Characteristics of person, place, and activity that trigger failure to speak in children with selective mutism

Selective Mutism (SM) is an anxiety disorder with predictable and circumscribed situations in which children remain silent while they speak unaffectedly in others. However, core features of anxiety inducing stimuli have rarely been studied so far. Parents of children with elevated SM symptomatology participated in an online-based study and answered open ended questions about specific characteristics of a person, place, and activity that elicit failure to speak in their child. The final sample consisted of n = 91 parents with children aged between 3 and 17 years (M = 8.02 years, SD = 3.94). Answers were analyzed by qualitative content analysis. Characteristics of a person were assigned to five categories with lack of distance as the most frequently reported feature. With respect to a place, the majority of parents mentioned unknown places as a silence trigger. The most frequently mentioned feature of an activity that was designated to be associated to silence was new activity. There were only few associations between the designation of these features, age, and gender. For the first time, anxiety inducing triggers related to person, place, and activity were comprehensively assessed in children with SM. This allows a differentiated and deeper understanding of an understudied disorder. The majority of characteristics can be associated with proposed etiological factors such as increased behavioral inhibition, conditioning processes, social anxiety, and a strong need for control. Implications for effective treatments are discussed.

Faults and magma reservoirs along the Southern Andes Volcanic zone (SAVZ): linking oservations and numerical models of stress change controlling magmatic and hydrothermal fluid flow

<p> The Chilean margin is amongst the most active seismic and volcanic areas on Earth. It hosts active and fossil geothermal and mineralized systems of economic interest documenting significant geofluid migration through the crust. By comparing numerical models with field and geophysical data, we aim at pinning when and where fluid migration occurs through porous domains, fault zone conduits, or remains stored at depth awaiting a more appropriate stress field. <span>Dyking and volcanic activity occur within fault zones</span> <span>along the S</span><span>A</span><span>VZ, linked with stress field variations</span> <span>in spatial and temporal association with</span> –<span>short therm-</span> <span>seismicity</span> <span>and -long term- oblique </span><span>plate </span><span>convergence.</span> <span>Volcanoes and geothermal domains are mostly located along or at the intersection of margin-oblique fault zones (Andean Transverse Faults), and along margin-parallel strike slip zones, some which may cut the entire lithosphere (Liquiñe-Ofqui fault system). Wh</span><span>ereas</span><span> the big picture displays</span> <span>fluid flow straight to the surface, at close look significant offsets between crustal structures occur. 3D numerical models using conventional elasto-plastic rheology provide insights on the interaction of (i) an inflating magmatic cavity, (ii) a slipping fault zone, and (iii) regional tectonic stresses. Applying either (i) a magmatic overpressure or (ii) a given fault slip can trigger failure of the intervening rock, and generate either i) fault motion or ii) magmatic reservoir failure, respectively, but only for distances less than the structures' breadth even at low rock</span> <span>strength. However, at greater inter-distances the bedrock domain in between the fault zone and the magmatic cavity undergoes dilatational strain of the order of 1-5x10-5. This dilation opens the bedrock’s pore space and forms «pocket domains» that may store up-flowing over-pressurized fluids, which may then further chemically</span> interact<span> with the bedrock, for the length of time</span> <span>that</span> <span>these pockets remain open. These porous pockets</span> <span>can reach kilometric size, questioning their parental link with outcropping plutons along the margin. Moreover, bedrock permeability may also increase as fluid flow diminishes effective bedrock friction and cohesion. Comparison with rock experiments indicates that such stress and fluid pressure changes may eventually trigger failure at the intermediate timescale (repeated slip or repeated inflation). Finally, incorporating far field compression (iii)</span> <span>loads the bedrock to</span> <span>a state of stress at the verge of failure. Then, failure around the magmatic </span><span>reservoir</span><span> or </span><span>at</span> <span>the fault zone occurs for lower load</span><span>ing</span><span>.</span> <span>Permanent tectonic loading on the one hand, far field episodic seismic inversion of the stress field on the other, and localized failure all together promote a transient stress field, thus explaining the occurrence of transient fluid pathways on seemingly independent timescales. These synthetic models are then discussed with regards to specific cases along the SVZ, particularly the Tatara-San Pedro area (~36°S), where magnetotelluric profiles </span><span>document</span><span> conductive volumes at different depths underneath active faults, volcanic edifices and geothermal vents. We discuss the mechanical link between these deep sources and surface structures</span>.</p>

Reconsidering electrophysiological markers of response inhibition in light of trigger failures in the stop-signal task

We investigate the neural correlates underpinning response inhibition using a parametric ex-Gaussian model of stop-signal task performance, fit with hierarchical Bayesian methods, in a large healthy sample (N=156). The parametric model accounted for trigger failure (i.e., failures to initiate the inhibition process) and returned an SSRT estimate (SSRTEXG3) that was attenuated by ≈65ms compared to traditional non-parametric SSRT estimates (SSRTint). The amplitude and latency of the N1 and P3 event related potential components were derived for both stop-success and stop-failure trials and compared to behavioural estimates derived from traditional (SSRTint) and parametric (SSRTEXG3, trigger failure) models. Both the fronto-central N1 and P3 peaked earlier and were larger for stop-success than stop-failure trials. For stop-failure trials only, N1 peak latency correlated with both SSRT estimates as well as trigger failure and temporally coincided with SSRTEXG3, but not SSRTint. In contrast, P3 peak and onset latency were not associated with any behavioural estimates of inhibition for either trial type. While overall the N1 peaked earlier for stop-success than stop-failure trials, this effect was not found in poor task performers (i.e., high trigger failure/slow SSRT). These findings are consistent with attentional modulation of both the speed and reliability of the inhibition process, but not for poor performers. Together with the absence of any P3 onset latency effect, our findings suggest that attentional mechanisms are important in supporting speeded and reliable inhibition processes required in the stop-signal task.

Reliability of triggering inhibitory process is a better predictor of impulsivity than SSRT

The ability to control behaviour is thought to rely at least partly on adequately suppressing impulsive responses to external stimuli. However, the evidence for a relationship between response inhibition ability and impulse control is weak and inconsistent. This study investigates the relationship between response inhibition and both self-report and behavioural measures of impulsivity as well as engagement in risky behaviours in a large community sample (N=174) of healthy adolescents and young adults (15-35yrs). Using a stop-signal paradigm with a number parity go task, we implemented a novel hierarchical Bayesian model of response inhibition that estimates stop-signal reaction time (SSRT) as a distribution and also accounts for failures to react to the stop-signal (i.e., “trigger failure”), and failure to react to the choice stimulus (i.e., “go failure” or omission errors). In line with previous studies, the model reduced estimates of SSRT by approximately 100ms compared with traditional non-parametric SSRT estimation techniques. We found significant relationships between behavioural and self-report measures of impulsivity and traditionally estimated SSRT, that did not hold for the model-based SSRT estimates. Instead, behavioural impulsivity measures were correlated with rate of trigger failure. The relationship between trigger failure and impulsivity suggests that the former may index a higher order inhibition process, whereas SSRT may index a more automatic inhibition process. We suggest that the existence of distinct response inhibition processes that may be associated with different levels of cognitive control.