Acquired predator recognition via epidermal alarm cues but not dietary alarm cues by isolated pupfish.

We tested whether Shoshone pupfish Cyprinodon nevadensis shoshone and Amargosa River pupfish C. n. amargosae respond behaviourally to conspecific chemical alarm cues released when epidermal tissue is damaged by a predator. We found that both subspecies reduced activity and vertical position in the water column in response to alarm cues. We then tested if pupfish can use alarm cue to acquire recognition of a novel predator. We trained pupfish with (1) water + odour of largemouth bass fed a diet of earthworms, (2) alarm cues from skin extract (epidermal alarm cues) + odour of bass fed a diet of earthworms, or (3) water + odour of bass fed a diet of pupfish (dietary alarm cues). Pupfish responded to epidermal alarm cues but not to dietary alarm cues. Pupfish were retested with the odour of bass that were fed an earthworm diet. Pupfish that had previously received epidermal alarm cues reduced vertical position and activity relative to the other two treatments. This is the first demonstration of acquired recognition of a novel predator by a pupfish, the first report of partial predator naiveté, and opens the possibility of predator-recognition training as a tool for management and conservation of endangered desert fishes.

Making the dead talk: alarm cue-mediated antipredator behaviour and learning are enhanced when injured conspecifics experience high predation risk.

Due to the costs of antipredator behaviour, prey have the ability to finely modulate their response according to the risk they have experienced, and adjust it over different scales of ecological time. Information on which to base their responses can be obtained from direct experience, but also indirectly from nearby conspecifics. In aquatic environments, alarm cues from injured conspecifics are an important and reliable source of information about current predation risk. We used wood frog tadpoles, Lithobates sylvaticus, to investigate whether prey responses to alarm cues match the level of background predation risk experienced by injured conspecifics. We found that tadpoles exposed to alarm cues from conspecifics raised in a high-risk environment showed a stronger antipredator response and an enhanced learned response to novel predators, when compared with tadpoles exposed to alarm cues from conspecifics raised in a low-risk environment. Alarm cues not only allow prey to cope with an ongoing predation event, but also to adjust their behaviour to match background risk in the environment.

Rapid oestrogenic regulation of social and nonsocial learning.

Much research on oestrogens has focused on their long-term action, exerting behavioural effects within hours to days through gene transcription. Oestrogens also affect behaviour on a much shorter time scale. These rapid effects are assumed to occur through cell signalling and can elicit a behavioural effect as early as 15 min after treatment. These effects on behaviour have primarily been explored through the action of oestradiol at three well-known oestrogen receptors (ERs): ERα, ERß and the more recently described G protein-coupled ER1 (GPER1). The rapid effects of oestradiol and ER agonists have been tested on both social and nonsocial learning paradigms. Social learning refers to a paradigm in which an animal acquires information and modifies its behaviour based on observation of another animal, commonly studied using the social transmission of food preferences paradigm. When administered shortly before testing, oestradiol rapidly improves social learning on this task, although no ER agonist has definitive, comparable improving effects. Some evidence points to GPER1, whereas ERα impairs, and ERß activation has no effect on social learning. Conversely, ERα and GPER1 play a larger role than ERß in the rapid improving effect of oestrogens on nonsocial learning, including social and object recognition. In addition, when administered immediately post-acquisition, oestrogens also rapidly improve memory consolidation in a variety of learning paradigms: object recognition, object placement, inhibitory avoidance and the Morris water maze, indicating that oestradiol affects the consolidation of multiple types of memory. Evidence suggests that these improvements are the result of oestrogens acting in the dorsal hippocampus where selective activation of all three ERs shows rapid improving effects on spatial learning comparable to oestradiol. However, the hippocampus is not necessary for rapid oestradiol improvements on social recognition. Although acute treatment with oestradiol enhances learning and memory on various social and nonsocial learning paradigms, the specific ERs play different roles in each type of learning. Future research should aim to further determine the roles of ERs with respect to the enhancing effects of oestradiol on learning and memory, and also determine where in the brain oestradiol acts to affect social and nonsocial learning.

Construção de um teste transmodal de memória de reconhecimento / Construction of a cross-modal recognition memory test

O objetivo do estudo foi construir um teste de reconhecimento pelo modelo de Rach composto por 64 itens de reconhecimento, 32 itens estudados e 32 distratores. Os itens compreendiam pares de palavras escritas ou de figuras, eram modais ou transmodais e metade pertencia a uma mesma categoria semântica e metade a diferentes categorias. Os pares foram agrupados por essas características e hipotetizou-se que esses grupos seguissem uma determinada ordem de dificuldade e que suas médias de dificuldade se diferenciassem significativamente. O teste foi aplicado coletivamente em 231 estudantes de uma universidade particular. Os resultados indicaram um bom ajuste dos itens em relação ao infit e outfit e um bom índice de precisão. A ordem de dificuldade esperada foi obtida empiricamente, mas não foram encontradas diferenças significativas entre as médias de todas as categorias dos itens.

The aim of this study was to construct a recognition test, using the Rasch model, composed of 64 items to be recognized, 32 items for study and 32 distracters. The pairs of items comprised written words or figures, they were either modal or cross-modal; half of them belonged to the same semantic category and the other half to a variety of other categories. The pairs were grouped according to these features and it was predicted that they would follow a given order of difficulty and that their mean of difficulty would be significantly different. The test was collectively administered to 231 students from a private university. The outcomes indicated a very good item fit as regards infit and outfit and also a good index of precision. The expected orders of difficulty were obtained empirically, although the means of some groups of items were not significantly different.

Construção de um teste transmodal de memória de reconhecimento / Construction of a cross-modal recognition memory test

O objetivo do estudo foi construir um teste de reconhecimento pelo modelo de Rach composto por 64 itens de reconhecimento, 32 itens estudados e 32 distratores. Os itens compreendiam pares de palavras escritas ou de figuras, eram modais ou transmodais e metade pertencia a uma mesma categoria semântica e metade a diferentes categorias. Os pares foram agrupados por essas características e hipotetizou-se que esses grupos seguissem uma determinada ordem de dificuldade e que suas médias de dificuldade se diferenciassem significativamente. O teste foi aplicado coletivamente em 231 estudantes de uma universidade particular. Os resultados indicaram um bom ajuste dos itens em relação ao infit e outfit e um bom índice de precisão. A ordem de dificuldade esperada foi obtida empiricamente, mas não foram encontradas diferenças significativas entre as médias de todas as categorias dos itens.(AU)

The aim of this study was to construct a recognition test, using the Rasch model, composed of 64 items to be recognized, 32 items for study and 32 distracters. The pairs of items comprised written words or figures, they were either modal or cross-modal; half of them belonged to the same semantic category and the other half to a variety of other categories. The pairs were grouped according to these features and it was predicted that they would follow a given order of difficulty and that their mean of difficulty would be significantly different. The test was collectively administered to 231 students from a private university. The outcomes indicated a very good item fit as regards infit and outfit and also a good index of precision. The expected orders of difficulty were obtained empirically, although the means of some groups of items were not significantly different.(AU)