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Inhibitory control (IC) is the ability to overcome impulsive or prepotent but ineffective responses in favour of more appropriate behaviours. The ability to inhibit internal predispositions or external temptations is vital in coping with a complex and variable world. Traditionally viewed as cognitively demanding and a main component of executive functioning and self‐control, IC was historically examined in only a few species of birds and mammals but recently a number of studies has shown that a much wider range of taxa rely on IC. Furthermore, there is growing evidence that inhibitory abilities may vary within species at the population and individual levels owing to genetic and environmental factors. Here we use a detour‐reaching task, a standard paradigm to measure motor inhibition in nonhuman animals, to quantify patterns of interindividual variation in IC in wild‐descendant female guppies, Poecilia reticulata. We found that female guppies displayed inhibitory performances that were, on average, half as successful as the performances reported previously for other strains of guppies tested in similar experimental conditions. Moreover, we showed consistent individual variation in the ability to inhibit inappropriate behaviours. Our results contribute to the understanding of the evolution of fish cognition and suggest that IC may show considerable variation among populations within a species. Such variation in IC abilities might contribute to individual differences in other cognitive functions such as spatial learning, quantity discrimination or reversal learning.

According to the dopamine (DA) hypothesis of schizophrenia and the strong evidence for decreased cerebral lateralization in schizophrenic patients, we postulated that hyperactivity of the dopaminergic system could be associated with a reduced behavioral lateralization in mice. Mice lacking the dopamine transporter (DAT) gene were used as a genetic model of persistent hyperdopaminergia. The DAT null mutation was transferred on C57BL/6JOrl (B6) and DBA/2JOrl (D2) inbred backgrounds for more than 10 generations of backcrossing to derive three DAT strains, B6, D2, and B6 Â D2(F 1 ). Adult mutant mice of the three DAT strains and their littermates were tested for paw preference using Collins' protocol. Our results demonstrated that, whatever the genetic background, persistent hyperdopaminergia directly impairs the degree of lateralization without affecting the direction. Our results support the degree of lateralization as a good candidate phenotype to further improve genetic analysis of cerebral lateralization in normal and pathological conditions. Neuropsychopharmacology Keywords: schizophrenia; direction and degree of asymmetry; paw preference; knockout mice; cocaine INTRODUCTIONAnomalies in behavioral, neuroanatomical, and neurophysiological asymmetry have been widely documented in schizophrenic patients, supporting lateralization as a good candidate symptom that could contribute to clarifying schizophrenia heterogeneity (Leboyer et al, 1998). A metaanalysis of 19 studies on schizophrenia showed that the prevalence of non-right-handedness was significantly higher in patients than in healthy subjects (Sommer et al, 2001). Similarly, in the meta-analysis of three prospective followup studies, pre-schizophrenic subjects were significantly more often non-right-handed than the general population (Sommer et al, 2001). Furthermore, in vivo imaging studies of schizophrenia have provided evidence that the right-left asymmetry of the dopamine (DA) synthesis capacity and of the dopamine transporter (DAT) binding in the caudate are both lost in antipsychotic-naive patients (Hietala et al, 1999(Hietala et al, , 1995Hsiao et al, 2003;Laakso et al, 2000). In addition, neuroleptics are able to change the balance of hemispheric activity, thus improving left-hemispheric attentional processes (for a review, see Gruzelier, 1999), and a recent study demonstrated that haloperidol-induced downregulation of DA synthesis was significantly greater in the left than in the right striatum (Grunder et al, 2003). Finally, a highly significant correlation was reported between depressive symptoms in antipsychotic-naive schizophrenia and DA synthesis capacity in the left striatum (Hietala et al, 1999).Taken together, these data support the hypothesis of a potential link between cerebral lateralization and schizophrenia, and suggest that abnormal asymmetry of the dopaminergic transmission could be one of the key neurobiological substrates for this functional relationship. Based on the DA hypothesis of schizophrenia, which attributes the positive sc...

Male phenotypic diversity experienced during ontogeny mediates female mate choice in Trinidadian guppies Originally published in: Behavioural Ecology Link to published article (if available): Usage guidelines Before reusing this item please check the rights under which it has been made available. Some items are restricted to non-commercial use. Please cite the published version where applicable.