title: Visual face-movement sensitive cortex is relevant for auditory-only speech recognition.
abstract: It is commonly assumed that the recruitment of visual areas during audition is not relevant for performing auditory tasks ('auditory-only view'). According to an alternative view, however, the recruitment of visual cortices is thought to optimize auditory-only task performance ('auditory-visual view'). This alternative view is based on functional magnetic resonance imaging (fMRI) studies. These studies have shown, for example, that even if there is only auditory input available, face-movement sensitive areas within the posterior superior temporal sulcus (pSTS) are involved in understanding what is said (auditory-only speech recognition). This is particularly the case when speakers are known audio-visually, that is, after brief voice-face learning. Here we tested whether the left pSTS involvement is causally related to performance in auditory-only speech recognition when speakers are known by face. To test this hypothesis, we applied cathodal transcranial direct current stimulation (tDCS) to the pSTS during (i) visual-only speech recognition of a speaker known only visually to participants and (ii) auditory-only speech recognition of speakers they learned by voice and face. We defined the cathode as active electrode to down-regulate cortical excitability by hyperpolarization of neurons. tDCS to the pSTS interfered with visual-only speech recognition performance compared to a control group without pSTS stimulation (tDCS to BA6/44 or sham). Critically, compared to controls, pSTS stimulation additionally decreased auditory-only speech recognition performance selectively for voice-face learned speakers. These results are important in two ways. First, they provide direct evidence that the pSTS is causally involved in visual-only speech recognition; this confirms a long-standing prediction of current face-processing models. Secondly, they show that visual face-sensitive pSTS is causally involved in optimizing auditory-only speech recognition. These results are in line with the 'auditory-visual view' of auditory speech perception, which assumes that auditory speech recognition is optimized by using predictions from previously encoded speaker-specific audio-visual internal models.
authors: Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Deptartment of Psychiatry and Psychotherapy, University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany; Neuroimaging Center, Technische Universität Dresden, Dresden, Germany. Electronic address: philipp.riedel@uniklinikum-dresden.de.
authors: Philipp
authors: P
authors: Riedel
authors: Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany. Electronic address: ragert@cbs.mpg.de.
authors: Patrick
authors: P
authors: Ragert
authors: Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany. Electronic address: schelinski@cbs.mpg.de.
authors: Stefanie
authors: S
authors: Schelinski
authors: Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Neuroimaging Center, Technische Universität Dresden, Dresden, Germany. Electronic address: kiebel@cbs.mpg.de.
authors: Stefan J
authors: SJ
authors: Kiebel
authors: Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; Psychology Department, Humboldt University of Berlin, Berlin, Germany. Electronic address: kriegstein@cbs.mpg.de.
authors: Katharina
authors: K
authors: von Kriegstein
mesh_terms: D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D002540:Cerebral Cortex / Q000502:physiology; D004566:Electrodes; D005145:Face / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008959:Models, Neurological; D009068:Movement / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D013067:Speech Perception / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation / Q000009:adverse effects; D014793:Visual Cortex / Q000502:physiology*; D055815:Young Adult
keywords: Auditory; Lip-reading; Prediction; Speech; pSTS; tDCS