Rate Of Habituation Research Articles

Decoupling of desire and salivation over repeated chocolate consumption and the moderating role of food legalizing

This study aimed to investigate the responses in desire and salivation during repeated chocolate consumption, and examining how these responses are influenced by a relaxed relationship with food, or 'food legalizing'. Salivation is often used as a proxy for desire, though evidence for this correlation is mixed. We hypothesized that both desire and salivation would decrease with repeated chocolate intake. Additionally, research has suggested that eating styles may affect habituation rates. We proposed that individuals with the food legalizing trait would habituate more rapidly to chocolate, providing an alternative mechanism to reward sensitivity associated with restrained eating. Fifty healthy-weight individuals participated in the study, consuming five blocks of chocolate (each 4 g, 22 calories) over trials. After the trials, participants were allowed to eat as much chocolate as they desired. The results showed that salivation was not correlated with self-reported desire over repeated chocolate consumption. While desire decreased with repeated intake and predicted ad libitum consumption, salivation increased and did not predict ad libitum consumption. Furthermore, food legalizing moderated the rate of responding in terms of the desire to eat but did not affect salivary flow. These findings suggest that salivation is not a reliable physiological measure of desire when eating chocolate. Instead, salivation appears to reflect sensitization to the sensory characteristics of chocolate and is less predictive of subsequent ad libitum chocolate consumption than self-reported desire. Lastly, having a carefree relationship with chocolate may help regulate its consumption, highlighting the potential benefits of a relaxed attitude toward food.

Distinct acute stressors exert an antagonistic effect on complex grooming during novelty habituation in rats

Grooming is a common readout in multiple rat models of neuropsychiatric diseases. It is usually associated with distress and negative emotionality, but also with emotional de-arousal after stress. These seemingly conflicting interpretations may result from specific grooming sequences appearing at different arousal levels and during distinct phases of the stress response. To further explore this hypothesis, we analyzed how distinct stressors affect grooming syntaxis and kinetics. To that end, we explored the independent and interacting effects of foot shocks, corticosterone (CORT), and novelty on exploratory activity, grooming, and ultrasonic vocalizations (USVs) in an open-field test (OF). Wistar rats were intraperitoneally injected either with vehicle or CORT, placed in a chamber where half of them were foot-shocked and then assessed in the OF. The next day, animals were re-exposed to the shock chamber and then tested in the OF without receiving any treatment. On day 1, foot shocks and –to a less extent CORT– increased freezing and inhibited rearing in the chamber, but only foot shocks increased distress USVs. In the OF, both treatments suppressed complex grooming, with foot-shocks also inhibiting exploration and CORT marginally reducing rearing. On day 2, foot-shocked rats showed conditioned fear when re-exposed to the chamber. When tested in the OF, foot-shocked and CORT-treated animals still showed low levels of complex grooming, with the former group also showing increased distress USVs. In this study, all different stressors inhibited complex grooming, suggesting an inverse association between these grooming subtypes and negative emotionality.

Effects of chronic delta-opioid receptor agonist on the excitability of hippocampal glutamate and brainstem monoamine neurons, anxiety, locomotion, and habituation in rats.

Short-term treatment with non-peptide agonists of delta-opioid receptors, such as agonist SNC80, induced behavioral effects in rodents, which could be modulated via changes in central neurotransmission. The present experiments aimed at testing the hypothesis that chronic treatment with SNC80 induces anxiolytic effects associated with changes in hippocampal glutamate and brainstem monoamine pathways. Adult male Wistar rats were used in experiments. Rats were treated with SNC80 (3mg/kg/day) for fourteen days. Neuronal excitability was assessed using extracellular in vivo single-unit electrophysiology. The behavioral parameters were examined using the elevated plus maze and open field tests. Chronic SNC80 treatment increased the excitability of hippocampal glutamate and ventral tegmental area dopamine neurons and had no effect on the firing activity of dorsal raphe nucleus serotonin cells. Chronic SNC80 treatment induced anxiolytic effects, which were, however, confounded by increased locomotor activity clearly confirmed in an open field test. The ability to cope with stressful situations and habituation processes in a novel environment was not influenced by chronic treatment with SNC80. Our study suggests that the psychoactive effects of SNC80 might be explained by its ability to stimulate hippocampal glutamate and mesolimbic dopamine transmission.

