Habituation Task Research Articles

Attrition in a large-scale habituation task administered at home.

Infant research often struggles with selective samples, especially when focusing on behavioural measures, such as those drawn from habituation tasks. However, selectivity may threaten the generalizability and interpretation of results, which is why the current study investigates attrition in a habituation task administered in a household setting in 7-month-old infants. We used a large-scale German dataset, focusing on the children's socioeconomic background, and investigated two aspects of attrition, namely, participation and task completion. The findings suggest significant effects of the children's socioeconomic background on attrition: Maternal education, parental occupation, household income and household language (German vs. other) were positively related to participation and task completion. The analyses indicate that multiple barriers may prevent parents from lower socioeconomic backgrounds from letting their children participate. The study concludes with a critical discussion of possible mechanisms of selectivity in behavioural measures as well as the household setting, in which the data were collected.

Socioeconomic differences in looking behavior in habituation tasks in the first two years of life

ABSTRACT Studies on the emergence of effects of socioeconomic inequality typically report that socioeconomic background is positively associated with early cognitive abilities. However, studies on looking behaviour in habituation tasks rarely investigate this association, although such tasks are standard in measuring cognitive abilities in infants. The current study aimed to explore the emergence and magnitude of the effects of socioeconomic background, as one aspect of socioeconomic inequality, on cognitive abilities in the first two years of life, using a dataset from a large-scale German cohort study. We modelled looking behaviour using growth curve modelling and found no significant effects at 7 months. However, we found positive effects of socioeconomic background on the initial looking time (intercept) and overall looking time at 17 months, but not on the looking decrement (slope). The results are discussed regarding the specificities of the data, as the habituation task was administered in a household setting.

The role of the claustrum in the acquisition, consolidation and reconsolidation of memories in mice

The claustrum is a brain structure that remains shrouded in mystery due to the limited understanding of its cellular structure, neural pathways, functionality and physiological aspects. Significant research has unveiled connections spanning from the claustrum to the entire cortex as well as subcortical areas. This widespread connectivity has led to speculations of its role in integrating information from different brain regions, possibly contributing to processes such as attention, consciousness, learning and memory. Our working hypothesis posits that claustrum neural activity contributes to the acquisition, consolidation and reconsolidation of long-term memories in mice. We found evidence in CF-1 mice of a decline in behavioral performance in an inhibitory avoidance task due to intra-claustral administration of 2% lidocaine immediately after a training session or memory recall. Nevertheless, this does not seem to be the case for the acquisition or retrieval of this type of memory, although its neural activity is significantly increased after training, evaluated through c-Fos expression. Moreover, inhibition of the claustrum’s synaptic activity appears to impair the consolidation but not acquisition or retrieval of an unconditioned memory formed in a nose-poke habituation task.

Visual statistical learning in preverbal infants at a higher likelihood of autism and its association with later social communication skills.

Visual statistical Learning (SL) allows infants to extract the statistical relationships embedded in a sequence of elements. SL plays a crucial role in language and communication competencies and has been found to be impacted in Autism Spectrum Disorder (ASD). This study aims to investigate visual SL in infants at higher likelihood of developing ASD (HL-ASD) and its predictive value on autistic-related traits at 24-36 months. At 6 months of age, SL was tested using a visual habituation task in HL-ASD and neurotypical (NT) infants. All infants were habituated to a visual sequence of shapes containing statistically predictable patterns. In the test phase, infants viewed the statistically structured, familiar sequence in alternation with a novel sequence that did not contain any statistical information. HL-ASD infants were then evaluated at 24-36 months to investigate the associations between visual SL and ASD-related traits. Our results showed that NT infants were able to learn the statistical structure embedded in the visual sequences, while HL-ASD infants showed different learning patterns. A regression analysis revealed that SL ability in 6-month-old HL-ASD infants was related to social communication and interaction abilities at 24-36 months of age. These findings indicate that early differences in learning visual statistical patterns might contribute to later social communication skills.

Individual differences in processing speed and curiosity explain infant habituation and dishabituation performance.

