Global and local attentional processing following optic neuritis

Abstract

After an optic neuritis (i.e., acute inflammation of the optic nerve), several patients report visual discomfort although ophthalmologic assessments show a complete recovery. To evaluate if attentional impairment could contribute to these complaints, the present study investigated global and local processing in healthy individuals and patients with recovered optic neuritis. Ten healthy controls (38.39±6.15 years) and eleven patients (33.81±5.57 years) with recovered right or left optic neuritis episode(s) completed a letter-detection task. The target to-be-detected (the letter “O”) was presented either in the right or the left hemifield and either as a small letter surrounded by flankers or as a single large letter. Response time and response accuracy were recorded. Although no significant group effect was observed regarding the number of erroneous responses, a trend toward a significant group x stimulus size x hemifield interaction was observed (F(1,19)=42.63; p=.059). With large stimuli, participants, either controls or patients, showed a lower number of errors when stimuli were presented in the left than in the right hemifield. When small stimuli were presented, healthy controls showed a similar number of errors in both hemifields whereas optic neuritis patients made a greater number of errors when these stimuli were presented in the right than in the left hemifield. Regarding response time, no significant group main effect or interaction was observed. However, a significant stimulus size x hemifield interaction revealed that small stimuli were processed faster when presented in the right hemifield whereas large stimuli were processed faster when presented in the left hemifield. Altogether, our results did not suggest any global or local attentional anomaly in optic neuritis patients. Both healthy controls and patients showed the classic hemispheric specialization for local and global attention, in that the right hemisphere is dominant for global processing while the left hemisphere is dominant for local processing.

Footnotes

 This work was supported by Foundations Edmond and Benjamin de Rothschild (Genève, Switzerland and New York, USA).