RT Journal Article
SR Electronic
T1 Unleashing Potential: Transcranial Direct Current Stimulation over the Right Posterior Parietal Cortex Improves Change Detection in Low-Performing Individuals
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 10554
OP 10561
DO 10.1523/JNEUROSCI.0362-12.2012
VO 32
IS 31
A1 Philip Tseng
A1 Tzu-Yu Hsu
A1 Chi-Fu Chang
A1 Ovid J.L. Tzeng
A1 Daisy L. Hung
A1 Neil G. Muggleton
A1 Vincent Walsh
A1 Wei-Kuang Liang
A1 Shih-kuen Cheng
A1 Chi-Hung Juan
YR 2012
UL http://www.jneurosci.org/content/32/31/10554.abstract
AB The limits of human visual short-term memory (VSTM) have been well documented, and recent neuroscientific studies suggest that VSTM performance is associated with activity in the posterior parietal cortex. Here we show that artificially elevating parietal activity via positively charged electric current through the skull can rapidly and effortlessly improve people's VSTM performance. This artificial improvement, however, comes with an interesting twist: it interacts with people's natural VSTM capability such that low performers who tend to remember less information benefitted from the stimulation, whereas high performers did not. This behavioral dichotomy is explained by event-related potentials around the parietal regions: low performers showed increased waveforms in N2pc and contralateral delay activity (CDA), which implies improvement in attention deployment and memory access in the current paradigm, respectively. Interestingly, these components are found during the presentation of the test array instead of the retention interval, from the parietal sites ipsilateral to the target location, thus suggesting that transcranial direct current stimulation (tDCS) was mainly improving one's ability to suppress no-change distractors located on the irrelevant side of the display during the comparison stage. The high performers, however, did not benefit from tDCS as they showed equally large waveforms in N2pc and CDA, or SPCN (sustained parietal contralateral negativity), before and after the stimulation such that electrical stimulation could not help any further, which also accurately accounts for our behavioral observations. Together, these results suggest that there is indeed a fixed upper limit in VSTM, but the low performers can benefit from neurostimulation to reach that maximum via enhanced comparison processes, and such behavioral improvement can be directly quantified and visualized by the magnitude of its associated electrophysiological waveforms.