1,720,981 research outputs found
The impact of brain development, context change, individual differences, and entropy on animal habituation
No full textIn a world full of information, animals have evolved cognitive mechanisms to ignore irrelevant stimuli and selectively focus on important ones. Among these mechanisms, those controlling habituation allow the suppression of the response elicited by irrelevant stimuli that repeat over time.
To better understand this behavioral and phenomenon, we capitalized on the domestic chick (Gallus gallus), whose brain develops almost completely in the egg, which makes this animal mobile and independent from parental cares soon after hatching. By testing chicks from the first day after hatching we found that the neural mechanisms underlying habituation are immediately active in chicks, but newborn chicks can habituate to a greater extent than older animals. This shows an early period of increased plasticity in the chick brain that rapidly decreases in the first three days after hatching. Together with habituation, we found that dishabituation is also fully developed in newborn chicks. Comparator theories of habituation predict that both mechanisms stem from a common memory mechanism. Our results represent the first evidence to support this conclusion using a developmental approach.
Previous studies have shown that habituation is context-specific and cannot be entirely transferred to a new context. We reviewed the evidence in support of this conclusion and demonstrated that the neural mechanisms underlying context-specific habituation are functional in chicks’ embryos and modulate the postnatal recalling of a habituated response acquired prenatally. We found context-specific habituation also in an invertebrate species phylogenetically distant from the domestic chick, the bumblebee (Bombus terrestris). This result adds to the existing evidence that the cognitive mechanisms underlying context-specific habituation are widespread in the animal reign, irrespective of the complexity of the nervous systems considered. Before exploring context-specific habituation in bumblebees, we developed a new paradigm to study habituation and dishabituation of the defensive behaviour in this species.
By testing several behavioural traits of inexperienced chicks and measuring their body size, we found that more exploratory chicks have greater variability of habituation rate than less exploratory ones. This variability is linked to the body size of the more exploratory chicks. Bigger chicks are more responsive to a loud sound but habituate to a greater extent than smaller ones. Since in our experiments chicks were born and reared in a controlled environment, our results suggest that an innate biological factor may be involved in the covariation between exploration, body size and habituation.
We studied the generalization capacity of the invasive crayfish Procambarus clarkii. By using a habituation-dishabituation paradigm we found that crayfish can transfer a habituated response to a new stimulus. Generalization takes place after a single trial in which the new stimulus is presented following the habituation one and last for at least 45 days. Generalization may contribute to the superior behavioural flexibility of this invasive crayfish compared to native species.
Finally, together we developed a new model of rate-sensitivity of habituation. This model accounts for the information conveyed by the temporal sequence of stimulus repetitions exploiting the notion of entropy. We found that the amount of habituation of the freezing response elicited by a loud sound decreases as a function of the entropy apported by a new stimulus repetition.
