Speckle-scale focusing in the diffusive regime with time reversal of variance-encoded light (TROVE)

Focusing of light in the diffusive regime inside scattering media has long been considered impossible. Recently, this limitation has been overcome with time reversal of ultrasound-encoded light (TRUE), but the resolution of this approach is fundamentally limited by the large number of optical modes within the ultrasound focus. Here, we introduce a new approach, time reversal of variance-encoded light (TROVE), which demixes these spatial modes by variance encoding to break the resolution barrier imposed by the ultrasound. By encoding individual spatial modes inside the scattering sample with unique variances, we effectively uncouple the system resolution from the size of the ultrasound focus. This enables us to demonstrate optical focusing and imaging with diffuse light at an unprecedented, speckle-scale lateral resolution of ~5 µm

Tremor stability index:a new tool for differential diagnosis in tremor syndromes

Background Misdiagnosis among tremor syndromes is common, and can impact on both clinical care and research. To date no validated neurophysiological technique is available that has proven to have good classification performance, and the diagnostic gold standard is the clinical evaluation made by a movement disorders expert. We present a robust new neurophysiological measure, the Tremor Stability Index, which can discriminate Parkinson’s disease tremor and essential tremor with high diagnostic accuracy. Methods The Tremor Stability Index is derived from kinematic measurements of tremulous activity. It was assessed in a test cohort comprising 16 rest tremor recordings in tremor-dominant Parkinson’s disease and 20 postural tremor recordings in essential tremor, and validated on a second, independent cohort comprising a further 50 tremulous Parkinson’s disease and essential tremor recordings. Clinical diagnosis was used as gold standard. 100 seconds of tremor recording were selected for analysis in each patient. The classification accuracy of the new index was assessed by binary logistic regression, and by receiver operating characteristic (ROC) analysis. The diagnostic performance was examined by calculating the sensitivity, specificity, accuracy, likelihood ratio positive, likelihood ratio negative, area under the ROC curve, and by cross-validation. Results Tremor Stability Index with a cutoff of 1.05 gave good classification performance for Parkinson’s disease tremor and essential tremor, in both test and validation datasets. Tremor Stability Index maximum sensitivity, specificity and accuracy were 95%, 95% and 92%, respectively. ROC analysis showed an AUC of 0.916 (95% C.I. 0.797 – 1.000) for the Test dataset and a value of 0.855 (95% C.I. 0.754 – 0.957) for the Validation dataset. Classification accuracy proved independent of recording device and posture. Conclusion The Tremor Stability Index can aid in the differential diagnosis of the two most common tremor types. It has a high diagnostic accuracy, can be derived from short, cheap, widely available and noninvasive tremor recordings, and is independent of operator or postural context in its interpretation

Landslide kinematics inferred from in situ measurements: the Cliets rock-slide (Savoie, French Alps)

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Encoding of Oscillations by Axonal Bursts in Inferior Olive Neurons

Inferior olive neurons regulate plasticity and timing in the cerebellar cortex via the climbing fiber pathway, but direct characterization of the output of this nucleus has remained elusive. We show that single somatic action potentials in olivary neurons are translated into a burst of axonal spikes. The number of spikes in the burst depends on the phase of subthreshold oscillations and, therefore, encodes the state of the olivary network. These bursts can be successfully transmitted to the cerebellar cortex in vivo, having a significant impact on Purkinje cells. They enhance dendritic spikes, modulate the complex spike pattern, and promote short-term and long-term plasticity at parallel fiber synapses in a manner dependent on the number of spikes in the burst. Our results challenge the view that the climbing fiber conveys an all-or-none signal to the cerebellar cortex and help to link learning and timing theories of olivocerebellar function