Habituation and dishabituation are the most prevalent measures of infant cognitive functioning, and they have reliably been shown to predict later cognitive outcomes. Yet, the exact mechanisms underlying infant habituation and dishabituation are still unclear. To investigate them, we tested 106 8-month-old infants on a classic habituation task and a novel visual learning task. We used a hierarchical Bayesian model to identify individual differences in sustained attention, learning performance, processing speed and curiosity from the visual learning task. These factors were then related to habituation and dishabituation. We found that habituation time was related to individual differences in processing speed, while dishabituation was related to curiosity, but only for infants who did not habituate. These results offer novel insights in the mechanisms underlying habituation and serve as proof of concept for hierarchical models as an effective tool to measure individual differences in infant cognitive functioning. RESEARCH HIGHLIGHTS: We used a hierarchical Bayesian model to measure individual differences in infants' processing speed, learning performance, sustained attention, and curiosity. Faster processing speed was related to shorter habituation time. High curiosity was related to stronger dishabituation responses, but only for infants who did not habituate.

Systematic characterization of a non-transgenic Aβ1–42 amyloidosis model: synaptic plasticity and memory deficits in female and male mice

BackgroundThe amyloid-β (Aβ) cascade is one of the most studied theories linked to AD. In multiple models, Aβ accumulation and dyshomeostasis have shown a key role in AD onset, leading to excitatory/inhibitory imbalance, the impairments of synaptic plasticity and oscillatory activity, and memory deficits. Despite the higher prevalence of Alzheimer’s disease (AD) in women compared to men, the possible sex difference is scarcely explored and the information from amyloidosis transgenic mice models is contradictory. Thus, given the lack of data regarding the early stages of amyloidosis in female mice, the aim of this study was to systematically characterize the effect of an intracerebroventricular (icv.) injection of Aβ1–42 on hippocampal-dependent memory, and on associated activity-dependent synaptic plasticity in the hippocampal CA1–CA3 synapse, in both male and female mice.MethodsTo do so, we evaluated long term potentiation (LTP) with ex vivo electrophysiological recordings as well as encoding and retrieval of spatial (working, short- and long-term) and exploratory habituation memories using Barnes maze and object location, or open field habituation tasks, respectively.ResultsAβ1–42 administration impaired all forms of memory evaluated in this work, regardless of sex. This effect was displayed in a long-lasting manner (up to 17 days post-injection). LTP was inhibited at a postsynaptic level, both in males and females, and a long-term depression (LTD) was induced for the same prolonged period, which could underlie memory deficits.ConclusionsIn conclusion, our results provide further evidence on the shifting of LTP/LTD threshold due to a single icv. Aβ1–42 injection, which underly cognitive deficits in the early stages of AD. These long-lasting cognitive and functional alterations in males and females validate this model for the study of early amyloidosis in both sexes, thus offering a solid alternative to the inconsistence of amyloidosis transgenic mice models.

Respiratory response to an odor throughout development in rats.

Odor-induced sniffing has proven to be a useful behavioral readout for assessing olfactory performance in adult rats. However, little is known about how the respiratory response changes throughout ontogeny. Thus, this study aimed at characterizing respiratory response to an odor in rats using paradigms suitable to infants, juveniles, and adults. We first analyzed the respiratory response to a neutral, novel odor. Then the value of the odor was changed either through its repeated presentation (odor habituation), or its association with a foot-shock (odor fear). In the habituation task, we found that the first presentation of the novel odor induced a clear sniffing response at all 3 ages, but the peak respiratory frequency was higher in adults than in juveniles and infants. When the odor was presented repeatedly, the sniffing response gradually faded and the younger the animal, the faster the fading of the response. In the fear conditioning task, the odor induced an increase in respiratory rate that persisted until the end of the session in adults and infants, but not in juveniles. In another group for which the odor was explicitly unpaired with the foot-shock, the respiratory response to the odor did not last as long over the session than in the paired condition at all 3 ages. Finally, we observed that shock delivery induced a similar respiratory response at the 3 investigated ages in the paired and unpaired conditions. Collectively, these data show that the respiratory response constitutes a faithful index to assess rat's olfactory abilities throughout ontogeny.

