Visuomotor system uses target features unavailable to conscious awareness

doi:10.1073/pnas.0702307104

Visuomotor system uses target features unavailable to conscious awareness

*College of Kinesiology, Neural Systems and Plasticity Research Group, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B2;
^‡Department of Psychology, University of Waterloo, Waterloo, ON, Canada N2L 3G1;
^§School of Kinesiology, University of Western Ontario, London, ON, Canada N6A 5B8; and
^¶Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada T1K 3M4

Edited by Dale Purves, Duke University Medical Center, Durham, NC, and approved June 25, 2007 (received for review March 12, 2007)

Abstract

After lesions to primary visual cortex, patients lack conscious awareness of visual stimuli. Interestingly, however, some retain the ability to make accurate judgments about the visual world (i.e., so-called blindsight). Similarly, damage to inferior occipitotemporal regions of cortex (e.g., lateral occipital cortex) can result in an inability to perceive object properties while retaining the ability to act on them (i.e., visual form agnosia). In the present work, we demonstrate that the ability to interact with objects in the absence of conscious awareness is not isolated to those with restricted neuropathologic conditions. Specifically, neurologically intact individuals are able to program and execute goal-directed reaching movements to a target object without awareness of extrinsic target properties; they accurately tune the dynamics of their movement and modulate it online without conscious access to features of the goal object. Thus, the planning and execution of actions are not dependent on conscious awareness of the environment, suggesting that the phenomenon of blindsight (and agnosia) reflect normal conditions of the visual system.

Footnotes

^†To whom correspondence should be sent at the present address:
Faculty of Health and Social Development, University of British Columbia, Kelowna, BC, Canada V1V 1V7.
E-mail: gordon.binsted{at}ubc.ca
Author contributions: G.B. designed research; K.B. and Z.V. performed research; G.B. and K.B. analyzed data; and G.B., M.H., and D.S. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
↵ † It should be noted that evidence regarding the integrity and utilization of retino-tectal pathways for carriage of visual information to extrastriate regions is based on findings in the macaque and therefore are only speculative with regard to human function.
Abbreviations:

LOC,

lateral occipital cortex;

V1,

primary visual cortex.