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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 -
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 -
ELife Jan 2024No preclinical experimental approach enables the study of voluntary oral consumption of high-concentration Δ-tetrahydrocannabinol (THC) and its intoxicating effects,...
No preclinical experimental approach enables the study of voluntary oral consumption of high-concentration Δ-tetrahydrocannabinol (THC) and its intoxicating effects, mainly owing to the aversive response of rodents to THC that limits intake. Here, we developed a palatable THC formulation and an optimized access paradigm in mice to drive voluntary consumption. THC was formulated in chocolate gelatin (THC-E-gel). Adult male and female mice were allowed ad libitum access for 1 and 2 hr. Cannabimimetic responses (hypolocomotion, analgesia, and hypothermia) were measured following access. Levels of THC and its metabolites were measured in blood and brain tissue. Acute acoustic startle responses were measured to investigate THC-induced psychotomimetic behavior. When allowed access for 2 hr to THC-E-gel on the second day of a 3-day exposure paradigm, adult mice consumed up to ≈30 mg/kg over 2 hr, which resulted in robust cannabimimetic behavioral responses (hypolocomotion, analgesia, and hypothermia). Consumption of the same gelatin decreased on the following third day of exposure. Pharmacokinetic analysis shows that THC-E-gel consumption led to parallel accumulation of THC and its psychoactive metabolite, 11-OH-THC, in the brain, a profile that contrasts with the known rapid decline in brain 11-OH-THC levels following THC intraperitoneal (i.p.) injections. THC-E-gel consumption increased the acoustic startle response in males but not in females, demonstrating a sex-dependent effect of consumption. Thus, while voluntary consumption of THC-E-gel triggered equivalent cannabimimetic responses in male and female mice, it potentiated acoustic startle responses preferentially in males. We built a dose-prediction model that included cannabimimetic behavioral responses elicited by i.p. versus THC-E-gel to test the accuracy and generalizability of this experimental approach and found that it closely predicted the measured acoustic startle results in males and females. In summary, THC-E-gel offers a robust preclinical experimental approach to study cannabimimetic responses triggered by voluntary consumption in mice, including sex-dependent psychotomimetic responses.
Topics: Mice; Male; Female; Animals; Dronabinol; Reflex, Startle; Hypothermia; Gelatin; Behavior, Animal
PubMed: 38214701
DOI: 10.7554/eLife.89867 -
Ideggyogyaszati Szemle Sep 2023
Ciprofloxacin (CIP) is a broad-spectrum antibiotic widely used in clinical practice to treat musculoskeletal infections. Fluoroquinolone-induced neurotoxic adverse...
BACKGROUND AND PURPOSE
Ciprofloxacin (CIP) is a broad-spectrum antibiotic widely used in clinical practice to treat musculoskeletal infections. Fluoroquinolone-induced neurotoxic adverse events have been reported in a few case reports, all the preclinical studies on its neuropsychiatric side effects involved only healthy animals. This study firstly investigated the behavioral effects of CIP in an osteoarthritis rat model with joint destruction and pain, which can simulate inflammation-associated musculoskeletal pain. Furthermore, effects of CIP on regional brain-derived neurotrophic factor (BDNF) expression were examined given its major contributions to the neuromodulation and plasticity underlying behavior and cognition.
.METHODS
Fourteen days after induction of chronic osteoarthritis, animals were administered vehicle, 33 mg/kg or 100 mg/kg CIP for five days intraperitoneally. Motor activity, behavioral motivation, and psychomotor learning were examined in a reward-based behavioral test (Ambitus) on Day 4 and sensorimotor gating by the prepulse inhibition test on Day 5. Thereafter, the prolonged BDNF mRNA and protein expression levels were measured in the hippocampus and the prefrontal cortex.
.RESULTS
CIP dose-dependently reduced both locomotion and reward-motivated exploratory activity, accompanied with impaired learning ability. In contrast, there were no significant differences in startle reflex and sensory gating among treatment groups; however, CIP treatment reduced motor activity of the animals in this test, too. These alterations were associated with reduced BDNF mRNA and protein expression levels in the hippocampus but not the prefrontal cortex.
.CONCLUSION
This study revealed the detrimental effects of CIP treatment on locomotor activity and motivation/learning ability during osteoarthritic condition, which might be due to, at least partially, deficient hippocampal BDNF expression and ensuing impairments in neural and synaptic plasticity.
.Topics: Humans; Rats; Animals; Brain-Derived Neurotrophic Factor; Ciprofloxacin; Reflex, Startle; Learning; RNA, Messenger; Hippocampus
PubMed: 37782061
DOI: 10.18071/isz.76.0327 -
Cognitive, Affective & Behavioral... Aug 2023A widely shared framework suggests that anxiety maps onto two dimensions: anxious apprehension and anxious arousal. Previous research linked individual differences in...
