Which Differences in Priming Effect Between Neglect and Hemianopia? A Case Description of a Bilateral Brain-Lesioned Patient

Abstract

It is widely known that visuospatial neglect and hemianopia maybe superimposed. We considered the differences in implicit information processing which is effective in patients with neglect but not with hemianopia. We then hypothesize that a prime-word in the neglected field should determine a semantic activation effect but not in a blind hemifield. Moreover eye movements could provide further details. In this work we considered a patient with a bilateral with the presence of either a left visual neglect and a right homonymous hemianopia. Our results supported implicit information processing in the space affected by neglect but not by hemianopia.

Keywords: Eye movements; hemianopia; neglect; semantic priming.

Figure 1.

Brain MRI, T2/FLAIR weighted. Neuroimaging shows bilateral lesion involving both left and right hemispheres, in particular fronto-temporal areas on the right and occipital lobe on the left.

Figure 2.

The arrow in bold indicates the sequence of events for any experimental trial. Fixation point lasting for 500 ms; a blank followed by prime-word, which lasted on the screen for 200 ms. The square projection indicates the six possible positions in which the prime-word could occur (A = extreme left to F = extreme right). After the 250-ms blank, the target-word appeared in the centre of the screen.

Figure 3.

Comparison between patient AAP and healthy participants (HPs) at experimental task. In columns, HP results for both related and unrelated conditions: as expected, HPs have low reaction times for related condition when prime-word occurs in any of the six positions. In lines, AAP results: only when prime-word occurs on the left (A, B, C positions), reaction times are lower in related condition.

Figure 4.

(A) Average of AAP’s reaction times to the first fixation. The more extreme was the prime, the longer was time to orient gaze. No right-side movements were recorded. (B) Average of AAP’s durations for first fixation. Length of fixation reduced with a leftward gradient with shorter fixations at the left extremities.