The aim of this study was to test whether variation in behavioralplasticity correlate with brain size in a wild Chestnut Thrush (Turdus rubrocanus) population. Quan- tification of behavioralplasticity under natural condi- tions could be a challenge. First, environmental variables may show little variation, and it may be difficult to quan- tify a given condition experienced by the subject (Lefeb- vre et al. 2004). Second, conspecifics and heterospecifics in the surroundings can affect the measurement of an individual’s behavior (Kluen et al. 2012). Thus it may be better to evaluate individual behaviors in an artificial, standard environment. Therefore, we used a modi- fied simple cage test developed by Kluen et al. (2012) to quantify individual behavioralplasticity of activity. Activ- ity level may be a key trait that links behavior to feeding rate and predation risk (Sih et al. 2004). The response to novel stimuli has been described as a simple mechanism to regulate ecological plasticity (Brown et al. 2013). So we use the change of activity in the presence and absence of the novel object to quantify the behavioralplasticity. Brain size is tightly correlated with head volume, so we use head volume as a proxy for brain size (Møller 2010; Öst and Jaatinen 2015). For reasons discussed above, we predicted that behavioralplasticity is positively corre- lated with head volume.
It is well attested that we perceive speech through the filter of our native language: a classic ex- ample is that of Japanese listeners who cannot discriminate between the American /l/ and /r/ and identify both as their own /r/ phoneme (Goto, H., 1971. Neuropsychologia 9, 317-323.). Studies in the laboratory have shown, however, that perception of non-native speech sounds can be learned through training (Lively, S.E., Pisoni, D.B., Yamada, R.A., Tohkura, Y.I., Yamada, T., 1994. Journal of the Acoustical Society of America 96 (4), 2076-2087). This is consistent with neurophysiologi- cal evidence showing considerable experience-dependent plasticity in the brain at the first levels of sensory processing (Edeline, J.-M., Weinberger, N.M., 1993. Behavioral Neuroscience 107, 82103; Merzenich, M.M., Sameshima, K., 1993. Current Opinion in Neurobiology 3, 187-196; Weinberger, N.M., 1993. Current Opinion in Neurobiology 3, 577-579; Kraus, N., McGee, T., Carrel, T.D., King, C., Tremblay, K., Nicol, T., 1995. Journal of Cognitive Neuroscience 7 (1), 25-32). Outside of the laboratory, however, the situation seems to differ: we here report a study involving Spanish-Catalan bilingual subjects who have had the best opportunities to learn a new contrast but did not do it. Our study demonstrates a striking lack of behavioralplasticity: early and extensive exposure to a second language is not sufficient to attain the ultimate phonological competence of native speakers.
Animals adapt to their environment by adjusting behavioral strategies in response to experience. The nematode Caenorhabditis elegans exhibits several forms of behavioralplasticity in response to food-dependent cues. For example, C. elegans moves more slowly in the presence of bacterial food than in its absence, and the degree of slowing depends on prior starvation (Sawin et al., 2000). Starvation causes a variety of changes in C. elegans’ behavior that may improve its likelihood of finding food. For example, when C. elegans is removed from food, its initial behavioral strategy is area-restricted search of its immediate vicinity. After several minutes of prolonged starvation, C. elegans changes its strategy to long-range dispersal, which is characterized by extended periods of uninterrupted forward movement (Hills et al., 2004; Tsalik and Hobert, 2003; Wakabayashi et al., 2004; Gray et al., 2005). Rhythmic pumping of the pharyngeal muscles enables C. elegans to consume food, and starvation increases the pumping
Fourth, we assume that, in a final step, the recurrence of maternal stress during pregnancy and the corre- sponding masculinization of daughters over thousands or millions of generations have led to canalization of the effects in a way originally envisaged by Waddington . Thus, masculinized daughters ought to be better prepared to compete with other females in adverse environments, so that natural selection will enhance the effects of maternal programming. Over evolutionary times, phenotypic plasticity has to be sacrificed for such canalization to occur, and adaptive canalization (i.e. ben- efits > costs) is indeed most likely to occur in conditions where the affected traits have direct consequences for survival or fecundity . Costs of maintaining plasti- city are higher in high stress environments , which, if persistent and predictable, further decrease the bene- fits of plasticity, so that natural selection is more likely to favor fixed phenotypes . For example, maintain- ing the ability to breed year-round may not be adaptive for most lemur species and has presumably therefore been given up in favor of seasonal breeding. Finally, emerging genetic adaptations to environmental stress may have benefitted from synergistic epistasis, i.e. muta- tions that occur against a genetic background that has a prior history of adaptation to environmental stress can be favored [210,211]. Thus, evolutionary mechanisms to consolidate initially plastic developmental process under relevant environmental homogeneity and cost benefit ratios into a suite of stable adaptive traits do exist, and other mechanisms have been suggested for other traits subject to developmental plasticity . However, despite its theoretical plausibility, it is impossible to reconstruct the details of these evolutionary processes during lemur evolution conclusively. Given a suitable model system, such as small mammal species that can be bred experimentally under laboratory conditions, however, it should be possible to test the prediction that conditions of chronic environmental and social stress will lead to stable female masculinization that persists at some point also under benign conditions.
