Differentiate neglect and hemianopia with semantic priming paradigm. Evidences in three patients with acquired brain lesion

Background: A prime word in neglected visual field should determine semantic activation effect even when the patient does not consciously perceive it, while no activation effect should be expected if the prime occurs in a blind hemifield. Objective: We aim to provide evidences on different information processing between neglect and hemianopia and find a task which could differentiate between them. Methods: We enrolled three patients: two with left neglect; one with a bilateral lesion which determined left neglect and right homonymous hemianopia. Task:Patients were required to press the space bar when a target word was deemed as “living entity”; each target was Firstly preceded by a prime word occurring in six possible positions on the horizontal line of the screen. Three different prime-target conditions were present: related, unrelated and neutral. Results: We analyzed results as a multiple single case with a Crawford analysis:patientswithleftneglectshowed a significant activation effect in all portions of space (in average 60 ms quicker in “related condition”, p<.05), except when the prime occurred in the extreme left position. The patient with left neglect and right hemianopia showed semantic activation in the left neglected space (related condition, p<.001), but not in the right space (hemianopic field). Conclusions: These results confirm the initial hypothesis: we found a semantic activation in the space affected by neglect but not in the hemianopic field; on these first data our task seems to allow a differentiation between the two deficits even though a test on a larger sample of patient is now in progress.