Shifting attention in viewer- and object-based reference frames after unilateral brain injury

The aims of the present study were to investigate the respective roles that object- and viewer-based reference frames play in reorienting visual attention, and to assess their influence after unilateral brain injury. To do so, we studied 16 right hemisphere injured (RHI) and 13 left hemisphere injured (LHI) patients. We used a cueing design that manipulates the location of cues and targets relative to a display comprised of two rectangles (i.e., objects). Unlike previous studies with patients, we presented all cues at midline rather than in the left or right visual fields. Thus, in the critical conditions in which targets were presented laterally, reorienting of attention was always from a midline cue. Performance was measured for lateralized target detection as a function of viewer-based (contra- and ipsilesional sides) and object-based (requiring reorienting within or between objects) reference frames. As expected, contralesional detection was slower than ipsilesional detection for the patients. More importantly, objects influenced target detection differently in the contralesional and ipsilesional fields. Contralesionally, reorienting to a target within the cued object took longer than reorienting to a target in the same location but in the uncued object. This finding is consistent with object-based neglect. Ipsilesionally, the means were in the opposite direction. Furthermore, no significant difference was found in object-based influences between the patient groups (RHI vs. LHI). These findings are discussed in the context of reference frames used in reorienting attention for target detection

Acquired Learning Disability for Reading after Left Temporal Lobe Damage in Childhood

A 6-Year-Old Boy Developed Hemorrhage in the Left Temporal Lobe and Subsequently Underwent Left Temporal Lobectomy. afterwards, He Was Completely Unable to Learn to Read or Write. Psychological Tests Showed Impairment in Verbal Learning and Memory, with Right Ear and Right Visual Field Superiority in Verbal Perception. a Wada Test Showed No Aphasia after Right Carotid Injection. We Conclude that Damage to the Speech-Dominant Temporal Lobe Resulted in the Inability to Learn to Read or Write. Despite the Lesion, Speech Remained Strongly Lateralized to the Left Hemisphere, Accounting for the Right-Sided Advantage in Verbal Perception. Some Patients with Developmental Dyslexia May Have Dysfunction of a Strongly Dominant Left Hemisphere Rather Than a Delay or Incompleteness of Language Lateralization. © 1981 American Academy of Neurology