstimulus-interval on the amplitude, offset, decay constant and cumulative distance travelled. Instead, the intensity of the flashed light did not contribute to significant behavioural variations. The findings provide novel insights as to the influence of different stimuli parameters on the startle reflex habituation and constitute a helpful reference framework for further investigation.
Topics: Acoustic Stimulation; Animals; Computer Simulation; Habituation, Psychophysiologic; Larva; Models, Animal; Reflex, Startle; Zebrafish
PubMed: 33436805
DOI: 10.1038/s41598-020-79923-6 -
Scientific Reports Aug 2023Ketamine is a rapid-acting antidepressant that also influences neural reactivity to affective stimuli. However, the effect of ketamine on behavioral affective reactivity... (Randomized Controlled Trial)
Randomized Controlled Trial
Ketamine is a rapid-acting antidepressant that also influences neural reactivity to affective stimuli. However, the effect of ketamine on behavioral affective reactivity is yet to be elucidated. The affect-modulated startle reflex paradigm (AMSR) allows examining the valence-specific aspects of behavioral affective reactivity. We hypothesized that ketamine alters the modulation of the startle reflex during processing of unpleasant and pleasant stimuli and weakens the resting-state functional connectivity (rsFC) within the modulatory pathway, namely between the centromedial nucleus of the amygdala and nucleus reticularis pontis caudalis. In a randomized, double-blind, placebo-controlled, cross-over study, thirty-two healthy male participants underwent ultra-high field resting-state functional magnetic resonance imaging at 7 T before and 24 h after placebo and S-ketamine infusions. Participants completed the AMSR task at baseline and one day after each infusion. In contrast to our hypothesis, ketamine infusion did not impact startle potentiation during processing of unpleasant stimuli but resulted in diminished startle attenuation during processing of pleasant stimuli. This diminishment significantly correlated with end-of-infusion plasma levels of ketamine and norketamine. Furthermore, ketamine induced a decrease in rsFC within the modulatory startle reflex pathway. The results of this first study on the effect of ketamine on the AMSR suggest that ketamine might attenuate the motivational significance of pleasant stimuli in healthy participants one day after infusion.
Topics: Male; Humans; Reflex, Startle; Cross-Over Studies; Ketamine; Brain; Emotions
PubMed: 37587171
DOI: 10.1038/s41598-023-40099-4 -
Scientific Reports Nov 2021The startle reflex in larval zebrafish describes a C-bend of the body occurring in response to sudden, unexpected, stimuli of different sensory modalities. Alterations...
The startle reflex in larval zebrafish describes a C-bend of the body occurring in response to sudden, unexpected, stimuli of different sensory modalities. Alterations in the startle reflex habituation (SRH) have been reported in various human and animal models of neurological and psychiatric conditions and are hence considered an important behavioural marker of neurophysiological function. The amplitude, offset and decay constant of the auditory SRH in larval zebrafish have recently been characterised, revealing that the measures are affected by variation in vibratory frequency, intensity, and interstimulus-interval. Currently, no study provides a model-based analysis of the effect of physical properties of light stimuli on the visual SRH. This study assessed the effect of incremental light-stimulus intensity on the SRH of larval zebrafish through a repeated-measures design. Their total locomotor responses were normalised for the time factor, based on the behaviour of a (non-stimulated) control group. A linear regression indicated that light intensity positively predicts locomotor responses due to larger SRH decay constants and offsets. The conclusions of this study provide important insights as to the effect of light properties on the SRH in larval zebrafish. Our methodology and findings constitute a relevant reference framework for further investigation in translational neurophysiological research.
Topics: Animals; Behavior, Animal; Habituation, Psychophysiologic; Larva; Light; Locomotion; Models, Animal; Reflex, Startle; Zebrafish
PubMed: 34789729
DOI: 10.1038/s41598-021-00535-9 -
Neurological Sciences : Official... Oct 2022Tic related disorders affect 4-20% of the population, mostly idiopathic, can be grouped in a wide spectrum of severity, where the most severe end is Tourette Syndrome... (Review)
Review
Tic related disorders affect 4-20% of the population, mostly idiopathic, can be grouped in a wide spectrum of severity, where the most severe end is Tourette Syndrome (TS). Tics are arrhythmic hyperkinesias to whom execution the subject is forced by a "premonitory urge" that can be classified as sensory tic, just-right experience or urge without obsession. If an intact volitional inhibition allows patients to temporarily suppress tics, a lack or deficit in automatic inhibition is involved in the genesis of the disorder. Studies have assessed the presence of intrinsic microscopic and macroscopic anomalies in striatal circuits and relative cortical areas in association with a hyperdopaminergic state in the basal forebrain. Prepulse inhibition (PPI) of the startle reflex is a measure of inhibitory functions by which a weak sensory stimulus inhibits the elicitation of a startle response determined by a sudden intense stimulus. It is considered an operation measure of sensorimotor gating, a neural process by which unnecessary stimuli are eliminated from awareness. Evidence points out that the limbic domain of the CSTC loops, dopamine and GABA receptors within the striatum play an important role in PPI modulation. It is conceivable that a sensorimotor gating deficit may be involved in the genesis of premonitory urge and symptoms. Therefore, correcting the sensorimotor gating deficit may be considered a target for tic-related disorders therapies; in such case PPI (as well as other indirect estimators of sensorimotor gating) could represent therapeutic impact predictors.