Overall, our findings support comparator theories of habituation and provide strong evidence in support of the associative nature of habituation
Artificial light at night alters risk-related behaviors of the ground-dwelling isopod Porcellionides pruinosus
No full textArtificial light at night (ALAN) has emerged as a significant ecological disruptor, affecting various behavioral and physiological processes in numerous species. This study investigated the impact of ALAN on the risk-related behaviors and activity patterns of the ground-dwelling isopod Porcellionides pruinosus. Isopods were exposed to one of three different illuminance conditions (<0.01, 1 and 10 lx) over a period of 14 consecutive nights. Behavioral assays included emergence, open-field, habituation to a looming stimulus, and spatial navigation tests. Additionally, the distribution and activity patterns of the isopods within the terraria were monitored. Our results indicate that ALAN significantly disrupted the repeatability of risk-related behaviors, suggesting individual-level behavioral alterations. At the group level, ALAN-exposed isopods exhibited prolonged freezing durations in response to a looming stimulus, increased shelter-seeking behavior and reduced dispersal in the terrarium. These findings suggest that ALAN-induced transformation of activity pattern of isopods is linked to the adoption of more prudent behaviors. A similar phenomenon may affect the activity pattern of other ground-dwelling invertebrates, leading to severe alterations of the soil invertebrate community
Individual differences in habituation: Innate covariation between habituation, exploration, and body size in naïve chicks (Gallus gallus)
Get PDFHabituation to novel stimuli has been associated with behavioural differences among individuals in numerous animal species. Because the habituation mechanisms depend on previous experiences with a stimulus, one would expect individuals to develop their habituation capacity based on the life experiences that also shape their behavioural traits. And indeed, in adult lizards, exploratory behaviour and body size correlates with habituation. However, here we show that the same factors correlate with habituation of domestic chicks reared under controlled laboratory conditions and tested in the first 3 days after hatching. This result indicates that the covariation between habituation, exploration, and body size does not necessarily depend on experience. Rather, it represents an innate association between exploratory behaviour and risk assessment, which may provide an immediate survival advantage to new-borns of this precocial avian species
Long-lasting generalization triggered by a single trial event in the invasive crayfish Procambarus clarkii
Get PDFBehavioural flexibility allows to adapt to environmental changes, a situation that invasive species have often to face when colonizing new territories. Such flexibility is ensued by a set of cognitive mechanisms among which generalization plays a key role, as it allows to transfer past solution to solve similar new problems. By means of a habituation paradigm, we studied generalization in the invasive crayfish Procambarus clarkii. Once crayfish habituated their alarming response to a specific water jet, we tested whether habituation transferred to a new type of water jet. Although habituation did not generalize when the new stimulus was initially presented, it surprisingly emerged 15 and 45 days later. Hence, remarkably, in P. clarkii a single presentation of a new event was sufficient to trigger a long-lasting form of learning generalization from previous similar stimuli, a cognitive ability that may concur in providing adaptive advantages to this invasive species
Ignoring distractors takes its (memory) toll
Get PDFEffective attentional selection requires filtering task-irrelevant stimuli. We examined the cognitive cost of such filtering using an object-based attention paradigm across four experiments (N = 320). Participants discriminated the orientation of a Gabor patch presented either alone or overlapped with an irrelevant object or scrambled stimulus. The filtering cost was measured as an increase in response times on distractor-absent trials embedded in 'mixed' blocks (with interleaved distractor-present trials) compared to 'pure' distractor-absent blocks. The filtering cost was robust and scaled with distractor probability and with the presence of one, two or four possible distractors occurring within the session. The cost disappeared when eight distractors were interleaved randomly, but re-emerged when the same eight distractors were presented orderly, one in each sequential mini-block, indicating a strategy shift once working-memory capacity is exceeded. The cost correlated negatively with interference on distractor-present trials and was unaffected by distractor semantic content, consistent with the active maintenance in working memory of distractor templates
Context learning before birth: evidence from the chick embryo
No full textLearning contextual information to form associative memories with stimuli of interest is an important brain function in both human and non-human animals. Intuitively, one would expect that such a sophisticated cognitive skill develops postnatally, as the organism starts exploring the surrounding environment to search for significant contingencies among stimuli. Here we show, instead, that even before hatching, domestic chicks are capable of forming associative memories between discrete alerting sounds and the surrounding context, as attested by the fact that habituation of the freezing response to the sounds is affected by the context of stimulation. This finding indicates that, while in the egg, chicks recognize and learn the context in which they are stimulated. Hence, context learning in chicks is an innate brain function already active before birth, which can provide an immediate survival advantage to the newborns of this precocial avian species
