Event-related fMRI for the suppression of speech-associated artifacts in stuttering Christine Preibisch, a, * Peter Raab, a Katrin Neumann, b Harald A. Euler, c Alexander W. von Gudenberg, d Volker Gall, b Heinrich Lanfermann, a and Friedhelm Zanella a a Department of Neuroradiology, University Frankfurt, Frankfurt, Germany b Clinic for Phoniatrics and Paedaudiology, University Frankfurt, Frankfurt, Germany c Department of Psychology, University Kassel, Kassel, Germany d Kasseler Stottertherapie, Kassel, Germany Received 23 January 2002; revised 5 August 2002; accepted 3 March 2003 Abstract The purpose of this study was to establish functional magnetic resonance imaging (fMRI) for the investigation of brain function during overt speech production in stuttering. Up to now this technique has rarely been used for the investigation of speech production paradigms because artifacts related to overt speaking largely impair the sensitivity toward task-related activation. Recently, the temporal delay of the hemodynamic response has been exploited to achieve a suppression of speech-related artifacts. By the limitation to very short utterances (one word), a temporal segregation of the respective effects was accomplished by means of an event-related experimental design. However, the investigation of speech production in persons who stutter requires a more extensive speaking situation. Since longer and more complex utterances evoke more symptoms of stuttering than reading of single words, a useful task should at least include the reading of full sentences. In this study we performed simulations to investigate the correlation of speech-related artifacts with the respective hemodynamic response in dependency on speech duration and rate of data sampling. Furthermore, we show that prolonged stimulus durations and repetition times of 3 s still allow an effective suppression of speech-related artifacts in fluent as well as in nonfluent speakers. Not only were obvious false activations at high contrast cerebrospinal fluid tissue borders widely eliminated, subjects also displayed consistent activation in speech- related and motor areas. As these results widely resemble those obtained by earlier neuroimaging studies on language production, event-related fMRI seems to be capable of recording neurophysiological correlates of overt speech production. © 2003 Elsevier Science (USA). All rights reserved. Introduction In the last decade, functional magnetic resonance imag- ing (fMRI) has evolved into a valuable tool for the imaging of human brain function. However, from the very beginning the detrimental effects of subject motion have been recog- nized (Hajnal et al., 1994; Birn et al., 1998; Bullmore et al., 1999; Field et al., 2000), and efforts were taken to develop methods for correcting the destructive effects of bulk head motion in image time series (Friston et al., 1995a; Hajnal et al., 1995; Woods et al., 1993). Even more severe problems arise from overt speech (Achten et al., 2000; Barch et al., 1999): Artifacts are not only caused by bulk head motion (Hajnal et al., 1994; Bullmore et al., 1999), which could potentially be corrected for (Friston et al., 1995a; Hajnal et al., 1995; Woods et al., 1993), but also by magnetic field variations caused by the changing pharyngeal space during speaking (Birn et al., 1998). This type of artifact is espe- cially destructive because it leads to signal fluctuations and image distortions that depend on the individual anatomy and movement patterns during speaking. Theoretically, one could take simultaneous measurements of magnetic field changes and carry out an individual unwarping of all ac- quired images, but even with complete information this task would be hardly possible to perform (Birn et al., 1998). This * Corresponding author. Institut fu ¨r Neuroradiologie, Universita ¨t Frankfurt, Schleusenweg 2-16, D-60528 Frankfurt, Germany. Fax: +49- 69-6301-5989. E-mail address: preibisch@em.uni-frankfurt.de (C. Preibisch). NeuroImage 19 (2003) 1076 –1084 www.elsevier.com/locate/ynimg 1053-8119/03/$ – see front matter © 2003 Elsevier Science (USA). All rights reserved. doi:10.1016/S1053-8119(03)00157-5