Multiple serotonergic mechanisms contributing to sensitization in aplysia: evidence of diverse serotonin receptor subtypes

The neurotransmitter serotonin (5-HT) plays an important role in memory encoding in Aplysia. Early evidence showed that during sensitization, 5-HT activates a cyclic AMP-protein kinase A (cAMP-PKA)-dependent pathway within specific sensory neurons (SNs), which increases their excitability and facilitates synaptic transmission onto their follower motor neurons (MNs). However, recent data suggest that serotonergic modulation during sensitization is more complex and diverse. The neuronal circuits mediating defensive reflexes contain a number of interneurons that respond to 5-HT in ways opposite to those of the SNs, showing a decrease in excitability and/or synaptic depression. Moreover, in addition to acting through a cAMP-PKA pathway within SNs, 5-HT is also capable of activating a variety of other protein kinases such as protein kinase C, extracellular signal-regulated kinases, and tyrosine kinases. This diversity of 5-HT responses during sensitization suggests the presence of multiple 5-HT receptor subtypes within the Aplysia central nervous system. Four 5-HT receptors have been cloned and characterized to date. Although several others probably remain to be characterized in molecular terms, especially the Gs-coupled 5-HT receptor capable of activating cAMP-PKA pathways, the multiplicity of serotonergic mechanisms recruited into action during learning in Aplysia can now be addressed from a molecular point of view.     

Isn't there a catch in it somewhere?

The relationship between skill, vision, and proprioception in simple one-handed catching has recently been researched by Fischman and Schneider (1985). The parts of their work addressed to the necessity of being able to see the hand for optimal performance are critically evaluated in the light of earlier published studies, and other methodological and interpretative problems are signalled.     

The representational status of pretence: Evidence from typical development and autism

The question of whether understanding pretend play requires meta‐representational skill was examined among typically developing children and individuals with autism. Participants were presented with closely equated true and false pretence trials in which they had to judge a protagonist's pretend reading of a situation, which either matched or differed from their own. Results showed that individuals' theory of mind abilities determined their performance on false, but not true, pretence trials. These findings imply that meta‐representation is involved when an individual has to make sense of a pretend state of mind that differs from their own, but, crucially, they also show that pretend play can often be understood without meta‐representational competence.     

Free(z)ing Degrees of Freedom in Skill Acquisition

This study reports an empirical investigation into Bernstein's (1967) ideas that in the early stages of the acquisition of a movement skill the coordination problem is reduced by an initial freezing out of degrees of freedom, followed later in the learning process by the release of these degrees of freedom and their incorporation into a dynamic, controllable system. “Freezing” degrees of freedom was made operational both as a rigid fixation of individual degrees of freedom and as the formation of rigid couplings between multiple degrees of freedom. Five subjects practiced slalom-like ski movements on a ski apparatus for 7 consecutive days. Results showed that at the early phases of learning, the joint angles of the lower limbs and torso displayed little movement, as expressed by their standard deviations and ranges of angular motion, whereas joint couplings were high, as shown by the relatively high cross correlations between joint angles. Over practice, angular movement significantly increased in all joint angles of the lower limbs and torso, although the cross correlations decreased. Support for the processes of freezing and releasing degrees of freedom was thus given at both levels of operationalization. In addition, a consistent change from laterally symmetric to laterally asymmetric cross-correlation patterns were observed as a function of practice. Overall, the findings provide empirical support for Bernstein's ideas regarding the mastery of redundant degrees of freedom in the acquisition of coordination.     

Dynamic Visual Acuity and Performance in a Catching Task

Each of 30 Ss was given tests of dynamic and static visual acuity and then participated in a ball-catching task. Performance in the latter task was an inverted U-shaped function of duration of the occluded period, the time between the termination of the 80-msec. viewing period and the estimated onset of the “latency period” (the point in time at which the ball could no longer serve to cue Ss response). Dynamic and static visual acuity scores were not significantly correlated but, with static visual acuity partialled out, dynamic visual acuity and catching performance were significantly correlated.     

Observational Research of Negative Communication and Self-Reported Relationship Satisfaction

Clinical researchers suggest more real-world types of data are needed to understand negative communication in couples. This study asked, what is the relationship between partners’ reports of relationship satisfaction and frequencies of observed markers of negative communication? Fifty-three clinical and community couples completed self-report assessments and ten-minute discussions of relationship concerns. Data were analyzed using pooled regression to account for both actor and partner effects of relationship quality scores on hostility, distress-maintaining attributions, dysphoric affect, and withdrawal. Results yielded a significant actor female effect for hostility and a significant male-to-female partner effect for distress-maintaining attribution.