Spatial localisation: does extraocular muscle proprioception play a role?

Our ability to determine the position of targets in surrounding visual spac e (spatial localisation) is an important aspect of visual function and requ ires the integration of both visual (ie retinal) and non-visual (ie extrare tinal) information. Afferent signals derived from extraocular muscle propri oceptors are though to contribute to this extraretinal information However. this has proved to be a contentious issue. This article considers the role of extraocular muscle proprioception in spatial localisation in greater de tail by discussing the evidence supporting this viewpoint. This is obtained from two main sources: firstly observations in patients in whom the propri oceptive input has been disrupted either pathologically or surgically, and secondly experimental studies in normal subjects in whom the proprioceptive input has been manipulated. The review concludes by emphasising that whils t proprioception is not the predominant source of extraretinal information that helps us determine visual direction, it is still likely to be a contri butory factor.