| Lesions of the right inferior particle lobe typically result in left hemi-spatial neglect or extinction. Recent evidence from single-pulse transcranial magnetic stimulation (TMS) suggests that visuo-spatial perception may be disrupted by TMS applied to the right inferior particle cortex (Fierro, et al., 2001). The present set of experiments explored the timing of activity in the angular gyrus of the right inferior particle lobe during TMS induced inattention. In experiment 1, participants were required to respond to a single asterisk presented to the contralateral or ipsilateral side of the computer screen or two asterisks presented simultaneously. A single TMS pulse was delivered at 120, 140, 160, 180, or 200 milliseconds following stimulus onset. The results suggested an effect of TMS on visual perception at 140 milliseconds. For experiment 2, participants were required to localize and identify single letters (E, F, O, or C) appearing on the contralateral or ipsilateral side of the computer screen or two letters presented simultaneously that varied in terms of letter similarity (for example, EE, EF, or EC). The results suggested a possible effect of TMS although they were inconclusive. Taken together, these results provide tentative support for the notion that the angular gyrus of the right particle lobe is crucial in the perception and localization of stimuli, suggesting that damage to this area may be critical in the genesis of extinction and neglect. Suggestions for possible future studies stimulating this brain region were discussed. |
