RunDAE model: Running denoising autoencoder models for denoising ECG signals.

Background: The denoising autoencoder (DAE) is commonly used to denoise bio-signals such as electrocardiogram (ECG) signals through dimensional reduction. Typically, the DAE model needs to be trained using correlated input segments such as QRS-aligned segments or long ECG segments. However, using long ECG segments as an input can result in a complex deep DAE model that requires many hidden layers to achieve a low-dimensional representation, which is a major drawback.

DualSort: online spike sorting with a running neural network.

Spike sorting, i.e. the detection and separation of measured action potentials from different extracellularly recorded neurons, remains one of the bottlenecks in deciphering the brain.

Multiple ECG segments denoising autoencoder model.

Objectives: Denoising autoencoder (DAE) with a single hidden layer of neurons can recode a signal, i.e., converting the original signal into a noise-reduced signal.

[The G-BA innovation fund's project "Avenue-Pal" - analysis and improvement of cross-sectoral and cross-departmental interface and relocation management in palliative care].

Background: About 80% of all people in Germany die in inpatient care. Around every fifth person in inpatient care is relocated to another care area in the last phase of their life. That is more than 150,000 people being relocated, often without indication.

High speed external cavity diode laser concept based on a resonantly driven MEMS scanner for the mid-infrared region.

The rapid detection of trace gases is of great relevance for various spectroscopy applications. In this regard, the technology of external cavity diode lasers (ECDLs) has firmly established itself due to its excellent properties. Outside of the laboratory environment, however, these still have some restrictions, especially with regard to high acquisition rates for sensitive spectroscopy applications and mode-hop-free tuning.

Fractal Characterization of Subviral Particle Motion: On the Influence of Spatio-Temporal Interpolation Methods.

Due to the rapid globalization there is an increasing danger for pandemic outbreaks. The high death toll of fast spreading diseases like the Ebola infection demand the fast development of new medicines. Thus, the automation of pharmaceutical processes is an indispensable but challenging task.

Estimation of Sparse VAR Models with Artificial Neural Networks for the Analysis of Biosignals.

Vector autoregressive models (VAR models) are often used to model and to analyze multivariate time series, especially to provide short-term forecasts. A common method of estimating coefficients of these VAR models is solving the Yule- Walker equations. This work introduces and investigates a method to set up "sparse" VAR models, in order to obtain a comparable prognosis quality with significantly fewer coefficients.

An optically powered single-channel stimulation implant as test system for chronic biocompatibility and biostability of miniaturized retinal vision prostheses.

A microsystem based microimplant with an optically powered single-channel stimulator was designed and developed as test system for an epi-retinal vision implant. Biostability of the hybrid assembly and the encapsulation materials were evaluated in pilot experiments in chronic implantations in a cat animal model. The implant was fabricated on a flexible polyimide substrate with integrated platinum electrode, interconnection lines, and contact pads for hybrid integration of electronic components.

Intraocular fluid-air exchange reduces retinal ganglion cell activity.

Aim: To demonstrate the influence of intraocular fluid-air exchange on retinal ganglion cell activity.

Methods: In two cats lensectomy and vitrectomy were performed in a two-step approach 2 weeks prior to recording experiments. To measure retinal activity, up to two fiber microelectrodes were inserted via a scleral port.

Visualization of the visual cortex in minipigs using fMRI.

Minipigs are widely used to examine physiologic mechanisms under experimental settings. The purpose of our study was to localize the visual cortex of minipigs using visual stimulation in functional magnetic resonance imaging (fMRI). Five male Göttinger minipigs were studied with fMRI during visual stimulation with series of light impulses conducted into the MR cabin via fibre optical wave guides (EPI sequences, block design, 1.

Visual resolution with retinal implants estimated from recordings in cat visual cortex.

We investigated cortical responses to electrical stimulation of the retina using epi- and sub-retinal electrodes of 20-100 microm diameter. Temporal and spatial resolutions were assessed by recordings from the visual cortex with arrays of microelectrodes and optical imaging. The estimated resolutions were approximately 40 ms and approximately 1 degrees of visual angle.

Implantation and testing of subretinal film electrodes in domestic pigs.

By definition, an electronic subretinal visual prosthesis requires the implantation of stimulation electrodes in the subretinal space of the eye. Polyimide film electrodes with flat contacts were implanted subretinally and used for electrical stimulation in acute experiments in anaesthetised domestic pigs. In two pigs, the film electrode was inserted through a sclerostomy into the vitreous cavity and, subsequently, via a retinotomy into the subretinal space around the posterior pole (ab interno approach).

