The in-vivo optical imaging of the cortical surface provides the ability to record different types of biophysiological signals, e.g., structural information, intrinsic signals, like blood oxygenation coupled reflection changes as well as extrinsic properties of voltage sensitive probes, like fluorescent voltage-sensitive dyes. The recorded data sets have very high temporal and spatial resolutions on a meso- to macroscopic scale, which surpass conventional multi-electrode recordings. Both, intrinsic and functional data sets, each provide unique information about temporal and spatial dynamics of cortical functioning, yet have individual drawbacks. To optimize the informational value it would thus be opportune to combine different types of optical imaging in a near simultaneous recording.Due to the low signal-to-noise ratio of voltage-sensitive dyes it is necessary to reduce stray light pollution below the level of the camera's dark noise. It is thus impossible to record full-spectrum optical data sets. We address this problem by a time-multiplexed illumination, bespoke to the utilized voltage sensitive dye, to record an alternating series of intrinsic and extrinsic frames by a high-frequency CMOS sensor. These near simultaneous data series can be used to compare the mutual influence of intrinsic and extrinsic dynamics (with regards to extracorporeal functional imaging) as well as for motion compensation and thus for minimizing frame averaging, which in turn results in increased spatial precision of functional data and in a reduction of necessary experimental data sets (3R principle).

We seek to understand the relation between invasive high-resolution data and non-invasive measurement in an animal model in an auditory sensory adaptation experimental setting. In a previous study, we estimated the mutual information between the phase of auditory evoked responses (AER) with the phase of local field potentials (LFP) of auditory cortices at different frequency ranges. The results showed a consistently high level of information sharing between the AER activities as well as the responses from the granular layer, which was known as the main thalamo-recipient layer. However, mutual information was fundamentally an undirected measure of information flow. In this study we investigated how well we could characterize direction of information flow, by using Granger causality (GC), between different cortical laminae and functional projections on to the AER activities. We obtained that based on the GC coefficients, we are able to extract the connectivity between different cortical laminae to some extend and also a strong connection between the AER and granular layer. In our future study, we would like to construct a reliable picture of network connectivity, both functionally and anatomically, between different layers at more specified frequencies and much finer temporal resolutions.

Intracranial, functional optical imaging (OI) of intrinsic signals (like blood oxygenation coupled reflection changes) and of extrinsic properties of voltage sensitive probes (like voltage-sensitive dyes) belongs to a group of invasive neuroimaging techniques with very high temporal and spatial resolutions on a meso-to macroscopic scale. Voltage sensitive dye imaging (VSDI) images brain activity with low temporal delays, but the raw signal has a poor signal to noise ratio. An important pre-processing step for many biomedical imaging techniques is image registration and motion compensation. We can apply motion compensation successfully for optical imaging of intrinsic signals but VSDI recordings have low spatial contrast and often do not contain fine grained texture details which are crucial for successful image based motion compensation. In this work, we design a semi-synthetic dataset based on real recordings and a dummy voltage sensitive dye response for the evaluation of advanced motion compensation strategies for VSDI. This dataset aims to be used as a benchmark for the development of novel motion compensation strategies for VSDI and to derive error bounds of the methodologies with respect to motion.

Recent work has shown that sharp spectral edges in acoustic stimuli might have advantageous effects in the treatment of tonal tinnitus. In the course of this paper, we evaluate the long-term effects of spectrally notched hearing aids on the subjective tinnitus distress. By merging recent experimental work with a computational tinnitus model, we modified the commercially available behind-the-ear hearing aids so that a frequency band of 0.5 octaves, centered on the patient's individual tinnitus frequency, was blocked out. Those hearing aids employ a steep notch filter that filters environmental sounds to suppress the tinnitus-related changes in neural firing by lateral inhibition. The computational model reveals a renormalization of pathologically increased neural response reliability and synchrony in response to spectrally modified input. The target group, fitted with spectrally notched hearing aids, was matched with a comparable control group, fitted with standard hearing aids of the same type but without a notch filter. We analyze the subjective self-assessment by tinnitus questionnaires, and we monitor the objective distress correlates in auditory evoked response phase data. Both, subjective and objective results show a noticeable trend of a larger therapeutic benefit for notched hearing correction.

