Pseudoneglect in Visual Search: Behavioral Evidence and Connectional Constraints in Simulated Neural Circuitry

Gigliotta, Onofrio; Malkinson, Tal Seidel; Miglino, Orazio; Bartolomeo, Paolo · 2017 · OpenAlex-citations

DOI: 10.1523/eneuro.0154-17.2017

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Summary

This study investigates the neural mechanisms underlying pseudoneglect, a physiological leftward spatial bias observed in healthy individuals during visual search and line bisection tasks. While previous research suggests this bias stems from hemispheric asymmetries in attentional networks, the specific causal mechanisms remain unclear due to limitations in human neuroimaging and non-human primate models. The authors address this gap by combining behavioral data from human participants with computational simulations of artificial neural networks controlling simulated robots (neurorobots). In Experiment 1, 101 right-handed participants performed a visual search task on a touch-sensitive tablet, canceling five randomly scattered targets. Results confirmed a significant leftward bias, with participants consistently initiating search from the left side of the display (average X coordinate: -80.23 pixels). In Experiment 2, the authors trained populations of neurorobots using genetic algorithms to perform an identical task. The neurorobots were controlled by artificial neural networks simulating the human ventral attentional network (VAN) and dorsal attentional network (DAN). Seven distinct populations were tested, varying in connectional constraints such as hemispheric asymmetry of VAN-DAN connections, the valence of these connections (excitatory vs. inhibitory), and the presence of interhemispheric inhibition between DANs. The simulation results demonstrated that anatomical asymmetry alone was insufficient to generate pseudoneglect. Neurorobots with symmetrical connections (Population C0) showed no lateral bias, while those with bilateral competence in the right hemisphere but no interhemispheric inhibition (Population E) exhibited a rightward bias. Crucially, only neurorobots equipped with biologically plausible right-lateralized VAN-DAN connections, excitatory VAN-to-DAN pathways, and inhibitory interhemispheric connections between DANs (Populations B, C, and F) replicated the human leftward bias. Furthermore, these specific constraints conferred an evolutionary advantage, resulting in higher cancellation accuracy compared to populations lacking interhemispheric inhibition. Neural analysis revealed that the leftward bias in successful models arose from an initial imbalance favoring right-hemisphere DAN activity, driven by the asymmetric network architecture. These findings provide proof of concept for the causal link between specific connectional asymmetries and pseudoneglect. The study identifies that interhemispheric inhibition and excitatory VAN influence on the ipsilateral DAN are critical biological constraints for generating physiological spatial asymmetries. This work bridges behavioral observation and neural modeling, offering a mechanistic explanation for why healthy individuals preferentially explore the left side of space, distinct from the pathological neglect seen in brain-injured patients.

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• visual search