Early in the period of reproductive inactivity none of the pheromone response behaviors normally elicited by reproductively active male moths to pheromone (Evenden and Gries, 2008) were enhanced by methoprene treatment (Fig. 5A). These data demonstrate that JHA treatment of summer males does not readily induce reproductive activity. By contrast, a greater proportion of males treated with methoprene in the autumn displayed wing fanning, lock-on to the pheromone plume, upwind-oriented flight and source contact behaviors than control moths treated with acetone alone (Fig. 5B). Although behavioral response to pheromone by summer and autumn males cannot be statistically compared because the experiments were necessarily conducted at different times, together the experiments show that the effect of methoprene treatment on the induction of pheromone responsiveness varies throughout the period of reproductive inactivity.
The ability to alter one’s behavior based on experience is critical for survival. Social experience, in particular, can serve as a critical stimulus for behavioral change. Our laboratory examines the striking physiological and behavioral changes that occur following a single social defeat session in male Syrian hamsters. Syrian hamsters are solitary animals that will normally defend their territory against intruding conspecifics. If a hamster is paired with a larger, more aggressive animal and is defeated, however, it subsequently becomes highly submissive and fails to defend its home cage, even when paired with a smaller, non-aggressive animal. Instead of attacking the intruding animal, previously defeated hamsters avoid social interaction and readily submit to intruders. This behavioral change has been called conditioned defeat (CD; Potegal et al. 1993). Given the drastic behavioral changes observed in CD, we believe that it is an attractive model with which to study the behavioralplasticity following exposure to a biologically- relevant stressor.
In support of the hypothesis that monoamines in the auditory system mediate the influence of song exposure on neural and behavioralplasticity, previous studies in both European starling females and males and in Lin- coln’s sparrow males found that monoaminergic activity in CMM and NCM was higher following extended expo- sure to high-quality songs compared to low-quality songs [Sockman et al., 2002; Sockman and Salvante, 2008; Sal- vante et al., 2009; Sewall et al., 2013]. However, these studies measured both monoamine levels and behavior in birds on the morning following 1 week of exposure to songs. In this study, we measured monoaminergic activ- ity in the auditory telencephalon of females and males after one morning of exposure to songs, and thus the dif- ferent experiments captured the responses to different stimuli. In the previous experiments, changes in mono- amines may have reflected long-term changes in the brain (i.e., neuroplasticity) due to the weeklong exposure to stimuli, whereas in the current study, variation in mono- amines may have reflected short-term, real-time respons- es to the stimuli as they were occurring, even if those short-term responses might form an underlying basis to long-term plasticity.
The findings presented here are derived from whole-brain transcriptomes, so they represent an aggregate of the individual states of each neuronal and glial cell in the brain. Brains are highly compartmentalized and consist of numerous specialized regions and neuronal subtypes. Only a subset of these neurons is likely to be activated in a given social context, and recently it was shown that even neurons of the same subtype and lineage can exhibit strikingly different transcriptomic profiles (Poulin et al., 2016). However, transcriptome-wide differences in brain expression associated with naturally occurring behavior have been reported for a variety of species (Hughes et al., 2012; Oliveira et al., 2016) ever since they were first discovered in honey bees (Whitfield et al., 2003). Given that many behaviors are known to be orchestrated in specific regions of invertebrate and vertebrate brains, why should there be such robust patterns of behaviorally related gene expression at the whole-brain level in honey bees and other organisms? A technical explanation is that the whole-brain transcriptomic profile largely reflects the profiles of the larger brain regions; in honey bees, this would include the mushroom bodies and optic lobes, which together account for ∼ 2/3 of the neurons in the adult bee brain. A biological explanation is that the whole-brain transcriptomic profile arises because there are similarities in gene expression in different brain regions. For instance, numerous neuromodulators and hormones are known to directly contribute to long-term changes in honey bee behavior (Hamilton et al., 2017), and many are known to have receptors in multiple regions of the adult insect brain (Baumann et al., 2017; Perry and Barron, 2013). This makes it likely that at least some neuromodulators and hormones are capable of coordinating gene expression across brain regions. Determining the role that either or both of these explanations play in contributing to the dynamics of brain transcriptional regulatory plasticity, and neural and behavioralplasticity in general, will require integrating information at the cellular level. Recent advances in single-cell RNA sequencing make this feasible for the first time, and future studies should use these exciting new developments to examine transcriptional regulatory plasticity at the level of individual neurons.