Video motion magnification forms a relatively novel family of visualization techniques, that aim to magnify imperceivably small motions in videos. The most prominent techniques are based on Eulerian video processing and local phase shifting, which modify pixel time courses, rather than relying on explicit motion estimation.In this work, we show that under ideal conditions in the context of psychophysiological experiments, a Lagrangian motion magnification approach based on dense optical flow estimation, can be superior to Eulerian motion magnification strategies. We present a novel, continuous and motion magnitude driven forward warping scheme of small motions, which implements motion compensation and magnification into a single motion estimation step. Our approach does not rely on temporal filtering and works in the presence of large motion. It does not require the explicit identification of fast moving objects and more generally no segmentation and or matting in the image domain is necessary. We apply our method to the visualization of blinking related modulations in micro-saccadic eye movements ((i.a.. iridodonesis), pupil dilation (hippus) and micro-expression analysis.

Functional optical imaging (OI) of intrinsic signals (like blood oxygenation coupled reflection changes) and of extrinsic properties of voltage sensitive probes (like voltage-sensitive dyes (VSD)) forms a group of invasive neuroimaging techniques, that possess up to date the highest temporal and spatial resolution on a meso- to macroscopic scale.

Recent studies have focused on modeling the response of the early auditory processing stages to sound stimuli. However, the influence of sound on the higher stages like the auditory thalamus are not well identified. To understand how different sound stimuli affect the response of neurons in these higher stages, it is necessary to model the auditory pathway from the auditory nerve (AN) through the different stages up to the cortex. In this article we present a model of one of the paths through which sound travels from the AN to the cortex. The model presented is a compound of several sub models of different stages of the auditory pathway which offers a detailed resolution due to the subsequent simulation of processing stages. We consider neurons from the AN, the dorsal cochlear nucleus (DCN), the thalamus (specific and non-specific thalamic cells and reticular nucleus) and cortical columns simulating attended and unattended conditions. We use pure tone stimuli with different frequencies as an input and analyze the power spectra of the thalamic and cortical neurons. The main difference in the power spectra can be seen in the specific thalamic cells (STC), where a clear loss of power in the gamma band of the neurons responsible for processing the sound input occurred.

Clinical OtolaryngologyVolume 42, Issue 1 p. 172-175 Correspondence: Our Experience Notched environmental sounds: a new hearing aid-supported tinnitus treatment evaluated in 20 patients D.J. Strauss, Corresponding Author D.J. Strauss daniel.strauss@uni-saarland.de Systems Neuroscience and Neurotechnology Unit, Saarland University, Faculty of Medicine, Neurocenter, Homburg/Saar, Germany Leibniz-Institut for New Materials, Saarbruecken, Germany Key Numerics, Saarbruecken, GermanyCorrespondence: Daniel J. Strauss, Systems Neuroscience & Neurotechnology Unit, Saarland University, Faculty of Medicine, Neurocenter, Building 90.5, D–66421 Homburg/Saar, Germany. Tel.: +49-6841-1624090; Fax: +49-6841-1624092; e-mail: daniel.strauss@uni-saarland.deSearch for more papers by this authorF.I. Corona-Strauss, F.I. Corona-Strauss Systems Neuroscience and Neurotechnology Unit, Saarland University, Faculty of Medicine, Neurocenter, Homburg/Saar, Germany Key Numerics, Saarbruecken, GermanySearch for more papers by this authorH. Seidler, H. Seidler Ear, Nose, and Throat Center, MediClin Bosenberg Clinic, St. Wendel, GermanySearch for more papers by this authorL. Haab, L. Haab Systems Neuroscience and Neurotechnology Unit, Saarland University, Faculty of Medicine, Neurocenter, Homburg/Saar, GermanySearch for more papers by this authorR. Hannemann, R. Hannemann Sivantos GmbH, Erlangen, GermanySearch for more papers by this author D.J. Strauss, Corresponding Author D.J. Strauss daniel.strauss@uni-saarland.de Systems Neuroscience and Neurotechnology Unit, Saarland University, Faculty of Medicine, Neurocenter, Homburg/Saar, Germany Leibniz-Institut for New Materials, Saarbruecken, Germany Key Numerics, Saarbruecken, GermanyCorrespondence: Daniel J. Strauss, Systems Neuroscience & Neurotechnology Unit, Saarland University, Faculty of Medicine, Neurocenter, Building 90.5, D–66421 Homburg/Saar, Germany. Tel.: +49-6841-1624090; Fax: +49-6841-1624092; e-mail: daniel.strauss@uni-saarland.deSearch for more papers by this authorF.I. Corona-Strauss, F.I. Corona-Strauss Systems Neuroscience and Neurotechnology Unit, Saarland University, Faculty of Medicine, Neurocenter, Homburg/Saar, Germany Key Numerics, Saarbruecken, GermanySearch for more papers by this authorH. Seidler, H. Seidler Ear, Nose, and Throat Center, MediClin Bosenberg Clinic, St. Wendel, GermanySearch for more papers by this authorL. Haab, L. Haab Systems Neuroscience and Neurotechnology Unit, Saarland University, Faculty of Medicine, Neurocenter, Homburg/Saar, GermanySearch for more papers by this authorR. Hannemann, R. Hannemann Sivantos GmbH, Erlangen, GermanySearch for more papers by this author First published: 27 October 2015 https://doi.org/10.1111/coa.12575Citations: 11Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume42, Issue1February 2017Pages 172-175 RelatedInformation

