Behavioral Responses Research Articles

Behaviour, biochemical and histological responses of the freshwater mussels Unio ravoisieri exposed to wastewater from Wadi Guenniche (Northeastern Tunisia)

ABSTRACT Wastewater effluents increase contaminant levels in the aquatic environment, leading to various disruptive effects. In this study, responses of Unio ravoisieri transplanted into wastewater from Wadi Guenniche were monitored using filtration rate, oxidative stress, lipo-peroxidation, neurotoxicity and histopathological markers. The filtration rate was significantly increased by exposure to diluted wastewater, rising from 35.13 mg indiv−1 h−1 in the control to 63.49 mg indiv−1 h−1 in the mussels after 96 h of exposure. In contrast, this exposure significantly reduces catalase, glutathione-S-transferase and acetylcholinesterase activities in both organs. This decrease is dependent on the effluent concentration and time exposure. The malondihaldehyde content showed an increasing profile in both organs. It is only in the gills that this increase is significant for mussels transplanted in situ for 48 h. Contamination by wastewater causes histopathological changes in both organs, marked by infiltration, vacuolisation, secretion of lipofuscins and cell necrosis. The intensity of these lesions depends on the duration of exposure and the degree of pollution. The mean incidence of lesions increases depending on effluent concentration and exposure time in both organs. Our study contributes to the database on behavioural, biochemical and histopathological effects in mussels following the discharge of wastewater effluent into a freshwater ecosystem.

The Infralimbic, but not the Prelimbic Cortex is needed for a Complex Olfactory Memory Task.

The medial prefrontal cortex (mPFC) plays a key role in memory and behavioral flexibility, and a growing body of evidence suggests that the prelimbic (PL) and infralimbic (IL) subregions contribute differently to these processes. Studies of fear conditioning and goal-directed learning suggest that the PL promotes behavioral responses and memory retrieval, while the IL inhibits them. Other studies have shown that the mPFC is engaged under conditions of high interference. This raises the possibility that the PL and IL play differing roles in resolving interference. To examine this, we first used chemogenetics (DREADDs) to suppress mPFC neuronal activity and tested subjects on a conditional discrimination task known to be sensitive to muscimol inactivation. After confirming the effectiveness of the DREADD procedures, we conducted a second experiment to examine the PL and IL roles in a high interference memory task. We trained rats on two consecutive sets of conflicting odor discrimination problems, A and B, followed by test sessions involving a mid-session switch between the problem sets. Controls repeatedly performed worse on Set A, suggesting that learning Set B inhibited the rats' ability to retrieve Set A memories (i.e. retroactive interference). PL inactivation rats performed similarly to controls. However, IL inactivation rats did not show this effect, suggesting that the IL plays a critical role in suppressing the retrieval of previously acquired memories that may interfere with retrieval of more recent memories. These results suggest that the IL plays a critical role in memory control processes needed for resolving interference.

Repeated presentation of visual threats drives innate fear habituation and is modulated by environmental and physiological factors.

To survive predation, animals must be able to detect and appropriately respond to predator threats in their environment. Such defensive behaviors are thought to utilize hard-wired neural circuits for threat detection, sensorimotor integration, and execution of ethologically relevant behaviors. Despite being hard-wired, defensive behaviors (i.e. fear responses) are not fixed, but rather show remarkable flexibility, suggesting that extrinsic factors such as threat history, environmental contexts, and physiological state may alter innate defensive behavioral responses. The goal of the present study was to examine how extrinsic and intrinsic factors influence innate defensive behaviors in response to visual threats. In the absence of a protective shelter, our results indicate that mice showed robust freezing behavior following both looming (proximal) and sweeping (distal) threats, with increased behavioral vigor in response to looming stimuli, which represent a higher threat imminence. Repeated presentation of looming or sweeping stimuli at short inter-trial intervals resulted in robust habituation of freezing, which was accelerated at longer inter-trial intervals, regardless of contextual cues. Finally, physiological factors such as acute stress further disrupted innate freezing habituation, resulting in a delayed habituation phenotype, consistent with a heightened fear state. Together, our results indicate that extrinsic factors such as threat history, environmental familiarity, and physiological stressors have robust and diverse effects on defensive behaviors, highlighting the behavioral flexibility in how mice respond to predator threats.

