Altered morphology of the nucleus accumbens in persistent developmental stuttering

• Published in: Journal of fluency disorders Vol. 55; pp. 84 - 93
• Main Authors: Neef, Nicole E., Bütfering, Christoph, Auer, Tibor, Metzger, F. Luise, Euler, Harald A., Frahm, Jens, Paulus, Walter, Sommer, Martin
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-03-2018; Elsevier Science Ltd
• Subjects: Brain; Goal-directed behavior; Magnetic resonance imaging; Medical imaging; Motivation; Neurology; Nucleus accumbens; Social factors; Social-motivational behavior; Stuttering; Vertex-wise shape analysis; Nucleus accumbens; Vertex-wise shape analysis; Social-motivational behavior; Goal-directed behavior
• ISSN: 0094-730X; 1873-801X
• DOI: 10.1016/j.jfludis.2017.04.002

•This is the first study to test the volume and shape of limbic structures in stuttering.•The right nucleus accumbens is larger in persons who stutter compared to fluent speakers.•The brain substrate concerned is tightly linked to social motivational behavior.
Neuroimaging studies in persistent developmental stuttering repeatedly report altered basal ganglia functions. Together with thalamus and cerebellum, these structures mediate sensorimotor functions and thus represent a plausible link between stuttering and neuroanatomy. However, stuttering is a complex, multifactorial disorder. Besides sensorimotor functions, emotional and social-motivational factors constitute major aspects of the disorder. Here, we investigated cortical and subcortical gray matter regions to study whether persistent developmental stuttering is also linked to alterations of limbic structures.
The study included 33 right-handed participants who stutter and 34 right-handed control participants matched for sex, age, and education. Structural images were acquired using magnetic resonance imaging to estimate volumetric characteristics of the nucleus accumbens, hippocampus, amygdala, pallidum, putamen, caudate nucleus, and thalamus.
Volumetric comparisons and vertex-based shape comparisons revealed structural differences. The right nucleus accumbens was larger in participants who stutter compared to controls.
Recent theories of basal ganglia functions suggest that the nucleus accumbens is a motivation-to-movement interface. A speaker intends to reach communicative goals, but stuttering can derail these efforts. It is therefore highly plausible to find alterations in the motivation-to-movement interface in stuttering. While behavioral studies of stuttering sought to find links between the limbic and sensorimotor system, we provide the first neuroimaging evidence of alterations in the limbic system. Thus, our findings might initialize a unified neurobiological framework of persistent developmental stuttering that integrates sensorimotor and social-motivational neuroanatomical circuitries.