A role for Synapsin in associative learning: the Drosophila larva as a study case

Synapsins are evolutionarily conserved, highly abundant vesicular phosphoproteins in presynaptic terminals. They are thought to regulate the recruitment of synaptic vesicles from the reserve pool to the readily-releasable pool, in particular when vesicle release is to be maintained at high spiking rates. As regulation of transmitter release is a prerequisite for synaptic plasticity, we use the fruit fly Drosophila to ask whether Synapsin has a role in behavioral plasticity as well; in fruit flies, Synapsin is encoded by a single gene (syn). We tackled this question for associative olfactory learning in larval Drosophila by using the deletion mutant syn^97CS, which had been backcrossed to the Canton-S wild-type strain (CS) for 13 generations. We provide a molecular account of the genomic status of syn^97CS by PCR and show the absence of gene product on Western blots and nerve-muscle preparations. We found that olfactory associative learning in syn^97CS larvae is reduced to ~50% of wild-type CS levels; however, responsiveness to the to-be-associated stimuli and motor performance in untrained animals are normal. In addition, we introduce two novel behavioral control procedures to test stimulus responsiveness and motor performance after “sham training.” Wild-type CS and syn^97CS perform indistinguishably also in these tests. Thus, larval Drosophila can be used as a case study for a role of Synapsin in associative learning.     

Olfactory blocking and odorant similarity in the honeybee

Blocking occurs when previous training with a stimulus A reduces (blocks) subsequent learning about a stimulus B, when A and B are trained in compound. The question of whether blocking exists in olfactory conditioning of proboscis extension reflex (PER) in honeybees is under debate. The last published accounts on blocking in honeybees state that blocking occurs when odors A and B are similar (the "similarity hypothesis"). We have tested this hypothesis using four odors (1-octanol, 1-nonanol, eugenol, and limonene) chosen on the basis of their chemical and physiological similarity (experiment 1). We established a generalization matrix that measured perceptual similarity. Bees in the "block group" were first trained with an odor A and, in the second phase, with the mixture AB. Bees in the "novel group" (control group) were first trained with an odor N and, in the second phase, with the mixture AB. After conditioning, bees in both groups were tested for their response to B. We assayed all 24 possible combinations for the four odors standing for A, B, and N. We found blocking in four cases, augmentation in two cases, and no difference in 18 cases; odor similarity could not account for these results. We also repeated the experiments with those six odor combinations that gave rise to the similarity hypothesis (experiment 2: 1-hexanol, 1-octanol, geraniol) and found augmentation in one and no effect in five cases. Thus, blocking is not a consistent phenomenon, nor does it depend on odor similarity.     

Individual differences in relatedness and individuality: An exploration of two constructs

Sociotropy and autonomy are two personality dimensions that relate to an individual's vulnerability to depression. Independent and interdependent self-construals are two distinctive cognitive formulations of the self derived from cross-cultural research. Both of these sets of constructs reflect self and other orientations. The purpose of the present study was to empirically examine the various factors that emerge when these two constructs are integrated. 652 participants responded to the Personal Style Inventory [Robins, C. J., Ladd, J., Welkowitz, J., Blaney, P. H., Diaz, R. & Kutcher, G. (1991). The Personal Style Inventory: Preliminary validation studies of new measures of sociotropy and autonomy. Journal of Psychopathology and Behavioral Assessment, 16, 277–300.], the Sociotropy-Autonomy Scale [Clark, D. A. & Beck, A. T. (1991). Personality factors in dysphoria: A psychometric refinement of Beck's Sociotropy-Autonomy Scale. Journal of Psychopathology and Behavioral Assessment, 13, 369–388.] and the Self-Construal Scale [Singelis, T. M. (1994). The measurement of independent and interdependent self-construals. Personality and Social Psychology Bulletin, 20, 580–591.]. Four factors emerged from a factor analysis conducted on the items of the three scales measuring sociotropy-autonomy and independent and interdependent self-construal. These four factors are discussed in the context of vulnerability to depression.     

