Implicit task sequence learning and consolidation: a continuous theta burst stimulation (cTBS) study

Previous results showed that patients with bilateral lesions on the dorsolateral prefrontal cortex (DLPFC) do not show implicit learning of a sequence of tasks, namely implicit task sequence learning. However, these results do not give insights on the causality of the DLPFC. The aim of this study was to test the causality of the right DLPFC for implicit task sequence learning and consolidation. Temporary inhibition of the right DLPFC in healthy participants was induced by using continuous theta burst (cTBS) transcranial magnetic stimulation. Afterwards, participants performed the task sequence learning paradigm (TSL), which measures implicit task sequence learning. Additionally, to show that the primary motor cortex (M1) was not involved in eventual cTBS effects on the TSL, the excitability of the M1 was measured before and after cTBS. Consolidation was assessed by repeating the TSL 24 hours later. The results showed that sequence learning was present in both sessions but cTBS did not influence performance. Furthermore, the excitability of the M1 did not change after cTBS. In conclusion, cTBS above the right DLPFC does not change the excitability of the M1, and does not influence implicit task sequence learning and consolidation.