Transcranial Direct Current Stimulation over the Posterior Parietal Cortex Increases Nontarget Retrieval during...

Area of Science:

• Cognitive Neuroscience
• Neuroimaging
• Human Brain Research

Background:

• Visual working memory (VWM) relies on accurate feature binding.
• The posterior parietal cortex (PPC) is implicated in VWM feature binding.
• The causal role of the PPC in VWM feature binding requires further investigation.

Purpose of the Study:

• To causally investigate the role of the posterior parietal cortex (PPC) in feature binding during visual working memory (VWM).
• To examine the effects of transcranial direct current stimulation (tDCS) over the PPC on VWM performance.
• To differentiate the impact of PPC stimulation on misbinding versus informed guessing.

Main Methods:

• Three transcranial direct current stimulation (tDCS) experiments were conducted.
• Participants completed delayed estimation and change detection tasks.
• tDCS was applied over the PPC, occipital cortex, or sham condition.

Main Results:

• PPC stimulation selectively increased recall response time (RT) and the probability of nontarget responses (pNT), indicating impaired feature binding.
• The effects of PPC stimulation on RT were more pronounced in informed guessing trials compared to misbinding trials.
• PPC stimulation did not affect recognition RT or accuracy in a change detection task.

Conclusions:

• Direct causal evidence supports the specific involvement of the PPC in feature binding during VWM retrieval.
• PPC stimulation impacts both the speed and response preference aspects of VWM feature binding.
• These findings advance the understanding of the neural underpinnings of feature binding in VWM.