Reduced corticolimbic habituation to negative stimuli characterizes bipolar depressed suicide attempters

Suicide attempts in Bipolar Disorder are characterized by high levels of lethality and impulsivity. Reduced rates of amygdala and cortico-limbic habituation can identify a fMRI phenotype of suicidality in the disorder related to internal over-arousing states. Hence, we investigated if reduced amygdala and whole-brain habituation may differentiate bipolar suicide attempters (SA, n = 17) from non-suicide attempters (nSA, n = 57), and healthy controls (HC, n = 32). Habituation was assessed during a fMRI task including facial expressions of anger and fear and a control condition. Associations with suicidality and current depressive symptomatology were assessed, including machine learning procedure to estimate the potentiality of habituation as biomarker for suicidality. SA showed lower habituation compared to HC and nSA in several cortico-limbic areas, including amygdalae, cingulate and parietal cortex, insula, hippocampus, para-hippocampus, cerebellar vermis, thalamus, and striatum, while nSA displayed intermediate rates between SA and HC. Lower habituation rates in the amygdalae were also associated with higher depressive and suicidal current symptomatology. Machine learning on whole-brain and amygdala habituation differentiated SA vs. nSA with 94% and 69% of accuracy, respectively. Reduced habituation in cortico-limbic system can identify a candidate biomarker for attempting suicide, helping in detecting at-risk bipolar patients, and in developing new therapeutic interventions.

Effects of Chronic Delta-Opioid Receptor Agonist on the Excitability of Hippocampal Glutamate and Brainstem Monoamine Neurons, Anxiety, Locomotion, And Habituation in Rats

Effects of Chronic Delta-Opioid Receptor Agonist on the Excitability of Hippocampal Glutamate and Brainstem Monoamine Neurons, Anxiety, Locomotion, And Habituation in Rats

Muscarinic regulation of self-grooming behavior and ultrasonic vocalizations in the context of open-field habituation in rats

Laboratory rats repeatedly exposed to an open field (OF) apparatus display increasingly high levels of grooming –especially that characterized by long and complex sequences– which has been taken as an additional index of novelty habituation. We hypothesized that disrupting such a learning process by administering an amnesic drug as the antimuscarinic scopolamine (SCP) could delay the appearance of more complex grooming subtypes. Thus, rats were pretreated either with SCP (15 mg/kg or 30 mg/kg) or vehicle (VEH) upon four one-day apart OF (OF1–4). On a fifth assessment, all rats received VEH to analyze the likely carry-over effect of SCP. Finally, we measured 50-kHz and 22-kHz ultrasonic vocalizations (USVs) as reliable markers of positive and negative emotionality, respectively. We found that SCP increased locomotion during OF1 and reduced rearing on OF1–OF4, causing no disruption in habituation over tests. SCP prevented the increase of total grooming time by inhibiting complex grooming subtypes and promoting short cephalic sequences. Despite the SCP-induced alterations on grooming agreed with our hypotheses, those changes may have resulted from a motor impairment that could have also affected rearing behavior. Additionally, SCP suppressed 50-kHz USVs while marginally increased 22-kHz calls. Once SCP was withdrawn, rearing, grooming, and some 50-kHz USVs subtypes returned to VEH levels, suggesting that novelty habituation occurred despite the SCP administration. Altogether, that mixed profile of SCP-induced behavioral changes may derive from the complex interplay between the contrasting action of SCP on different brain regions and the doses here used.

Contributions of Luminance and Motion to Visual Escape and Habituation in Larval Zebrafish.

