Extinguishing Extinction: Hemispheric Differences in the Modulation of TMS-induced Visual Extinction by Directing Covert Spatial Attention

Abstract

The topic of spatial attention is of great relevance for researchers in various fields, including neuropsychology, cognitive neuroscience, and cognitive psychology, as well as for clinical practice. Deficits of spatial attentional arising from parietal brain damage remain largely confined to the left visual field. The mechanisms underlying this hemispheric asymmetry are still elusive. We mimicked the neuropsychological syndrome of contralesional extinction by temporarily inducing a spatial attentional bias in healthy volunteers with TMS. We investigated whether directing covert spatial attention could enhance or, more importantly, counteract the resulting behavioral deficits. Although both the left and right parietal TMS induced contralateral extinction, only left hemifield extinction following right parietal TMS was severely aggravated by a competing stimulus in the ipsilesional (right) hemifield. We put forward the hypothesis that an asymmetry with respect to the ability of detaching attention from a distractor is contributing to the right hemispheric lateralization with regard to extinction. On a broader level, we suggest that "virtual patients" might be used for evaluating neuropsychological treatment in an early stage of development, reducing the burden on actual patients.

TMS Over the Right Precuneus Reduces the Bilateral Field Advantage in Visual Short Term Memory Capacity

“…Note also that there was no effect on performance after rTMS over the right precuneus if targets were presented unilaterally. One could suggest that bilateral presentation induce competition for representation which is augmented after TMS over the right precuneus similar to the phenomenon of extinction [36,37].…”

“…It has been shown that the right PPC and the right frontal eye field seem to represent both sides of space while the left PPC and the left frontal eye field seem to be representing only the contralateral right visual space (see also Ref. [36]). How visual space is represented in the precuneus was not well understood.…”

The time course for visual extinction after a ‘virtual’ lesion of right posterior parietal cortex

“…Examples include TMS-induced attentional biases in line bisection judgments and visual search difficulties similar to the pathological rightward biases and exploratory deficits found in patients with spatial neglect (Ashbridge, Walsh, & Cowey, 1997;Bjoertomt, Cowey, & Walsh, 2002;Ellison, Schindler, Pattison, & Milner, 2004;Fierro, Brighina, Piazza, Oliveri, & Bisiach, 2001;Kim et al, 2005;Muggleton et al, 2006). Another example is a TMS-induced impairment in the detection of visual objects appearing contralateral to the stimulation site during bilateral stimulus presentation, similar to the contralesional visual extinction often observed in patients with visual neglect (Bien, Goebel, & Sack, 2012;Dambeck et al, 2006;Hilgetag et al, 2001;Jin & Hilgetag, 2008;Meister et al, 2006;Pascual-Leone et al, 1994).…”

The Effects of Electrical Brain Stimulation Upon Visual Attention and Neglect

“…In a similar vein, "virtual lesion" models may be developed to test treatment strategies on a larger group of (more readily available) healthy subjects, with neglect symptoms transiently induced by stimulation (see, for example, Bien, Goebel, & Sack, 2012). So far, similar to Dambeck et al (2006), the set-up by Bien et al (2012) has served rather to clarify the underlying neuronal mechanisms quite specifically than to fully model treatment or disease yet.…”

“…So far, similar to Dambeck et al (2006), the set-up by Bien et al (2012) has served rather to clarify the underlying neuronal mechanisms quite specifically than to fully model treatment or disease yet. They investigated whether covert spatial attention (induced by cueing) affected lateralized visual extinction induced by TMS.…”