Dyadic interactions during infant learning: Exploring infant-parent exchanges in experimental eye-tracking studies

The role of parental behaviour in modulating infant learning during experimental studies has been rarely explored. Yet, multiple strands of research suggest that dyadic infant-parent interactions could be as important for infant learning and regulation during experimental studies with infants, as they are during their free, unconstrained play. Recently, we have developed a coding scheme for analysing the quantity and quality of various extraneous behaviours of both the parent and the infant during standard eye-tracking experiments. Here, we present a quantitative analysis of selected parental behaviours and their role in modulating infant task performance. We analysed whether parental looking (at the screen or at the infant), talking and pointing and physical contact change with the task that the infant is performing. The results showed subtle, systematic adjustments of parental behaviours in relation to the task. Moreover, parental behaviours were related to infant performance for tasks that involve learning (habituation task) and free viewing of visual stimuli, but not for those involving simple orienting responses (gap-overlap task). Additional dynamic analyses using Cross-Recurrence Quantification Analysis indicated that parents were closely following the infants' shifts, looking toward and away from the screen. Altogether, these results indicate that infant performance in eye-tracking tasks are associated with subtle adjustments of parental behaviours. This may suggest that early on infants perform learning tasks in coordination with parental behaviour as a dyadic unit of learning.

Associations Between Repetitive Negative Thinking and Habituation of Defensive Responding Within and Between Sessions.

The online version contains supplementary material available at 10.1007/s42761-022-00121-w.

But that’s possible! Infants, pupils, and impossible events

Infants’ expectations of the world around them have been extensively assessed through the violation of expectation paradigm and related habituation tasks. Typically, in these tasks, longer looking to impossible events following familiarisation with possible equivalents is taken to reflect surprise at their occurrence, thus revealing infants’ knowledge. In this study, the role of learning during the task itself is explored by switching the archetypal approach on its head and familiarising infants to impossible events. In a partial replication of Jackson and Sirois (2009), nine-month-old infants were presented with short video clips of toy trains moving around a circular track. A tunnel over a short section of the track meant trains were briefly occluded as they completed a circuit. In impossible versions of events, the train switched colours while occluded by the tunnel. Both looking times and pupil dilation were used as dependent measures. Using a factorial design in which perceptual (novelty-familiarity) and conceptual (possible-impossible) variables were independently and jointly analysed, we show that infants showed greater responding to possible events than to impossible events following familiarisation. Pupil dilation data successfully allowed for more precise interpretation of infants’ perception of events than could have been achieved through looking times alone. These findings suggest a central role for learning in violation of expectation tasks, and also further support the use of pupil dilation as a dependent measure in infancy work.

Infants' visual exploration strategies for adult and child faces.

By the end of the first year of life, infants' discrimination abilities tune to frequently experienced face groups. Little is known about the exploration strategies adopted to efficiently discriminate frequent, familiar face types. The present eye-tracking study examined the distribution of visual fixations produced by 10-month-old and 4-month-old singletons while learning adult (i.e., familiar) and child (i.e., unfamiliar) White faces. Infants were tested in an infant-controlled visual habituation task, in which post-habituation preference measured successful discrimination. Results confirmed earlier evidence that, without sibling experience, 10-month-olds discriminate only among adult faces. Analyses of gaze movements during habituation showed that infants' fixations were centered in the upper part of the stimuli. The mouth was sampled longer in adult faces than in child faces, while the child eyes were sampled longer and more frequently than the adult eyes. At 10months, but not at 4months, global measures of scanning behavior on the whole face also varied according to face age, as the spatiotemporal distribution of scan paths showed larger within- and between-participants similarity for adult faces than for child faces. Results are discussed with reference to the perceptual narrowing literature, and the influence of age-appropriate developmental tasks on infants' face processing abilities.

Aberrant Neural Response During Face Processing in Girls With Fragile X Syndrome: Defining Potential Brain Biomarkers for Treatment Studies

BackgroundChildren and adolescents with fragile X syndrome (FXS) manifest significant symptoms of anxiety, particularly in response to face-to-face social interaction. In this study, we used functional near-infrared spectroscopy to reveal a specific pattern of brain activation and habituation in response to face stimuli in young girls with FXS, an important but understudied clinical population. MethodsParticipants were 32 girls with FXS (age: 11.8 ± 2.9 years) and a control group of 28 girls without FXS (age: 10.5 ± 2.3 years) matched for age, general cognitive function, and autism symptoms. Functional near-infrared spectroscopy was used to assess brain activation during a face habituation task including repeated upright/inverted faces and greeble (nonface) objects. ResultsCompared with the control group, girls with FXS showed significant hyperactivation in the frontopolar and dorsal lateral prefrontal cortices in response to all face stimuli (upright + inverted). Lack of neural habituation (and significant sensitization) was also observed in the FXS group in the frontopolar cortex in response to upright face stimuli. Finally, aberrant frontopolar sensitization in response to upright faces in girls with FXS was significantly correlated with notable cognitive-behavioral and social-emotional outcomes relevant to this condition, including executive function, autism symptoms, depression, and anxiety. ConclusionsThese findings strongly support a hypothesis of neural hyperactivation and accentuated sensitization during face processing in FXS, a phenomenon that could be developed as a biomarker end point for improving treatment trial evaluation in girls with this condition.

