The Sound of Feelings: Electrophysiological Responses to Emotional Speech in Alexithymia Katharina Sophia Goerlich1*, Andre´ Aleman1,2, Sander Martens1 1 Neuroimaging Center, Department of Neuroscience, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands, 2 Department of Psychology, University of Groningen, Groningen, The Netherlands Abstract Background: Alexithymia is a personality trait characterized by difficulties in the cognitive processing of emotions (cognitive dimension) and in the experience of emotions (affective dimension). Previous research focused mainly on visual emotional processing in the cognitive alexithymia dimension. We investigated the impact of both alexithymia dimensions on electrophysiological responses to emotional speech in 60 female subjects. Methodology: During unattended processing, subjects watched a movie while an emotional prosody oddball paradigm was presented in the background. During attended processing, subjects detected deviants in emotional prosody. The cognitive alexithymia dimension was associated with a left-hemisphere bias during early stages of unattended emotional speech processing, and with generally reduced amplitudes of the late P3 component during attended processing. In contrast, the affective dimension did not modulate unattended emotional prosody perception, but was associated with reduced P3 amplitudes during attended processing particularly to emotional prosody spoken in high intensity. Conclusions: Our results provide evidence for a dissociable impact of the two alexithymia dimensions on electrophysiological responses during the attended and unattended processing of emotional prosody. The observed electrophysiological modulations are indicative of a reduced sensitivity to the emotional qualities of speech, which may be a contributing factor to problems in interpersonal communication associated with alexithymia. Citation: Goerlich KS, Aleman A, Martens S (2012) The Sound of Feelings: Electrophysiological Responses to Emotional Speech in Alexithymia. PLoS ONE 7(5): e36951. doi:10.1371/journal.pone.0036951 Editor: Andreas Keil, University of Florida, United States of America Received December 15, 2011; Accepted April 13, 2012; Published May 15, 2012 Copyright: 2012 Goerlich et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by a European Science Foundation EURYI grant (NWO no. 044035001) awarded to Andre´ Aleman. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: Co-author Andre Aleman is a PLoS ONE Editorial Board member. This does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials. * E-mail: K.Goerlich@med.umcg.nl Introduction Alexithymia is a personality trait characterized by difficulties in the cognitive processing and experience of emotions. With a prevalence rate of up to 10 percent [1], alexithymia has been recognized as a risk factor for a variety of psychiatric and medical disorders, including somatization, anxiety, depression, hyperten- sion, and chronic pain [2]. In addition, alexithymia exhibits high comorbidity with disorders of the Autism spectrum [3–6]. The term alexithymia (‘no words for feelings’) was coined by Sifneos [7] to describe individuals who exhibited difficulty identifying, analyzing, and verbalizing their feelings. In addition to these cognitive impairments in emotional processing (cognitive dimension), alexithymia is defined by difficulty emotionalizing (the degree to which someone is emotionally aroused by emotion- inducing events) and fantasizing (the degree to which someone is inclined to imagine, day-dream, etc.). These latter two character- istics refer to the level of emotional experience (affective dimension). While the majority of research on alexithymia has focused on its cognitive dimension, the importance of its affective dimension has recently been pointed out [8], and the two dimensions have been suggested to exert a dissociable impact on emotional processing [9,10]. Individuals with alexithymia show a paucity of facial emotional expressions and a somewhat stiff wooden posture [2], are described as cold and distant [11] and interpersonally indifferent [12], leading to problems in social communication. Behavioral studies demonstrated that alexithymia is associated with impair- ment identifying facial expressions of emotion [13–15] matching verbal with non-verbal emotional stimuli [16], and remembering words with emotional connotations [17]. Neurobiological dysfunction in alexithymia The right hemisphere is thought to be more involved in emotion processing than the left hemisphere [18,19], a model based on evidence for verbal, analytical, conscious processing taking place in the left hemisphere [20,21] and nonverbal, emotional, sub- conscious processing taking place in the right hemisphere [22– 25]. Derived from this model, alexithymia has been proposed to result from a deficit in the interhemispheric communication between the two cerebral hemispheres, or from a dysfunction of the right hemisphere, possibly paired with a left hemisphere preference for the processing of emotions [26,27]. Several studies have provided evidence for a hypoactivity of the right hemisphere and a hyperactivity of the left hemisphere in alexithymia. For PLoS ONE | www.plosone.org 1 May 2012 | Volume 7 | Issue 5 | e36951