When humans visually explore an image, they typically tend to start exploring its left side. This phenomenon, so-called pseudoneglect, is well known, but its time-course has only sparsely been studied. Furthermore, it is unclear whether age influences pseudoneglect, and the relationship between visuo-spatial attentional asymmetries in a free visual exploration task and a classical line bisection task has not been established. To address these questions, 60 healthy participants, aged between 22 and 86, were assessed by means of a free visual exploration task with a series of naturalistic, colour photographs of everyday scenes, while their gaze was recorded by means of a contact-free eye-tracking system. Furthermore, a classical line bisection task was administered, and information concerning handedness and subjective alertness during the experiment was obtained. The results revealed a time-sensitive window during visual exploration, between 260 and 960 ms, in which age was a significant predictor of the leftward bias in gaze position, i.e., of pseudoneglect. Moreover, pseudoneglect as assessed by the line bisection task correlated with the average gaze position throughout a time-window of 300–1490 ms during the visual exploration task. These results suggest that age influences visual exploration and pseudoneglect in a time-sensitive fashion, and that the degree of pseudoneglect in the line bisection task correlates with the average gaze position during visual exploration in a time-sensitive manner.

Objective: Slow waves are thought to mediate an overall reduction in synaptic strength during sleep. The specific contribution of the thalamus to this so‐called synaptic renormalization is unknown. Thalamic stroke is associated with daytime sleepiness, along with changes to sleep electroencephalography and cognition, making it a unique “experiment of nature” to assess the relationship between sleep rhythms, synaptic renormalization, and daytime functions.Methods: Sleep was studied by polysomnography and high‐density electroencephalography over 17 nights in patients with thalamic (n = 12) and 15 nights in patients with extrathalamic (n = 11) stroke. Sleep electroencephalographic overnight slow wave slope changes and their relationship with subjective daytime sleepiness, cognition, and other functional tests were assessed.Results: Thalamic and extrathalamic patients did not differ in terms of age, sleep duration, or apnea–hypopnea index. Conversely, overnight slope changes were reduced in a large cluster of electrodes in thalamic compared to extrathalamic stroke patients. This reduction was related to increased daytime sleepiness. No significant differences were found in other functional tests between the 2 groups.Interpretation: In patients with thalamic stroke, a reduction in overnight slow wave slope change and increased daytime sleepiness was found. Sleep‐ and wake‐centered mechanisms for this relationship are discussed. Overall, this study suggests a central role of the thalamus in synaptic renormalization. ANN NEUROL 2021;90:821–833

Fluent reading is characterized by fast and effortless decoding of visual and phonological information. Here we used event-related potentials (ERPs) and neuropsychological testing to probe the neurocognitive basis of reading in a sample of children with a wide range of reading skills. We report data of 51 children who were measured at two time points, i.e., at the end of first grade (mean age 7.6 years) and at the end of fourth grade (mean age 10.5 years). The aim of this study was to clarify whether next to behavioral measures also basic unimodal and bimodal neural measures help explaining the variance in the later reading outcome. Specifically, we addressed the question of whether next to the so far investigated unimodal measures of N1 print tuning and mismatch negativity (MMN), a bimodal measure of audiovisual integration (AV) contributes and possibly enhances prediction of the later reading outcome. We found that the largest variance in reading was explained by the behavioral measures of rapid automatized naming (RAN), block design and vocabulary (46%). Furthermore, we demonstrated that both unimodal measures of N1 print tuning (16%) and filtered MMN (7%) predicted reading, suggesting that N1 print tuning at the early stage of reading acquisition is a particularly good predictor of the later reading outcome. Beyond the behavioral measures, the two unimodal neural measures explained 7.2% additional variance in reading, indicating that basic neural measures can improve prediction of the later reading outcome over behavioral measures alone. In this study, the AV congruency effect did not significantly predict reading. It is therefore possible that audiovisual congruency effects reflect higher levels of multisensory integration that may be less important for reading acquisition in the first year of learning to read, and that they may potentially gain on relevance later on.

