Progesterone to ovariectomized mice enhances cognitive performance in the spontaneous alternation, object recognition, but not placement, water maze, and contextual and cued conditioned fear tasks

Research on how steroid hormones mediate mnemonic processes have focused on effects of 17β-estradiol (E₂); yet, progesterone (P₄) co-varies with E₂ across endogenous hormonal milieu, and itself may influence cognitive processes. We investigated the hypothesis that acute P₄ treatment enhances cognitive performance compared to vehicle. Ovariectomized (OVX) c57/BL6J mice were randomly assigned to be subcutaneously injected with oil vehicle or P₄ (10 mg/kg). Mice were trained in the spontaneous alternation, object recognition, object placement, water maze, or fear conditioning tasks, and injected with vehicle or P₄ before training or immediately post-training, and then were tested 1, 4, or 24 h later. The data obtained from these experiments supported our hypothesis. P₄ increased the percentage of spontaneous alterations made in a T-maze more so than did vehicle. P₄, compared to vehicle, increased the percentage of time spent exploring the novel object in the object recognition task, but did not alter performance in the object placement task. P₄, compared to vehicle, decreased latencies to reach the location in the water maze where the platform had been during training in a probe trial, but did not alter performance in the control, cued trial. Compared to vehicle, P₄ treatment increased freezing in contextual and cued fear testing. Thus, acute P₄ treatment to OVX mice can improve cognitive performance across a variety of tasks.     

Intracranial self-stimulation improves memory consolidation in rats with little training

Post-training intracranial electrical self-stimulation can improve learning and memory consolidation in rats. However, the molecular mechanisms involved are not known yet. Since previous paradigms of this kind of facilitation are relatively unsuitable to try a molecular approach, here we develop a single and short model of learning and memory facilitation by post-training self-stimulation that could make easier the research of its neural and molecular basis. Thus, three consecutive experiments were carried out to ascertain whether post-training self-stimulation is able to facilitate memory when learning consists of only a brief (5 trials) two-way active avoidance conditioning session. The results of Experiment 1 showed that it is actually possible, and that 48 h after the acquisition session is a very good time to observe the memory improvement. As a way to probe the retroactive effect of self-stimulation, in Experiment 2 we observed that the same self-stimulation treatment given to the subjects not post-training but 48 h before a single two-way active avoidance session does not improve the acquisition of conditioning. In Experiment 3, we showed that the SS facilitative effect observed 48 h after the acquisition session in Experiment 1 was still maintained one week later. We concluded that post-training intracranial self-stimulation can consistently improve memory consolidation even when little acquisition training is given to the animals in a single training session.     

Decisions among time saving options: when intuition is strong and wrong

When people judge the time that can be saved by increasing the speed of an activity, they are often victims of a time saving bias. That is, they overestimate the time that can be saved by increasing the speed. Judgments of time savings following speed increase when driving follow the Proportion heuristic [Svenson, O. (1970). A functional measurement approach to intuitive estimation as exemplified by estimated time savings. Journal of Experimental Psychology, 86, 204-210]. In a choice between time saving options, this heuristic simplifies to the Ratio rule. The first study tested this rule and found that the Ratio rule predicted incorrect decisions when planning to save traveling time in road traffic. The second study showed that the time saving bias was also present in planning of health care; to specify, in decisions about which one of two clinics to reorganize to save more of the doctors' time for personal contacts with patients. To further test the Ratio rule, Study 3 used a matching procedure in which two decision alternatives were made equal by the participants. The results supported the Ratio rule. Practical implications of the results are discussed including the Planning fallacy. In conclusion, the present set of studies have illustrated a time saving bias and provided evidence explaining why people make systematic errors when judging and deciding about time saved following a speed increase.     

Learning generalization in problem solving by a blue-fronted parrot (<Emphasis Type="Italic">Amazona aestiva</Emphasis>)

Pepperberg (The Alex studies: cognitive and communicative abilities of gray parrots. Harvard University Press, Cambridge;1999) showed that some of the complex cognitive capabilities found in primates are also present in psittacine birds. Through the replication of an experiment performed with cotton-top tamarins (Saguinus oedipus oedipus) by Hauser et al. (Anim Behav 57:565-582; 1999), we examined a blue-fronted parrot's (Amazona aestiva) ability to generalize the solution of a particular problem in new but similar cases. Our results show that, at least when it comes to solving this particular problem, our parrot subject exhibited learning generalization capabilities resembling the tamarins'.     

