Influence of Cranial Irradiation with High-Energy Protons on the Visuomotor Behavior in Monkeys

The visually driven instrumental conditioning of a single monkey (Macaca mulatta) was conducted after single-dose cranial irradiation with high-energy protons. The monkey executed saccades toward the visual stimuli and then responded by manually pressing right or left lever for stimuli in right or left half-field, respectively. The percentage of correct responses with dominant right hand exceeded the percentage of such responses with left hand and temporarily decreased two months after irradiation. A month later, the percentage of correct right-hand responses returned to the level before irradiation. No significant dynamic was found for changes in percentage of correct left-hand responses. The proton irradiation effect on right-hand responses suggests possible short-term disturbances in the eye-hand coordination for right handedness while the visual perception remains unaffected.