TY - JOUR
T1 - Optokinetic stimulation modulates neglect for the number space
T2 - Evidence from mental number interval bisection
AU - Priftis, Konstantinos
AU - Pitteri, Marco
AU - Meneghello, Francesca
AU - Umiltà, Carlo
AU - Zorzi, Marco
PY - 2012/2/5
Y1 - 2012/2/5
N2 - Behavioral, neuropsychological, and neuroimaging data support the idea that numbers are represented along a mental number line (MNL), an analogical, visuo-spatial representation of number magnitude. The MNL is left-to-right oriented in Western cultures, with small numbers on the left and larger numbers on the right. Left neglect patients are impaired in the mental bisection of numerical intervals, with a bias towards larger numbers that are relatively to the right on the MNL. In the present study we investigated the effects of optokinetic stimulation (OKS)-a technique inducing visuospatial attention shifts by means of activation of the optokinetic nystagmus-on number interval bisection. One patient with left neglect following right hemisphere stroke (BG) and four control patients with right hemisphere damage, but without neglect, performed the number interval bisection task in three conditions of OKS: static, leftward, and rightward. In the static condition, BG misbisected to the right of the true midpoint. BG misbisected to the left following leftward OKS, and again to the right of the midpoint following rightward OKS. Moreover, the variability of BG's performance was smaller following both leftward and rightward OKS, suggesting that the attentional bias induced by OKS reduced the "indifference zone" that is thought to underlie the length effect reported in bisection tasks. We argue that shifts of visuospatial attention, induced by OKS, may affect number interval bisection, thereby revealing an interaction between the processing of the perceptual space and the processing of the number space.
AB - Behavioral, neuropsychological, and neuroimaging data support the idea that numbers are represented along a mental number line (MNL), an analogical, visuo-spatial representation of number magnitude. The MNL is left-to-right oriented in Western cultures, with small numbers on the left and larger numbers on the right. Left neglect patients are impaired in the mental bisection of numerical intervals, with a bias towards larger numbers that are relatively to the right on the MNL. In the present study we investigated the effects of optokinetic stimulation (OKS)-a technique inducing visuospatial attention shifts by means of activation of the optokinetic nystagmus-on number interval bisection. One patient with left neglect following right hemisphere stroke (BG) and four control patients with right hemisphere damage, but without neglect, performed the number interval bisection task in three conditions of OKS: static, leftward, and rightward. In the static condition, BG misbisected to the right of the true midpoint. BG misbisected to the left following leftward OKS, and again to the right of the midpoint following rightward OKS. Moreover, the variability of BG's performance was smaller following both leftward and rightward OKS, suggesting that the attentional bias induced by OKS reduced the "indifference zone" that is thought to underlie the length effect reported in bisection tasks. We argue that shifts of visuospatial attention, induced by OKS, may affect number interval bisection, thereby revealing an interaction between the processing of the perceptual space and the processing of the number space.
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U2 - 10.3389/fnhum.2012.00023
DO - 10.3389/fnhum.2012.00023
M3 - Article
AN - SCOPUS:84933674671
JO - Frontiers in Human Neuroscience
JF - Frontiers in Human Neuroscience
SN - 1662-5161
IS - FEBRUARY 2012
ER -