Fathers' rejection sensitivity: Links with fathers' and children's social information processing

AbstractObjectiveJoining efforts to reveal how fathers affect their children's social competence, we examined whether fathers' rejection sensitivity was associated with biases in their children's social information processing. We also explored whether this link was indirect via biases in fathers' social information processing of their children's peer interactions and, in particular, fathers' behavioral responses.BackgroundChildren's social information processing biases predict their social competence and well‐being. Studies have explored how mothers' rejection sensitivity may impact children's social information processing. Yet, little is known about the role of fathers in this context.MethodParticipants were 85 fathers living in Israel (68.24% Jewish; 31.76% Arab) and their kindergarten children (55.29% female; MChild age in months = 68.70, SD = 5.59). Fathers completed the Adult Rejection Sensitivity Questionnaire and reported their attributions, emotions, and likely behaviors in ambiguous hypothetical scenarios that might suggest a rejection of their child by peers using the Peer Rejection Scenarios measure. Children were interviewed using the Social Information Processing Interview–Preschool Version, tapping hypothetical peer interactions.ResultsFathers' rejection sensitivity was indirectly related to children's generation of maladaptive responses to ambiguous peer interactions through fathers' reports of their more negative emotions and overinvolved behavioral responses.ConclusionResults underscore the role of fathers' rejection sensitivity and emotional and behavioral responses in children's social information processing.ImplicationsThe study points to the need to consider paternal rejection sensitivity in research and interventions focused on promoting children's social competence.

Maximizing the "Functional" in the Functional External Memory Aid Tool for Patient-Centered Treatment Planning in Mild Cognitive Impairment.

The Functional External Memory Aid Tool (FEMAT) is an 11-item performance-based measure that simulates everyday tasks (e.g., medication management) to measure one's use of compensation (e.g., pill organizer). The FEMAT is not a norm-referenced diagnostic tool; rather, it is designed to provide clinicians with information about a patient's function and compensation in a standardized format. To provide further evidence for validity of the FEMAT, the purpose of this study was to conduct a mixed-methods analysis of FEMAT responses to operationalize the types of behaviors elicited during test administration. We adopted an embedded single-case study design to analyze the FEMAT administrations of 12 community-dwelling female participants, ages 73-90 years, who met criteria for mild cognitive impairment. These participants were part of the original validation sample during which they completed the FEMAT (Version 1.0) in a single session with an assessor. Sessions were video-recorded and transcribed. We analyzed the data qualitatively in two phases using theme and subtheme codes and then quantitatively analyzed the data for response trends. Our thematic analysis revealed four themes to operationalize participants' verbal and behavioral FEMAT responses: (a) used an external memory aid (EMA), (b) described using a strategy, (c) discussed memory and comprehension, and (d) discussed functional information. While completing the FEMAT, most participants described using a strategy (85%) and discussed their self-perceived memory and comprehension (33%). Several subthemes also emerged within each theme (e.g., self-perceived memory strengths and barrier). Our analysis suggests that beyond a 4-point item score, the FEMAT elicits behavioral (e.g., used an EMA) and verbal (e.g., discussion of health information) content that may be useful for person-centered treatment planning. This study is part of a comprehensive research agenda establishing the evidence for the validity of the FEMAT to support its use to inform person-centered treatment approaches.

