Transcranial direct current stimulation (tDCS) of the parietal cortex leads to increased false recognition

A robust finding is that brain activity in the lateral posterior parietal cortex (PPC) correlates with successful recognition. Here we test whether the PPC has a causal role in memory retrieval using transcranial direct current stimulation (tDCS). Participants were given a modified version of the Deese-Roediger-McDermott (DRM) paradigm, a well-established method for producing false recognition with high confidence. In Experiment 1, false recognition was significantly greater for active compared to sham tDCS when the anode was placed over left parietal cortex (CP3) and the cathode over right parietal cortex (CP4). These findings were replicated in Experiment 2, with both anode CP3/cathode CP4 and anode CP4/cathode CP3 active stimulation leading to greater false recognition. Differences also emerged, with anode CP4/cathode CP3 active stimulation leading to greater hits. Our findings support the proposal that the lateral PPC plays a causal role in episodic memory retrieval and can lead to enhanced subjective aspects of memory.