The application of the first order system transfer function for fitting the 3-arm radial maze learning curve

A mathematical model is described based on the first order system transfer function in the form Y=B3∗exp(−B2∗(X−1))+B4∗(1−exp(−B2∗(X−1))), where X is the learning session number; Y is the quantity of errors, B2 is the learning rate, B3 is resistance to learning and B4 is ability to learn. The model is tested in a light-dark discrimination learning task in a 3-arm radial maze using Wistar and albino rats. The model provided good fits of experimental data under acquisition and reacquisition, and was able to detect strain differences among Wistar and albino rats. The model was compared to Rescorla-Wagner, and was found to be mutually complementary. Comparisons with Tulving’s logarithmic function and Valentine’s hyperbola and the arc cotangent functions are also provided. Our model is valid for fitting averaged group data, if averaging is applied to a subgroup of subjects possessing individual learning curves of an exponential shape.     

The origins of concepts

Certain of our concepts are innate, but many others are learned. Despite the plausibility of this claim, some have argued that the very idea of concept learning is incoherent. I present a conception of learning that sidesteps the arguments against the possibility of concept learning, and sketch several mechanisms that result in the generation of new primitive concepts. Given the rational considerations that motivate their deployment, I argue that these deserve to be called learning mechanisms. I conclude by replying to the objections that these mechanisms cannot produce genuinely new content and cannot be part of genuinely cognitive explanations.

4.5-month-old infants’ learning, retention and use of object boundary information

4.5-month-old infants can use information learned from prior experience with objects to help determine the boundaries of objects in a complex visual scene (Needham, 1998; Needham, Dueker, & Lockhead, 2002). The present studies investigate the effect of delay (between prior experience and test) on infant use of such experiential knowledge. Results indicate that infants can use experience with an object to help them to parse a scene containing that object 24 (Experiment 1). Experiment 2 suggests that after 24 h infants have begun to forget some object attributes, and that this forgetting promotes generalization from one similar object to another. After a 72-h delay, infants did not show any beneficial effect of prior experience with one of the objects in the scene (Experiments 3A and B). However, prior experience with multiple objects, similar to an object in the scene, facilitated infant segregation of the scene 72 h later, suggesting that category information remains available in infant memory longer than experience with a single object. The results are discussed in terms of optimal infant benefit from prior experiences with objects.     

Montserratian mothers’ and English teachers’ perceptions of teaching and learning

After the explosion of a previously dormant volcano in Montserrat (an island in the Caribbean, in the Leeward Islands of the West Indies, overseas territory of the UK) in 1996, about 3000 people emigrated to England. As the children settled into English schools, the pattern of underachievement observed with previous West Indian immigrants started to repeat itself. However, a new fact emerged: Montserratian parents were unhappy with the standards of mathematics and science in English schools, which they considered low. This paper reports a case study of how two Montserratian mothers and their four children perceived English schools. The parents, a Montserratian and an English teacher were interviewed about their views of teaching and learning. The parents were also videotaped while helping their children with homework; the English teacher watched one of these tapes and commented on the session.The interviews and videos were analysed by themes. The interpretation of the themes identified in the interviews was later checked against the events in the homework sessions. Different implicit conceptions of school emerged from the analysis: Montserratian schools appear to fit an ‘interdependent’ style of socialisation whereas English schools fit a more ‘independent’ style. These implicit conceptions of schooling resulted in misunderstandings between teachers and parents, who did not perceive each other as truly helping the children. Differences were also observed in implicit teaching and learning aims. These differences seem to explain the Montserratian parents’ perceptions of a low standard of work being asked of their children in English schools.It is suggested that teachers of immigrant children would find it useful to understand pupils’ and parents’ implicit conceptions of schools when they receive immigrants in their community. Their communication with parents might work better if it fits with the parental expectations and parents have time to learn the ways of schooling in the host country.     

Achievement and avoidance motivational orientations in the domain of mentoring

To extend research on fundamental motivational orientations into a new domain, we explored the achievement (positive) and avoidance (negative) orientations of formal organization-based mentors and protégés as joint predictors of personal learning experienced by both parties. We also examined the extent of mentoring functions provided by mentors as a hypothesized partial mediator. Regression analyses of 8-month data from 61 dyads revealed that mentors’ personal learning was predicted by protégés’ achievement (positive) and avoidance (negative) orientations, whereas protégés’ personal learning was predicted by their own achievement orientation (positive). Although the extent of mentoring functions facilitated personal learning equally among mentors and protégés, it did not function as a mediator. Finally, mentor-protégé congruence on achievement orientation had implications for the personal learning of protégés.