Tinnitus is associated with increased extracellular matrix density in the auditory cortex of Mongolian gerbils

Most scientists agree that subjective tinnitus is the pathological result of an interaction of damage to the peripheral auditory system and central neuroplastic adaptations. Here we investigate such tinnitus related adaptations in the primary auditory cortex (AC) 7 and 13 days after noise trauma induction of tinnitus by quantifying the density of the extracellular matrix (ECM) in the AC of Mongolian gerbils (Meriones unguiculatus). The ECM density has been shown to be relevant for neuroplastic processes and synaptic stability within the cortex. We utilized a mild monaural acoustic noise trauma in overall 22 gerbils to induce tinnitus and a sham exposure in 16 control (C) animals. Tinnitus was assessed by a behavioral response paradigm. Animals were separated for a presence (T) or absence (NT) of a tinnitus percept by a behavioral task. The ECM density 7 and 13 days after trauma was quantified using immunofluorescence luminance of Wisteria floribunda lectin-fluoresceine-5-isothiocyanate (WFA-FITC) on histological slices of the primary AC, relative to the non-auditory brainstem as a reference area. At both timepoints, we found that the WFA-FITC luminance of the AC of NT animals was not significantly different from that of C animals. However, we found a significant increase of luminance in T animals’ ACs compared to NT or C animals’ cortices. This effect was found exclusively on the AC side contralateral to the trauma ear. These results point to a hemisphere specific process of stabilization of synaptic connections in primary AC, which may be involved in the chronic manifestation of tinnitus.

Compressed sensing based approach identifies modular neural circuitry driving learned pathogen avoidance.

An animal's survival hinges on its ability to integrate past information to modify future behavior. The nematode C. elegans adapts its behavior based on prior experiences with pathogen exposure, transitioning from attraction to avoidance of the pathogen. A systematic screen for the neural circuits that integrate the information of previous pathogen exposure to modify behavior has not been feasible because of the lack of tools for neuron type specific perturbations. We overcame this challenge using methods based on compressed sensing to efficiently determine the roles of individual neuron types in learned avoidance behavior. Our screen revealed that distinct sets of neurons drive exit from lawns of pathogenic bacteria and prevent lawn re-entry. Using calcium imaging of freely behaving animals and optogenetic perturbations, we determined the neural dynamics that regulate one key behavioral transition after infection: stalled re-entry into bacterial lawns. We find that key neuron types govern pathogen lawn specific stalling but allow the animal to enter nonpathogenic E. coli lawns. Our study shows that learned pathogen avoidance requires coordinated transitions in discrete neural circuits and reveals the modular structure of this complex adaptive behavioral response to infection.

Trust Dynamics in Financial Decision Making: Behavioral Responses to AI and Human Expert Advice Following Structural Breaks.

This study explores the trust dynamics in financial forecasting by comparing how individuals perceive the credibility of AI and human experts during significant structural market changes. We specifically examine the impact of two types of structural breaks on trust: Additive Outliers, which represent a single yet significant anomaly, and Level Shifts, which indicate a sustained change in data patterns. Grounded in theoretical frameworks such as attribution theory, algorithm aversion, and the Technology Acceptance Model (TAM), this research investigates psychological responses to AI and human advice under uncertainty. This experiment involved 157 participants, recruited via Amazon Mechanical Turk (MTurk), who were asked to forecast stock prices under different structural break scenarios. Participants were randomly assigned to either the AI or human expert treatment group, and the experiment was conducted online. Through this controlled experiment, we find that, while initial trust levels in AI and human experts are comparable, the credibility of advice is more severely compromised following a structural break in the Level Shift condition, compared to the Additive Outlier condition. Moreover, the decline in trust is more pronounced for human experts than for AI. These findings highlight the psychological factors influencing decision making under uncertainty and offer insights into the behavioral responses to AI and human expert systems during structural market changes.

Does nonacceptance of emotions and the fear of guilt influence the association between trait guilt and obsessive-compulsive symptoms? A moderation analysis in a non-clinical sample

