Internal and External Attention in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a pervasive neurodevelopmental condition affecting individuals throughout the lifespan. Sensory hypersensitivity and superior perceptual acuity are well documented in individuals with ASD, and may indicate heightened orientation of attention to external stimuli, as attention can augment sensory perception. Recent evidence from mind-wandering research suggests that the ability to disengage attention from the external environment and direct it internally to self-generated mentation is crucial for adaptive cognition and behavior, as it allows for incorporation of past knowledge and experience in the interpretation of novel situations. We hypothesized that ASD is related to an imbalance between externally and internally directed attention, where excessive allocation of attention to external (sensory) information (i.e., external attention) limits spontaneous attention to self-generated mentation (i.e., internal attention). This attention bias restricts accessibility of internal information (e.g., memories, thoughts, knowledge) and consequently, the ability to form adaptive predictions and interpretations of the world. To test this hypothesis, three studies were conducted, examining both spontaneous and voluntary allocation of attention to internal and external stimuli, with and without competing external and internal information. Sixteen high-functioning adults with ASD and 15 typically-developing control (TDC) participants were recruited for the studies. Results demonstrated that participants with ASD had an overall reduced cognitive efficiency compared to TDC. Importantly, performance in the ASD group was less influenced by presentation of conflict and incongruency. However, no statistical evidence was found for group differences in internal or external attention across tasks. Thus, the findings suggest reduced utilization of contextual information and previous experience (i.e., internal information) in interpretation of external stimuli, but do not support the hypothesis that this deficit is related to external over internal attention bias. Multiple factors, such as within-group variability, small sample-size, and limited ecological validity of the tasks may account for these results. Our findings are discussed in relation to a range of potential explanations, as well as to other cognitive models of ASD

Neuroanatomical Alterations in High-Functioning Adults with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a pervasive neurodevelopmental condition, affecting cognition and behavior throughout the life span. With recent advances in neuroimaging techniques and analytical approaches, a considerable effort has been directed toward identifying the neuroanatomical underpinnings of ASD. While gray-matter abnormalities have been found throughout cortical, subcortical, and cerebellar regions of affected individuals, there is currently little consistency across findings, partly due to small sample-sizes and great heterogeneity among participants in previous studies. Here, we report voxel-based morphometry of structural magnetic resonance images in a relatively large sample of high-functioning adults with ASD (n = 66) and matched typically-developing controls (n = 66) drawn from multiple studies. We found decreased gray-matter volume in posterior brain regions, including the posterior hippocampus and cuneus, as well as increased gray-matter volume in frontal brain regions, including the medial prefrontal cortex, superior and inferior frontal gyri, and middle temporal gyrus in individuals with ASD. We discuss our results in relation to findings obtained in previous studies, as well as their potential clinical implications

Autonomic and Brain Responses Associated with Empathy Deficits in Autism Spectrum Disorder

Accumulating evidence suggests that autonomic signals and their cortical representations are closely linked to emotional processes, and that related abnormalities could lead to social deficits. Although socio-emotional impairments are a defining feature of autism spectrum disorder (ASD), empirical evidence directly supporting the link between autonomic, cortical, and socio-emotional abnormalities in ASD is still lacking. In this study, we examined autonomic arousal indexed by skin conductance responses (SCR), concurrent cortical responses measured by functional magnetic resonance imaging, and effective brain connectivity estimated by dynamic causal modeling in seventeen unmedicated high-functioning adults with ASD and seventeen matched controls while they performed an empathy-for-pain task. Compared to controls, adults with ASD showed enhanced SCR related to empathetic pain, along with increased neural activity in the anterior insular cortex, although their behavioral empathetic pain discriminability was reduced and overall SCR was decreased. ASD individuals also showed enhanced correlation between SCR and neural activities in the anterior insular cortex.Importantly, significant group differences in effective brain connectivity were limited to greater reduction in the negative intrinsic connectivity of the anterior insular cortex in the ASD group, indicating a failure in attenuating anterior insular responses to empathetic pain. These results suggest that aberrant interoceptive precision, as indexed by abnormalities in autonomic activity and its central representations, may underlie empathy deficits in AS

Autonomic and Brain Responses Associated with Empathy Deficits in Autism Spectrum Disorder

Accumulating evidence suggests that autonomic signals and their cortical representations are closely linked to emotional processes, and that related abnormalities could lead to social deficits. Although socio-emotional impairments are a defining feature of autism spectrum disorder (ASD), empirical evidence directly supporting the link between autonomic, cortical, and socio-emotional abnormalities in ASD is still lacking. In this study, we examined autonomic arousal indexed by skin conductance responses (SCR), concurrent cortical responses measured by functional magnetic resonance imaging, and effective brain connectivity estimated by dynamic causal modeling in seventeen unmedicated high-functioning adults with ASD and seventeen matched controls while they performed an empathy-for-pain task. Compared to controls, adults with ASD showed enhanced SCR related to empathetic pain, along with increased neural activity in the anterior insular cortex, although their behavioral empathetic pain discriminability was reduced and overall SCR was decreased. ASD individuals also showed enhanced correlation between SCR and neural activities in the anterior insular cortex.Importantly, significant group differences in effective brain connectivity were limited to greater reduction in the negative intrinsic connectivity of the anterior insular cortex in the ASD group, indicating a failure in attenuating anterior insular responses to empathetic pain. These results suggest that aberrant interoceptive precision, as indexed by abnormalities in autonomic activity and its central representations, may underlie empathy deficits in AS

