Constable CL (2017) Disrupting tactile working memory using transcranial magnetic stimulation over primary somatosensory cortex. BSc Thesis, University of Nottingham, 30pp.
The primary somatosensory cortex (S1) has been found to be involved in vibrotactile working memory by acting as a storage site of tactile information. Previous research has shown that the memory trace of a vibration resides in S1 after 600ms, however not at 900ms. The aim of the current study was to determine whether working memory in S1 could be disrupted after 600ms using transcranial magnetic stimulation (TMS). Seven participants took part in a 2- interval forced choice tactile discrimination task where two vibrations of different intensities were delivered to their index fingertip. The two vibrations were separated by a retention interval in which TMS was delivered over contralateral S1 at varying time delays after the cessation of the first vibration (600, 700, 800 or 900ms). TMS was also delivered to lateral occipital cortex (LOC) which acted as a control brain area. Participants were required to determine which one of the two vibrations had the higher intensity. The performance of the participants was significantly reduced when TMS was presented over S1 compared to when presented over LOC. T-tests revealed a nonsignificant effect of time delay on performance. The results suggest that working memory cannot be disrupted by TMS after 600ms and that the memory trace in S1 may decay earlier than 600ms