Animals from insects to humans perform visual escape behavior in response to looming stimuli, and these responses habituate if looms are presented repeatedly without consequence. While the basic visual processing and motor pathways involved in this behavior have been described, many of the nuances of predator perception and sensorimotor gating have not. Here, we have performed both behavioral analyses and brain-wide cellular-resolution calcium imaging in larval zebrafish while presenting them with visual loom stimuli or stimuli that selectively deliver either the movement or the dimming properties of full loom stimuli. Behaviorally, we find that, while responses to repeated loom stimuli habituate, no such habituation occurs when repeated movement stimuli (in the absence of luminance changes) are presented. Dim stimuli seldom elicit escape responses, and therefore cannot habituate. Neither repeated movement stimuli nor repeated dimming stimuli habituate the responses to subsequent full loom stimuli, suggesting that full looms are required for habituation. Our calcium imaging reveals that motion-sensitive neurons are abundant in the brain, that dim-sensitive neurons are present but more rare, and that neurons responsive to both stimuli (and to full loom stimuli) are concentrated in the tectum. Neurons selective to full loom stimuli (but not to movement or dimming) were not evident. Finally, we explored whether movement- or dim-sensitive neurons have characteristic response profiles during habituation to full looms. Such functional links between baseline responsiveness and habituation rate could suggest a specific role in the brain-wide habituation network, but no such relationships were found in our data. Overall, our results suggest that, while both movement- and dim-sensitive neurons contribute to predator escape behavior, neither plays a specific role in brain-wide visual habituation networks or in behavioral habituation.

Additive and multiplicative probabilistic models of infant looking times.

Additive and multiplicative regression models of habituation were compared regarding the fit to looking times from a habituation experiment with infants aged between 3 and 11 months. In contrast to earlier studies, the current study considered multiple probability distributions, namely Weibull, gamma, lognormal and normal distribution. In the habituation experiment the type of contrast between the habituation and the test trial was varied (luminance, color or orientation contrast), crossed with the number of habituation trials (1, 3, 5, or 7 habituation trials) and crossed with three age cohorts (4, 7, 10 months). The initial mean LT to dark stimuli (around 3.7 s) was considerably shorter than the mean LT to green and gray stimuli (around 5 s). Infants showed the strongest dishabituation to changes from dark to bright (luminance contrast) and weak-to-no dishabituation to a 90-degrees rotation of the gray stimuli (orientation contrast). The dishabituation was stronger after five and seven habituation trials, but the result was not statistically robust. The gamma distribution showed the best fit in terms of log-likelihood and mean absolute error and the best predictive performance. Furthermore, the gamma distribution showed small correlations between parameters relative to other models. The normal additive model showed an inferior fit and medium correlations between the parameters. In particular, the positive correlation between the initial looking time (LT) and the habituation rate was likely responsible for a different interpretation relative to the multiplicative models of the main effect of age on the habituation rate. Otherwise, the additive and multiplicative models provided similar statistical conclusions. The performance of the model versions without pooling and with partial pooling across participants (also called random-effects, multi-level or hierarchical models) were compared. The latter type of models showed worse data fit but more precise predictions and reduced correlations between the parameters. The performance of model variants with auto-regressive time structures were explored but showed considerably worse fit. The performance of quadratic models that allowed non-monotonic changes in LTs were investigated as well. However, when fitted with LT data, these models did not produce non-monotonic change in LTs. The study underscores the utility of partial-pooling models in terms of providing more accurate predictions. Further, it agrees with previous research in that a multiplicative LT model is preferable. Nevertheless, the current results suggest that the impact of the choice of an additive model on the statistical inference is less dramatic then previously assumed.

Habituation in Aedes aegypti mosquito larvae is context specific.