Pentingnya Pendidikan Karakter Di Masa Pandemi Covid 19

<p><em>Character</em><em> education is very important in order to shape the character of the nation. Character education can make students become social beings who help each other, are civilized and polite. Teaching and learning activities carried out in Indonesia previously were face-to-face or offline learning. At the time of face-to-face or offline learning, teachers can easily observe the character of students and can provide direction and character education easily. However, the COVID-19 pandemic has forced the change of face-to-face or offline learning to be replaced by online or virtual. For this reason, collaboration and communication between teachers and parents of students to jointly apply character education is very necessary. Teachers can provide good habituation tasks, by implementing PPK (Strengthening Character Education) in online or virtual activities, and parents working with teachers to supervise student activities from home.</em></p>

Dysfunctions in Infants\u2019 Statistical Learning are Related to Parental Autistic Traits

Statistical learning refers to the ability to extract the statistical relations embedded in a sequence, and it plays a crucial role in the development of communicative and social skills that are impacted in the Autism Spectrum Disorder (ASD). Here, we investigated the relationship between infants’ SL ability and autistic traits in their parents. Using a visual habituation task, we tested infant offspring of adults (non-diagnosed) who show high (HAT infants) versus low (LAT infants) autistic traits. Results demonstrated that LAT infants learned the statistical structure embedded in a visual sequence, while HAT infants failed. Moreover, infants’ SL ability was related to autistic traits in their parents, further suggesting that early dysfunctions in SL might contribute to variabilities in ASD symptoms.

The Histologic Effect of Baclofen in Rat’s brain: An Experimental Study

Background: Baclofen is the only clinically available metabotropic GABAB receptor agonist. Several reports has been discussed the efficacy of baclofen but the available data on its effect of the behavior and brains' histology are still limited.Objectives: This work aims to assess the effects of long term exposure to baclofen (8weeks) on behavior and brains' histology in ratsMethods: Analysis of data of Twenty five healthy male Albino rats were performed. Rats weighing about 200–210 g with mean age of 65 days were randomly selected and categorized into three groups: Group 1(LD50 group): included five rats that gavaged with single dose of baclofen to test the LD50 of drug (145mg per Kg) .Group 2. (control group):included eight rats were gavaged with distilled water for 2 months. Group 3.(baclofen group): included 12 rats gavaged with 15mg/kg of baclofen (1/10th LD50) for 2 month. Behavioral Tests were conducted on all animals in group 2 and 3 including: Open-field test ,Open -field habituation task ,and object recognition(Novel) to examine the influence of drug on the cognition of rats. All animals were euthanized with ether after 24hours of last day of treatment. Brains were excised and collected from rats of group 2 and 3.Fixation of tissues was done using buffered solution of ten percent of formalin for twenty four hours with paraffin wax embedding. Sectioning and staining by hematoxylin and eosin protocol (H&E) and prepared to be examine histologically. To differentiate between the data of group 2 and 3 ,statistical analysis was performed by 1- way analysis of variance (ANOVA) .Least significant difference test with Duncan test was used . Value of P of equal or less than 0.05 means the difference is significant .Results: This study revealed that the rats of baclofen group traveled a greater total distance(in both sessions) when compared with those of control indicating their hyperactivity. The zone specific analysis showed that the rats that were administered with baclofen consumed markedly greater time nearby the walls in the peripheral part in the arena throughout the first and 2nd 15- min session in comparison with those of control group indicating the generalized hyperactivity and exploration. Rats of control group preferred the novel object in comparison with those of baclofen group. However there is no marked difference in the index of discrimination among rats of group 2 and 3. Histological sections of rats’ brains in group that were administered with 15mg/kg of baclofen for 2 month( baclofen group) revealed a diminished thickness in the pyramidal cells’ layer, irregular faintly stained cells with shrinkage in the some pyramidal nerve cells, dark staining cytoplasm and losing the characteristics of their nuclei.Conclusions:Chronic administration with baclofen (15mg/kg/day/2months) induces changes in the brain histology in rats, however, baclofen has no adverse effect on the behavior. To the best of our information, our work is the 1st that focus on the influence of baclofen on both the behavior and brains' histology. Our data suggesting that baclofen may have clinical utility.

