An emerging hypothesis postulates that internal noise is a key factor influencing perceptual abilities in autism spectrum disorder (ASD). Given fundamental and inescapable effects of noise on nearly all aspects of neural processing, this could be a critical abnormality with broad implications for perception, behavior, and cognition. However, this proposal has been challenged by both theoretical and empirical studies. A crucial question is whether and how internal noise limits perception in ASD, independently from other sources of perceptual inefficiency, such as the ability to filter out external noise. Here, we separately estimated internal noise and external noise filtering in ASD. In children and adolescents with and without ASD, we computationally modeled individuals’ visual orientation discrimination in the presence of varying levels of external noise. The results revealed increased internal noise and worse external noise filtering in individuals with ASD. For both factors, we also observed high inter-individual variability in ASD, with only the internal noise estimates significantly correlating with severity of ASD symptoms. We provide evidence for reduced perceptual efficiency in ASD that is due to both increased internal noise and worse external noise filtering, while highlighting internal noise as a possible contributing factor to variability in ASD symptoms.

Atypical visual motion perception has been widely observed in individuals with autism spectrum disorder (ASD). The pattern of results, however, has been inconsistent. Emerging mechanistic hypotheses seek to explain these variable patterns of atypical motion sensitivity, each uniquely predicting specific patterns of performance across varying stimulus conditions. Here, we investigated the integrity of two such fundamental mechanisms—response gain control and receptive field size. Twenty children and adolescents with ASD and 20 typically developing (TD) age- and IQ-matched controls performed a motion discrimination task. To adequately model group differences in both mechanisms of interest, we tested a range of 23 stimulus conditions varying in size and contrast. Results revealed a motion perception impairment in ASD that was specific to the smallest sized stimuli (1°), irrespective of stimulus contrast. Model analyses provided evidence for larger receptive field size in ASD as the mechanism that explains this size-specific reduction of motion sensitivity.

Segregation of objects from their backgrounds is a fundamental visual function and one that is particularly effective when objects are in motion. Theoretically, suppressive center-surround mechanisms are well suited for accomplishing motion segregation. This longstanding hypothesis, however, has received limited empirical support. We report converging correlational and causal evidence that spatial suppression of background motion signals is critical for rapid segmentation of moving objects. Motion segregation ability is strongly predicted by both individual and stimulus-driven variations in spatial suppression strength. Moreover, aging-related superiority in perceiving background motion is associated with profound impairments in motion segregation. This segregation deficit is alleviated via perceptual learning, but only when motion segregation training also causes decreased sensitivity to background motion. We argue that perceptual insensitivity to large moving stimuli effectively implements background subtraction, which, in turn, enhances the visibility of moving objects and accounts for the observed link between spatial suppression and motion segregation.

The current study investigated whether attentional mechanisms operate on ensembles as higher-order units for selection. In Experiment 1, we presented sets of circles and asked participants to compare the mean sizes of the sets while concurrently detecting a small probe appearing at a centroid of one of the sets. We found that, both with and even without the task instruction to favour larger mean sizes, people's mean size judgement was more accurate for the sets with larger mean sizes. In addition, detection of the probe appearing in the set with the largest mean size was facilitated by a matching task instruction. However, when the task instruction favoured smaller mean sizes, mean size judgement became more accurate for the sets with smaller mean sizes. These results suggest that attentional selection can be based on ensembles. In Experiment 2, we found further evidence that attention was directed towards the centroid of an ensemble, rather than towards an individual member of the ensemble. Together, these results suggest that attentional modulation can operate at the level of ensembles instead of selecting individuals separately and that the centroid of an ensemble can be the locus of selection based on an ensemble.

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The incidence of small thyroid malignancy has increased. However, there is no evidence-based guideline for managing thyroid nodules ≤ 5 mm on ultrasonography (US). We evaluated how to manage thyroid nodules ≤ 5 mm. Thyroid nodules ≤ 5 mm in size on US that had undergone surgery and US-guided fine-needle aspiration were eligible. A total of 3,117 thyroid nodules in 3,012 patients were included. The size changes of malignant and benign nodules during follow-up were evaluated. Thyroid malignancies were classified according to follow-up and surgery time within and after 12 months. Clinico-pathological characteristics were compared. Of 3,117 nodules, 1,639 nodules in 1,619 patients were benign and 1,478 in 1,427 were malignant. Only 5.8 and 1.2 % of malignant nodules and 6.8 and 4.2 % of benign nodules increased in size when a 2-mm and 3-mm change on US were referenced. Of 1,079 patients with an index malignancy ≤ 5 mm, extrathyroidal extension, lymph node metastasis, recurrence, and mortality were not significantly different between patients with and without follow-up and between patients with surgery within 12 months and after 12 months. None of the patients who underwent surgery had distant metastasis and none died of thyroid malignancy. In thyroid nodules ≤ 5 mm found on US, US-FNA could be recommended in cases of increased size during US follow-up if lateral LNM was not found because a delay in surgery did not impact cancer recurrence and mortality.

Keywords: tRNS1, perception2, stimulation3, noise4, psychophysics5, vision6. (Min.5-Max. 8) 26 27 tRNS improves vision-in-noise 2 Abstract (250 words) 28 29Transcranial random noise stimulation (tRNS), a relatively recent addition to the field of non-30 invasive, electrical brain stimulation, has been shown to improve perceptual and cognitive functions 31 across a wide variety of tasks. However, the underlying mechanisms of visual improvements caused 32 by tRNS remain unclear. To study this question, we employed a well-established, equivalent-noise 33 approach, which measures perceptual performance at various levels of external noise and is 34 formalized by the Perceptual Template Model (PTM). This approach has been used extensively to 35 infer the underlying mechanisms behind changes in visual processing, including those from 36 perceptual training, adaptation and attention. Here, we used tRNS during an orientation 37 discrimination task in the presence of increasing quantities of external visual white noise and fit the 38 PTM to gain insights into the effects of tRNS on visual processing. Our results show that tRNS 39 improves visual processing when stimulation is applied during task performance, but only at high 40 levels of external visual white noise-a signature of improved external noise filtering. There were no 41 significant effects of tRNS on task performance after the stimulation period. Of interest, the reported 42 effects of tRNS on visual processing mimic those previously reported for endogenous spatial 43 attention, offering a potential area of investigation for future work. 44 45 46 47 tRNS improves vision-in-noise 3