Congenital Melanotic Macule of the Tongue: Report of Two Cases and Literature Review.

BACKGROUND: Congenital melanotic macule of the tongue (CMMT) has been described as a distinct entity, despite its unknown etiology. However, the diagnosis and management of affected newborns may challenge clinicians and pediatric dentists. METHODS: We document here the clinicopathological findings of two additional cases of CMMT. A literature review of CMMT reports identified across PubMed, Web of Science, Embase, and Scopus was also conducted. RESULTS: The patients, 2- and 4 month-old Venezuelan boys, respectively, presented at birth with a single or multiple dark-brown-pigmented macule exclusively on the dorsum of the tongue. Histopathological features revealed increased melanin pigmentation in the basal epithelial layer with overlying hyperkeratosis and pigment-laden subepithelial macrophages with normal morphological appearance. Nine studies comprising 17 cases of CMMT have been described hitherto. Most cases were from the USA and France (n = 6 each). Twelve (70.6%) patients were males, eight (50%) were white, and median age was 2.7 months. CMMT presented as brownish to black, solitary or multiple pigmentations located in the right or left region of the dorsum of the tongue, ranging in size from 3.0 to 30.0 mm. CONCLUSION: An important feature for the diagnosis of CMMT is the information about the manifestation at birth and consequent proportional growth. This report intends to draw the attention of pediatricians and dentists to this apparently underdiagnosed condition for decision-making and management of affected newborns.

Atypical EEG in autism spectrum disorder: Comparing a dimensional and a categorical approach.

Myriad studies have found group differences in neural dynamics between people with and without autism spectrum disorder (ASD). However, the extent to which variation in neural dynamics is related to variation in the autism phenotype across the population is not known. Here we measured behavioral characteristics of autism alongside intertrial phase coherence (ITC) and multiscale entropy (MSE) computed from EEG in order to address this question. Data were obtained from 99 adults, 38 of whom had an ASD diagnosis. Phenotypic information was obtained from the Social Responsiveness Scale (Revised), the Repetitive Behavior Questionnaire, the WHO Adult ADHD Self-Report Scale Screener, and the Beck Anxiety Inventory (Trait version). ITC and MSE were computed from EEG recorded during visual stimulation and eyes-closed rest. We found no evidence to suggest that population variance in autistic traits is underpinned by variance in neural dynamics, despite finding that ITC and MSE are more likely to be reduced in people with ASD than in those without. We conclude that there are likely to be multiple neural profiles underpinning ASD, and suggest that while individual differences in the autism phenotype exist across the population, their distribution is not underpinned by individual differences in neural dynamics. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Lateral inhibition in the autism spectrum: An SSVEP study of visual cortical lateral interactions.

Circuit level brain dysfunction has been suggested as a common mechanism through which diverse genetic risk factors and neurobiological sequelae lead to the core features of autism spectrum disorder (Geschwind 2009; Port et al. 2014). An important mediator of circuit level brain activity is lateral inhibition, and a number of authors have suggested that lateral inhibition may be atypical in ASD. However, evidence regarding putative atypical lateral connections in ASD is mixed. Here we employed a steady state visual evoked potential (SSVEP) paradigm to further investigate lateral connections within a group of high functioning adults with ASD. At a group level, we found no evidence of altered lateral interactions in ASD. Exploratory analyses reveal that greater ASD symptom severity (increased ADOS score) is associated with increased short range lateral inhibition. These results suggest that lateral interactions are not altered in ASD at a group-level, but that subtle alterations in such neurobiological processes may underlie the heterogeneity seen in the autism spectrum in terms of sensory perception and behavioral phenotype.

Understanding perceptual judgment in autism spectrum disorder using the drift diffusion model.

OBJECTIVE: Two-alternative forced-choice tasks are widely used to gain insight into specific areas of enhancement or impairment in individuals with autism spectrum disorder (ASD). Data arising from these tasks have been used to support myriad theories regarding the integrity, or otherwise, of particular brain areas or cognitive processes in ASD. The drift diffusion model (DDM) provides an account of the underlying processes which give rise to accuracy and reaction time (RT) distributions, and parameterizes these processes in terms which have direct psychological interpretation. Importantly, the DDM provides further insight into the origin of potential group differences in task performance. Here, for the first time, we used the DDM to investigate perceptual decision making in ASD. METHOD: Adults with (N = 25) and without ASD (N = 32) performed an orientation discrimination task. A drift diffusion model was applied to the full RT distributions. RESULTS: Participants with ASD responded more slowly than controls, the groups did not differ in accuracy. Modeled parameters indicated that: (a) participants with ASD were more cautious than controls (wider boundary separation); (b) nondecision time was increased in ASD; and (c) the quality of evidence extracted from the stimulus (drift rate) did not vary between groups. CONCLUSIONS: Taking the behavioral data in isolation would suggest reduced perceptual sensitivity in ASD. However, DDM results indicated that despite response slowing, there was no evidence of differential perceptual sensitivity between participants with and without ASD. Future use of the DDM in investigations of perception and cognition in ASD is highly recommended. (PsycINFO Database Record