title: Bidirectional Modulation of Numerical Magnitude.
abstract: Numerical cognition is critical for modern life; however, the precise neural mechanisms underpinning numerical magnitude allocation in humans remain obscure. Based upon previous reports demonstrating the close behavioral and neuro-anatomical relationship between number allocation and spatial attention, we hypothesized that these systems would be subject to similar control mechanisms, namely dynamic interhemispheric competition. We employed a physiological paradigm, combining visual and vestibular stimulation, to induce interhemispheric conflict and subsequent unihemispheric inhibition, as confirmed by transcranial direct current stimulation (tDCS). This allowed us to demonstrate the first systematic bidirectional modulation of numerical magnitude toward either higher or lower numbers, independently of either eye movements or spatial attention mediated biases. We incorporated both our findings and those from the most widely accepted theoretical framework for numerical cognition to present a novel unifying computational model that describes how numerical magnitude allocation is subject to dynamic interhemispheric competition. That is, numerical allocation is continually updated in a contextual manner based upon relative magnitude, with the right hemisphere responsible for smaller magnitudes and the left hemisphere for larger magnitudes.
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: Qadeer
authors.initials: Q
authors.lastname: Arshad
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Nigmatullina
authors.affiliation: Institut für Quantenphysik and Centre for Integrated Quantum Science and Technology (IQST), Albert Einstein Allell, Universität Ulm, Ulm D-89069, Germany.
authors.forename: Ramil
authors.initials: R
authors.lastname: Nigmatullin
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: Paladd
authors.initials: P
authors.lastname: Asavarut
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: Usman
authors.initials: U
authors.lastname: Goga
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Khan
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: Kaija
authors.initials: K
authors.lastname: Sander
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: Shuaib
authors.initials: S
authors.lastname: Siddiqui
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: R E
authors.initials: RE
authors.lastname: Roberts
authors.affiliation: Department of Experimental Psychology, Oxford University, Oxford 0X1 3UD, UK.
authors.forename: Roi
authors.initials: R
authors.lastname: Cohen Kadosh
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: Adolfo M
authors.initials: AM
authors.lastname: Bronstein
authors.affiliation: Division of Brain Sciences, Imperial College London, London W6 8RF, UK.
authors.forename: Paresh A
authors.initials: PA
authors.lastname: Malhotra
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001288:Attention / Q000502:physiology; D001921:Brain / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D004424:Ear Canal / Q000502:physiology; D005133:Eye Movements; D005260:Female; D005625:Frontal Lobe / Q000502:physiology; D006801:Humans; D008297:Male; D055641:Mathematical Concepts; D008959:Models, Neurological; D009433:Neural Inhibition; D009760:Nystagmus, Physiologic; D010812:Physical Stimulation; D013028:Space Perception; D065908:Transcranial Direct Current Stimulation; D015348:Vision, Binocular / Q000502:physiology; D055815:Young Adult
keywords: VOR; dynamic interhemispheric competition; mental number line; numerical magnitude; vestibular cognition