Mosquito larvae live in water and perform a stereotyped escape response when a moving object projects its shadow on the water surface, indicating potential risk of predation. Repeated presentations of the shadow induce a decrease in the response as a result of habituation, a form of non-associative learning defined as the progressive and reversible decrease in response to a specific reiterative innocuous stimulus. Nevertheless, habituation can be context specific, which indicates an association between the context and the stimulus. The aim of this work was to study context specificity in habituation in mosquito larvae Aedes aegypti. Larvae were individually placed in Petri dishes positioned over black, white or black-white striped cardboard as background (visual context). Larvae were presented with a shadow produced by a cardboard square (training) over the course of 15 trials. After the 15th trial, the background was changed and the stimulus was presented once again (test). To analyse habituation in different contexts, we developed a series of learning curve models. We performed a Bayesian model selection procedure using those models and the data from the experiments to find which model best described the results. The selected model was a power law learning curve with six parameters (habituation rate; context-specific asymptotic habituation response, with one parameter per context, i.e. 3 parameters in total; response increase; and autocorrelation) describing the whole experimental setup with a generalised r2 of 0.96. According to the model, a single habituation rate would indicate that habituation was independent of the context, whilst asymptotic habituation would be context specific. If the background was changed after training, there was an increase in response in the test, evincing context specificity in habituation.

Habituation of the Light-Startle Response of Orange Head Cockroaches (Eublaberus posticus): Effects of Acclimation, Stimulus Duration, Presence of Food, and Intertrial Interval.

Simple SummaryThis paper investigates habituation of the light-startle response (LSR) in orange head cockroaches (Eublaberus posticus) to improve our understanding of comparative insect psychology. Across four experiments, we found that cockroaches quickly learned to respond less to sudden changes in lighting. We also documented a number of findings common to habituation research, connecting our results to those of other popular model organisms. Our work lays a strong foundation for future research on the behavior of orange head cockroaches as well as learning in cockroaches in general.The purpose of this paper is to establish the orange head cockroach (Eublaberus posticus) as a useful insect subject for research in comparative psychology by investigating habituation of the light-startle response (LSR). While one goal of comparative psychology is to compare the behavior of a diversity of species, many taxa, including cockroaches, are grossly underrepresented. Our work serves to improve this deficit by investigating habituation learning in the orange head cockroach in four experiments. In our first experiment, we found that LSR, and habituation of LSR, occurs to both lights being turned on and lights being turned off. In our second experiment, we found that the duration of a light did not affect response, and that spontaneous recovery of LSR occurs after 24 h intervals. In our third experiment, we found that the presence of food inhibited LSR. In our final experiment, we found that the rate of LSR habituation decreased as intertrial interval increased, in a manner predicted by established principles of habituation. Our work lays a strong foundation for future research on the behavior of orange head cockroaches as well as learning in cockroaches in general. We hope that our findings help establish cockroaches as practical insect subjects for research in comparative psychology and related fields such as behavior analysis and behavioral ecology.

Improving Delivery Behaviors During Exposure Therapy: A Cluster Randomized Controlled Training Trial with Community Therapists

ABSTRACT This study tested whether a new training tool, the Exposure Guide (EG), improved in-session therapist behaviors that have been associated with youth outcomes in prior clinical trials of exposure therapy. Sixteen therapists in practice settings treated 46 youths with an anxiety disorder or obsessive-compulsive disorder (OCD). Therapists were randomly assigned to receive “gold-standard” exposure therapy training with weekly consultation (GS) or “gold-standard” training with weekly consultation plus the EG (EG). The primary outcome was therapist behavior during in-session exposures, observed using a validated coding system. Secondary outcomes included training feasibility/acceptability and observer-rated patient fear habituation; we also explored independent evaluator-rated clinical outcome. As hypothesized, therapists used similarly high rates of exposure with patients in both groups, but those in the EG condition used more fear-increasing behaviors and fewer fear-decreasing behaviors compared with those in the GS condition. Attendance data and therapist feedback support EG feasibility and acceptability. Patients treated by EG-trained therapists showed increased rates of in-session habituation. Descriptive clinical outcome data showed a slightly higher treatment response rate in the EG group (66.7% EG, 58.8% GS) that was more pronounced among patients completing a posttreatment assessment (83.3% EG, 60.0% GS). Results confirm the effectiveness of EG training for improving therapist delivery behaviors. Future studies will be needed to determine whether EG training can improve rates of patient treatment response via improved delivery behaviors. Public Health Significance: This study shows that the Exposure Guide, a therapist training tool, improves therapist delivery of exposure.

Reduced Sensory Habituation in Autism and Its Correlation with Behavioral Measures.

