Low-frequency repetitive transcranial magnetic stimulation of the anterior temporal lobes does not dissociate social versus nonsocial semantic knowledge

Social conceptual knowledge is imperative to communicate with, interact with, and interpret human society; however, little is known about the neural basis of social concepts. Previous research has predominantly suggested that the right anterior temporal lobe (ATL) may specifically represent social conceptual knowledge, whereas the left ATL is necessary for general semantic processing. However, this view has not always been supported by empirical studies. Employing a lateralized design and two different semantic tasks and a nonsemantic control task, we aimed to clarify some of these ambiguities by potentially dissociating left from right functionality and social from nonsocial concepts, using inhibitory repetitive transcranial magnetic stimulation (rTMS) coupled with a sham and control site stimulation (N = 56). The results showed that stimulation of the left ATL led to overall faster processing times without affecting accuracy, whilst the right ATL and control groups did not significantly change in reaction times or accuracy. No difference occurred between social and nonsocial concepts after stimulation. This study is the first to show that inhibition of the left temporal lobe may improve performance on a semantic task and provides evidence that the ATLs may be lateralized in conceptual processing. The results do not confirm that the right temporal lobe is crucial for social conceptual processing, as inhibition did not significantly affect performance for social concepts.