DIFFERENTIAL REINFORCEMENT OF ALTERNATIVE BEHAVIOR AND DEMAND FADING IN THE TREATMENT OF ESCAPE-MAINTAINED DESTRUCTIVE BEHAVIOR

The escape-maintained destructive behavior of a boy with autism was reduced during instructional sequences with differential reinforcement of compliance (DRA), escape extinction without physical guidance, and demand fading. The procedure decreased destructive behaviors to near-zero levels and greatly increased compliance.     

Memory conformity and the perceived accuracy of self versus other

Here, we demonstrate that the decision to conform to another person’s memory involves a strategic trade-off that balances the accuracy of one’s own memory against that of another person. We showed participants three household scenes, one for 30 s, one for 60 s, and one for 120 s. Half were told that they would encode each scene for half as long as their virtual partner, and half were told that they would encode each scene for twice as long as their virtual partner. On a subsequent two-alternative-forced choice (2AFC) memory test, the simulated answer of the partner (accurate, errant, or no response) was shown before participants responded. Conformity to the partner’s responses was significantly enhanced for the 30-s versus the 60- and 120-s scenes. This pattern, however, was present only in the group who believed that they had encoded each scene for half as long as their partner, even though the short-duration scene had the lowest baseline 2AFC accuracy in both groups and was also subjectively rated as the least memorable by both groups. Our reliance on other people’s memory is therefore dynamically and strategically adjusted according to knowledge of the conditions under which we and other people have acquired different memories.     

Behavioral and Emotional Problems on the Teacher’s Report Form: A Cross-National,Cross-Clinic Comparative Analysis of Gender Dysphoric Children and Adolescents

For gender dysphoric children and adolescents, the school environment may be challenging due to peer social ostracism and rejection. To date, information on the psychological functioning and the quality of peer relations in gender dysphoric children and adolescents has been studied via parental report, peer sociometric methods, and social interactions in laboratory play groups. The present study was the first cross-national investigation that assessed behavior and emotional problems and the quality of peer relations, both measured by the Teacher’s Report Form (TRF), in a sample of 728 gender dysphoric patients (554 children, 174 adolescents), who were referred to specialized gender identity clinics in the Netherlands and Canada. The gender dysphoric adolescents had significantly more teacher-reported emotional and behavioral problems than the gender dysphoric children. In both countries, gender dysphoric natal boys had poorer peer relations and more internalizing than externalizing problems compared to the gender dysphoric natal girls. Furthermore, there were significant between-clinic differences: both the children and the adolescents from Canada had more emotional and behavioral problems and a poorer quality of peer relations than the children and adolescents from the Netherlands. In conclusion, gender dysphoric children and adolescents showed the same pattern of emotional and behavioral problems in both countries. The extent of behavior and emotional problems was, however, higher in Canada than in the Netherlands, which appeared, in part, an effect of a poorer quality of peer relations. Per Bronfenbrenner’s (American Psychologist, 32, 513–531, 1977) ecological model of human development and well-being, we consider various interpretations of the cross-national, cross-clinic differences on TRF behavior problems at the level of the family, the peer group, and the culture at large.     

Changes in cue-induced, prefrontal cortex activity with video-game play

Brain responses, particularly within the orbitofrontal and cingulate cortices, to Internet video-game cues in college students are similar to those observed in patients with substance dependence in response to the substance-related cues. In this study, we report changes in brain activity between baseline and following 6 weeks of Internet video-game play. We hypothesized that subjects with high levels of self-reported craving for Internet video-game play would be associated with increased activity in the prefrontal cortex, particularly the orbitofrontal and anterior cingulate cortex. Twenty-one healthy university students were recruited. At baseline and after a 6-week period of Internet video-game play, brain activity during presentation of video-game cues was assessed using 3T blood oxygen level dependent functional magnetic resonance imaging. Craving for Internet video-game play was assessed by self-report on a 7-point visual analogue scale following cue presentation. During a standardized 6-week video-game play period, brain activity in the anterior cingulate and orbitofrontal cortex of the excessive Internet game-playing group (EIGP) increased in response to Internet video-game cues. In contrast, activity observed in the general player group (GP) was not changed or decreased. In addition, the change of craving for Internet video games was positively correlated with the change in activity of the anterior cingulate in all subjects. These changes in frontal-lobe activity with extended video-game play may be similar to those observed during the early stages of addiction.