Russell S (2017) The involvement of the primary somatosensory cortex in tactile detection and tactile working memory. BSc Thesis, University of Nottingham, 27pp.
Whilst the role of the primary somatosensory cortex (S1) in tactile discrimination is well established, its role in tactile detection is less well understood. Recent research suggests S1 has a task-dependent role in tactile detection. This suggests it is not necessary for tasks with a low memory demand where the tactile stimulus must be held in working memory for only one second, but it is necessary for tasks with a higher memory demand where the tactile stimulus must be held for longer periods. The present study was designed to provide further insight into the role of S1 in tactile detection and identify a more specific point at which it becomes necessary for tactile working memory. TMS was applied to either S1 or the lateral occipital cortex (LOC) as a control whilst participants carried out a two-interval forced choice detection task. The delay between intervals was varied from 1 to 18s to manipulate the task demand and the time a memory trace of the first interval must be held in tactile working memory. There was no significant difference in performance with a 1s delay but performance was significantly worse with TMS over S1 compared to LOC with a 6s delay. This suggests S1 is required when a memory trace must be held in tactile working memory for 6s but not 1s, supporting its task-dependent role. No differences in performance were found with 12s or 18s delays. These results are explained in terms of participants using a different technique in completing these trials, which did not require the maintenance of a tactile memory trace.