title: The processing of chimeric and dichotic emotional stimuli by connected and disconnected cerebral hemispheres.
abstract: Hemispheric asymmetries have been widely explored in both the visual and the auditory domain, but little is known about hemispheric asymmetries in audio-visual integration. We compared the performance of a partially callosotomized patient, a total split-brain patient and a control group during the evaluation of the emotional valence of chimeric faces and dichotic syllables (an emotional syllable in one ear and white noise in the other ear) presented unimodally (only faces or only syllables) or bimodally (faces and syllables presented simultaneously). Stimuli could convey happy and sad expressions and participants were asked to evaluate the emotional content of each presentation, using a 5-point Likert scale (from very sad to very happy). In unimodal presentations, the partially callosotomized patient's judgments depended on the emotional valence of the stimuli processed by the right hemisphere, whereas those of the total split-brain patient showed the opposite lateralization; in these conditions, the control group did not show asymmetries. Moreover, in bimodal presentations, results provided support for the valence hypothesis (i.e., left asymmetry for positive emotions and vice versa) in both the control group and the partially callosotomized patient, whereas the total split-brain patient showed a tendency to evaluate the emotional content of the right hemiface even when asked to focus on the acoustic modality. We conclude that partial and total hemispheric disconnections reveal opposite patterns of hemispheric asymmetry in auditory, visual and audio-visual emotion processing. These results are discussed in the light of the right-hemisphere hypothesis and the valence hypothesis.
authors: Department of Neuroscience and Imaging, 'G. d'Annunzio' University of Chieti-Pescara, Chieti, Italy. Electronic address: giulia.prete@unich.it.
authors: Giulia
authors: G
authors: Prete
authors: Department of Psychological Science, Humanities and Territory, 'G. d'Annunzio' University of Chieti-Pescara, Chieti, Italy.
authors: Daniele
authors: D
authors: Marzoli
authors: Department of Psychological Science, Humanities and Territory, 'G. d'Annunzio' University of Chieti-Pescara, Chieti, Italy.
authors: Alfredo
authors: A
authors: Brancucci
authors: Department of Clinical and Experimental Medicine, Neuroscience and Cell Biology Section, Polytechnic University of Marche, Ancona, Italy.
authors: Mara
authors: M
authors: Fabri
authors: Regional Epilepsy Centre, Neurological Clinic, "Ospedali Riuniti", Ancona, Italy.
authors: Nicoletta
authors: N
authors: Foschi
authors: Department of Psychological Science, Humanities and Territory, 'G. d'Annunzio' University of Chieti-Pescara, Chieti, Italy.
authors: Luca
authors: L
authors: Tommasi
mesh_terms: D000328:Adult; D001307:Auditory Perception; D054022:Cerebrum / Q000502:physiology*; D004644:Emotions; D005149:Facial Expression; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006240:Happiness; D006801:Humans; D008297:Male; D008875:Middle Aged; D050812:Split-Brain Procedure; D014796:Visual Perception
keywords: Audio-visual integration; Chimeric face; Dichotic stimulation; Hemispheric asymmetry; Split-brain