Effects of theta tACS on tactile texture memory consolidation

Tactile texture memory has been underexplored compared to visual and auditory memory, despite its importance in daily functioning. Prior research indicates that theta oscillations support memory consolidation across modalities, and frontal midline theta transcranial alternating current stimulation (tACS) has been shown to enhance long-term visual and auditory memory. This study examined whether theta-frequency tACS similarly influences tactile texture memory. 59 participants were randomly assigned to theta tACS (3 Hz), beta tACS (16 Hz), or sham stimulation administered immediately after encoding. During encoding, blindfolded participants explored 25 textures twice under auditory and visual masking. Following 20 min of stimulation and a two-hour delay, participants completed a recognition task with 25 studied textures and 25 foils, providing old/new judgments with confidence ratings. Analyses revealed no significant differences in recognition accuracy across conditions. Similarly, theta stimulation did not increase subsequent confidence in recognition judgments. These findings indicate that, unlike visual and auditory domains, post-encoding theta tACS did not enhance tactile texture memory accuracy. The results highlight potential modality-specific mechanisms in tactile memory consolidation.