earthquake records. Non linear elastoplastic analyses show that the seismic loading induces plasticity in a large part of the shell and in the lower part of the core. The variation of the displacement in the middle height shows a sharp increase at the extremities, which could indicate the imminence of instability in this area. The upper third part of the crest should be designed carefully, and a design should take into account dominant frequency of the load and the dam where the movement could be significantly amplified. On the other hand, it can be observed that the plastic deformation leads to a decrease in the velocity amplification, in particular in the upper part of the dam. Parametric analysis shows that mechanical role of the core is not significant compared to the shell in the overall seismic induced response of the earth dam. Analysis shows that plasticity should be considered in the investigation of the seismic response of the dam, because it leads to a decrease in the natural frequencies of the dam together to an increase in energy dissipation, which could significantly affect the seismic response of the dam. Plastic analysis constitutes also a good tool for the verification of the stability of the dam under seismic loading.
Phenotypic plasticity may contribute to the invasive success of an alien species in a new environment. A highly plastic species may survive and reproduce in more diverse environments, thereby supporting establishment and colonization. We focused on plasticity in the circadian rhythm of activity, which can favour species coexistence in invasion, for the invasive species Drosophila suzukii, which is expected to be a weaker direct competitor than other Drosophila species of the resident community. We compared the circadian rhythms of the locomotor activity in adults and the expression of clock genes in response to temperature in the invasive D. suzukii and the resident Drosophila melanogaster. We showed that D. suzukii is active in a narrower range of temperatures than D. melanogaster and that the activities of the two species overlap during the day, regardless of the temperature. Both species are diurnal and exhibit rhythmic activity at dawn and dusk, with a much lower activity at dawn for D. suzukii females. Our results show that the timeless and clock genes are good candidates to explain the plastic response that is observed in relation to temperature. Overall, our results suggest that thermal phenotypic plasticity in D. suzukii activity is not sufficient to explain the invasive success of D. suzukii and call for testing other hypotheses, such as the release of competitors and/or predators.
Since the offset of strain typically used to define the yield point (stress at which material begins to deform plastically) of metals is very small; approximately 0.2% of the strain, the formulation is limited to small elastic deformation with large rotation; hence, the Mandel stress tensor is symmetric. Hill’s yield criterion is adopted to characterise the plasticity of orthotropic materials. It can be observed that this yield criterion has been widely used in industrial simulations and provides reasonably good results as well as being numerically efficient. The expansion of the new material model yield surface (hardening part) is characterised by a referential curve of the thermally micromechanical-based model, the Mechanical Threshold Model (MTS). Generally, a finite “saturation stress”, or what can be described as a constant but small hardening rate, is achievable at finite strains of most metallic materials. The other models such as Johnson-Cook (JC) and Zerilli-Armstrong (ZA) models are unable to capture this behaviour. Moreover, the MTS model fits the experimental data more reasonably at various strains of the saturation stress.
a slight recovery of the temporoammonic response but not back to pre-DA levels. A combination of D1 and D2 receptor antagonists also did not fully recover the response. A full recovery was only found when clozapine was applied (Otmakhova & Lisman, 1999; Rosen et al, 2015). Clozapine binds to a variety of receptors, including serotonin, D1, D2, and D4 (Van Tol et al, 1991). It is also possible that the DA antagonists can prevent DA action, but not recover DA action. Rosen and colleagues (2015) investigated the role of DA, though they used optogenetics to endogenously release DA from the VTA. When they compared their results from their optogenetic experiments to results from slices that had DA applied exogenously, they found opposing results: exogenous DA impaired the temporoammonic response, similar to Otmakhova and Lisman (1999), while having no effect on the SC-CA1 synapse, but endogenously released DA did not affect the temporoammonic response while affecting the SC-CA1 response. They also found that D4 receptor activation inhibited the SC-CA1 synapse by increasing excitation of the SC-interneuron synapse while D1 receptor activation enhanced excitatory transmission, and it is possible that a similar effect may occur at the temporoammonic synapse during synaptic plasticity. Therefore, one theory may be that when DA is released from the VTA to the CA1, it is mediated by at least these three receptor subtypes which have opposing effects to cancel one another out, with D2 receptors having a facilitative effect and D4 receptors having an inhibitory effect.
In this report, we describe the discovery of HAD2, a second HAD family member in P. falciparum. We found that HAD2 is a cytosolic phosphatase required for metabolic homeostasis. Loss of HAD2 dysregulates glycolysis and misroutes metabolites toward the MEP pathway, conferring drug resistance. In our study, we harnessed a ﬁtness defect in had2 parasite strains to employ an innovative screen for suppression of drug resistance in the parasite. Selection for suppression of drug resistance identiﬁed mutations in PFK9, which encodes the canonical glycolytic regulatory enzyme phos- phofructokinase (PFK). Reduction in PFK9 activity rescued the metabolic dysregulation in our resistant mutants and restored FSM sensitivity. Our unique approach thus reveals PFK9 as a site of exceptional metabolic plasticity in the parasite and uncovers a novel genetic mechanism by which P. falciparum malaria parasites may adapt to metabolic stress and drug selective pressure.
