The thalamus interrupts top-down attentional control

Abstract

Slower response times are observed only when salient distractors occur in the hemifield opposite the one attention is focalized on (the meridian effect). Neurophysiological data suggest that the thalamus participates in the generation of visual salience. What may be the role of the thalamus in the capture by visual onsets when attentional control is in action? Three patients with unilateral thalamic infarcts participated in a task where attentional control was interrupted by a distractor. The meridian effect was present only when distractors occurred in the ipsilesional hemifield. This result suggests that when an important signal appears during attentional focalization, the thalamus interrupts current focalization and permits the compilation of an attentional program in the midbrain aiming at generating an orienting response towards the source of this signal.