Molholm, S. J. | bioRxiv Science

bioRxiv2026

Asymmetric neural dynamics of visuospatial attention in autism spectrum disorder

BackgroundSelective attention enables the prioritization of behaviorally relevant information in complex sensory environments. Despite substantial evidence for altered attention in autism spectrum disorder (ASD), the neurophysiological mechanisms underlying these differences remain poorly understood. MethodsHere, we integrate high-density electroencephalography (EEG), pupillometry, and behavioral measures collected during a cued covert visuospatial selective attention task to characterize mechanisms of spatial attention in children and adolescents with ASD (n = 18; 13.4 {+/-} 3.0 YO), and how they differ from age- and IQ- matched individuals with typical-development (TD) (n = 21; 14.7 {+/-} 3.8 YO). ResultsBoth groups demonstrated high target detection accuracy and comparable response times, with no significant between-group differences in behavioral performance. Furthermore, neurophysiological measures demonstrated that during leftward attention, both TD and ASD participants exhibited canonical attentional processes, including lateralized anticipatory parieto-occipital alpha modulation and enhanced P1 sensory responses to attended stimuli. Additionally, across both groups, trial-level analyses revealed that decreased anticipatory alpha power and increased P1 amplitude contralateral to the attended hemifield were associated with faster reaction times. In contrast, there were notable group differences in the neural dynamics supporting rightward spatial attention. TD participants showed early sensory gain (P1 modulation) without alpha-band modulation, whereas ASD participants exhibited modulation of posterior alpha power without effective sensory gain. Interestingly, for rightward attention, only P1 amplitude predicted reaction time, and this was the case for both groups. Resting-state alpha dynamics did not differ between groups, indicating that the attended hemifield differences reflect task-dependent differences in attentional control rather than baseline oscillatory differences. LimitationsLimitations include modest sample size and restriction to autistic individuals with relatively low support needs, which may limit the generalizability of these findings to the broader autism spectrum. ConclusionsThe similarity of leftward attention mechanisms across groups, which includes intact recruitment of anticipatory alpha modulation, argues against a global disruption of basic visuo-spatial attentional function in autistic individuals with low support needs. However, group differences emerged specifically during rightward attention, where ASD participants showed a more uniform pattern of oscillatory modulation, warranting further investigation. Collectively, these findings provide novel insight into the neural architecture of visuospatial attention in ASD, revealing how preparatory oscillatory activity shapes early sensory responses and behavior during selective attention.

neuroscience↗

bioRxiv2026

Frontal theta phase modulates asymmetric posterior neural mechanisms of spatial attention

Selective attention enables prioritization of behaviorally relevant information through coordinated control of neural excitability. Although theta-band (3-7 Hz) rhythms are implicated in top-down attentional sampling in non-human primates, how intrinsic theta phase organizes sensory gain and behavior in humans, and whether this control operates symmetrically across hemispheres, remains unknown. We recorded electroencephalography (EEG) and pupillometry in typically developing human participants (n = 21; 14.7 {+/-} 3.8 YO) performing a covert spatial attention task. Behaviorally, participants responded faster during leftward relative to rightward attention. This behavioral asymmetry was paralleled in the neural data: anticipatory modulation of parieto-occipital alpha and beta power emerged selectively during leftward attention, whereas rightward attention did not recruit comparable posterior oscillatory processes. Mechanistically, ipsilateral fronto-central theta phase emerged as a potential driver of this asymmetry. Intrinsic theta phase predicted trial-by-trial reaction time (RT) in a cue-direction-specific manner. During leftward attention, 3-Hz theta-phase over left fronto-central cortex modulated behavior and was significantly coupled to coordinated posterior alpha-band activity. In contrast, 6-7-Hz theta-phase over right fronto-central cortex modulated behavior during rightward attention but showed no relationship with alpha or beta modulation; instead, it modulated early sensory gain, indexed by P1 amplitude. Consistent with these distinct architectures, RT was jointly predicted by lower pre-stimulus alpha power and higher P1 amplitude over the attended hemisphere during leftward attention, whereas only P1 amplitude predicted performance during rightward attention. Resting-state alpha power did not differ across hemispheres, indicating that these effects were task-evoked rather than baseline spectral differences. Critically, older participants, who demonstrated enhanced behavioral performance, also exhibited a larger hemispheric asymmetry. Together, these findings reveal developmentally emerging, direction-specific neural control dynamics underlying human spatial attention. Significance StatementSpatial attention is often assumed to rely on symmetric neural mechanisms across left and right space. Using EEG in typically developing children and adolescents, we show that intrinsic theta rhythms organize attention through direction-specific control architectures. Leftward attention engages slower frontal theta (3-Hz) that coordinates posterior alpha and beta activity, consistent with oscillatory sensory gating. Rightward attention instead relies on faster theta (6-7-Hz) that modulates early sensory responses without coordinated alpha dynamics. These asymmetric mechanisms occur despite lack of hemispheric differences in resting alpha activity, indicating that they emerge during active control rather than reflecting baseline biases. These findings reveal that human attentional sampling is rhythmically organized but fundamentally asymmetric across space.

neuroscience↗