Home-administered transcranial direct current stimulation is a feasible intervention for depression: an observational cohort study

Transcranial direct current stimulation (tDCS) is an emerging treatment for major depression. We recruited participants with moderate-to-severe major depressive episodes for an observational clinical trial using Soterix Medical's tDCS telehealth platform as a standard of care. The acute intervention consisted of 28 sessions (5 sessions/week, 6 weeks) of the left anodal dorsolateral prefrontal cortex (DLPFC) tDCS (2.0 mA × 30 min) followed by a tapering phase of weekly sessions for 4 weeks (weeks 7–10). The n = 16 completing participants had a significant reduction in depressive symptoms by week 2 of treatment [Montgomery–Åsberg Depression Rating Scale (MADRS), Baseline: 28.00 ± 4.35 vs. Week 2: 17.12 ± 5.32, p < 0.001] with continual improvement across each biweekly timepoint. Acute intervention responder and remission rates were 75 and 63% and 88 and 81% following the taper period (week 10)

Statistical hadronization with exclusive channels in e+e- annihilation

We perform a systematic analysis of exclusive hadronic channels in e+e- collisions at centre-of-mass energies between 2.1 and 2.6 GeV within the statistical hadronization model. Because of the low multiplicities involved, calculations have been carried out in the full microcanonical ensemble, including conservation of energy-momentum, angular momentum, parity, isospin, and all relevant charges. We show that the data is in an overall good agreement with the model for an energy density of about 0.5 GeV/fm^3 and an extra strangeness suppression parameter gamma_S ~ 0.7, essentially the same values found with fits to inclusive multiplicities at higher energy.Comment: 27 pages, 12 figure

Effects of adult exposure to bisphenol A on genes involved in the physiopathology of rat prefrontal cortex

Several neurological and behavioral dysfunctions have been reported in animals exposed to bisphenol A (BPA). However, little is known about the impact of adult exposure to BPA on brain physiopathology. Here, we focused on prefrontal cortex (PFC) of rats, because it is an important area for cognitive control, complex behaviors and is altered in many psychopathologies. Gamma-aminobutyric acid (GABA) and serotonin (5-HT) systems are essential for PFC function. Therefore, we examined the effects of adult exposure to BPA on 5α-Reductase (5α-R) and cytochrome P450 aromatase (P450arom), enzymes that synthesize GABAA receptor modulators, and tryptophan hydroxylase (Tph), the rate-limiting enzyme in 5-HT biosynthesis. To gain better understanding of BPA’s action in the adult PFC, 84 genes involved in neurotoxicity were also analysed. Adult male and female rats were subcutaneously injected for 4 days with 50 µg/kg/day, the current reference safe dose for BPA. mRNA and protein levels of 5α-R, P450arom and Tph were quantified by real-time RT-PCR and Western blot. Genes linked to neurotoxicity were analyzed by PCR-Array technology. Adult exposure to BPA increased both P450arom and Tph2 expression in PFC of male and female, but decreased 5α-R1 expression in female. Moreover, we identified 17 genes related to PFC functions such as synaptic plasticity and memory, as potential targets of BPA. Our results provided new insights on the molecular mechanisms underlying BPA action in the physiopathology of PFC, but also raise the question about the safety of short-term exposure to it in the adulthood.This research was supported by grants from Ministerio de Ciencia e Innovación (BFU2008-05340) and by the Junta de Andalucía (CTS202-Endocronología y Metabolismo)

Bisphenol A Does Not Affect Memory Performance in Adult Male Rats

Bisphenol A (BPA) is an estrogenic endocrine disruptor used for producing polycarbonate plastics and epoxy resins. This study investigated the effects of oral BPA administration on memory performance, general activity, and emotionality in adult male Sprague Dawley rats using a battery of behavioral tests, including an appetite-motivated maze test (MAZE test) used to assess spatial memory performance. In addition, in order to confirm the effects of BPA on spatial memory performance, we examined whether intrahippocampal injection of BPA affects spatial memory consolidation. In the MAZE test, although oral BPA administration at 10 mg/kg significantly altered the number of entries into the incorrect area compared to those of vehicle-treated rats, male rats given BPA through either oral administration or intrahippocampal injection failed to show significant differences in latencies to reach the reward. Also, oral BPA administration did not affect fear-motivated memory performance in the step-through passive avoidance test. Oral BPA administration at 0.05 mg/kg, the lowest dose used in this study, was correlated with a decrease in locomotor activity in the open-field test, whereas oral administration at 10 mg/kg, the highest dose used in this study, was correlated with a light anxiolytic effect in the elevated plus-maze test. The present study suggests that BPA in adulthood has little effect on spatial memory performance in male rats