Autism is strongly associated with sensory processing difficulties. We investigate sensory habituation, given its relevance for understanding important phenotypic traits like hyper- and hypo-sensitivities. We collected electroencephalography data from 22 neuro-typical(NT) and 13 autistic(ASD) children during the presentation of visual and auditory sequences of repeated stimuli. Our data show that the ASD children have significantly reduced habituation relative to the NT children for both auditory and visual stimuli. These results point to impaired habituation as a modality-general phenomenon in ASD. Additionally, the rates of habituation are correlated with several clinical scores associated with competence along diverse phenotypic dimensions. These data suggest that the sensory difficulties in autism are likely to be associated with reduced habituation and are related to clinical symptomology.

Rationale and protocol for translating basic habituation research into family-based childhood obesity treatment: Families becoming healthy together study

This publication describes the rationale and protocol, including design, aims, intervention, and measures, of Families Becoming Healthy Together, a randomized clinical trial examining the effect of a limited RED (non-nutrient-dense, energy-dense) food variety prescription delivered within an 18-month family-based behavioral obesity treatment (FBT) on body mass index (BMI) and habituation rate to RED foods. One hundred fifty-six children (ages: 8–12 y; BMI: ≥ 85th percentile-for-age) and a caregiver (BMI: ≥ 25 kg/m2), both with overweight or obesity, will be randomized to one of two, interventions: FBT or FBT + Variety. All participants will receive 29 sessions of FBT and be prescribed the Traffic Light Diet (1000–1500 kcal/day, ≤ 2 RED food servings/day), and a physical activity goal (≥ 60 min/day [child] or 150 min/week [adult] of moderate-vigorous physical activity (MVPA)). FBT + Variety will also identify two RED foods, a dinner entrée and snack food, and develop meal plans that reduce variety of RED foods by regularly consuming these foods and limiting consumption of other RED foods. Measures of anthropometrics, dietary intake, habituation of salivary response to food cues, and physical activity will be assessed at 0, 6, 12, and 18-months. This study translates a line of basic behavioral research examining how dietary variety influences habituation into a dietary prescription that will be tested within an efficacy trial. It is hypothesized that a novel, limited dietary variety prescription within FBT should promote a faster food habituation rate, reducing energy intake and amplifying long-term weight loss in children.

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.

The diurnal variation of open-field habituation in rats

The present study aimed to establish the effect of time of the day on habituation in the open-field test, one of the most elementary forms of non-associative hippocampal-dependent learning. Open-field test was performed in young adult male Wistar rats at the beginning (08:30−10:00 h; defined as Zeitgeber time (ZT) ZT0.5−2), mid-time (13:00−14:30 h, ZT5−6.5) and at the end (18:30−20:00 h, ZT10.5−12) of the light period. Our results revealed that in the acquisition trial there were no significant differences among the six parameters recorded through tested periods. In contrast, the level of habituation in the ambulation and rearing rose as followed: ZT0.5−2 < ZT10.5−12 < ZT5−6.5. In both trials, the principal component analysis highlights two components: component 1 was mainly loaded by ambulation in the outer and inner area, rearing and freezing behaviors, whereas component 2 was mostly loaded on grooming activity and defecation. The correlation between parameters varied across the period of day and trial. Animals that expressed a higher level of grooming, defecation (ZT5−6.5) and freezing behavior (ZT0.5−2 and ZT5−6.5) at acquisition trial habituated better on those parameters on the retention trial. In conclusion, habituation outcomes to the open-field test and correlation between tested parameters highly depend on daytime.

When It's Impossible to Ignore: Development and Validation of the Sensory Habituation Questionnaire.

