NemoImage 13, Number 6, 2001, Part 2 of 2 Parts ID Ealw
EMOTION
& COGNITION
Cortical Activation Patterns of Affective and Linguistic Prosody Processing Hans Pihan*, Matthias Tabertt,
Colum D. Mad&non*,
Joan Borod*$
*Department of Neurology, The Mount Sinai Medical Center, New York tDepartment of Psychiatry, Columbia University, New York *Department of Psychology, Queens College and The Graduate Center of CUNl( New York Introduction and objective: Successful speech communication often depends on evaluation of meaning delivered by the tone of voice in relation to the verbal linguistic message. Speech components yielding affective, pragmatic or linguistic information via the tone of voice are referred to as ‘prosody’. Acoustic correlates of intonational features, such as the contour of fundamental frequency (FO) or temporal dimensions, such as the duration of stressedsyllables, potentially characterize affective speaker statesas well as subserve linguistic functions, for example, in determining sentence focus or sentence type (question vs. statement). Although lesion studies and functional imaging experiments have equivocally localized circumscribed brain areas as prerequisites for perceptual and expressive language functions, particularly in the left hemisphere (Posner & Raichle, 1995), no consensus has been achieved in localizing the processing of prosodic features subserving affective, pragmatic and diverse linguistic impressions (Heilman et al., 1993; Baum & Pell, 1999). In a preceding study, discrimination of affective speech components yielded’a high significant lateralization towards the RI-I, largely independent of emotional stimulus category (Pihan et al., 1997). Additional subvocal articulatory demands resulted in a bilateral activation with left-frontal preponderance. We suggested that neural networks in the frontal lobe of the LH provide information on motor aspects of suprasegmental signal characteristics and contribute to the evaluation of affective speech (Pihan et al., 2000). The present study focuses on the perceptual and neurophysiological interface of linguistic and affective prosodic processing and investigates the following questions: 1. What are the specific interaction effects (behavioural and in the topography of cortical activation) arising from simultaneous perception of emotional and linguistic intonation patterns? 2. To what degree do left and right hemisphere activation depend on hemispheric specialization in processing spectral and temporal information? 3. Do male and female subjects differ in the topography of cortical activation? Do interaction effects occur between subjects’ sex and speakers’ sex? Methods: By means of digital acoustic analysis/synthesis, variants of spoken statements were created differing exclusively in the course of FO: (i) upward direction, signaling questions or emphatic statements in the linguistic domain and increasing emotional expressiveness in the affective field, (ii) horizontal pitch course and (iii) downward direction, corresponding to typical statements and signaling decreasing speaker affect. A second set of synthesized stimuli was created from (i) variants exhibiting increasing duration of voiced segments. They are expected to enhance the intended effects described above. Stimuli will be presented as pairs of successive sentences, both with identical wording and differing only with respect to the acoustic parameters described above. Subjects either make affective (which sentence shows higher emotional expressiveness?) or linguistic (which sentence better indicates a question?) judgments on the whole set of stimuli in subsequent sessions. DC (direct current) components of the EEG @channels) will be analyzed by relating the mean amplitudes of presentation periods to a baseline taken from a prestimulus interval. Results: Latest behavioural and electrophysiological results will be presented and discussed.
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