ABSTRACT Objective Although cognitive-behavioural theory suggests a link between guilt and obsessive-compulsive disorder (OCD), the evidence is mixed. Given that how we relate to our emotions can determine behavioural responses, it is possible that high fear of guilt and a nonacceptance of emotions might increase the effects of guilt on OCD, and therefore explain mixed findings in previous research. Method We investigated whether fear of guilt and nonacceptance of emotions moderated the association between trait guilt and obsessive-compulsive symptoms in a non-clinical online MTurk sample (n = 231) recruited from cloudresearch.com. Participants completed measures of OCD, trait guilt, fear of guilt, nonacceptance of emotions, depression, and anxiety. Results We found that fear of guilt and nonacceptance of emotions, but not trait guilt, significantly predicted obsessive-compulsive symptoms even after controlling for depression and anxiety. Nonacceptance of emotions moderated the relationship between trait guilt and obsessive-compulsive symptoms, however fear of guilt did not. Simple slopes analyses showed a significant positive association between trait guilt and obsessive-compulsive symptoms for individuals with high nonacceptance of emotions. Conclusion Results support findings that nonacceptance of emotions, and to a lesser extent fear of guilt, play important roles in subclinical OCD. Furthermore, they suggest that a stronger acceptance of emotions may be linked to more adaptive experiences of guilt and reductions in obsessive-compulsive behaviour.

Sex differences in prelimbic cortex calcium dynamics during stress and fear learning

In recent years, research has progressively increased the importance of considering sex differences in stress and fear memory studies. Many studies have traditionally focused on male subjects, potentially overlooking critical differences with females. Emerging evidence suggests that males and females can exhibit distinct behavioral and neurophysiological responses to stress and fear conditioning. These differences may be attributable to variations in hormone levels, brain structure, and neural circuitry, particularly in regions such as the prefrontal cortex (PFC). In the present study, we explored sex differences in prelimbic cortex (PL) calcium activity in animals submitted to immobilization stress (IMO), fear conditioning (FC), and fear extinction (FE). While no significant sex differences were found in behavioral responses, we did observe differences in several PL calcium activity parameters. To determine whether these results were related to behaviors beyond stress and fear memory, we conducted correlation studies between the movement of the animals and PL activity during IMO and freezing behavior during FC and FE. Our findings revealed a clear correlation between PL calcium activity with movement during stress exposure and freezing behavior, with no sex differences observed in these correlations. These results suggest a significant role for the PL in movement and locomotion, in addition to its involvement in fear-related processes. The inclusion of both female and male subjects is crucial for studies like this to fully understand the role of the PFC and other brain areas in stress and fear responses. Recognizing sex differences enhances our comprehension of brain function and can lead to more personalized and effective approaches in the study and treatment of stress and fear-related conditions.

Dose-dependent effect of acute THC on extinction memory recall and fear renewal: a randomized, double-blind, placebo-controlled study.

Prior work from our lab and others demonstrates that the endocannabinoid system is a promising avenue for improving fear memory deficits in posttraumatic stress disorder (PTSD). Specifically, 7.5mg of delta-9-tetrahydrocannabinol (THC) decreases fear responding in healthy adults and increases prefrontal cortex activation during extinction learning and fear renewal in adults with PTSD. The present study will determine whether there is a dose-dependent effect of THC on short-term (24h) and long-term (one week) fear learning and memory in adults with PTSD. Using a randomized, double-blind, placebo-controlled design, N = 36 adults with PTSD completed the study and were randomized to receive placebo (PBO, n = 11), 5mg of THC (n = 11), or 10mg of THC (n = 14) prior to fear extinction learning. Participants completed a Pavlovian conditioning paradigm with extinction recall and fear renewal occurring 24h and one week later, where we measured concurrent functional imaging and behavioral responses. Twenty-four hours after drug administration, individuals with PTSD given 5mg of THC exhibited greater anterior cingulate cortex and prefrontal cortex activation during early fear renewal. One week later, individuals given 10mg of THC exhibited greater hippocampus activation during extinction recall and prefrontal cortex activation during fear renewal. These data suggest that dosing and timing are critical for facilitating fear memory processes in PTSD, and that low-dose oral THC prior to extinction learning can affect brain indices of fear learning and memory both acutely and one week after administration.

