Targeted reactivation during sleep differentially affects negative memories in socially anxious and healthy children and adolescents

Cognitive models propose a negative memory bias as one key factor contributing to the emergence and maintenance of social anxiety disorder (SAD). The long-term consolidation of memories relies on memory reactivations during sleep. We investigated in SAD patients and healthy controls the role of memory reactivations during sleep in the long-term consolidation of positive and negative information. Socially anxious and healthy children and adolescents learnt associations between pictures showing ambiguous situations and positive or negative words defining the situations' outcome. Half of the words were re-presented during post-learning sleep (i.e. they were cued). Recall of picture-word associations and subjective ratings of pleasantness and arousal in response to the pictures was tested for cued and uncued stimuli. In the morning after cueing, cueing facilitated retention of positive and negative memories equally well in SAD patients and healthy controls. One week later, cueing led to reduced ratings of pleasantness of negative information in SAD but not in healthy controls. These findings were coincided by more pronounced EEG theta activity over frontal, temporal and parietal regions in response to negative stimuli in SAD patients. Our findings suggest that the preferential abstraction of negative emotional information during sleep might represent one factor underlying the negative memory bias in SAD. SIGNIFICANCE STATEMENT We aim to uncover mechanisms underlying the characteristic negative memory bias in social anxiety disorder (SAD). The formation of long-lasting memories - a process referred to as memory consolidation - depend on the reactivation of newly acquired memories during sleep. We could demonstrate that experimentally induced memory reactivation during sleep renders long-term memories of negative experiences more negative in SAD patients but not in healthy controls. In parallel, reactivating negative experiences was coincided by more pronounced oscillatory theta activity in these patients. These results provide first evidence that memory reactivation during sleep might contribute to the negative memory bias in SAD

Prior knowledge is essential for the beneficial effect of targeted memory reactivation during sleep

Prior knowledge speeds up system consolidation and accelerates integration of newly acquired memories into existing neocortical knowledge networks. By using targeted memory reactivations, we demonstrate that prior knowledge is also essential for successful reactivation and consolidation of memories during sleep, both on the behavioral and oscillatory level (i.e., theta and fast spindle activity). Thus, prior knowledge is a prerequisite for new memories to enter processes of system consolidation during sleep

Widespread reduction in sleep spindle activity in socially anxious children and adolescents

Social anxiety disorder (SAD) is one of the most prevalent psychiatric diseases typically emerging during childhood and adolescence. Biological vulnerabilities such as a protracted maturation of prefrontal cortex functioning together with heightened reactivity of the limbic system leading to increased emotional reactivity are discussed as factors contributing to the emergence and maintenance of SAD. Sleep slow wave activity (SWA, 0.75-4.5 Hz) and sleep spindle activity (9-16 Hz) reflect processes of brain maturation and emotion regulation. We used high-density electroencephalography to characterize sleep SWA and spindle activity and their relationship to emotional reactivity in children and adolescents suffering from SAD and healthy controls (HC). Subjectively rated arousal was assessed using an emotional picture-word association task. SWA did not differ between socially anxious and healthy participants. We found a widespread reduction in fast spindle activity (13-16 Hz) in SAD patients compared to HC. SAD patients rated negative stimuli to be more arousing and these arousal ratings were negatively correlated with fast spindle activity. These results suggest electrophysiological alterations that are evident at an early stage of psychopathology and that are closely linked to one core symptom of anxiety disorders such as increased emotional reactivity. The role of disturbed GABAergic neurotransmission is discussed as an underlying factor

Memory cueing during sleep modifies the interpretation of ambiguous scenes in adolescents and adults

The individual tendency to interpret ambiguous situations negatively is associated with mental disorders. Interpretation biases are already evident during adolescence and due to the greater plasticity of the developing brain it may be easier to change biases during this time. We investigated in healthy adolescents and adults whether stabilizing memories of positive or negative scenes modulates the later interpretation of similar scenes. In the evening, participants learnt associations between ambiguous pictures and words that disambiguate the valence of the pictures in a positive or negative direction. Half of the words were acoustically presented (i.e. cued) during post-learning sleep which is known to benefit memory consolidation by inducing reactivation of learned information. Cued compared to un-cued stimuli were remembered better the next morning. Importantly, cueing positively disambiguated pictures resulted in more positive interpretations whereas cueing negatively disambiguated pictures led to less positive interpretations of new ambiguous pictures with similar contents the next morning. These effects were not modulated by participants’ age indicating that memory cueing was as efficient in adolescents as in adults. Our findings suggest that memory cueing during sleep can modify interpretation biases by benefitting memory stabilization and generalization. Implications for clinical settings are discussed

Photocatalytic Activity for NO Degradation by Construction Materials: Parametric Study and Multivariable Correlations

Various standards have been published in an effort to rationalize and unify the evaluation and quantification of photocatalytic activity. The experimental conditions stated in the published standards and test methods differ in many aspects that make it very difficult to compare different results. This paper focuses on the influence of the different parameters involved in the photocatalytic process. The photocatalytic active material consists of white mortar, surface coated by TiO2. The activity has been determined by quantifying the photocatalytic oxidation of NO. In the studied concentration interval the kinetics was estimated by a first order reaction. The influence on the activity by the relative humidity, temperature, irradiance, contaminant concentration and catalyst load has been studied. Most influent parameters are the catalyst load and light intensity until reaching plateau values at higher amount and intensity. Humidity influence the activity above 40% RH and an increased temperature lowers the activity. A global empirical correlation, including the mentioned variables, has been developed, allowing the determination of the photocatalytic activity at different environmental conditions (within the constraints of this research) and, when necessary, for comparison with reference conditions.Peer reviewe