Hebbian learning is a synaptic plasticity rule where a synapse between two neurons is strengthened when its pre and post synaptic neurons have highly correlated outputs. Spike Timing Dependent Plasticity (STDP) is an asymmetric form of Hebbian learning induced by tight temporal correlations between the presynaptic and postsynaptic neuron spikes , . The Bienenstock, Cooper, and Munro (BCM) synaptic modification rule modulates the postsynaptic activity if it deviates from the required response , . In this paper, we use a self-repairing learning rule  that uses evidence  to explain how the STDP and BCM learning rules co-exist to give a learning function that is under the control of postsynaptic neuron activity.
Administration of the neurotoxicant 6-hydroxydopamine (6-OHDA), with desmethylimipramine pretreatment, results in the selective destruction of dopamine- containing neurons (Smith et al., 1973). Rats bilaterally lesioned with 6-OHDA as neonates have increased susceptibility for aggression, hyperexcitability, and self-injurious behavior in response to dopamine (DA) receptor agonists (Breese et al., 1984a). These behaviors are similar to those observed clinically with Lesch-Nyhan syndrome (LNS), a developmental disorder characterized by reduced brain DA, choreoathetoid movements, and compulsive self-injurious behavior (Lesch and Nyhan, 1964). The susceptibility for self-injurious behavior observed in neonate-lesioned rats is not present in rats lesioned with 6-OHDA as adults, the latter of which mimic Parkinson's disease (Breese et al., 1984a; Marsden, 1984). Thus, the neonatal rat brain must retain sufficient plasticity to allow for the development of compensatory mechanisms that attenuate, to some degree, the debilitating effects of DA depletion.
In recent years, developmental research in humans has accumulated evidence that high levels of physiological stress reactivity (adrenocortical and autonomic) and negative affectivity (irritability, shyness, fearfulness, ner- vousness) predict increased plasticity in a broad range of traits including sociability, aggression, impulsivity, depressive symptoms, and maturation timing [4,6]. Genetic studies aiming to identify “plasticity alleles” typically converge on genes involved in serotonergic and dopaminergic pathways [4,6,34]; these pathways are cri- tically implicated in processing rewards and punish- ments and show deep, bidirectional connections with one another and with the stress response system [31,33]. Other candidates showing associations with plasticity include genes involved in HPA signaling such as the corticotropin-releasing hormone receptor 1 gene (CRHR1) , as well as the brain-derived neurotrophic factor gene (BDNF) and the acetylcholine receptor gene, both of which regulate learning and neuronal growth . Converging findings that emotional and physiologi- cal reactivity are associated with increased plasticity have been reported in studies of nonhuman primates, birds, and rodents [32,36], although the evidence from nonhuman species is considerably more sparse.
Mitochondrial apoptotic pathway and caspase-3 in LTD Synaptic plasticity, the ability of synapses to adjust their strength, is an important means by which the nervous system responds to prior experience and adapts to environmental changes. The change in synaptic strength can be transient (seconds to minutes) or last for pro- longed period of time. Long-lasting forms of synaptic plasticity play a crucial role in the refinement of neuro- nal connections during development and in cognitive functions such as learning and memory [18,19]. In the mammalian brain, NMDA receptor-dependent long- term potentiation (LTP) and long-term depression (LTD) of synaptic transmission are two major forms of
Knowledge of host selection is not only important for evaluating the vectorial capacity of a vector population, but also for guiding vector-based malaria control pro- grams, such as the distribution of long-lasting insecticidal nets (LLIN). The implementation of LLIN is appropriate if we know that local vectors are sufficiently anthropophilic that LLIN will have the intended effect . The inflexibil- ity of anthropophilic species to utilize alternative hosts causes them to pursue humans inside houses and thus in- creases their likelihood of becoming exposed to the insec- ticides in the LLIN fabric. The increased likelihood of contacting LLIN enables reduction of their population size to levels insufficient to support transmission. In contrast, if the mosquitoes are opportunistic and exhibit plasticity in host selection, then LLIN may have little effect because these mosquitoes can maintain high population size by feeding on non-human hosts outdoors. By maintaining high population size, the proportion of opportunistic vec- tors that feed on human individuals before they go under their bed nets can sufficiently sustain residual transmis- sion in the community. Treating the alternative hosts with endectocides lethal to blood-feeding mosquitoes may be more appropriate for controlling such opportunistic vec- tors. By implementing both methods, the anthropophilic and opportunistic vectors can be successfully controlled.