Amodal completion of coincidentally occluded angles: a matter of visual approximation
Get PDFIn the Gerbino illusion a regular but coincidentally occluded polygon appears distorted. Such a display represents a critical condition for amodal completion (AC), in which the smooth continuations of contour fragments—however small—conflict with their possible monotonic interpolation. Smoothness and monotonicity are considered the fundamental constraints of AC at the contour level. To account for the Gerbino illusion we contrasted two models derived from alternative AC frameworks: visual interpolation, based on the literal representation of contour fragments, vs. visual approximation, which tolerates a small misorientation of contour fragments, compatible with smoothness and monotonicity constraints. To measure the perceived misorientation of sides of coincidentally occluded angles we introduced a novel technique for analyzing data from a multiple probe adjustment task. An unsupervised cluster analysis of errors in extrapolation and tilt adjustments revealed that the distortion observed in the Gerbino illusion is consistent with visual approximation and, in particular, with the concatenation of misoriented and locally shrinked amodally completed angles. Implications of our technique and obtained results shed new light on visual completion processes
Goal-directed behavior in Tenebrio molitor larvae
Get PDFCan signs of intentional behavior be traced in an insect larva, traditionally thought to be driven only by mere reflexes? We trained Tenebrio molitor coleoptera larvae in a uniform Y-maze to prefer one target branch to get access to food, observing their ability to learn and retain access to the reward-associated side for up to 24 h. During reward devaluation, the reward food (experimental group) and a different food (control group) were paired with an aversive stimulus in a new environment. When tested again in the Y-maze, mealworms of the experimental group significantly reduced their visits to the target branch, whereas mealworms of the control group did not. Importantly, we found that the larvae did not have to experience the unpleasant consequences directly in the target branch to halt their behavior, as the exposure to the aversive taste occurred in a separate unfamiliar context. This is evidence that the mealworms formed a mental representation of action-consequence relationships, demonstrating flexible control of their actions to achieve desired outcomes at an early stage of their development
Unlocking the symmetric transfer of irrelevant information: gene-environment interplay and enhanced interhemispheric cross-talk
Get PDFHemispheric specialization influences stimulus processing and behavioural control, affecting responses to relevant stimuli. However, most sensory input is irrelevant and must be filtered out to prevent interference with task-relevant behaviour, a process known as habituation. Despite habituation's vital role, little is known about hemispheric specialization for this brain function. We conducted an experiment with domestic chicks, an elite animal model to study lateralization. They were exposed to distracting visual stimuli while feeding when using binocular or monocular vision. Switching the viewing eye after habituation, we examined if habituation was confined to the stimulated hemisphere or shared across hemispheres. We found that both hemispheres learned equally to ignore distracting stimuli. However, embryonic light stimulation, influencing hemispheric specialization, revealed an asymmetry in interhemispheric transfer of the irrelevant information discarded via habituation. Unstimulated chicks exhibited a directional bias, with the right hemisphere failing to transfer distracting stimulus information to the left hemisphere, while transfer from left to right was possible. Nevertheless, embryonic light stimulation counteracted this asymmetry, enhancing communication from the right to the left hemisphere and reducing the pre-existing imbalance. This sharing extends beyond hemisphere-specific functions and encompasses a broader representation of irrelevant events
The social nature of consonant sounds. Insights from chicks
No full textDo we like consonant sounds before any exposure to music? One hypothesis is that consonant sounds represent biological determinants in agents’ identification: consonant ratios are predominant in human vocalizations and, when in agreement, people produce consonant utterances in dyadic conversations. Consonance seems also a cue we are predisposed to attend to: human newborns readily show neural circuits to encode consonance as different from dissonance. However, only data from completely naïve organisms could disentangle whether consonant sounds have an innate biological value. In a previous study, the young of the domestic fowl (Gallus gallus) showed to prefer consonant sounds. Here, with the aim at investigating the reason for such preference, we analyzed the ratio of fundamental frequencies between specific points in the spectrogram of four different types of positive/negative valenced calls and we quantified the frequency of consonant/dissonant intervals. Consonant ratios prevailed in chicks’ calls and this was true also for fear thrills, thus fueling the idea that consonant sounds are biologically relevant, likely facilitating the detection of an organism. In sum, there would be a highly social component in consonant organization of sounds that has nothing to do with experience
- …
