Gaze-Centered Updating of Remembered Visual Space During Active Whole-Body Translations

Abstract

Van Pelt S, Medendorp WP. Gaze-centered updating of remembered visual space during active whole-body translations. J Neurophysiol 97: 1209Neurophysiol 97: -1220Neurophysiol 97: , 2007. First published November 29, 2006; doi:10.1152/jn.00882.2006. Various cortical and sub-cortical brain structures update the gaze-centered coordinates of remembered stimuli to maintain an accurate representation of visual space across eyes rotations and to produce suitable motor plans. A major challenge for the computations by these structures is updating across eye translations. When the eyes translate, objects in front of and behind the eyes' fixation point shift in opposite directions on the retina due to motion parallax. It is not known if the brain uses gaze coordinates to compute parallax in the translational updating of remembered space or if it uses gaze-independent coordinates to maintain spatial constancy across translational motion. We tested this by having subjects view targets, flashed in darkness in front of or behind fixation, then translate their body sideways, and subsequently reach to the memorized target. Reach responses showed parallax-sensitive updating errors: errors increased with depth from fixation and reversed in lateral direction for targets presented at opposite depths from fixation. In a series of control experiments, we ruled out possible biasing factors such as the presence of a fixation light during the translation, the eyes accompanying the hand to the target, and the presence of visual feedback about hand position. Quantitative geometrical analysis confirmed that updating errors were better described by using gaze-centered than gaze-independent coordinates. We conclude that spatial updating for translational motion operates in gaze-centered coordinates. Neural network simulations are presented suggesting that the brain relies on ego-velocity signals and stereoscopic depth and direction information in spatial updating during self-motion.

Parallax-sensitive remapping of visual space in occipito-parietal alpha-band activity during whole-body motion

“…Our behavioral results show that subjects are able to perform (although not perfectly) the necessary update of spatial location for an intervening passive whole-body motion, which is in line with previous studies Medendorp et al 2003b;Van Pelt and Medendorp 2007). The direction of the systematic errors, or biases (a deviation to the left or right of the veridical location), depended on the depth of the target and motion direction of the subject, consistent with the findings of Clemens et al (2012).…”

“…If the translation is misjudged in this case, updating errors arise that have the same magnitude and the same sign irrespective of the depth of the target relative to the fixation. However, we recently falsified this model by showing that updating errors during active and passive body translations increase with depth from fixation and reverse in sign for objects presented at opposite depths from fixation (Clemens et al 2012;Van Pelt and Medendorp 2007). Thus these gazecentered errors indicate that the internal remapping mechanism accounts for the geometry of motion parallax, although not perfectly.…”

“…Various cortical and subcortical regions have been implicated in this remapping during saccadic eye movements in both primates (Colby and Goldberg 1999;Duhamel et al 1992) In geometric terms, when the body translates through space, world-stationary objects move at different speeds and in different directions relative to the retina, depending on their distance from the eyes' fixation point (Van Pelt and Medendorp 2007). This geometric property, called motion parallax, does not play a role in visual remapping during saccades but must be taken into account by a gaze-centered remapping mechanism during body translations.…”

Spatial constancy mechanisms in motor control

“…Recently, Van Pelt & Medendorp [126] examined the dominant reference frame in the updating of reach targets during active translation of the whole body. Targets were presented at opposite positions (near versus far) from the subjects' fixation plane (figure 6a, middle panel).…”

The Relationship Between Low Vision and Musculoskeletal Complaints. A Case Control Study Between Age-related Macular Degeneration Patients and Age-matched Controls with Normal Vision

“…[10][11][12] Low vision does produce poor and insufficient visual information regarding the location of objects in the external environment and adversely influences motor control, thereby leading to muscle stiffness and pain. 18,19 Balance/proprioception disturbances are also classical outcomes of musculoskeletal disorders. 20 As more adults are extending their working life into old age, it may become progressively more important to prevent disorders in the neck/scapular area muscles that originate from low vision and prolonged exposure to mechanical loads in near-work conditions.…”