title: Alien Hand, Restless Brain: Salience Network and Interhemispheric Connectivity Disruption Parallel Emergence and Extinction of Diagonistic Dyspraxia.
abstract: Diagonistic dyspraxia (DD) is by far the most spectacular manifestation reported by sufferers of acute corpus callosum (CC) injury (so-called "split-brain"). In this form of alien hand syndrome, one hand acts at cross purposes with the other "against the patient's will". Although recent models view DD as a disorder of motor control, there is still little information regarding its neural underpinnings, due to widespread connectivity changes produced by CC insult, and the obstacle that non-volitional movements represent for task-based functional neuroimaging studies. Here, we studied patient AM, the first report of DD in patient with complete developmental CC agenesis. This unique case also offers the opportunity to study the resting-state connectomics of DD in the absence of diffuse changes subsequent to CC injury or surgery. AM developed DD following status epilepticus (SE) which resolved over a 2-year period. Whole brain functional connectivity (FC) was compared (Crawford-Howell [CH]) to 16 controls during the period of acute DD symptoms (Time 1) and after remission (Time 2). Whole brain graph theoretical models were also constructed and topological efficiency examined. At Time 1, disrupted FC was observed in inter-hemispheric and intra-hemispheric right edges, involving frontal superior and midline structures. Graph analysis indicated disruption of the efficiency of salience and right frontoparietal (FP) networks. At Time 2, after remission of diagnostic dyspraxia symptoms, FC and salience network changes had resolved. In sum, longitudinal analysis of connectivity in AM indicates that DD behaviors could result from disruption of systems that support the experience and control of volitional movements and the ability to generate appropriate behavioral responses to salient stimuli. This also raises the possibility that changes to large-scale functional architecture revealed by resting-state functional magnetic resonance imaging (fMRI) (rs-fMRI) may provide relevant information on the evolution of behavioral syndromes in addition to that provided by structural and task-based functional imaging.
authors.affiliation: Aix-Marseille Université, CNRS, CRMBM UMR 7339Marseille, France; APHM, Hôpitaux de la Timone, CEMEREMMarseille, France.
authors.forename: Ben
authors.initials: B
authors.lastname: Ridley
authors.affiliation: APHM, Hôpitaux de la Timone, Service de Neurologie et Neuropsychologie Marseille, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Beltramone
authors.affiliation: Aix-Marseille Université, CNRS, CRMBM UMR 7339Marseille, France; APHM, Hôpitaux de la Timone, CEMEREMMarseille, France; Aix Marseille Université, Inserm, INS, Institut de Neurosciences des SystèmesMarseille, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wirsich
authors.affiliation: Aix-Marseille Université, CNRS, CRMBM UMR 7339Marseille, France; APHM, Hôpitaux de la Timone, CEMEREMMarseille, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Le Troter
authors.affiliation: APHM, Hôpitaux de la Timone, Service de Neurologie et NeuropsychologieMarseille, France; Aix Marseille Université, Inserm, INS, Institut de Neurosciences des SystèmesMarseille, France.
authors.forename: Eve
authors.initials: E
authors.lastname: Tramoni
authors.affiliation: AP-HM, Hôpitaux de la Timone & Hôpital Henri-Gastaut, Service de Neurophysiologie Clinique Marseille, France.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Aubert
authors.affiliation: GIPSA-Lab F-38000, University Grenoble AlpesGrenoble, France; GIPSA-Lab, F-38000, Centre National de la Recherche Scientifique (CNRS)Grenoble, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Achard
authors.affiliation: Aix-Marseille Université, CNRS, CRMBM UMR 7339Marseille, France; APHM, Hôpitaux de la Timone, CEMEREMMarseille, France.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Ranjeva
authors.affiliation: Aix-Marseille Université, CNRS, CRMBM UMR 7339Marseille, France; APHM, Hôpitaux de la Timone, CEMEREMMarseille, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: Guye
authors.affiliation: APHM, Hôpitaux de la Timone, Service de Neurologie et NeuropsychologieMarseille, France; Aix Marseille Université, Inserm, INS, Institut de Neurosciences des SystèmesMarseille, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Felician
keywords: alien hand; callosal agenesis; disconnection syndrome; epilepsy; functional connectivity; graph theory; resting-state