Deficits in Human Visual Spatial Attention Following Thalamic Lesions.
WASHINGTON UNIV ST LOUIS MO
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There has been recent speculation concerning the role that thalamic nuclei play in directing attention to locations in visual space. We measured covert shifts of visual attention in three patients with unilateral thalamic hemorrhages both shortly after the lesion and after a six month delay. The experiment measured reaction time to targets that occurred at locations to which attention had been previously cued valid trials or at a current unattended location invalid trials. Although the patients showed no deficits in visual fields with perimetry and no neglect in the six month followup, we found slow reaction times for targets on the side contralateral to the lesion whether or not attention had been cued to that location. Deficits have also been found in this task with cortical and midbrain lesions, but the patterns of performance are quite different. The results with thalamic patients suggest they have a specific deficit in the ability to use attention to improve the efficiency of processing visual targets contralateral to the lesion engage operation. This finding is in accord with ideas of a thalamic link between cortical visual attention and pattern recognition systems.
- Anatomy and Physiology