A widely shared framework suggests that anxiety maps onto two dimensions: anxious apprehension and anxious arousal. Previous research linked individual differences in these dimensions to differential neural response patterns in neuropsychological, imaging, and physiological studies. Differential effects of the anxiety dimensions might contribute to inconsistencies in prior studies that examined neural processes underlying anxiety, such as hypersensitivity to unpredictable threat. We investigated the association between trait worry (as a key component of anxious apprehension), anxious arousal, and the neural processing of anticipated threat. From a large online community sample (N = 1,603), we invited 136 participants with converging and diverging worry and anxious arousal profiles into the laboratory. Participants underwent the NPU-threat test with alternating phases of unpredictable threat, predictable threat, and safety, while physiological responses (startle reflex and startle probe locked event-related potential components N1 and P3) were recorded. Worry was associated with increased startle responses to unpredictable threat and increased attentional allocation (P3) to startle probes in predictable threat anticipation. Anxious arousal was associated with increased startle and N1 in unpredictable threat anticipation. These results suggest that trait variations in the anxiety dimensions shape the dynamics of neural processing of threat. Specifically, trait worry seems to simultaneously increase automatic defensive preparation during unpredictable threat and increase attentional responding to threat-irrelevant stimuli during predictable threat anticipation. The current study highlights the utility of anxiety dimensions to understand how physiological responses during threat anticipation are altered in anxiety and supports that worry is associated with hypersensitivity to unpredictable, aversive contexts.
Topics: Humans; Reflex, Startle; Anxiety; Evoked Potentials; Anxiety Disorders; Arousal; Anticipation, Psychological
PubMed: 37106311
DOI: 10.3758/s13415-023-01094-4 -
Iranian Journal of Child Neurology 2023The objective assessment tests overcome the variability of subjective methods. Cortical recordings with gap pre-pulse inhibition of the acoustic startle reflex stimulus...
OBJECTIVES
The objective assessment tests overcome the variability of subjective methods. Cortical recordings with gap pre-pulse inhibition of the acoustic startle reflex stimulus have been used as objective tinnitus assessments in humans. This study aims to investigate this possible objective tinnitus test and compare gap-induced inhibition in different stimulus parameters and brain regions.
MATERIALS & METHODS
Twenty People (18-50 years old) without hearing loss and tinnitus were included. The sound stimuli consisted of continuous background noise with a loud startle tone preceded by a silent gap (20 and 40 ms duration, 120 and 150 ms distance from the startle). The N1-P2 complex amplitude and topoplot maps were extracted in 27-channel cortical response recording after signal processing. Four brain regions of interest (ROI) of anterior-frontal, centro-frontal, right, and left temporal were investigated.
RESULTS
The results showed that the maximum inhibition occurred in a 40 ms gap duration and 150 ms distance in all 4 ROIs. In comparing ROIs, the centro-frontal and left temporal regions revealed the most inhibition (p<0.05). The decrease in the amplitude of the N1 and P2 in that region could also be traced in the 100 and 200 ms topoplots.
CONCLUSION
Gap-induced inhibition was observed in all gap-embedded stimuli and all ROIs. However, the 40-150 mode and centro-frontal and left temporal regions had maximum inhibition in normal subjects. It provides a promising tool for objectively assessing tinnitus in humans with particular implications in children.
PubMed: 38074929
DOI: 10.22037/ijcn.v17i4.42300 -
Biology Letters Jul 2023Boldness, the way an individual reacts to risk, is a commonly studied personality trait in animals. Consistent among-individual differences in startle response durations...
Boldness, the way an individual reacts to risk, is a commonly studied personality trait in animals. Consistent among-individual differences in startle response durations (latency to recover from a startling stimulus) are frequently assumed to reflect variation in boldness. An alternative explanation is that these latencies are not directly driven by variation in responses to information on risk, but by underlying differences in dynamic performance capacities. Here we investigate this possibility by analysing relationships between locomotory speed, a measure of whole-body dynamic performance capacity in hermit crabs, and startle response duration, a repeatable latency measure used as an index of boldness. Individuals differed in mean startle response duration, in the consistency of their startle responses, in their reaction norms across repeated observations, and mean startle responses increased with crab mass. However, there were no relationships between startle responses and locomotory speed. This indicates that startle responses do not reflect underlying performance capacities and suggests that they provide insight into differences in how individuals respond to risky situations. Since similar latencies are used as measures of boldness in other animals, we suggest that potential relationships between apparent boldness and performance capacity should be tested.
Topics: Animals; Behavior, Animal; Anomura; Reflex, Startle
PubMed: 37490943
DOI: 10.1098/rsbl.2023.0224 -
Scientific Reports Oct 2023Acoustic Harassment Devices (AHD) are widely used to deter marine mammals from aquaculture depredation, and from pile driving operations that may otherwise cause hearing...
