TY - GEN A1 - Lehnen, Nadine A1 - Schröder, Lena A1 - Henningsen, Peter A1 - Glasauer, Stefan A1 - Ramaioli, Cecilia T1 - Deficient head motor control in functional dizziness: Experimental evidence of central sensory-motor dysfunction in persistent physical symptoms T2 - Progress in Brain Research N2 - Understanding the mechanisms of symptoms that are insufficiently explained by organic dysfunction remains challenging. Recently, it has been proposed that such “functional symptoms” are based on erroneous sensory processing in the central nervous system (CNS), with internal expectations dominating sensory inputs. In a pilot study, we used a head motor control set-up to assess the interplay between sensory input and expectation on the example of patients with functional dizziness. Eight patients and 11 age-matched healthy controls performed large active eye-head gaze shifts towards visual targets in the natural situation and with the head moment of inertia 3.3-fold increased. The latter induces head oscillations and the expected sensory outcome of the movement, estimated in the CNS, does not match the actual sensory input. Head oscillations were assessed in patients and in healthy subjects and compared to prior results from patients with organic disease (vestibular loss and cerebellar ataxia). Head oscillations in patients with functional dizziness were different from those of healthy subjects (F(1,17) = 27.26, P < 0.001, partial η2 = 0.62), and similar to those of patients with cerebellar ataxia, and with vestibular loss (F(2,19) = 0.56, P = 0.58). Even in the natural, unweighted, condition, head oscillations were higher in functional dizziness patients than in healthy subjects (P = 0.001). Since an extensive work-up failed to demonstrate any explanatory peripheral vestibular, motor, or cerebellar organic dysfunction, these motor control deficits are a first indication of erroneous interplay between expectations and sensory input in the CNS that could account for persistent physical symptoms. Y1 - 2019 U6 - https://doi.org/10.1016/bs.pbr.2019.02.006 SN - 1875-7855 SN - 0079-6123 VL - 249 SP - 385 EP - 400 ER - TY - GEN A1 - Schröder, Lena A1 - Werder, Dina von A1 - Ramaioli, Cecilia A1 - Wachtler, Thomas A1 - Henningsen, Peter A1 - Glasauer, Stefan A1 - Lehnen, Nadine T1 - Unstable Gaze in Functional Dizziness: A Contribution to Understanding the Pathophysiology of Functional Disorders T2 - Frontiers in Neuroscience N2 - Objective: We are still lacking a pathophysiological mechanism for functional disorders explaining the emergence and manifestation of characteristic, severely impairing bodily symptoms like chest pain or dizziness. A recent hypothesis based on the predictive coding theory of brain function suggests that in functional disorders, internal expectations do not match the actual sensory body states, leading to perceptual dysregulation and symptom perception. To test this hypothesis, we investigated the account of internal expectations and sensory input on gaze stabilization, a physiologically relevant parameter of gaze shifts, in functional dizziness. Methods: We assessed gaze stabilization in eight functional dizziness patients and 11 healthy controls during two distinct epochs of large gaze shifts: during a counter- rotation epoch (CR epoch), where the brain can use internal models, motor planning, and resulting internal expectations to achieve internally driven gaze stabilization; and during an oscillation epoch (OSC epoch), where, due to terminated motor planning, no movement expectations are present, and gaze is stabilized by sensory input alone. Results: Gaze stabilization differed between functional patients and healthy controls only when internal movement expectations were involved [F(1,17) = 14.63, p = 0.001, and partial η2 = 0.463]: functional dizziness patients showed reduced gaze stabilization during the CR (p = 0.036) but not OSC epoch (p = 0.26). Conclusion: While sensory-driven gaze stabilization is intact, there are marked, well- measurable deficits in internally-driven gaze stabilization in functional dizziness pointing at internal expectations that do not match actual body states. This experimental evidence supports the perceptual dysregulation hypothesis of functional disorders and is an important step toward understanding the underlying pathophysiology. Y1 - 2021 U6 - https://doi.org/10.3389/fnins.2021.685590 SN - 1662-453X SN - 1662-4548 VL - 15 ER - TY - GEN A1 - Schröder, Lena A1 - Regnath, Franziska A1 - Glasauer, Stefan A1 - Hackenberg, Anna A1 - Hente, Juliane A1 - Weilenmann, Sonja A1 - Pohl, Daniel A1 - Känel, Roland von A1 - Lehnen, Nadine T1 - Altered sensorimotor processing in irritable bowel syndrome: Evidence for a transdiagnostic pathomechanism in functional somatic disorders T2 - Frontiers in Neuroscience N2 - Objective A recent hypothesis suggests that functional somatic symptoms are due to altered information processing in the brain, with rigid expectations biasing sensorimotor signal processing. First experimental results confirmed such altered processing within the affected symptom modality, e.g., deficient eye-head coordination in patients with functional dizziness. Studies in patients with functional somatic symptoms looking at general, trans-symptomatic processing deficits are sparse. Here, we investigate sensorimotor processing during eye-head gaze shifts in irritable bowel syndrome (IBS) to test whether processing deficits exist across symptom modalities. Methods Study participants were seven patients suffering from IBS and seven age- and gender-matched healthy controls who performed large gaze shifts toward visual targets. Participants performed combined eye-head gaze shifts in the natural condition and with experimentally increased head moment of inertia. Head oscillations as a marker for sensorimotor processing deficits were assessed. Bayes statistics was used to assess evidence for the presence or absence of processing differences between IBS patients and healthy controls. Results With the head moment of inertia increased, IBS patients displayed more pronounced head oscillations than healthy controls (Bayes Factor 10 = 56.4, corresponding to strong evidence). Conclusion Patients with IBS show sensorimotor processing deficits, reflected by increased head oscillations during large gaze shifts to visual targets. In particular, patients with IBS have difficulties to adapt to the context of altered head moment of inertia. Our results suggest general transdiagnostic processing deficits in functional somatic disorders. KW - irritable bowel syndrome (IBS) KW - functional somatic disorders KW - somatoform disorders KW - predictive processing KW - transdiagnostic mechanism KW - gaze shift Y1 - 2022 U6 - https://doi.org/10.3389/fnins.2022.1029126 SN - 1662-453X VL - 16 ER -