| While learning has been extensively examined in sensory and motor systems, it is less well known how learning affects a system which supports continued flexibility of processing to enable goal-directed behavior. Long-term WM training can impact the system such that practice effects transfer to other tasks, however, it is unclear which WM subprocesses are affected by practice or if this same result can occur with short-term training. Previous studies have found increased neural efficiency with short-term WM practice; however, they were unable to distinguish which representations and processes of the WM network improved with practice. Thus, questions remain regarding if short-term WM practice can improves WM subprocesses and transfers to unpracticed tasks to enable increased information processing. To investigate this, we proposed that two subprocesses of the WM system could be improved with short-term training: WM storage and the interference resistant maintenance. This would suggest that short-term training is sufficient to yield generalized practice effects, as well as pinpointing the subprocesses affected by training. The results found that neither storage nor interference protection was improved with object WM practice. Further, after WM training on a spatial WM task, maintaining spatial information in the face of interfering information improved, again suggesting that effects of training are specific to the type of information practiced with and do not generalize to other information types. Experiment 3 investigated the effects of short-term practice further, using fMRI, and found that with short-term practice, more efficient top-down control was largely a result of more efficient WM representations of task processes. Together, these findings present a more complete picture of how this flexible system is affected by short-term training. Our results suggest that short-term training does not provide generalized improvements in WM storage and interference protection, as changes in performance were typically due to improvements in representations of specific stimulus items or circumscribed to one type of information. Additionally, we extend the concept of 'information representation' to include representations of task processes as another type of information represented in the brain that can be differentially affected by practice. Long-term training and increased neural activation may be required to enable more generalized changes to the WM system that transfer to unpracticed tasks. |