Acoustic Harassment Devices (AHD) are widely used to deter marine mammals from aquaculture depredation, and from pile driving operations that may otherwise cause hearing damage. However, little is known about the behavioural and physiological effects of these devices. Here, we investigate the physiological and behavioural responses of harbour porpoises (Phocoena phocoena) to a commercial AHD in Danish waters. Six porpoises were tagged with suction-cup-attached DTAGs recording sound, 3D-movement, and GPS (n = 3) or electrocardiogram (n = 2). They were then exposed to AHDs for 15 min, with initial received levels (RL) ranging from 98 to 132 dB re 1 µPa (rms-fast, 125 ms) and initial exposure ranges of 0.9-7 km. All animals reacted by displaying a mixture of acoustic startle responses, fleeing, altered echolocation behaviour, and by demonstrating unusual tachycardia while diving. Moreover, during the 15-min exposures, half of the animals received cumulative sound doses close to published thresholds for temporary auditory threshold shifts. We conclude that AHD exposure at many km can evoke both startle, flight and cardiac responses which may impact blood-gas management, breath-hold capability, energy balance, stress level and risk of by-catch. We posit that current AHDs are too powerful for mitigation use to prevent hearing damage of porpoises from offshore construction.
Topics: Animals; Porpoises; Phocoena; Noise; Reflex, Startle; Sound; Acoustics
PubMed: 37794093
DOI: 10.1038/s41598-023-43453-8 -
Royal Society Open Science Mar 2024Individual variation in fearfulness can be modified during ontogeny, and high levels of fear can affect animal welfare. We asked whether early-life environmental...
Individual variation in fearfulness can be modified during ontogeny, and high levels of fear can affect animal welfare. We asked whether early-life environmental complexity and genetic strain affect fear behaviour in young laying hens (pullets). Four replicates of brown (B) and white (W) genetic strains (breeds) of layers were each raised in four environmental treatments (housing): conventional cages () and different rearing aviaries with increasing space and complexity ( < < ). We used a startle reflex test (weeks 4 and 14) to measure startle amplitude and autonomic response (i.e. comb temperature). A combination of novel arena (NA) and novel object (NO) tests was used (week 14) to assess NA exploration and alertness, latency to approach the centre and initial NO avoidance and investigation. Housing × strain affected startle amplitude (B-Conv, B-High < B-Low, B-Mid; B > W; no housing effect in W) but not autonomic response. Fear behaviour was affected by housing (NA exploration, investigation: Conv < Low, Mid, High; NO avoidance: Conv, High < Low, Mid), strain (NA alertness: B > W, NO avoidance: W > B) and their interaction (NA centre approach: B-Conv < all other groups). We present evidence for strain-specific fear responses depending on early experience.
PubMed: 38511084
DOI: 10.1098/rsos.231075 -
Brain and Behavior May 2024Chronic adolescent stress profoundly affects prefrontal cortical networks regulating top-down behavior control. However, the neurobiological pathways contributing to...
INTRODUCTION
Chronic adolescent stress profoundly affects prefrontal cortical networks regulating top-down behavior control. However, the neurobiological pathways contributing to stress-induced alterations in the brain and behavior remain largely unknown. Chronic stress influences brain growth factors and immune responses, which may, in turn, disrupt the maturation and function of prefrontal cortical networks. The tumor necrosis factor alpha-converting enzyme/a disintegrin and metalloproteinase 17 (TACE/ADAM17) is a sheddase with essential functions in brain maturation, behavior, and inflammatory responses. This study aimed to determine the impact of stress on the prefrontal cortex and whether TACE/ADAM17 plays a role in these responses.
METHODS
We used a Lewis rat model that incorporates critical elements of chronic psychosocial stress, such as uncontrollability, unpredictability, lack of social support, and re-experiencing of trauma.
RESULTS
Chronic stress during adolescence reduced the acoustic startle reflex and social interactions while increasing extracellular free water content and TACE/ADAM17 mRNA levels in the medial prefrontal cortex. Chronic stress altered various ethological behavioral domains in the observation home cages (decreased ingestive behaviors and increased walking, grooming, and rearing behaviors). A group of rats was injected intracerebrally either with a novel Accell™ SMARTpool TACE/ADAM17 siRNA or a corresponding siRNA vehicle (control). The RNAscope Multiplex Fluorescent v2 Assay was used to visualize mRNA expression. Automated puncta quantification and analyses demonstrated that TACE/ADAM17 siRNA administration reduced TACE/ADAM17 mRNA levels in the medial prefrontal cortex (59% reduction relative to control). We found that the rats that received prefrontal cortical TACE/ADAM17 siRNA administration exhibited altered eating patterns (e.g., increased food intake and time in the feeding zone during the light cycle).
CONCLUSION
This study supports that the prefrontal cortex is sensitive to adolescent chronic stress and suggests that TACE/ADAM17 may be involved in the brain responses to stress.
Topics: Animals; Male; Rats; ADAM17 Protein; Behavior, Animal; Prefrontal Cortex; Rats, Inbred Lew; Reflex, Startle; Stress, Psychological; Female
PubMed: 38715397
DOI: 10.1002/brb3.3482