Functional optical imaging (OI) of intrinsic signals (like blood oxygenation coupled reflection changes) and of extrinsic properties of voltage sensitive probes (like voltage-sensitive dyes (VSD)) forms a group of neuroimaging techniques that possess up to date highest temporal and spatial resolution on a meso-to macroscopic scale. An inherent problem of OI is a very low signal to noise ratio (SNR), which restricts the recordings to be completely motionless and requires detailed knowledge of the properties of the different noise sources. In our experiments we performed a durectomy and did not use an imaging chamber to allow us future joint electroencephalography-optical imaging (EEG-OI) measures, which resulted in movement artifacts. With the goal of motion compensation in OI recordings and magnification of signal changes, we present a novel processing pipeline, which is based on optic flow guided denoising and gradient domain tone mapping for spatiotemporal contrast enhancement.

Functional Optical Imaging (OI) through the opened skull forms a group of Neuroimaging techniques characterized by a high temporal and spatial resolution on a meso-to macroscopic scale. State of the art OI experiments are generally difficult to execute, with a very timely surgical preparation preceding the experiment, that requires a skilled surgeon to mount a sealed imaging chamber onto the skull. The chamber reduces brain pulsation artifacts and swelling of the brain through movement restriction. In this work, we present preliminary results of a novel approach that does not rely on the usage of an imaging chamber with the goal to facilitate heavily the surgical animal preparation and to allow straightforward joint Electroencephalography - Optical Imaging recordings in the future. We carried out experiments to compare the movement restricting properties of the imaging chamber with the movement in a recording of an unconstrained and periodically irrigated brain. We used high-level image processing techniques to reduce brain pulsation artifacts and did a quantitative movement analysis of the recordings. Our results suggest that while recordings with imaging chamber show less sagittal movement, both with and without imaging chamber comprise the same lateral movements.

During the last years, the demand of accurate diagnostic tools for individualized tinnitus treatment gradually increased. Today several different psychometric instruments for the estimation of the patients degree of decompensation with clinical relevance have emerged. All of these tools are questionnaires for a subjective self-assessment and have deficits in comparability due to severe differences in their factor structure in the anamnesis. Those questionnaires thus they are only of limited value in the design of an individualized therapeutic approach. Objective diagnostic tools for the categorization of the patients' distress level are lacking in clinical routine. Scientific approaches yet demonstrated the feasibility of individual distress assessment by objective markers in the EEG. In this article we present the preliminary results of our study of a use of habituation correlates as objective indicator for the decompensation degree in high-distress tinnitus patients.

