The role of the angular gyrus in the modulation of visuospatial attention by the mental number line

Abstract

article i nfo We tend to mentally organize numbers along a left-to-right oriented horizontal mental number line, with the smaller numbers occupying the more leftward positions. This mental number line has been shown to exert an influence onthevisuospatialallocation of attention, with presentation of numbers fromthelowand highends of the mental number line inducing covert shifts of spatial attention to the left and right side of visual space, respectively. However, the neural basis of this modulation is not known. Here we used transcranial magnetic stimulation (TMS) to study the role of the angular gyrus in shifts in visuospatial attention induced by the mental numberline.Weusedaprimingparadigmwithalinebisectiontasktoassessthebiasinspatialallocationofvisual attention induced by exposure to either small (16-24) or large (76-84) ends of the mental number line. In the Small Number Prime condition, when attention is presumably biased to the left side of visual space, TMS applied overtherightangulargyrusduringthedelaybetweentheprimeandthetargetlineabolishedtheeffectofnumber priming. In contrast, application of TMS over the left angular gyrus had no significant effect. In the Large Number Prime condition (which shifted attention to the right side of visual space) both left and right TMS over the angular gyrus modulated the effect of number priming. This pattern of results reveals the involvement of the angular gyrus in the interaction between the mental number line and visual spatial attention.