Altered Velocity Processing in Schizophrenia during Pursuit Eye Tracking

Smooth pursuit eye movements (SPEM) are needed to keep the retinal image of slowly moving objects within the fovea. Depending on the task, about 50%–80% of patients with schizophrenia have difficulties in maintaining SPEM. We designed a study that comprised different target velocities as well as testing for internal (extraretinal) guidance of SPEM in the absence of a visual target. We applied event-related fMRI by presenting four velocities (5, 10, 15, 20°/s) both with and without intervals of target blanking. 17 patients and 16 healthy participants were included. Eye movements were registered during scanning sessions. Statistical analysis included mixed ANOVAs and regression analyses of the target velocity on the Blood Oxygen Level Dependency (BOLD) signal. The main effect group and the interaction of velocity×group revealed reduced activation in V5 and putamen but increased activation of cerebellar regions in patients. Regression analysis showed that activation in supplementary eye field, putamen, and cerebellum was not correlated to target velocity in patients in contrast to controls. Furthermore, activation in V5 and in intraparietal sulcus (putative LIP) bilaterally was less strongly correlated to target velocity in patients than controls. Altered correlation of target velocity and neural activation in the cortical network supporting SPEM (V5, SEF, LIP, putamen) implies impaired transformation of the visual motion signal into an adequate motor command in patients. Cerebellar regions seem to be involved in compensatory mechanisms although cerebellar activity in patients was not related to target velocity

Regression analysis of target velocity and BOLD.

<p>The table shows the results of regression analysis of the velocity on the BOLD signal (Blood Oxygen Level Dependency) in patients and healthy subjects. The significance threshold was set at T = 3.5, family wise error correction (FWE) and small volume correction (SVC) of 10 mm sphere, t-values and P-values are depicted, and x, y and z (mm) refer to the coordinates defined by the Montreal Neurological Institute (MNI).</p

Activated regions revealed by the ANOVA and the regression analysis.

<p>Red or blue blobs in the ANOVA represent the calculated main effect (patients > controls and vice versa). For both contrasts family wise error correction at the p = 0.05 level was applied; Condition A: continuous target presentation, Condition B: target blanking. Bottom: Exemplarily the cerebellum during condition B is depicted.</p

Clinical spectrum of homozygous and heterozygous PINK1 mutations in a large German family with Parkinson disease: role of a single hit?

BACKGROUND: Although homozygous mutations in the PTEN-induced putative kinase 1 (PINK1) gene have been unequivocally associated with early-onset Parkinson disease (PD), the role of single heterozygous PINK1 mutations is less clear. OBJECTIVE: To investigate the role of homozygous and heterozygous PINK1 mutations in a large German pedigree (family W). DESIGN: Mutation analysis of PINK1 and results of standardized neurological and motor examination by 3 independent movement disorder specialists, including blinded video rating. SETTINGS: University of Lubeck. PARTICIPANTS: Twenty family members. MAIN OUTCOME MEASURES: The PINK1 genotype and PD status of all family members. RESULTS: The index patient of family W carried a homozygous nonsense mutation (c.1366C>T; p.Q456X) and presented with a phenotype closely resembling idiopathic PD but with an onset at 39 years of age. The family included a total of 4 affected homozygous members (age, 60-71 years; age at onset, 39-61 years), 6 members with slight or mild signs of PD (affected) and a heterozygous mutation (age, 31-49 years), and 5 unaffected heterozygous mutation carriers (age, 34-44 years). Although none of the heterozygous affected family members was aware of their signs (asymptomatic), the clinical findings were unequivocal and predominantly or exclusively present on their dominant right-hand side, eg, unilaterally reduced or absent arm swing and unilateral rigidity. The heterozygous members were all considerably younger than the affected homozygous mutation carriers. CONCLUSIONS: Heterozygous PINK1 mutations may predispose to PD, as was previously suggested by the presence of dopamine hypometabolism in asymptomatic mutation carriers. Long-term follow-up of our large family W provides an excellent opportunity to further evaluate the role of single heterozygous PINK1 mutations later in life, which will have major implications on genetic counseling

Western Star, 1908-11-04

The Western Star began publication on Newfoundland's west coast on 4 April 1900, appearing weekly with brief semiweekly periods up to 1952, when it became a daily. As of 17 April 2019 it continues as a free weekly community paper