Slide Slam F15
Influences of inhibitory TMS over visual area V5 on visual speech recognition
Lisa Jeschke1, Brian Mathias1, Katharina von Kriegstein1; 1TU Dresden, Dresden, Germany
The middle temporal visual area (V5) plays a critical role in the perception of low level motion stimuli such as random dot patterns, supported by studies using transcranial magnetic stimulation (TMS; e.g., Beckers & Zeki, 1995). In addition, functional magnetic resonance imaging (fMRI) studies demonstrate V5 responses to the rather complex biological motion that characterizes visual speech (Borowiak et al., 2018). However, whether there is a causal influence of V5 on visual speech recognition remains unclear. Here, we investigated the contribution of V5 to visual speech recognition (lip-reading) by using neuronavigated TMS on area V5, for which the coordinates were previously acquired with an fMRI localizer. 24 participants underwent offline continuous theta burst stimulation over bilateral V5 in one session, and over the vertex as control site in another session. Subsequently, we administered a visual speech recognition task and a motion direction (control) task using random-dot kinematograms. There are two main results. First, we found that TMS on V5 increased response times compared to the stimulation over the vertex region in both tasks. Second, there was no significant interaction of stimulation and task, indicating that there was no substantial difference of stimulation on the response times in motion-direction and visual-speech recognition. We conclude that the area V5 not only contributes to low-level motion recognition mechanisms, it also plays a role in the processing of complex visual human communication signals.