Biology subjects

Lima-Maximino, M. G.

Publications and source records attributed to Lima-Maximino, M. G..

3 recordsLinked to original sources

bioRxiv2018

Conditional approach as cooperation in predator inspection: a role for serotonin?

In guppies (Poecilia reticulata), a small number of individuals break away from a shoal and approach a potential predator, a behavior termed "predator inspection". These animals often employ a "conditional approach" strategy, in which an individual approaches the predator in the first move and subsequently approaches it only if a second individual swims even with it during inspection. This strategy is analogous to the "tit-for-tat" strategy of the Prisoners Dilemma, suggesting that it could be used to study cooperation. Serotonin is thought to mediate cooperative behavior in other fish species. Exposure to the animated image of a predator in a tank that contained a parallel mirror - mimicking an equally cooperating conspecific - promoted inspection and decreased refuge use, but increased freezing, suggesting that conditional approach is also associated with fear. To understand whether serotonin participates in conditional approach in guppies, we treated animals with either vehicle (Cortlands salt solution), fluoxetine (2.5 mg/kg) or metergoline (1 mg/kg), and tested then in a predator inspection paradigm. Fluoxetine increased the time the animal spent inspecting the predator image, while metergoline decreased it. Fluoxetine also decreased time spent avoiding the predator and increased freezing, while metergoline decreased freezing. These results suggest that phasic increases in serotonin levels promote conditional approach, suggesting a role for this neurotransmitter in cooperation. Preprint: https://doi.org/10.1101/436345; Data and scripts: https://github.com/lanec-unifesspa/TFT

animal behavior and cognition↗

bioRxiv2018

Metanalysis of genome-wide association studies for panic disorder suggest pathways and mechanisms of pathogenesis

Panic disorder (PD) is characterized by abrupt surges of intense fear and distress. There is evidence for a genetic component in this disorder. We ran a meta-analysis of genome-wide association studies of patients with PD, and found 25 single-nucleotide polymorphisms that were associated with the disorder. Causal gene prediction based on these polymorphisms uncovered 20 hits. Exploratory analyses suggested that these genes formed interactor networks, which was enriched in signaling pathways associated with immune and inflammatory responses, as well as growth factors and other developmental mediators. A subset of genes is enriched in limbic regions of the human brain and in microglia and myelinating oligodendrocytes of mice. While these genes were not associated with relevant neurobehavioral phenotypes in mutant mice, expression levels of several causal genes in the amygdala, prefrontal cortex, hippocampus, hypothalamus, and adrenal gland of recombinant mouse strains was associated with endophenotypes of fear conditioning. Drug repositioning prediction was unsuccessful, but this does not discard these genes and pathways as targets for investigational drugs. In general, ASB3, EIF2S2, RASGRF2, and TRMT2B (and its coded proteins) emerged as interesting targets for mechanistic research on PD. These exploratory findings point towards hypotheses of pathogenesis and neuropharmacology that need to be further investigated.

neuroscience↗

bioRxiv2018

Profiles of cooperative brains: A discriminant analysis of cleaner and client fish monoaminergic responses to different social contexts

Vertebrate cognitive function requires a dynamic coordination of multiple specialized areas of the brain. The challenge here is to understand how these brain areas respond in dependence to the neurophysiological mechanisms in place, as to enable the successful processing of information. For instance, social and cooperative behaviour has been linked to the activation of some specific brain areas, mostly associated with reward processing. Here we evaluated a classic model system of cooperation between species of fish and compared datasets of brain monoaminergic response. We analysed by using multivariate discriminant analysis the exposure of cleaners, Labroides dimidiatus, to several social-related conditions, as well as the response of one client species, Naso elegans, to similar contexts. We demonstrate that the variable appraisal of each social challenge contributes to brain dopaminergic and serotonergic changes, in cleaners and clients, with both showing the diencephalon and optic tectum as main areas of metabolite response. The role of the serotoninergic system activation was mostly demonstrated at the diencephalon and cerebellum of cleaners, a response that was driven by mutualistic interaction, contact with client. Our current evidence is the first to jointly demonstrate the level of selective similarity in brain monoaminergic mechanisms that underlie fish mutualistic and social engagement, for both sides of these partnerships.

neuroscience↗