Spatial learning in rats is impaired by microinfusions of protein kinase C-gamma antisense oligodeoxynucleotide within the nucleus accumbens

The nucleus accumbens (NAcc) has been shown to play a role in motor and spatial learning. Protein kinase C (PKC) has been implicated in the mechanisms of initiation and maintenance of long-term potentiation that is thought to be involved in the storage of long-term memory. In the present study, the importance of de novo synthesis of PKC-gamma within the NAcc in the acquisition and retention of spatial discrimination learning was assessed using an antisense knockdown approach. Separate groups of Long-Evans rats were exposed to acute microinfusions (6microg/microl) of PKC-gamma antisense oligodeoxynucleotide (AS-ODN), control oligodeoxynucleotide (C-ODN) or vehicle into the NAcc at 24 and 3h before each training session. Behavioral findings showed that the blockade of NAcc-PKC-gamma translation caused impairments in the early phase of learning and retention of spatial information. Biochemical experiments showed that PKC-gamma expression was reduced and Ca(2+)/phospholipid-dependent protein kinase C (PKC) activity was blocked significantly in the AS-ODN-treated rats in comparison with control rats. The present findings suggest that NAcc-PKC-gamma plays a role during the early acquisition of spatial learning. Also, retention test results suggest that NAcc-PKC-gamma may be working as an intermediate factor involved in the onset of molecular mechanisms necessary for spatial memory consolidation within the NAcc.     

Is the unilateral lesion of the left substantia nigra pars compacta sufficient to induce working memory impairment in rats?

Adult male Wistar rats with a substantia nigra pars compacta (SNc) lesion induced by intranigral administration of 1 micromol 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were used as a model of early phase Parkinson's disease (PD). This lesion caused a partial depletion of striatal dopamine (DA). The animals were submitted to a spatial working memory version of the water maze task in which they had to find a hidden (submersed) platform using online-maintained information that the platform remains in the same place during four consecutive trials, but that it is moved to another place every training day. Left, but not right SNc-lesioned rats were impaired in finding the platform in the second trial. This result suggests that the left SNc plays a key role in spatial working memory. Control experiments ruled out the possibility that motor impairment, sensory neglect, and/or impairment in the mental representation of the contralateral spatial environment had affected performance of the SNc-lesioned rats.     

The Five-factor Personality Inventory as a measure of the Five-factor Model: Belgian, American, and Hungarian comparisons with the NEO-PI-R

The lexically based Five-Factor Personality Inventory (FFPI) was correlated with the factors and facets of the Revised NEO Personality Inventory (NEO-PI-R) in Belgian (N = 265), American (N = 116), and Hungarian (N = 320) samples. Results were similar across the three cultures. Analysis of orthogonalized FFPI factors showed that three of them--emotional stability, extraversion, and agreeableness--showed a direct correspondence to their NEO-PI-R counterparts. Autonomy, however, was not clearly related to openness, and facet analysis suggested that it might be interpreted as a dominance factor Better matches to NEO-PI-R conscientiousness and openness could be obtained by using vectors rotated 30 degrees from the FFPI positions. Raw scale scores showed similar results. Researchers should not assume that all measures of the Five-Factor Model are qualitatively similar     

The endowment-institutional affinity effect

The endowment effect occurs when ownership of a good leads consumers to value the good more than its market value. Students who were given College of Business Administration insignia mugs to keep valued them significantly more than students who were given the same mugs to examine and return (nonendowment condition). The endowment effect also occurred for plain white mugs. Students who were given plain white mugs to keep valued them more than students who were given the same mugs to examine and return. Ownership of insignia mugs not only resulted in the endowment effect but also resulted in an institutional affinity effect: Students provided higher satisfaction ratings with the College of Business Administration than did students endowed with plain white mugs and students in nonendowed conditions. This study demonstrates the impact of the endowment effect on institutional affinity for insignia goods. However, the tandem endowment-affinity effect occurs at the attitude formation stage, not when an attitude has already been formed.     

A function of form: terror management and structuring the social world

Drawing on lay epistemology theory, the authors assessed a terror management analysis of the psychological function of structuring social information. Seven studies tested variations of the hypothesis that simple, benign interpretations of social information function, in part, to manage death-related anxiety. In Studies 1-4, mortality salience (MS) exaggerated primacy effects and reliance on representative information, decreased preference for a behaviorally inconsistent target among those high in personal need for structure (PNS), and increased high-PNS participants' preference for interpersonal balance. In Studies 5-7, MS increased high-PNS participants' preference for interpretations that suggest a just world and a benevolent causal order of events in the social world.     

The force of symmetry revisited: symmetry-to-noise ratios regulate (a)symmetry effects

Freyd and Tversky's [Am. J. Psychol. 97 (1984) 109] data suggested that human observers tend to overestimate relatively high levels of symmetry (symmetry effect), and tend to underestimate relatively low levels of symmetry (asymmetry effect). However, on the basis of their holographic approach to visual regularity, van der Helm and Leeuwenberg [Psychol. Rev. 103(3) (1996) 429] predicted that, at any level of symmetry, both symmetry and asymmetry effects may occur as a consequence of correct estimates of symmetry-to-noise ratios. This prediction was tested in two experiments, with tasks and stimuli similar to those in Freyd and Tversky's study. First, subjects had to judge whether a noisy symmetry is more similar to a slightly more symmetrical variant or to a slightly less symmetrical variant. Second, for every pair of stimuli in such a triadic comparison, subjects had to judge which stimulus is the more symmetrical one. The results from both experiments show that the occurrence of (a)symmetry effects indeed depends on symmetry-to-noise ratios.     

On quasivarieties and varieties as categories

Finitary quasivarieties are characterized categorically by the existence of colimits and of an abstractly finite, regularly projective regular generator G. Analogously, infinitary quasivarieties are characterized: one drops the assumption that G be abstractly finite. For (finitary) varieties the characterization is similar: the regular generator is assumed to be exactly projective, i.e., hom(G, –) is an exact functor. These results sharpen the classical characterization theorems of Lawvere, Isbell and other authors.Supported by the Czech Grant Agency (Project 201/02/0148).Special issue of Studia Logica: Algebraic Theory of Quasivarieties Presented by M. E. Adams, K. V. Adaricheva, W. Dziobiak, and A. V. Kravchenko     

Longitudinal analysis of flexibility and reorganization in early adolescence: a dynamic systems study of family interactions

A dynamic systems (DS) approach was used to study changes in the structure of family interactions during the early adolescent transition period. Longitudinal observational data were collected in 5 waves prior to, during, and after the transition. Boys (n = 149 families) were videotaped problem solving with their parents at 9-10 years old and every 2 years thereafter until they were 18 years old State space grids (a new DS method) were constructed for all families across all waves. Two variables indexing the variability of the family interactions were derived from the grids. As hypothesized, the DS variables revealed a significant quadratic effect related to a peak in variability at 13-14 years of age.     

The role of specific consequences in the maintenance of three types of questions

This research replicated and extended a study by Williams, Donley, and Keller (2000). In that study, children with autism received a box with an object inside and learned to ask “What's that?,” “Can I see it?,” and “Can I have it?” to have the name of the object, to see the object, and to get the object, respectively. The purpose of the present research was to determine if the three questions (a) were three independent repertoires of behavior, (b) constituted three instances of a single functional response class, or (c) belonged to a chain of behavior. The 3 boys with autism who participated responded independently to each question when the consequences for each question were altered. This indicates that the three target responses were three independent repertoires of behavior, each one reinforced and maintained with its specific consequences. Thus, this procedure serves to teach children with autism to ask questions with flexibility according to a variable context.