The summary of the current research on vibrotactile WM suggests that three major questions are still unresolved:

1. Which brain regions support the performance of the vibrotactile delayed discrimination task during the different task periods in the human brain?

For this purpose, an fMRI study was performed using the vibrotactile delayed discrimination task (Study I).

2. What is the role of S1 for actively maintaining the vibrotactile memory trace in the early delay period?

To address this issue, an EEG study was conducted to study the time course of S1 activity as indicated by the rolandic rhythms over the somatomotor cortex with a sufficiently high temporal resolution (Study II). In addition, the method of concurrent subliminal stimulation was used to selectively inhibit processing in S1 (Study III).

3. How is the performance of a vibrotactile WM task influenced by implicit LTM representations that are reflected by the TOE?

To answer this question, initial behavioral experiments were conducted to further investigate the TOE in vibrotactile WM (Study IV). The fMRI data from Study I were, then, re-analyzed to study the neural representations associated with the TOE (Study V).