Flexibly adapting to changing environments and switching between tasks is crucial for goal-directed behavior. Task switches require the updating of the relevant task set and the inhibition of the no-longer relevant set, resulting in lower performance on trials requiring a task switch vs. repetition (i.e., switch costs). While children show greater switch costs than adults, presumably due to less distinct task-set representations, age differences can be mitigated by training. Studies in adults suggest that neural task-set representations become more distinct with training and thus enable faster processing in the lateral prefrontal cortex (lPFC). However, it is still unclear how changes in neural representations contribute to training-related improvements of task switching in children.
We addressed this question using multivariate pattern analysis (MVPA) of fMRI data in children (8–11 years) that completed nine weeks of task-switching (N=32) or single-task (N=30) training. Pre-training, neural task-set representations were less distinct on switch compared to repeat trials. This effect did not differ between children and adults (20–30 years, N=53) that completed the pre-training fMRI session only. With training, children in the task-switching training group showed improved performance, accompanied by decreased activation in lPFC. However, MVPA showed that task-set decoding accuracy in the lPFC did not change with training. These results suggest that intensive training of task switching in childhood might be related to general improvements in meta-control processes, as evident in reduced activation in brain regions supporting the management of relevant rules, rather than to increasing distinctiveness of the specific task-set representations.