Gradients of Facial EMG and Cardiac Activity During Emotional Stimulation

Abstract

Abstract We investigated the effects of a serial presentation of short emotional stimuli on facial EMG, mood and autonomic functioning including total respiratory resistance (TRR). Twenty asthmatic and 20 nonasthmatic subjects viewed series of happy and depressing pictures and Velten statements. Each series consisted of nine affectively homogeneous stimuli plus one neutral stimulus. During prestimulus, presentation and imagination intervals of each stimulus presentation, heart period (HP) and EMG activity over corrugator supercilii, orbicularis oculi and zygomaticus major muscle sites were recorded. Each series was followed by 1 min measurements of TRR, HP, respiratory sinus arrhythmia, ventilation, and mood. Each stimulus was rated with respect to pleasure and arousal. Successive increases of corrugator EMG were observed throughout the series of depressing and happy stimuli. These gradients were comparable for prestimulus, presentation or imagination intervals, thus yielding no evidence for response habituation or sensitization. Other muscle sites showed only negligible EMG gradients, while HP revealed successive shortening over each stimulus series. Marginal evidence was found to support the suggestion that successive corrugator increases affected mood and stimulus evaluations. Subjects with significant positive corrugator EMG gradients throughout depressing pictures revealed significantly lower TRR following the stimulus series. The observed changes in HP and TRR are compatible with an economical model of autonomic-somatic coupling.