Topics: Humans; Prepulse Inhibition; Reflex, Startle; Sensory Gating; Tics; Tourette Syndrome
PubMed: 35781754
DOI: 10.1007/s10072-022-06235-0 -
Human Brain Mapping Nov 2021Startle reflex is modulated when a weaker sensory stimulus ("prepulse") precedes a startling stimulus ("pulse"). Prepulse Inhibition (PPI) is the attenuation of the...
Startle reflex is modulated when a weaker sensory stimulus ("prepulse") precedes a startling stimulus ("pulse"). Prepulse Inhibition (PPI) is the attenuation of the startle reflex (prepulse precedes pulse by 30-500 ms), whereas Prepulse Facilitation (PPF) is the enhancement of the startle reflex (prepulse precedes pulse by 500-6000 ms). Here, we critically appraise human studies using functional neuroimaging to establish brain regions associated with PPI and PPF. Of 10 studies, nine studies revealed thalamic, striatal and frontal lobe activation during PPI in healthy groups, and activation deficits in the cortico-striato-pallido-thalamic circuitry in schizophrenia (three studies) and Tourette Syndrome (two studies). One study revealed a shared network for PPI and PPF in frontal regions and cerebellum, with PPF networks recruiting superior medial gyrus and cingulate cortex. The main gaps in the literature are (i) limited PPF research and whether PPI and PPF operate on separate/shared networks, (ii) no data on sex differences in neural underpinnings of PPI and PPF, and (iii) no data on neural underpinnings of PPI and PPF in other clinical disorders.
Topics: Functional Neuroimaging; Humans; Perception; Prepulse Inhibition; Reflex, Startle; Schizophrenia; Sensation; Tourette Syndrome
PubMed: 34414633
DOI: 10.1002/hbm.25631 -
Hearing Research Feb 2023The startle reflex (SR), a robust, motor response elicited by an intense auditory, visual, or somatosensory stimulus has been widely used as a tool to assess...
The startle reflex (SR), a robust, motor response elicited by an intense auditory, visual, or somatosensory stimulus has been widely used as a tool to assess psychophysiology in humans and animals for almost a century in diverse fields such as schizophrenia, bipolar disorder, hearing loss, and tinnitus. Previously, SR waveforms have been ignored, or assessed with basic statistical techniques and/or simple template matching paradigms. This has led to considerable variability in SR studies from different laboratories, and species. In an effort to standardize SR assessment methods, we developed a machine learning algorithm and workflow to automatically classify SR waveforms in virtually any animal model including mice, rats, guinea pigs, and gerbils obtained with various paradigms and modalities from several laboratories. The universal features common to SR waveforms of various species and paradigms are examined and discussed in the context of each animal model. The procedure describes common results using the SR across species and how to fully implement the open-source R implementation. Since SR is widely used to investigate toxicological or pharmaceutical efficacy, a detailed and universal SR waveform classification protocol should be developed to aid in standardizing SR assessment procedures across different laboratories and species. This machine learning-based method will improve data reliability and translatability between labs that use the startle reflex paradigm.
Topics: Humans; Rats; Mice; Animals; Guinea Pigs; Reflex, Startle; Acoustic Stimulation; Reproducibility of Results; Tinnitus; Disease Models, Animal; Gerbillinae
PubMed: 36566642
DOI: 10.1016/j.heares.2022.108667 -
Schizophrenia Research Oct 2020Latency of the acoustic startle reflex is the time from presentation of the startling stimulus until the response, and provides an index of neural processing speed....
BACKGROUND
Latency of the acoustic startle reflex is the time from presentation of the startling stimulus until the response, and provides an index of neural processing speed. Schizophrenia subjects exhibit slowed latency compared to healthy controls. One prior publication reported significant heritability of latency. The current study was undertaken to replicate and extend this solitary finding in a larger cohort.