Dynamic changes in numerical acuity in 4-month-old infants.

Preverbal infants represent the approximate numerosity of visual and auditory arrays: By 6months old, they reliably discriminate eight dots or tones from 16 (a 1:2 ratio), but not eight from 12 (a 2:3 ratio). The precision of this approximate number sense improves gradually over childhood and into adulthood. However, less is known about numerical abilities in younger infants, and in particular, whether there is developmental change in the number sense in the first half year of life. Here, in four experiments, we measured numerical precision in 4-month-old infants (N=128) using a visual habituation task comparable to that in studies of older infants. We found that 4-month-olds exhibited poorer numerical discrimination than the 6-month-olds tested in previous studies, dishabituating to a 1:4 change in numerical ratio, but not a 1:3 change. Like older infants, 4-month-olds' numerical precision improved when they were provided with redundant visual and auditory input; when both visual and auditory information were present, 4-month-olds discriminated a 1:3 but not a 1:2 ratio. These results suggest that Approximate Number System precision develops in early infancy and may be sensitive to intersensory redundancy as early as four months of age.

High reinforcing value of food is related to slow habituation to food

BackgroundThe rate of habituation to food and reinforcing value of food are processes that are related to food intake and body weight. Reinforcing value of food provides an index of the motivation to eat, while habituation provides an index on how repeated presentations of food relate to reduced behavioral and physiological responses to that food. ObjectiveTo investigate the relationship between habituation phenotypes to salty, sweet and savory foods and reinforcing value of those foods. DesignA sample of 229 8–12-year-old children at risk for obesity completed reinforcing value and habituation tasks for foods that varied in savory, sweet or salty tastes. Multivariate Group Based Trajectory Modeling was used to create four unique patterns of habitation to foods based on detailed 10 s epochs of responding for food over a 24 min task. Differences in reinforcing value of food were assessed for these habituation phenotypes. ResultsResults showed a graded relationship between the overall habituation phenotypes and reinforcing value of food, as those with the relatively flat habituation phenotype found food more reinforcing than those with phenotypes that showed rapidly decelerating responding across all taste categories. ConclusionsThose who habituated slower found food more reinforcing than those with a rapid habituation phenotype. Implications of these phenotypes for understanding how habituation relates to food intake are discussed.

Sex differences in olfactory social recognition memory in meadow voles, Microtus pennsylvanicus

AbstractTerrestrial mammals, like rodents, use odors, and scent marks to indicate their presence in an area to conspecifics. These odors convey information about the scent donor's genotype, sex, condition, and age. The ability to discriminate among the scent marks of conspecifics and later recollect the identity of the donor is essential for choosing between familiar and unfamiliar mates. We tested the hypothesis that the promiscuous meadow vole (Microtus pennsylvanicus) can recollect the odor of a familiar, opposite‐sex conspecific and distinguish it from that of an unfamiliar, opposite‐sex conspecific. We also hypothesized that because reproductive success is highly skewed among male meadow voles and competition for mates is intense, males will be more likely than females to recollect the odor of a familiar, opposite‐sex conspecific and distinguish it from that of an unfamiliar, opposite‐sex conspecific, for a longer period of time. Using a habituation task, we first exposed the voles, 4 times successively, to the anogenital area scent of an opposite‐sex conspecific. Then, 1 hr, 24 hrs, 72 hrs, or 96 hrs after the fourth exposure, voles were presented with the odor of the donor from the exposure phase (familiar donor) and that of an unfamiliar, opposite‐sex conspecific. Female meadow voles spent similar amounts of time investigating the scent of the familiar male donor and that of an unfamiliar male donor after the 1‐hr and 24‐hr intervals. Male meadow voles, however, spent more time with the scent of an unfamiliar female donor than that of the familiar female donor after the 1‐hr, 24‐hr, and 72‐hr intervals, suggesting that male voles could recollect the scent mark of a familiar female for at least three days. The implications of these sex differences in social memory may reflect the different strategies male and female meadow voles use in the recognition of previous and potential mates. Recognition of an individual's scents may enhance fitness by allowing animals to direct appropriate behaviors toward those individuals.

