Prism adaptation in the healthy brain: The shift in line bisection judgments is long lasting and fluctuates

Prism adaptation power on spatial cognition: Adaptation to different optical deviations in healthy individuals

“…In the present study, the cognitive after-effects correspond to rightward neglect-like biases in line bisection tasks, as shown in previous studies e.g., [7,8]. Cognitive after-effects could be mediated via a bottom-up mechanism involving the parieto-cerebellar network [23][24][25][26].…”

“…These data were then fitted with a sigmoid function and the value on the x-axis corresponding to the point at which the participant responded 'right' 50% of the time. This point of equiprobability of 'left' and 'right' responses provided a measure of the subjective center of the line (e.g., [8]). …”

“…A perceptual bias may only be expressed following adaptation to a 15 • leftward optical deviation (i.e., when the strength of the optical deviation is stronger). Nevertheless, it should be noticed here that, although the majority of studies examining cognitive after-effects in healthy subjects have used 15 • leftward optical deviations e.g., [6][7][8][9], at least two studies have shown after-effects on the landmark task following adaptation to only a 10 • leftward optical deviation [14,20]. It is likely that the experimental conditions (e.g., different line locations presented on a computer screen [20]) or alternate data analyses (e.g., considering only the percentage of 'left responses' without determining the subjective center of the line [14]) led to a more sensitive method for expressing the perceptual bias in the landmark task.…”

“…In healthy subjects a mirror effect has been shown in simulating neglect-like symptoms. Following prism adaptation to a 15 • leftward optical deviation, rightward neglect-like biases http were observed on manual and perceptual (landmark) line bisection tasks which required participants to estimate the midpoint of line segments e.g., [7,8]. Many studies have replicated these results and extended the after-effects of prism adaptation to numerous cognitive functions e.g., [6,[9][10][11].…”

Leftward oculomotor prismatic training induces a rightward bias in normal subjects

“…When prisms are removed, they show a pointing error contralateral to prism deviation (the so-called aftereffect), which disappears after a few trials (Chapman et al 2010;Fortis et al 2011). This effect can be measured through different experimental tasks, such as open loop straight ahead pointing (SSA), visual straight ahead (VSA), line bisection, pre-bisected line length estimation (Colent et al 2000;Berberovic and Mattingley 2003;Girardi et al 2004;Schintu et al 2014), doublestep saccades tasks (Bultitude et al 2013), and computerized reaction-time tests of spatial attention (Striemer et al 2006). When initial prismatic deviation is directed leftwards, it is effective in transitorily inducing neglect-like behaviours in healthy participants (Michel et al 2003;Jacquin-Courtois et al 2013).…”