Factors determining semen sample collection and semen quality parameters in African penguins Spheniscus demersus

Our research focuses on semen collection from 42 African penguin males, grouped by age, habituation levels, and reproductive season timing. We assess behavioral and physiological responses to dorso-abdominal massage, evaluating species-specific seminal traits using conventional and advanced methods. Positive behavioral responses corresponded with successful semen collection. Young and human-reared males exhibited more favorable behaviors, and samples containing spermatozoa were more likely collected during the reproductive season. Age did not influence sample collectability or spermatozoa presence, though mature males produced higher semen volumes. Young males exhibited more sperm morphological abnormalities, especially outside the breeding season. Sperm concentration and number per ejaculate showed no significant differences across age or seasonal groups. Young males had higher motile and progressive sperm percentages, while mature males had more static sperm. Additionally, percentages of live sperm and intact acrosomes were higher in mature males. Young males and samples from non-reproductive season presented more dead sperm with damaged acrosomes. Plasma membrane integrity positively correlated with age for live sperm and negatively for dying sperm. This research demonstrates the feasibility of semen collection from African penguins regardless of habituation level, fills the knowledge gap by describing sperm morphological abnormalities, and provides insights into using flow cytometry in Sphenisciformes.

Alpha transcranial alternating current stimulation modulates pain anticipation and perception in a context-dependent manner.

Pain perception is closely tied to the brain's anticipatory processes, particularly involving the suppression of sensorimotor α-oscillations, which reflect the system's readiness for incoming pain. Higher sensorimotor α-oscillation levels are correlated with lower pain sensitivity. Alpha transcranial alternating current stimulation (α-tACS) can enhance these oscillations, potentially reducing pain perception, with effects that may be sustained and influenced by the certainty of pain expectations. Hence, this study investigated the immediate and sustained effects of α-tACS on pain anticipation and perception, focusing on how these effects are shaped by the certainty of expectations. In a double-blind, sham-controlled design, 80 healthy participants underwent a 20-minute session of real or sham α-tACS over the right sensorimotor region. Behavioral and neural responses related to pain anticipation and perception were recorded before, immediately after, and 30 minutes poststimulation under both certain and uncertain conditions. Compared with sham stimulation, real α-tACS disrupted the habituation of laser-evoked potentials (N2-P2 complex), particularly under certain expectations, with effects persisting 30 minutes poststimulation. In anticipatory brain oscillations, real α-tACS enhanced somatosensory α1-oscillations and increased midfrontal θ-oscillations in conditions of certainty, with θ-oscillation modulation showing sustained effects. Mediation analysis revealed that α-tACS reduced pain reactivity by enhancing somatosensory α1-oscillations but increased pain reactivity through the enhancement of midfrontal θ-oscillations, with the latter effect being more pronounced. These findings suggest that while α-tACS may provide pain relief through somatosensory α-oscillation augmentation, its stronger and longer-lasting impact on midfrontal θ-oscillations could lead to hyperalgesia, particularly in the context of certain pain expectations.

PVN-mPFC OT projections modulate pup-directed pup care or attacking in virgin mandarin voles

Many species of animals exhibit caregiving or aggression toward conspecific offspring. The neural mechanisms underlying the infanticide and pup care remain poorly understood. Here, using monogamous mandarin voles (Microtus mandarinus), we found that more oxytocin (OT) neurons in the paraventricular nucleus (PVN) were activated during pup caring than infanticide. Optogenetic activation of OT neurons in the PVN facilitated pup caring in male and female mandarin voles. In infanticide voles, optogenetic activation of PVN OT cells or PVN-medial prefrontal cortex (mPFC) OT projection fibers prolonged latency to approach and attack pups, whereas inhibition of these OT neurons or projections facilitated approach and infanticide. Optogenetic activation of PVN OT neuron projections to the mPFC in males shortened the latency to approach and retrieve pups and facilitated the initiation of pup care, but produced no effects on pup-care females. In addition, OT release in the mPFC increased upon approaching and retrieving pups, and decreased upon attacking pups. Intraperitoneal injection of OT promoted pup care and inhibited infanticide behavior. It is suggested that the OT system, especially PVN OT neurons projecting to mPFC, modulates pup-directed behaviors and OT can be used to treat abnormal behavioral responses associated with some psychological diseases such as depression and psychosis.

