r Human Brain Mapping 33:2477–2486 (2012) r The Role of the Left Posterior Parietal Lobule in Top-Down Modulation on Space-Based Attention: A Transcranial Magnetic Stimulation Study

r r Abstract: Converging evidence from neuroimaging as well as lesion and transcranial magnetic stimula-tion (TMS) studies has been obtained for the involvement of right ventral posterior parietal cortex (PPC) in exogenous orienting. However, the contribution of dorsal PPC to attentional orienting, partic-ularly endogenous orienting, is still under debate. In an informative peripheral cueing paradigm, in which the exogenous and endogenous orienting can be studied in relative isolation within a single task, we applied TMS over sub-regions of dorsal PPC to explore their possible distinct involvement in exogenous and endogenous processes. We found that disruption of the left posterior intraparietal sul-cus (pIPS) weakened the attentional effects of endogenous orienting, but did not affect exogenous proc-esses. In addition, TMS applied over the right superior parietal lobule (SPL) resulted in an overall increase in reaction times. The present study provides the causal evidence that the left pIPS plays a crucial role in voluntary orienting of visual attention, while right SPL is involved in the processing o