Low-Frequency Repetitive Transcranial Magnetic Stimulation Modulates Evoked-Gamma Frequency Oscillations in Autism Spectrum Disorder

Introduction. It has been reported that individuals with Autism Spectrum Disorder (ASD) have abnormal reactions to the sensory environment and visuo-perceptual abnormalities. Electrophysiological research has provided evidence that gamma band activity (30–80 Hz) is a physiological indicator of the coactivation of cortical cells engaged in processing visual stimuli and integrating different features of a stimulus. A number of studies have found augmented and indiscriminative gamma band power at early stages of visual processing in ASD; this may be related to decreased inhibitory processing and an increase in the ratio of cortical excitation to inhibition. Low frequency or “slow” (≤1HZ) repetitive transcranial magnetic stimulation (rTMS) has been shown to increase inhibition of stimulated cortex by the activation of inhibitory circuits.

Method. We wanted to test the hypothesis of gamma band abnormalities at early stages of visual processing in ASD by investigating relative evoked (i.e., ～100 ms) gamma power in 25 participants with ASD and 20 age-matched controls using Kanizsa illusory figures. In addition, we wanted to assess the effects of 12 sessions of bilateral “slow” rTMS to the dorsolateral prefrontal cortex on evoked gamma activity using a randomized controlled design.

Results. In individuals with ASD evoked gamma activity was not discriminative of stimulus type, whereas in controls early gamma power differences between target and nontarget stimuli were highly significant. Following rTMS individuals with ASD showed significant improvement in discriminatory gamma activity between relevant and irrelevant visual stimuli. We also found significant improvement in the responses on behavioral questionnaires (i.e., irritability, repetitive behavior) as a result of rTMS.

Conclusion. We propose that slow rTMS may have increased cortical inhibitory tone, which improved discriminatory gamma activity at early stages of visual processing. rTMS has the potential to become an important therapeutic tool in ASD treatment and has shown significant benefits in treating core symptoms of ASD with few, if any side effects.     

Healing of Fresh Extraction Sockets Filled with Bioactive Glass Particles: Histological Findings in Humans

Purpose: The aim of the present study was to histologically evaluate fresh human sockets filled with bioactive glass after 6 months of healing. Materials and Methods: In 13 patients, 32 single extraction sites in the anterior area underwent socket ridge preservation procedure (RPP) with a bioactive glass (BioRestore?, Inion Oy, Tampere, Finland). At implant installation, 22 bone cores were trephined out and processed for histomorphometric and immunohistochemical analysis. Results: Newly formed immature bone around residual particles of bioactive glass was found in all 22 biopsies. The histomorphometry of the amount of bone, provisional matrix, and residual graft returned a mean ± SD value of 54 ± 31%, 37.9 ± 25.6%, and 8.1 ± 7.8, respectively, 6 months after RPP. Conclusion: The use of this grafting material in fresh extraction sockets appears to delay the healing processes of the alveolar bone; therefore, its indication as a material for RPP when implant placement is considered within 6 months after extraction should be revised.     

Numerical analysis of the flow characteristics of rotary blood pump

Thrombus formation and hemolysis have been linked to the dynamics of blood flow in rotary blood pumps and ventricular assist devices. Hemolysis occurs as the blood passes through the pump housing, and thrombi develop in stagnation and low-velocity regions. The predicted velocities, pressure, and turbulence quantities from the numerical simulation are used to identify regions of high shear stress and internal recirculation. A nimerical technique is described that simulates the hydrodynamic characteristics of a rotary blood pump with a flow rate of 6 l/min at a rotational speed of 3000 RPM. A computational fluid dynamics (CFD) code, CFX 4, is used to solve the time-dependent incompressible Navier-Stokes equations using a transient finite volume method and three-dimensional structured grids. The simulation utilized the sliding mesh capabilities of this numerical code to model the rotating impeller and examine the effect of blade shape on the hydrodynamic performance of the blood pump in terms of pressure rise, flow rates, and energy losses. The first impeller model has six straight channels; the second impeller has six backward-curved channels. The results for two impeller configurations are presented and discussed. The curvedpump design resulted in higher pressure rise and maximum shear stresses than the straight-channel one. In general the paper demonstrates that CFD is an essential numerical tool for optimizing pump performance with the aim of reducing trauma to the blood cells.     

Whole‐brain atrophy as a measure of progression in premanifest and early Huntington's disease

Therapeutic trials in Huntington's disease (HD) are challenging as clinical progression is slow and variable and reliable biomarkers are lacking. We used magnetic resonance imaging and the brain boundary shift integral to quantify whole‐brain atrophy rates over 1 year in early and premanifest HD subjects, and controls. Early HD subjects had statistically significantly (P = 0.007) increased (threefold higher) rates of whole‐brain atrophy compared with controls. Higher atrophy rates were associated with longer CAG repeat length. MRI‐based measures of whole‐brain atrophy may have potential as a measure of progression in HD. © 2009 Movement Disorder Society     

Spiralometry: Computerized assessment of tremor amplitude on the basis of spiral drawing

Spiral drawing has been used for the assessment of the impact of therapy on motor performance in various movement disorders (e.g. in Parkinson's disease, especially for tremor and hypokinesia). Nevertheless, there are only few guidelines available providing some kind of standardized interpretation. The published protocol with the highest standard is that of Bain and Findley. Kinetic tremor assessed by spiral drawing is not quantified by alternative approaches so far and is not even considered by most rating scales. However, kinetic tremor is quite common and represents a significant impairment in the everyday life of parkinsonian patients. More complex instrumental methods for the quantification of kinetic tremor have not been practical as they, e.g., require relatively expensive equipment or have an unfavourable effort/benefit ratio. We pursued an alternative approach, where we scan drawn spirals to a computer‐algorithm that calculates the tremor amplitude. Our standardized method can be applied without difficulty in patients needing only paper and pencil. The evaluation is fully automated, and therefore, it is appropriate for the assessment of therapeutic efficacy in very large populations. The objectivity of the approach represents a significant advantage. In the actual paper, we present how we analyzed the original spirals published by Bain and Findley to validate our computerized assessment. We found a highly significant connection between both methods (explained variance: 88.9%). © 2010 Movement Disorder Society