Abstract
Behavioral studies have reported attention deficits in amblyopia. Here we used MRI-informed EEG source imaging to evaluate attentional modulation of neural populations in intraparietal sulcus (IPS), a region known to be involved in visual attention (Wojciulik & Kanwisher, 1999), in human adults with anisometropic and strabismic amblyopia. Our stimulus design was essentially identical to the one used in the Lauritzen et al. (2010) study. We presented two 8 deg gratings, flickering at 12.5 and 16.7 Hz, with centers 7 deg to the left and right of fixation, respectively. Observers fixated centrally and viewed the display monocularly while targets were presented bilaterally. A cue indicated that the observer should attend to the left or right gratings to detect a contrast increment on the cued grating. We recorded 128-channel evoked responses at the second harmonic of the stimulus driving frequencies. The functional area IPS was defined using multi-subject probabilistic atlases (Wang et al., 2015). Our results revealed that the modulation of the evoked responses in IPS due to attention is different between amblyopic and normal-vision observers and also different between subtypes of amblyopia. In strabismic amblyopes, both the amblyopic eye and the fellow eye showed weaker attentional modulation in both posterior and anterior IPS compared to the eyes of normal vision observers, while only the amblyopic eye of anisometropic amblyopes showed weaker attentional modulation in anterior IPS. Our results indicate that attentional modulation of neurons in IPS is strongly affected by amblyopia, especially in anterior IPS, consistent with the behavioral reports.