title: Functional connectivity changes related to cognitive and motor performance in spinocerebellar ataxia type 2.
abstract: BACKGROUND
  Several neuropathological studies in spinocerebellar ataxia type 2 (SCA2) have revealed significant atrophy of the cerebellum, brainstem, sensorimotor cortex, and several regions in the frontal lobe. However, the impact of the neurodegeneration on the functional integration of the remaining tissue is unknown. To analyze the clinical impact of these functional changes, we correlated the abnormal functional connectivity found in SCA2 patients with their scores in clinical scales. To obtain the functional connectivity changes, we followed two approaches. In one we used areas with significant cerebellar gray matter atrophy as anchor seeds, and in the other we performed a whole-brain data-driven analysis.
  
  
  METHODS
  Fourteen genetically confirmed SCA2 patients and aged-matched healthy controls participated in the study. Voxel-based morphometry and resting-state functional magnetic resonance imaging (fMRI) were done to analyze structural and functional brain changes. Independent component analysis and dual regression were used for intrinsic network comparison. Significant functional connectivity differences were correlated with the behavioral scores.
  
  
  RESULTS
  Seed-based analysis found reduced functional connectivity within the cerebellum and between the cerebellum and frontal/parietal cortices. Cerebellar functional connectivity increases were found with parietal, frontal, and temporal areas. Intrinsic network analysis found a functional decrease in the cerebellar network, and increase in the default-mode and fronto-parietal networks. Further analysis showed significant correlations between clinical scores and the abnormal functional connectivity strength.
  
  
  CONCLUSIONS
  Our findings show significant correlations between functional connectivity changes in key areas affected in SCA2 and these patients' motor and neuropsychological impairments, adding an important insight to our understanding of the pathophysiology of SCA2.
authors.affiliation: Consejo Nacional de Ciencia y Tecnología-Cátedras-Instituto de Neuroetologia, Universidad Veracruzana, México.
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Hernandez-Castillo
authors.affiliation: Programa de Doctorado en Neuroetología, Universidad Veracruzana, México.
authors.forename: Víctor
authors.initials: V
authors.lastname: Galvez
authors.affiliation: Cátedras CONACYT, Área de Neurociencias, Depto. de Biología de la Reproducción, Universidad Autónoma Metropolitana-Unidad Iztapalapa, México.
authors.forename: Roberto E
authors.initials: RE
authors.lastname: Mercadillo
authors.affiliation: Laboratorio de Neuropsicología, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, México.
authors.forename: Rosalinda
authors.initials: R
authors.lastname: Díaz
authors.affiliation: Departamento de Neurogenética y Biología Molecular, Instituto Nacional de Neurología y Neurocirugía. Manuel Velasco Suarez, México.
authors.forename: Petra
authors.initials: P
authors.lastname: Yescas
authors.affiliation: Departamento de Neurogenética y Biología Molecular, Instituto Nacional de Neurología y Neurocirugía. Manuel Velasco Suarez, México.
authors.forename: Leticia
authors.initials: L
authors.lastname: Martinez
authors.affiliation: Departamento de Neurogenética y Biología Molecular, Instituto Nacional de Neurología y Neurocirugía. Manuel Velasco Suarez, México.
authors.forename: Adriana
authors.initials: A
authors.lastname: Ochoa
authors.affiliation: Centro para la Investigación y Rehabilitación de las Ataxias Hereditarias, Cuba.
authors.forename: Luis
authors.initials: L
authors.lastname: Velazquez-Perez
authors.affiliation: Programa de Doctorado en Neuroetología, Universidad Veracruzana, México.|Laboratorio de Neuropsicología, Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, México.|Facultad de Psicología, Universidad Veracruzana, México.
authors.forename: Juan
authors.initials: J
authors.lastname: Fernandez-Ruiz
mesh_terms: D000328:Adult; D002531:Cerebellum / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000503:physiopathology*; D003072:Cognition Disorders / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D020754:Spinocerebellar Ataxias / Q000150:complications / Q000503:physiopathology*
keywords: SARA; Spinocerebellar ataxia type 2; cerebellum; functional connectivity