Sex differences and IQ

Ciliary ganglion (CG) neurons, like other neuronal populations, become dependent on their targets for survival during development. We have previously purified and cloned a secreted ciliary neurotrophic factor that was called growth-promoting activity (GPA). We report here the expression and purification of a highly active form of recombinant GPA, the preparation of GPA-specific polyclonal and monoclonal antibodies, and the use of these antibodies to investigate the cellular location and timing of GPA expression in tissues innervated by CG neurons. Virtually all of the trophic activity in extracts of embryonic eyes could be depleted by GPA-specific antibodies. GPA-like immunoreactivity was found in both targets of the CG: the arterial vasculature of the choroid layer and the ciliary body of the eye. In the choroid layer, GPA was localized to smooth muscle cells surrounding the choroid arteries. Staining in the choroid layer was first detectable at embryonic day (E) 10, or about 2 days after cell death has begun in the ganglion, then increased in intensity through E19. Quantification of trophic activity from whole eye extracts at various ages showed a small increase in activity observed between E9 and E12 and at least a 10-fold increase between E12 and E18. The presence of GPA protein in target cells of CG neurons during the specific developmental period when these neurons undergo cell death is consistent with its proposed function as a target-derived ciliary neurotrophic factor.     

Blocking in the spatial domain.

An initial series of experiments with rats in a swimming pool established that they could find a hidden platform the location of which was defined in terms of 3 or 4 landmarks and that, when trained with all 4, any subset of 3 (or even, after a sufficient number of swimming trials, 2) landmarks was sufficient to produce accurate performance. When only one landmark was present during testing, however, performance fell to chance. Two additional experiments demonstrated a significant blocking effect: If rats were first trained to locate the platform with 3 landmarks, they did not learn to use a 4th landmark added to their initial set of 3. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interpretation training influences memory for prior interpretations.

Anxiety is associated with memory biases when the initial interpretation of the event is taken into account. This experiment examined whether modification of interpretive bias retroactively affects memory for prior events and their initial interpretation. Before training, participants imagined themselves in emotionally ambiguous scenarios to which they provided endings that often revealed their interpretations. Then they were trained to resolve the ambiguity in other situations in a consistently positive (n = 37) or negative way (n = 38) before they tried to recall the initial scenarios and endings. Results indicated that memory for the endings was imbued with the emotional tone of the training, whereas memory for the scenarios was unaffected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Latent inhibition and perceptual learning in a swimming-pool navigation task

A retrospective case-control study of 1698 male pharyngeal and laryngeal cancers seen at the Tata Memorial Hospital, Mumbai from 1980 to 1984 was undertaken to assess the association between the cancers and chewing, smoking, and alcohol habits. Male controls were chosen from persons who attended the hospital during the same period and who were diagnosed as free from cancer, benign tumor, and infectious disease. Statistical analysis was based on unconditional logistic regression method. Bidi smoking and alcohol drinking emerged as significant factors for pharyngeal and laryngeal cancers. Illiterates had 50 to 60% excess risk for pharyngeal cancer only. Nonvegetarian diet did not emerge as significant factor in our study.     

The Easy to Hard Effect and Perceptual Learning in Flavor Aversion Conditioning.

In experiments on the easy to hard effect, pretraining on an easy discrimination results in better performance on a harder version of the discrimination than pretraining on the hard discrimination itself. In addition, some theories posit that unreinforccd preexposure to the easy discrimination should be as effective as differentially reinforced easy pretraining in producing the easy to hard effect. Two experiments on flavor aversion conditioning in rats demonstrated the basic easy to hard effect. However, in neither experiment was easy preexposure more effective than hard preexposure in enhancing learning of the hard discrimination. Indeed, in Experiment 2, rats preexposed to an easy discrimination learned the hard discrimination significantly more slowly than those preexposed to the hard discrimination itself. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Intradimensional and extradimensional shifts in spatial learning.

Animals trained on 2 discriminations learn the 2nd rapidly if the relevant stimuli are from the same dimension as the 1st (an intradimensional or ID shift) but slowly if the relevant stimuli for the 2 problems are from different dimensions (an extradimensional or ED shift). Four experiments examined ID and ED shifts in spatial learning. Rats trained on 2 spatial problems learned the 2nd more rapidly than rats whose 1st problem had been nonspatial. But this difference between ID and ED shifts depended on the spatial relationship between rewarded (S+) and unrewarded (S-) alternatives in the 2 spatial problems. The results imply that rats trained on a spatial discrimination do not learn to attend to all spatial landmarks but only to those that serve to differentiate S+ and S-. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reduced generalization following preexposure: Latent inhibition of common elements or a difference in familiarity?

Three experiments involving 158 male rats showed that Ss injected with lithium chloride after drinking a saline-lemon solution also reduced their consumption of saline-lemon and sucrose-lemon, but a single exposure to sucrose-lemon decreased the generalized aversion. Exp 1 showed that this decrease in the aversion to sucrose-lemon could not be explained by a decrease either in the aversion conditioned to saline-lemon or in neophobia to sucrose-lemon. Exp 2 ruled out the possibility that generalization between saline-lemon and sucrose-lemon was based on shared novelty. Exp 3 showed that generalization between the 2 solutions was related to the strength of the aversion to the lemon flavor they shared in common and that prior exposure to sucrose-lemon reduced generalization by causing latent inhibition of this common element. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Methods of the International Tobacco Control (ITC) Four Country Survey

This paper outlines the design features, data collection methods and analytic strategies of the International Tobacco Control (ITC) Four Country Survey, a prospective study of more than 2000 longitudinal respondents per country with yearly replenishments. This survey possesses unique features that sets it apart among surveys on tobacco use and cessation. One of these features is the use of theory-driven conceptual models. In this paper, however, the focus is on the two key statistical features of the survey: longitudinal and "quasi-experimental" designs. Although it is often possible to address the same scientific questions with a cross-sectional or a longitudinal study, the latter has the major advantage of being able to distinguish changes over time within individuals from differences among people at baseline (that is, differences between age and cohort effects). Furthermore, quasi-experiments, where countries not implementing a given new tobacco control policy act as the control group to which the country implementing such a policy will be compared, provide much stronger evidence than observational studies on the effects of national-level tobacco control policies. In summary, application of rigorous research methods enables this survey to be a rich data resource, not only to evaluate policies, but also to gain new insights into the natural history of smoking cessation, through longitudinal analyses of smoker behaviour.