Infralimbic Cortex and Behavioral Responses to Mild Stress after Repeated Social Stress Exposure

Major Depressive Disorder (MDD) is an emotional impairment that can have debilitating consequences for afflicted individuals. Social stress, including isolation or alienation, may be an important factor that contributes to MDD. In two experiments, repeated social defeat was utilized in rodents to induce social stress, modeling the social stressors that are thought to contribute to MDD in humans. Behavioral analyses revealed that dominance and submissive behaviors in the social defeat sessions were quite stable across repeated sessions. Accordingly, there appeared to be little variability between the rats in their social stress experience. This validates the model and allows for the study to draw inferences concerning the impacts of the stress experience from means testing of behavioral and physiological outcomes. The second experiment evaluated the impacts of repeated social defeat on cortical responses to the mild stress of a novel environment. RNAscope was utilized evaluate expression of c-Fos, GAD65, and VGluT1 mRNA in the infralimbic cortex. mRNA for c-Fos was labeled to identify which neurons were active in the infralimbic cortex. This was combined with labels for vGluT1 and GAD65 mRNAs to evaluate if those neurons were excitatory (glutamatergic) or inhibitory (GABAergic). The socially stressed rats exhibited increased mRNA expression for GAD65 in the infralimbic cortex. This suggests increased stress-induced biosynthesis of GABA in inhibitory neurons of the infralimbic cortex.

Mosquito taste responses to human and floral cues guide biting and feeding.

The taste system controls many insect behaviours, yet little is known about how tastants are encoded in mosquitoes or how they regulate critical behaviours. Here we examine how taste stimuli are encoded by Aedes albopictus mosquitoes-a highly invasive disease vector-and how these cues influence biting, feeding and egg laying. We find that neurons of the labellum, the major taste organ of the head, differentially encode a wide variety of human and other cues. We identify three functional classes of taste sensilla with an expansive coding capacity. In addition to excitatory responses, we identify prevalent inhibitory responses, which are predictive of biting behaviour. Certain bitter compounds suppress physiological and behavioural responses to sugar, suggesting their use as potent stop signals against appetitive cues. Complex cues, including human sweat, nectar and egg-laying site water, elicit distinct response profiles from the neuronal repertoire. We identify key tastants on human skin and in sweat that synergistically promote biting behaviours. Transcriptomic profiling identifies taste receptors that could be targeted to disrupt behaviours. Our study sheds light on key features of the taste system that suggest new ways of manipulating chemosensory function and controlling mosquito vectors.

Alpha-band fluctuations represent behaviorally relevant excitability changes as a consequence of top–down guided spatial attention in a probabilistic spatial cueing design

Abstract Spatial attention is a key function enabling the selection of relevant information and meaningful behavioral responses and is likely implemented by different neural mechanisms. In previous work, attention led to robust but uncorrelated modulations of Steady-State-Visual-Evoked-Potentials (SSVEPs) as a marker of early sensory gain and visual as well as motor alpha-band activity. We probed the behavioral relevance of attention-modulated trial-by-trial fluctuations of these measures. For this purpose, in an experiment with a classical probabilistic visuospatial attention cueing task, a to-be-discriminated target stimulus was validly, neutrally, or invalidly cued, while behavioral responses and EEG were recorded. Single-trial flicker-driven SSVEPs, visual and motor alpha-band activity were measured and the relationship between their amplitudes and reaction times was modeled via Bayesian regression models, respectively. We replicated previous findings that these neural measures and behavioral responses were overall modulated by the attentional cue. Beyond that, SSVEP amplitudes were not associated with behavior, while single-trial alpha-band amplitudes were predictive of reaction times: For trials with a valid or neutral cue, lower visual and motor alpha-band amplitudes measured contralateral to the target in the cue–target interval were associated with faster responses (and for valid cues also higher amplitudes ipsilateral to the target). For invalid cues, which required attentional reallocating to the uncued side, no such relationship was found. We argue that behavioral relevance of alpha-band modulations is a consequence but not a mechanism of top–down guided spatial attention, representing neural excitability in cortical areas activated by the attentional shift.