Optical Imaging using Voltage-sensitive Dyes is characterized by low fractional changes in fluorescent light intensity upon the application of a stimulus, which leads to slight value differences between pixels on an in-general noisy image sequence. The application of an anisotropic diffusion filtering scheme, in order to contribute to the denoising of the optical images, is proposed as one option to improve its quality and for a better understanding of the physiological processes they represent. We apply an image registration approach to compensate for motion artifacts, such that we do not need to mount a fixed cranial chamber onto the skull. In this work, electrical stimulation to the tibial nerve in a rat model was used to register evoke potentials, imaging the somatosensory cortex of the animal, which was previously stained with the RH1691 dye.

This study aims to decrease the gap between invasive high-resolution data acquisition and non-invasive measurement in the animal model under auditory stimuli. We approach this problem by analyzing the degree of shared information between the phase of local field potentials (LFPs) of auditory cortices and the phase of auditory evoked responses (AER) at different frequency domains. It has been extensively illustrated in previous studies that the phase of evoked responses align reliably in presence of a repetitive stimulus. Yet this implies that changes in the instantaneous phase over a series of stimulus presentations must also be mirrored in the laminar activity. To estimate the impact of laminar specific activity on the AER dynamics over a series of acoustic stimulation, we employ an information theoretic approach (mutual information) for quantifying the relevant information encoded in the phase of laminar LFPs and AERs.

Given a time series of data points, as obtained in biosignal monitoring, the change point problem poses the question of identifying times of sudden variations in the parameters of the underlying data distribution. We propose a method for extracting a discrete set of change points from directional data. Our method is based on a combination of the Bayesian change point model (CPM) and the Viterbi algorithm. We apply our method to the instantaneous phase information of single-trial auditory event-related potentials (ERPs) in a long term habituation paradigm. We have seen in previous studies that the phase information enters a phase-locked mode with respect to the repetition of a stimulus in the state of focused attention. With adaptation to an insignificant stimulus, attention tends to trail away (long-term habituation), characterized by changes in the phase signature, becoming more diffuse across trials. We demonstrate that the proposed method is suitable for detecting the effects of long-term habituation on phase information in our experimental setting.

In our preliminary work we were able to demonstrate habituation by analyzing attention correlates in single-trial sequences of auditory event-related potentials (ERPs). Despite different quantitative studies of instantaneous phase of ERPs in long-term habituation, there have been no former studies in generative process underlying the distribution of instantaneous phase information in the context of long-term habituation and its relation to attentional binding. For this means we used a von Mises model, representing the phase information over a set of single trial responses. Additionally we use a quantitative neurofunctional model to predict the dynamics of the instantaneous phase in single-trial ERP data during the long-term habituation. Measured habituation data is used to cross-validate the model's prediction. We conclude that the described method allows for an assessment of dynamic changes in the course of long-term habituation. The results also reinforce our neurofunctional multiscale model of long-term habituation and show the applicability of the described method for the experimental/clinical neurodiagnostic assessment of attentional binding.

The pathologic auditory sensation in decompensated tinnitus patients is accompanied by the inability to habituate even temporary to this sound. This disability might originate from simultaneous activation of brain areas for the appraisal of the stimulus valence as, e.g., the limbic system. This coactivation of limbic areas is likely to modulate the degree and persistence of selective attention assigned to the tinnitus stream, which in turn could also explain interindividual differences in tinnitus loudness perception. Preliminary studies demonstrate that the amount of allocated attention and the habituation deficit can be mapped to changes in auditory late evoked responses (ALRs). Utilizing a numerical model for the simulation of ALRs we were able to predict a general habituation behavior in two patient groups with different degrees of tinnitus severity. Evaluating the instantaneous phase of simulated and measured ALRs by its von Mises concentration parameter, we verify a habituation deficit relative to the degree of decompensation and thus provide additional support for our neurofunctional model of limbic influences on neural processing of sensory information.