A behavior-based circuit model of how outcome expectations organize learned behavior in larval Drosophila

Drosophila larvae combine a numerically simple brain, a correspondingly moderate behavioral complexity, and the availability of a rich toolbox for transgenic manipulation. This makes them attractive as a study case when trying to achieve a circuit-level understanding of behavior organization. From a series of behavioral experiments, we suggest a circuitry of chemosensory processing, odor-tastant memory trace formation, and the "decision" process to behaviorally express these memory traces--or not. The model incorporates statements about the neuronal organization of innate vs. conditioned chemosensory behavior, and the types of interaction between olfactory and gustatory pathways during the establishment as well as the behavioral expression of odor-tastant memory traces. It in particular suggests that innate olfactory behavior is responsive in nature, whereas conditioned olfactory behavior is captured better when seen as an action in pursuit of its outcome. It incorporates the available neuroanatomical and behavioral data and thus should be useful as scaffold for the ongoing investigations of the chemo-behavioral system in larval Drosophila.     

Re-emergence of extinguished auditory-cued conditioned fear following a sub-conditioning procedure: effects of hippocampal and prefrontal tetanic stimulations

Post-extinction exposure of rats to a sub-conditioning procedure can evoke conditioned fear, which may correspond to fear return and/or fear learning potentiation. The aim of the present study was to clarify this issue and examine the effects of tetanic stimulation of the hippocampus (HPC) and medial prefrontal cortex (mPFC), two brain regions implicated in post-extinction modulation of conditioned fear. Rats were initially submitted to five tone-shock pairings with either a 0.7-mA or 0.1-mA shock. Tone-evoked freezing was observed only with the higher shock intensity, indicating that the 0.1-mA shock corresponded to a sub-conditioning procedure. All conditioned rats underwent fear extinction with 20 tone-alone trials. When retrained with the sub-conditioning procedure, they displayed again tone-evoked freezing, except when the initial tone was unpaired or a new tone was paired with the 0.1-mA shock, demonstrating fear return rather than fear learning potentiation. We also found that HPC and mPFC tetanic stimulations, applied 24h after the sub-conditioning procedure, similarly reduced this fear return. However, mPFC inactivation abolished temporary HPC tetanus effect, whereas HPC inactivation did not interfere with mPFC tetanus effect. These data confirm our previous findings and reveal the nature of HPC-mPFC interactions in post-extinction modulation of conditioned fear.     

Hippocampal tauopathy in tau transgenic mice coincides with impaired hippocampus-dependent learning and memory, and attenuated late-phase long-term depression of synaptic transmission

We evaluated various forms of hippocampus-dependent learning and memory, and hippocampal synaptic plasticity in THY-Tau22 transgenic mice, a murine tauopathy model that expresses double-mutated 4-repeat human tau, and shows neuropathological tau hyperphosphorylation and aggregation throughout the brain. Focussing on hippocampus, immunohistochemical studies in aged THY-Tau22 mice revealed prominent hyper- and abnormal phosphorylation of tau in CA1 region, and an increase in glial fibrillary acidic protein (GFAP) in hippocampus, but without signs of neuronal loss. These mice displayed spatial, social, and contextual learning and memory defects that could not be reduced to subtle neuromotor disability. The behavioral defects coincided with changes in hippocampal synaptic functioning and plasticity as measured in paired-pulse and novel long-term depression protocols. These results indicate that hippocampal tauopathy without neuronal cell loss can impair neural and behavioral plasticity, and further show that transgenic mice, such as the THY-Tau22 strain, might be useful for preclinical research on tauopathy pathogenesis and possible treatment.     

Interference in visual perception by verbal and spatial cognitive activity

In two experiments we tested the hypothesis that cognitive processing based on spatial imagery produces more deterioration of visual perception than cognitive processing based on verbal codes. So, we studied the effect on visual perception of two cognitive tasks, one of spatial imagery and the other a verbal task. In the first one, with 30 participants, we analyzed the mental load and ocular behaviors in both cognitive tasks. In the second experiment, with 29 participants, we studied the effect of both tasks on a visual search task, using a dual-task experimental paradigm. The verbal task presented higher mental load than the imagery task when both tasks were carried out with visual search task, and there was more deterioration in stimulus detection with the verbal task. We can conclude that: (1) cognitive tasks produce important deterioration in the capacities of visual search and identification of stimuli; (2) this deterioration has two components: (a) an inefficient search, associated with alterations of the gaze patterns while performing cognitive tasks, and (b) a general interference, nonspecific to spatial codes, in the process of identification of looked-at stimuli; (3) this cognitive interference is related to the mental load or effort required by the cognitive task.     

Some Thoughts on A. H. Louie’s “More Than Life Itself: A Reflection on Formal Systems and Biology”

We review and discuss A. H. Louie’s book “More than Life Itself: A Reflexion on Formal Systems and Biology” from an interdisciplinary viewpoint, involving both biology and mathematics, taking into account new developments and related theories.     

Psychometric update of the Social Anxiety Screening Scale (SASS/EDAS) in a Spanish adolescent population

The aim of this work was to update the validation of the Social Anxiety Screening Scale (SASS/EDAS) in a sample of Spanish adolescents. To achieve this, one study with a sample of 1489 students in secondary education, of ages 14 to 17 years, were carried out. The psychometric properties of EDAS were examined through confirmatory factor analysis, reliability (Cronbach's alpha), temporal stability (test-retest), and concurrent criterion validity. The results supported the three-independent-factor structure (avoidance, distress and interference), that showed best fit indices compared to alternative models. They also showed that the scores of participants on EDAS scales were reliable in terms of internal consistency (alpha > .80) and moderately reliable concerning temporal stability (r = .48-.60) over a five-week period. The correlations between the EDAS factors and other social anxiety measures were positive and significant. Data provide empirical evidence of the estimation of reliability and validity of this scale. Future work should extend the validation of the EDAS in clinical samples.     

“Of course I will ...”: The combined effect of certainty and level of expectancies on persistence and performance

The importance of performance expectancies for the prediction of regulation of behavior and actual performance has long been established. Building on theories from the field of social cognition, we suggest that the level of performance expectancies, as well as the certainty of the expectancy, have a joint influence on an individual’s beliefs and behavior. In two studies (one cross sectional using a sample of secondary school students and one longitudinal using a sample of university students) we found that expectancies more strongly predicted persistence, and subsequent performance, the more certain the expectancy was. This pattern was found even if prior performance was controlled, as in Study 2. The data give an indication that it may be useful to include certainty as an additional variable in expectancy models.     

Life Satisfaction and Positive Adjustment as Predictors of Emotional Distress in Men With Coronary Heart Disease

This two-wave longitudinal study examines the ability of life satisfaction and adjustment strategies to predict anxious and depressive symptoms in coronary heart disease male patients. Studies have shown that most heart attack survivors report these symptoms, which may worsen the prognosis of the disease. At Time 1, immediately after the first cardiac episode, eighty-eight men reported their life satisfaction levels, adjustment strategies used, and anxious and depressive symptoms experienced. At Time 2, six months later, sixty-three of those patients reported only their anxious and depressive symptoms again. The results showed that, after controlling for demographic variables, anxious and depressive symptoms at Time 1 were predicted by positive adjustment and life satisfaction. At Time 2, after controlling for both demographic variables and Time 1-emotional symptoms, none of the psychological variables predicted anxious symptoms, while depressive symptoms were only predicted by life satisfaction. It is concluded that an adequate level of life satisfaction may help to decrease emotional distress, both short and long term, while the use of positive adjustment strategies is especially important immediately after diagnosis.