Sensory overresponsivity (SOR) in adults is frequently overlooked and misdiagnosed. In some cases, the sensory symptoms are attributed to psychopathology or negative emotionality. Developing sound tools for examining various dimensions of sensory overresponsivity in adults, particularly sensitivity versus habituation, can more precisely guide scientific and intervention efforts. To evaluate the psychometric properties, content validity, internal reliability, and construct validity of the new Sensory Habituation Questionnaire. A Classical Test Theory approach and a multitrait-multimethod matrix was used to evaluate the questionnaire's psychometric properties. A nonclinical sample of 160 adults ages 18-65 yr (mean = 31.85, standard deviation = 10.72); 56.87% were female. Participants completed the Sensory Habituation Questionnaire, Sensory Perception Quotient, Adolescent/Adult Sensory Profile, and the Brief Symptom Inventory. The Sensory Habituation Questionnaire had high internal reliability (α = .88) and was significantly correlated with other standardized SOR questionnaires (rs = .57-.61). In contrast to the Adolescent/Adult Sensory Profile overresponsivity score, the perceptually oriented measures (the Sensory Perception Quotient and the Sensory Habituation Questionnaire) were not associated with the Brief Symptom Inventory. The Sensory Habituation Questionnaire is a tool that can evaluate the ability to ignore daily sensations independent of psychopathology symptoms. It can guide practitioners and researchers in breaking down the dimensions of SOR. This article introduces a questionnaire for evaluating the rate of sensory habituation in adults, a dimension of SOR that greatly affects daily functioning. The questionnaire is also advantageous in identifying sensory difficulties that differ from psychopathological symptoms. Habituation is a crucial factor to consider in intervention, because it calls for work on the capacity to adjust to bothersome sensations.

Repeatability of behavior and physiology: No impact of reproductive investment

Animals have well-documented individual differences in their behaviour, including in their response to stressful stimuli. The physiological bases for the repeatability of these traits has been the focus of much research in recent years, in an attempt to explain the mechanistic drivers for behavioral syndromes. Whilst a range of studies have demonstrated repeatable individual differences in physiological traits, little is known about potential trade-offs between reproductive investment and the physiological responses to subsequent stressors. We therefore sought to test the behavioral and physiological responses of male zebra finches (Taeniopygia guttata) to a novel environment, quantifying a series of repeated “temporal reaction norms” before and after reproduction. Given that reproductive investment is costly both in time and energy, it is likely to affect expression of behavioral and physiological traits. We hypothesised that reproductive investment would impact the consistency of these temporal reaction norms. Specifically, we predicted that individuals which invested more in reproduction would show altered rates of habituation to a stressful stimulus. Therefore, we quantified temporal reaction norm components (i.e., intercept and slope) of two behaviours and metabolic rate (MR) within and among individuals before and after a breeding season. We found that individuals consistently differed in how their locomotor and feeding activity increased upon introduction into a novel environment and also how their MR decreased after being handled and confined within the metabolic chamber. We also found that the slope of the feeding activity reaction norm was negatively correlated with stress-induced corticosterone levels at the within-individual level. Finally, in contrast to our prediction, we found that neither the intercept nor slope of the reaction norms were influenced by the reproductive effort (the number of fledglings produced) displayed by individual males. This suggests that the substantial individual variation in the expression of physiological and behavioural traits is not plastic with respect to the immediate consequences of reproductive investment. This study is the first quantification of metabolic rate reaction norms and their relationships with fitness, which represents an important first step towards understanding the evolutionary significance of instantaneous habituation to stressful and novel situations.

Short-term exposure to unmanned aerial vehicles does not alter stress responses in breeding tree swallows.

Recent studies suggest that visual and acoustic anthropogenic disturbances can cause physiological stress in animals. Human-induced stress may be particularly problematic for birds as new technologies, such as drones, increasingly invade their low-altitude air space. Although professional and recreational drone usage is increasing rapidly, there is little information on how drones affect avian behavior and physiology. We examined the effects of drone activity on behavior and physiology in adult, box-nesting tree swallows (Tachycineta bicolor). Specifically, we monitored bird behavior during drone flights and in response to a control object and measured telomere lengths and corticosterone levels as indicators of longer-term physiological stress. We predicted that drone-exposed tree swallows would habituate behaviorally after multiple flights, but that telomeres would shorten more quickly and that baseline corticosterone levels would be altered. One significant and two strong, non-significant trends in behavioral assays indicated that adult swallows acted more aggressively towards drone presence compared to a control object, but were slower to approach the drone initially. Swallows were also more reluctant to use nest boxes during drone activity. Tree swallows habituated to drone presence as expected, although the rate of habituation often did not differ between drone-exposed and control groups. Contrary to our prediction, drone activity did not affect telomere length, corticosterone levels, body mass or fledging rates. Overall, our results indicate that a small number of short, targeted, drone flights do not impact tree swallow health or productivity differently than a non-invasive control object. Minor behavioral differences suggest that increasing the frequency of drone use could impact this species. We provide some of the first results addressing how drone activity alters behavioral, physiological and molecular responses to stress in songbirds. A better understanding of these impacts will allow ecologists to make more informed decisions on the use and regulation of new drone technologies.

