Abstract
The responses of neurons in the inferior colliculus, a key relay station in the primary and secondary auditory pathways, are considerably altered by auditory deprivation. Because cells of the inferior colliculus also project to the deep layers of the superior colliculus implicated in the control of eye movements, we hypothesis that the lack of auditory input during early infancy will also disrupt oculomotor control. We assessed single saccade-fixations and pursuit in 12 adults who are deaf since early infancy and in age- and gender-matched adults with normal hearing function. The results of the statistical analyses indicate no difference amongst the two groups on the single saccade-fixation task (p [[gt]] 0.05). In contrast, the oculomotor pursuit of a single target moving vertically, horizontally or in a circular manner is abnormal in deaf adults (p [[lt]]0.05). We found a greater number of fixations and saccades for the group of deaf adults. Moreover, their fixations were of shorter duration and their saccades of longer amplitude, indicating more interruptions in pursuit than for participants with normal hearing. These results support our hypothesis and suggest that early auditory deprivation disrupts the development of the neuronal circuitry underlying the control of dynamic pursuit eye movements.
Funded by NSERC and CFI grants to D.E.