title: Behavioral investigation on the frames of reference involved in visuomotor transformations during peripheral arm reaching.
abstract: BACKGROUND
  Several psychophysical experiments found evidence for the involvement of gaze-centered and/or body-centered coordinates in arm-movement planning and execution. Here we aimed at investigating the frames of reference involved in the visuomotor transformations for reaching towards visual targets in space by taking target eccentricity and performing hand into account.
  
  
  RESULTS
  We examined several performance measures while subjects reached, in complete darkness, memorized targets situated at different locations relative to the gaze and/or to the body, thus distinguishing between an eye-centered and a body-centered frame of reference involved in the computation of the movement vector. The errors seem to be mainly affected by the visual hemifield of the target, independently from its location relative to the body, with an overestimation error in the horizontal reaching dimension (retinal exaggeration effect). The use of several target locations within the perifoveal visual field allowed us to reveal a novel finding, that is, a positive linear correlation between horizontal overestimation errors and target retinal eccentricity. In addition, we found an independent influence of the performing hand on the visuomotor transformation process, with each hand misreaching towards the ipsilateral side.
  
  
  CONCLUSIONS
  While supporting the existence of an internal mechanism of target-effector integration in multiple frames of reference, the present data, especially the linear overshoot at small target eccentricities, clearly indicate the primary role of gaze-centered coding of target location in the visuomotor transformation for reaching.
authors.affiliation: Laboratory of Neuropsychology and Cognitive Neuroscience, Department of Neuroscience and Imaging, University "G. d'Annunzio", Chieti, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Ambrosini
authors.forename: Marco
authors.initials: M
authors.lastname: Ciavarro
authors.forename: Gina
authors.initials: G
authors.lastname: Pelle
authors.forename: Mauro Gianni
authors.initials: MG
authors.lastname: Perrucci
authors.forename: Gaspare
authors.initials: G
authors.lastname: Galati
authors.forename: Patrizia
authors.initials: P
authors.lastname: Fattori
authors.forename: Claudio
authors.initials: C
authors.lastname: Galletti
authors.forename: Giorgia
authors.initials: G
authors.lastname: Committeri
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001132:Arm; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement; D010775:Photic Stimulation; D011597:Psychomotor Performance; D014794:Visual Fields; D014796:Visual Perception; D055815:Young Adult