Abstract:
Past fMRI studies found that the left ventrolateral prefrontal cortex
(VLPFC) is engaged in selective encoding strategies for prioritizing
valuable information to promote memory efficiency (Cohen et al., 2014,
2016). Our study used high-definition Transcranial Direct Current
Stimulation to investigate left VLPFC’s causal role in supporting memory
advantage for high-value items. Three groups of college participants were
asked to memorize lists of words with arbitrarily assigned point values. In
the first stage, all groups received sham stimulation as they encoded five
lists of 30 words. Two of the lists were immediately tested with free
recall. The second stage was structured like the first, but the groups
differed in receiving either sham stimulation or anodal stimulation on the
left or right VLPFC. The remaining lists were tested one day later. Results
show that left anodal stimulation significantly increased participants’
recognition of high-value words and reduced their recognition of low-value
words while the right anodal and sham stimulation did not. These results
demonstrate a causal role for left VLPFC in the implementation of selective
encoding strategies in verbal memory.