0158 Loss of Connexin 36 Elicits Abnormalities in Thalamocortical Network Activity Relevant to Neuropsychiatric Disorders

Abstract Introduction Neuronal gap-junctions are extensively expressed in mammalian forebrain and suggested to contribute to state-regulation and thalamocortical network activity. However, the physiological role of gap-junctions on these processes remains poorly understood. Connexin-36 (Cxn36) is highly expressed in the brain, representing a mechanism for electrical coupling of inhibitory neurons. We examined the effects of global Cnx36 deletion on sleep/wake and spontaneous and evoked EEG activity. Methods We recorded in vivo EEG/EMG in Cxn36KO mice and littermate controls. Electrodes were stereotaxically implanted above frontal cortices. We analyzed sleep/wake states and algorithmically detected sleep spindles over 24 hours. Mice underwent auditory stimulation paradigms including the auditory steady state response (ASSR; 1 second train 20-50Hz clicks, 100 reps., 85dB) and mismatch negativity (MMN; 2.5kHz standard 90%, 10kHz deviant 10%, 300ms ISI, 90dB). Social behavior and investigation-evoked EEG activity were also assessed via the social habituation task (repeated 5 min exposures to novel mouse). Results Cnx36KO mice exhibited limited sleep/wake abnormalities (n=7/group). Power spectra of EEG revealed significant impairments in spontaneous gamma-band activity (30-80Hz; All States, Light & Dark Phases), and beta activity (15-25Hz; All States, Light Phase). Sigma activity (10-15Hz) was significantly decreased (NREM and REM, Light phase). This was particularly pronounced during NREM-REM transitions. Despite no changes in spindle density, both spindle amplitude and duration were significantly decreased in Cnx36KOs. Cxn36KOs exhibited a blunted gamma-band response to acute ketamine (15mg/kg; IP), impaired 30 & 40Hz ASSR, and an abnormal response in the MMN task (decrease ERP peak amplitude & gamma). Finally, Cxn36KO mice exhibit impaired social habituation and significantly decreased investigation evoked slow gamma-band activity (30 - 55Hz). Conclusion Our data suggest Cxn36 plays a critical role in regulating thalamocortical network activity. Further, impairments in Cnx36KO mice reflect abnormalities in neuropsychiatric disorders, including schizophrenia, implicating Cnx36 containing gap junctions as a novel therapeutic target. Support Research supported by VA CDA Award BX002130 (JMM), VA Merit Awards BX004500 (JMM), BX001404 (RB), and NIMH RO1 MH39683 (Ritchie E. Brown).

Intergenerational transmission of anxiety: linking parental anxiety to infant autonomic hyperarousal and fearful temperament.

BackgroundAutonomic hyperarousal has been proposed as a dispositional risk factor for anxiety disorders (ADs). Therefore, we studied physiological arousal in offspring of fathers and mothers with and without ADs and whether infant hyperarousal predicts subsequent fearful temperament.MethodsInfants (N = 128; age = 4 months) did a novel stimuli task (exposure to visual, olfactory, and acoustic stimuli and an unfamiliar male) and a habituation task (exposure to a repeated acoustic stimulus). Heart rate (HR) and heart rate variability (HRV) were measured during baseline, stimuli and post‐stimuli rest. Parents’ AD status and severity were measured using a diagnostic interview and their fearful temperament using a questionnaire. Child fearful temperament was measured at 4 months, 1 year and 2.5 years with observations during structured tasks.ResultsParents’ fearful temperament (significant in the habituation task), AD status (significant in the novel stimuli task) and AD severity (significant in both tasks) predicted a higher HR in their infants. Infants’ higher HR reactivity to novel stimuli and diminished HR recovery at 4 months predicted a more fearful temperament during infancy and toddlerhood. Infants’ higher HR at 4 months predicted a more fearful temperament at 2.5 years.ConclusionsParental prenatal anxiety (disorders) predicted infants’ autonomic arousal, which in turn predicted later fearful temperament in children. Outcomes suggest that autonomic hyperarousal is a dispositional risk factor of ADs.