METHODS
Schizophrenia probands, their relatives, and control subjects from the Consortium on the Genetics of Schizophrenia (COGS-1) were tested in a paradigm to ascertain magnitude, latency, and prepulse inhibition of startle. Trial types in the paradigm were: pulse-alone, and trials with 30, 60, or 120 ms between the prepulse and pulse. Comparisons of subject groups were conducted with ANCOVAs to assess startle latency and magnitude. Heritability of startle magnitude and latency was analyzed with a variance component method implemented in SOLAR v.4.3.1.
RESULTS
980 subjects had analyzable startle results: 199 schizophrenia probands, 456 of their relatives, and 325 controls. A mixed-design ANCOVA on startle latency in the four trial types was significant for subject group (F(2,973) = 4.45, p = 0.012) such that probands were slowest, relatives were intermediate and controls were fastest. Magnitude to pulse-alone trials differed significantly between groups by ANCOVA (F(2,974) = 3.92, p = 0.020) such that controls were lowest, probands highest, and relatives intermediate. Heritability was significant (p < 0.0001), with heritability of 34-41% for latency and 45-59% for magnitude.
CONCLUSION
Both startle latency and magnitude are significantly heritable in the COGS-1 cohort. Startle latency is a strong candidate for being an endophenotype in schizophrenia.
Topics: Acoustic Stimulation; Acoustics; Humans; Prepulse Inhibition; Reflex, Startle; Schizophrenia
PubMed: 33189519
DOI: 10.1016/j.schres.2020.11.003 -
Scientific Reports Aug 2023Two studies examined the amplitude of the startle response as a function of the Dark Tetrad of personality (narcissism, Machiavellianism, psychopathy, and sadism). We...
Two studies examined the amplitude of the startle response as a function of the Dark Tetrad of personality (narcissism, Machiavellianism, psychopathy, and sadism). We measured electromyographic activity of the orbicularis oculi muscle evoked by a startle stimulus while participants viewed images on a computer screen. Both studies revealed a negative correlation between general startle reactivity (averaged across positive, negative, and neutral images) and sadistic tendencies. In Study 2, all four dark traits were negative correlates of general startle reactivity. Study 2 also examined the personality correlates of aversive startle potentiation (ASP; indexed by greater reactivity while viewing negatively-valenced images than positive or neutral images). ASP correlated negatively with a variety of personality measures of psychopathy and sadism, their facets, and related personality tendencies (callousness, risk-taking, and restricted affect). These findings suggest that ordinary people with high levels of callousness and antagonism display physiological evidence of non-reactivity (i.e., blunted acoustic startle in general), whereas psychopathy and sadism are preferentially associated with reduced ASP.
Topics: Humans; Reflex, Startle; Sadism; Antisocial Personality Disorder; Personality Disorders; Personality
PubMed: 37648765
DOI: 10.1038/s41598-023-41043-2 -
Alcoholism, Clinical and Experimental... Oct 2018Researchers have long sought to understand how individuals respond to alcohol in social settings with the aim of elucidating pathways of risk for alcohol use disorder...
BACKGROUND
Researchers have long sought to understand how individuals respond to alcohol in social settings with the aim of elucidating pathways of risk for alcohol use disorder (AUD). But studies that incorporate a social context are still outnumbered by those that examine alcohol's subjective effects among participants drinking alcohol in isolation. Further, perhaps due to the challenges of capturing automatic affective processes in these settings, prior studies of alcohol response in social context have relied mainly on self-report measures, and so relatively little is known about alcohol's psychophysiological effects in social settings.
METHODS
Using a novel paradigm that integrated alcohol-administration procedures, startle methodology, and social context, this study examined the impact of alcohol and social context on startle eyeblink reflex among 40 social drinkers.
RESULTS
Results indicated that there was a significant effect of group presence, indicating that startle magnitude was larger when people were alone than with others. There was a significant group presence-by-alcoholic beverage interaction, with the effect of alcohol being significantly larger when people were alone versus with others. These effects were found both for the startle habituation data and during the picture-viewing task.
CONCLUSIONS
Results of this study highlight the importance of considering the presence of other individuals for understanding alcohol response and mechanisms of AUD risk. Findings are discussed in light of both emotional and cognitive correlates of startle reflex magnitude. Future research should examine these effects within larger samples of participants and further explore mechanisms that might underlie these effects.
Topics: Adult; Alcohol Drinking; Blinking; Female; Humans; Male; Photic Stimulation; Reflex, Startle; Social Environment; Young Adult
PubMed: 29989675
DOI: 10.1111/acer.13838