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Effects of Cathodal HD-tDCS to the rSTS on Symptoms and Audiovisual Integration in People with Psychosis Spectrum Disorders

Poster Session B - Sunday, March 8, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Rebekah L Trotti¹ (), Nicolas Raymond¹, David A Parker², Prachi Patel¹, Brendan Stiltner¹, Daphne Ying¹, Willa Molho¹, Robert MG Reinhart³, Matcheri Keshavan¹, Paulo Lizano^1,4; ¹Beth Israel Deaconess Medical Center, ²Emory University School of Medicine, ³Boston University, ⁴University of Rochester Medical Center

The right superior temporal sulcus (rSTS) is a causal node in the brain network underlying multisensory hallucination production and is associated with audiovisual integration (AVI). Psychosis-spectrum disorders feature both hallucinations and AVI deficits. We sought to reduce rSTS activity with cathodal, high-definition transcranial direct current stimulation (HD-tDCS) to reduce hallucinations and enhance audiovisual integration in people with psychotic disorders. In this double-blind, randomized, sham-controlled pilot study, HD-tDCS was applied to the rSTS using a ring montage with a cathode center and 3 anode surrounds. 12 individuals (6 active stimulation, 6 sham) received HD-tDCS for 5 days with 2 20-minute sessions per day. Symptoms and electroencephalography (EEG) were evaluated at baseline, 5-day follow-up, and 1-month follow-up. EEG tasks included a resting state and an AVI task pairing auditory and visual steady state stimuli. Changes were tested with nonparametric statistics (α=.10). Clinical measures demonstrated significant symptom reductions at the 5-day timepoint (clinician-measured: p=.06, self-reported: p=.06), which indexed overall illness severity. EEG measures indicated attenuated AVI-associated activity at 5-days and 1-month, reduced resting alpha power over the rSTS at 1-month, and enhanced auditory response at 1-month (all p<.10), suggesting longer-term neuroplastic changes. HD-tDCS of the rSTS may have a short-term effect on overall psychosis severity and longer-term effects on AVI and neurophysiology. We will further investigate rSTS engagement in this sample by examining source-space EEG measures. Given the small size of this pilot study, results provide preliminary proof-of-concept evidence supporting the initiation of a larger trial in people with hallucinations.

Topic Area: PERCEPTION & ACTION: Multisensory