| Abstract/Results: | ABSTRACT:
Working memory training (WMT) has been used to promote neuroplasticity in older people and tDCS has been proposed to boost WMT effects. Nevertheless, there is not robust evidence of WMT effectiveness and the few studies assessing the combination of tDCS with WMT used cognitive tasks as endpoints. However, the use of different markers, as the event-related potentials (ERPs), can be useful to better understand the combined or individual effects of these interventions. Thus, the studies presented in this dissertation aimed to assess WMT effects, as well as, the add-on effects of tDCS. Given the need to use different endpoints to measures WMT-induced neuroplasticity, an additional aim was to assess if the ERPs can be used as indexes of fluid intelligence (Gf), a commonly assessed constructed to infer generalization of WMT. In the first study, we presented a meta-analysis on the effects of WMT in healthy elderly. Small significant and long-lasting gains were observed in working memory (WM), but not in short-term memory (STM) and Gf tasks. Type of training tasks, the adopted outcome measures, the training duration, and the total number of training hours moderated WMT effects. In the second study, we performed a systematic review on the uses of tDCS to boost WM in healthy older adults. The studies suggest that tDCS may modulate WM in this population, improving the accuracy and shortening the reaction time. In the third study, we performed a randomized double-blind controlled experiment to evaluate the effects of 5-day WMT coupled with tDCS in healthy older adults. Fifty-four participants were assigned to one of three groups: 1) WMT (dual n-back task)+active tDCS (atDCS); 2) WMT+sham tDCS (stDCS); or 3) sham task + sham tDCS. During the training, both groups that performed the dual n-back task (WMT+atDCS; WMT+stDCS) improved throughout sessions, with no significant differences between them. However, the “WMT+atDCS” was the only group that presented gains in Gf and verbal STM after training (i.e., next day after the intervention) and at follow-up (i.e., 15 days follow-up). Finally, in the fourth study, we explored whether ERP components (i.e., P2, P3b and the LPC - late positive complex) are associated with Gf in the elderly. Fifty-seven participants performed a continuous performance task and a visual oddball paradigm while EEG was recorded. They were divided into high-performance (HP) and low performance (LP) groups according to their performance in the Raven’s Advanced Progressive Matrices test (RAPM). HP group presented significant higher LPC amplitudes in the CPT and shorter P3b latencies in the oddball task when compared to the LP group.
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Working memory and neuroplasticity in older people: A behavioral and neurofunctional approach