Transscleral implantation and neurophysiological testing of subretinal polyimide film electrodes in the domestic pig in visual prosthesis development.

Loss of photoreceptor function is responsible for a variety of blinding diseases, including retinitis pigmentosa. Advances in microtechnology have led to the development of electronic visual prostheses which are currently under investigation for the treatment of human blindness. The design of a subretinal prosthesis requires that the stimulation device should be implantable in the subretinal space of the eye.

Retino-cortical information transmission achievable with a retina implant.

Blind subjects with photoreceptor degeneration perceive phosphenes when their intact retinal ganglion cells are stimulated electrically. Is this approach suitable for transmitting enough information to the visual cortex for partially restoring vision? We stimulated the retina of anesthetized cats electrically and visually while recording the responses in the visual cortex. Transmission of retino-cortical information T was quantified by information theory.

Subretinal implantation and testing of polyimide film electrodes in cats.

Background: Progress in the field of microelectronics has led to the development of visual prostheses for the treatment of blinding diseases. One concept under investigation is an electronic subretinal prosthesis to replace the function of lost photoreceptors in degenerative diseases, such as retinitis pigmentosa.

Methods: In the subretinal prosthesis design concept, an array of stimulation electrodes is placed in the subretinal space.

Visual resolution with epi-retinal electrical stimulation estimated from activation profiles in cat visual cortex.

Blinds with receptor degeneration can perceive localized phosphenes in response to focal electrical epi-retinal stimuli. To avoid extensive basic stimulation tests in human patients, we developed techniques for estimating visual spatial resolution in anesthetized cats. Electrical epi-retinal and visual stimulation was combined with multiple-site retinal and cortical microelectrode recordings of local field potentials (LFPs) from visual areas 17 and 18.

Chronically implanted epidural electrodes in Göttinger minipigs allow function tests of epiretinal implants.

Background: To test the function of implantable devices for electrical stimulation of the retina, long-term registration tests of cortical-evoked potentials are required. Skin electrodes are not appropriate to provide representative recordings, due to the voluminous pneumatic frontal sinus of minipigs. Therefore, epidural electrodes were permanently implanted in minipigs and tested with visual and electrical retinal stimulation.

Towards the cortical representation of form and motion stimuli generated by a retina implant.

Background: A retina implant for restoring basic visual perception in patients who are blind due to photoreceptor loss should not only evoke focal phosphenes at high resolution, but should also generate cortical representations of form and motion. We are currently exploring these potential capabilities in anaesthetised cats.

Methods: Fibre electrodes were inserted through a small scleral incision onto the retinal surface for stimulation.

Activation zones in cat visual cortex evoked by electrical retina stimulation.

Background: A retina implant for restoring simple basic visual perception in patients who are blind due to photoreceptor loss requires optimisation of stimulation parameters for obtaining high spatio-temporal resolution. We developed effective low-power epi-retinal stimulation and intracortical recording in semichronically prepared cats.

Methods: Individually driveable fibre electrodes were inserted through a small scleral incision and positioned at the area centralis.

Classification of neural signals by a generalized correlation classifier based on radial basis functions.

A common problem in neuroscience is to identify the features by which a set of measurements can be segregated into different classes, for example into different responses to sensory stimuli. A main difficulty is that the derived distributions are often high-dimensional and complex. Many multivariate analysis techniques, therefore, aim to find a simpler low-dimensional representation.

[Physiological functional evaluation of retinal implants in animal models].

Retinal implants can--by electrical stimulation--create visual impressions in people with certain kinds of degenerative retinal diseases (e.g. Retinitis Pigmentosa).

Implantation of retina stimulation electrodes and recording of electrical stimulation responses in the visual cortex of the cat.

Background: Simple basic visual perception may be restored by epiretinal electrical stimulation in patients that are blind due to photoreceptor loss. To stimulate ganglion cells, epiretinally flat platinum microelectrodes embedded in thin polyimide film were developed and tested in the cat.

Methods: After removal of the lens and the vitreous body a thin microfilm electrode array was implanted through a corneoscleral incision in the cat eye (n = 4).

Phase correlation among rhythms present at different frequencies: spectral methods, application to microelectrode recordings from visual cortex and functional implications.

In classical EEG analysis rhythms with different frequencies occurring at separable regions and states of the brain are analysed. Rhythms in different frequency bands have often been assumed to be independent and their occurrence was interpreted as a sign of different functional operations. Independence has scarcely been proved because of conceptual and computational difficulties.