Citation

Bosco A, Lappe M, Fattori P. J. Neurosci. 2015; 35(43): 14448-14456.

Affiliation

Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy, and patrizia.fattori@unibo.it.

Copyright

(Copyright © 2015, Society for Neuroscience)

DOI

10.1523/JNEUROSCI.0129-15.2015

PMID

26511237

Abstract

UNLABELLED: When saccadic eye movements consistently fail to land on the intended target, saccade accuracy is maintained by gradually adapting the amplitude of successive saccades to the same target. Such saccadic adaptation is usually induced by systematically displacing a small visual target during the execution of the saccade. However, saccades are normally performed to extended objects. Here we report changes in saccade amplitude when the size of a target object is systematically changed during a saccade. Moreover, we find that this manipulation also affected the visual perception of the size of that object. Human subjects were tested in shortening and lengthening adaptation where they had to make saccades to targets of different sizes, which were each shortened or lengthened during saccade execution, respectively. In both experiments, a preadaptation and postadaptation phase required manually indicating the horizontal size of each target by grip aperture and, in a further experiment, a verbal size report. We evaluated the effect of change in visual perception on saccade and on the two modalities of judgment. We observed that (1) saccadic adaptation can be induced by modifying target object size and (2) this gradual change in saccade amplitude in the direction of the object size change evokes a concomitant change in perceived object size. These findings suggest that size is a relevant signal for saccadic system and its trans-saccadic manipulation entails considerable changes at multiple levels of sensorimotor performance. SIGNIFICANCE STATEMENT: Across a saccade to an object the visual system receives two views of that object, a presaccadic peripheral view and a postsaccadic foveal view. We show that manipulation of the size of the object after the saccade modifies presaccadic size perception and motor control. Saccade amplitudes become smaller when the postsaccadic object is smaller and perceived size estimates become smaller, too. The reverse is true when the object is larger after the saccade. These findings suggest that an object feature as size is a relevant signal that influences the saccadic system and the size distortion following saccadic adaptation indicates that the representation of the central part of visual field is critical for interaction between hand and object or object recognition.

Language: en