Timing matters in stress appraisal: The relationship between retrospective appraisal and stress responses

BackgroundAlthough psychosocial stressors are known to impact task performance and trigger neuroendocrine responses, the dynamic nature of the stress appraisal process is often neglected in research. GoalThis study aims to explore whether self-reported appraisals at various time points can accurately represent an individual’s behavioral and physiological stress responses. MethodsA total of 137 participants were recruited to induce individual stress states using the Trier Social Stress Test (TSST). Self-reported appraisals were measured both before (anticipatory appraisal) and after the stressor (retrospective appraisal) to capture the dynamic process. Concurrently, participants' cortisol responses and task performances were documented. ResultsFindings indicate that anticipatory appraisal does not significantly reflect task performance. In contrast, retrospective appraisal is strongly associated with the performance of corresponding tasks. Regarding cortisol levels, significantly negative results of multiple regression analysis revealed that the retrospective appraisal of the speech task is the sole variable to represent the cortisol response under stress. DiscussionThe results highlight that retrospective appraisals could represent individuals’ behavioral and physiological responses to stressors more accurately than anticipatory appraisals. These findings provide empirical evidence for choosing the appropriate timing to acquire accurate self-reported appraisals and also help to build a mapping relationship between self-reported, behavioral, and physiological data.

Behavioral Responses of Chironomus aprilinus Larvae as Proxies for Cyanobacterial Metabolite Interactions: Insights from Ternary Combinations.

This study aimed to assess the behavioral responses (immobilization, horizontal and vertical motility, and response to light) of Chironomus aprilinus larvae exposed to individual cyanobacterial metabolites aeruginosin 98B (AER-B), anabaenopeptin-B (ANA-B), and cylindrospermopsin (CYL), and their binary and ternary mixtures. The investigation revealed that single metabolites ANA-B and CYL exhibited the highest potency in immobilizing the larvae. Notably, the binary mixture AER-B+CYL induced a remarkably strong synergistic interaction, while other tested binary and ternary mixtures demonstrated antagonistic effects. Both individual metabolites and their mixtures led to a decrease in larval movement speed, with the AER-B+CYL combination showing a very synergistic effect, and strong antagonistic interactions between the oligopeptides in the ternary mixture. Conversely, while AER-B and the binary mixture ANA-B+CYL stimulated vertical movement, other single metabolites and binary and ternary mixtures decreased this parameter. Antagonistic interactions were observed in all mixtures. ANA-B emerged as the most potent inhibitor, yet all tested metabolites and their mixtures decreased larval response to light, displaying synergistic interactions, except for the AER-B+ANA-B mixture at 250 μg L-1 + 250 μg L-1. These findings underscore the sensitivity of Chironomus larvae behavioral parameters as indicators of environmental stressors and mixtures. Consequently, they are recommended for assessing toxic effects induced by cyanobacterial products and other bioactive chemicals.

Kelley's Paradox and strength skewness in research on unconscious mental processes.

A widely adopted approach in research on unconscious perception and cognition involves contrasting behavioral or neural responses to stimuli that have been presented to participants (e.g., old items in a memory test) against those that have not (e.g., new items), and which participants do not discriminate in their conscious reports. We demonstrate that such contrasts do not license inferences about unconscious processing, for two reasons. One is Kelley's Paradox, a statistical phenomenon caused by regression to the mean. In the inevitable presence of measurement error, true awareness of the contrasted stimuli is not equal. The second is a consequence, within the framework of Signal Detection Theory, of unequal skewness in the strengths of target and nontarget items. The fallacious reasoning that underlies the employment of this contrast methodology is illustrated through both computational simulations and formal analysis, and its prevalence is documented in a narrative literature review. Additionally, a recognition memory experiment is reported which tests and confirms a prediction of our analysis of the contrast methodology and corroborates the susceptibility of this method to artifacts attributable to Kelley's Paradox and strength skewness. This work challenges the validity of conclusions drawn from this popular analytic approach.