BACKGROUND: Thalamic stroke (TS) often presents with complex clinical manifestations, including sleep-wake disturbances, cognitive deficits, and autonomic dysregulation, yet the interaction between these functional alterations remains poorly understood. We aimed to investigate these interactions in a case-control lesion study. METHODS: Patients with acute TS and no-stroke controls were included prospectively in this study. The data were collected from June 2020 to September 2022 at the stroke unit or sleep laboratory of the Inselspital (Bern). Sleep-wake variables (questionnaires, actigraphy, polysomnography including electroencephalography-based sleep macroarchitecture and microarchitecture, and analysis of electroencephalography spectral power), nocturnal heart rate variability, and cognition (5 tests: processing speed, attention, working memory, visual memory, and verbal memory) were assessed at study inclusion (within 5 days poststroke for patients with stroke). RESULTS: Data from 16 patients with TS and 32 control volunteers were analyzed. All patients with stroke had lesions of the ventral nuclei, while 9 of 16 patients with stroke also had lesions in the mediodorsal nucleus (1 bilateral). TS was characterized by long sleep duration and high nocturnal heart rate variability with parasympathetic dominance. The alterations in sleep electroencephalography included a decrease in cyclic alternating pattern index, slow spindle density, the quantity of isolated sawtooth wave segments, and electroencephalography spectral power predominantly affecting the alpha band. The mediodorsal lesions were associated with a decrease in sleep spindle amplitude and slow wave amplitude and with an increase in phasic rapid eye movement sleep. Furthermore, patients with TS had deficits in processing speed, working memory, and verbal memory, mostly pronounced in patients with mediodorsal lesions. In a combined data set, multiple correlations were observed between sleep-wake, autonomic, and cognitive parameters, many of which depended on the presence of a TS. CONCLUSIONS: These findings emphasize the role of the thalamus in the regulation of sleep-wake, autonomic, and cognitive functions and their interactions and provide the theoretical basis for the therapies targeting the thalamus.

Transcranial Direct Current Stimulation (tDCS) has been employed to modulate visuo-spatial attentional asymmetries, however, further investigation is needed to characterize tDCS-associated variability in more ecological settings. In the present research, we tested the effects of offline, anodal conventional tDCS (Experiment 1) and HD-tDCS (Experiment 2) delivered over the posterior parietal cortex (PPC) and Frontal Eye Field (FEF) of the right hemisphere in healthy participants. Attentional asymmetries were measured by means of an eye tracking-based, ecological paradigm, that is, a Free Visual Exploration task of naturalistic pictures. Data were analyzed from a spatiotemporal perspective. In Experiment 1, a pre-post linear mixed model (LMM) indicated a leftward attentional shift after PPC tDCS; this effect was not confirmed when the individual baseline performance was considered. In Experiment 2, FEF HD-tDCS was shown to induce a significant leftward shift of gaze position, which emerged after 6 s of picture exploration and lasted for 200 ms. The present results do not allow us to conclude on a clear efficacy of offline conventional tDCS and HD-tDCS in modulating overt visuospatial attention in an ecological setting. Nonetheless, our findings highlight a complex relationship among stimulated area, focality of stimulation, spatiotemporal aspects of deployment of attention, and the role of individual baseline performance in shaping the effects of tDCS.

Random noise stimulation (tRNS) applied to the dorsolateral prefrontal cortex (DLPFC) enhances fluency and originality in verbal divergent thinking tasks. However, the underlying neural mechanisms of this behavioral change remain unclear. Given that the DLPFC is a key node of the executive control network (ECN) and that creativity is a two-stage process in which the ECN is primarily involved in the final idea selection stage, application of tRNS to this region shall not only result in an increase of originality and flexibility but also in a modulation of EEG activity. To test these assumptions, we collected 256-channel EEG of 40 participants before and after tRNS/sham applied to the DLPFC, during which participants performed two verbal creativity tasks. To assess stimulation-induced connectivity changes and to capture large-scale cortical communication, a source space alpha (8–12 Hz) imaginary coherence was calculated. We found that the tRNS-induced improvements in originality and flexibility were associated with bilateral DLPFC alpha coherence changes. From a large-scale networks perspective, these results suggest that tRNS-induced ECN activity is associated with increased originality and flexibility, potentially by enhancing selectivity in the idea evaluation phase. This study, for the first time, indicates a link between neurophysiological activity and tRNS-induced changes in verbal creativity.