A Single δ9-Tetrahydrocannabinol (THC) Dose During Brain Development Affects Markers of Neurotrophy, Oxidative Stress, and Apoptosis.

δ9-tetrahydrocannabinol (THC) is one of the most used drugs during pregnancy and lactation and efficiently crosses the placental and blood–brain barriers. Despite the recent legalization initiatives worldwide, the adverse outcome pathway (AOP) of THC following exposure during brain development is incompletely understood. We have previously reported that a single injection of THC on postnatal day (PND) 10 altered adult spontaneous behavior and habituation rates in adult mice. Similar behavioral alterations have been reported following PND 10 exposure to the commonly used over-the-counter analgesic acetaminophen (AAP; also known as paracetamol); as both THC and AAP interact with the endocannabinoid system, we hypothesize that this system might be involved in the AOP of both these pharmaceuticals/drugs. Here, we report that a single THC dose on PND 10 decreased transcript levels of tropomyosin receptor kinase b (Trkb) 24 h after exposure in both the frontal and parietal cortex, and in the hippocampus in mice. An increase in the nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap1) ratio were also found in both the parietal cortex and hippocampus following neonatal exposure to THC. In addition, THC exposure increased transcript levels of cannabinoid receptor type 1 (Cb1r) in the parietal cortex and increased the apoptosis regulator BAX in the frontal cortex. This study is important for mainly 3 reasons: 1) we are starting to get information on the developmental neurotoxic AOP of PND 10 exposure to THC, where we suggest that transcriptional changes of the neurotrophic receptor Trkb are central, 2) our PND 10 exposure model provides information relevant to human exposure and 3) since PND 10 exposure to AAP also decreased Trkb transcript levels, we suggest THC and AAP may share key events in their respective AOP through endocannabinoid-mediated alterations of the brain-derived neurotrophic factor (BDNF)-TRKB signaling pathway.

Habituation and ecological salience: insights into the foraging ecology of the fringed-lipped bat, Trachops cirrhosus

Animals are often confronted with more sensory stimuli than they can attend to, and so should pay attention to stimuli that are relevant to them and habituate to those that are not. We investigated attention in the fringe-lipped bat, Trachops cirrhosus, by playing repeated prey sounds to bats in a habituation-discrimination paradigm. We measured two behavioral responses: initial response and habituation rate, and also tested whether the bats discriminated between the different sounds. We found that bats habituated more quickly to sounds of unpalatable prey species, but contrary to our expectation, a bat’s initial response was unrelated to prey palatability. Furthermore, discrimination was only detectable when bats became strongly habituated and they were less attracted to the habituated sound compared to the subsequently presented sound in the stimulus pair. Our results support the idea that in nature, many sounds can draw an animal’s attention initially, but only sounds of ecological significance and perceptual salience maintain an animal’s attention over time. Habituation is an almost ubiquitous way that animals filter environmental information, but is often overlooked in behavioral experiments. Animals may habituate faster to sounds that are unlikely to affect their lives and more slowly to ones that are associated with food or threats. We studied the predatory bat Trachops cirrhosus that hunts using prey sounds. We presented bats with prey and non-prey sounds and observed their responses over time. We found that although bats responded similarly to all the sounds at their onset, they paid attention longer to sounds from palatable prey and habituated quickly to sounds from inedible animals. This species initially attends to new sounds that it hears, but habituates in a way that helps it selectively attend to important stimuli.