1,721,332 research outputs found
Estimation of Cortical Connectivity in Humans: Advanced Signal Processing Techniques
No full textIn the last ten years many different brain imaging devices have conveyed a lot of information about the brain functioning in different experimental conditions. In every case, the biomedical engineers, together with mathematicians, physicists and physicians are called to elaborate the signals related to the brain activity in order to extract meaningful and robust information to correlate with the external behavior of the subjects. In such attempt, different signal processing tools used in telecommunications and other field of engineering or even social sciences have been adapted and re-used in the neuroscience field. The present book would like to offer a short presentation of several methods for the estimation of the cortical connectivity of the human brain. The methods here presented are relatively simply to implement, robust and can return valuable information about the causality of the activation of the different cortical areas in humans using non invasive electroencephalographic recordings. The knowledge of such signal processing tools will enrich the arsenal of the computational methods that a engineer or a mathematician could apply in the processing of brain signals
Novel therapies related to cochlear implants.
No full textIntra-cochlear drug delivery may represent a key issue in cochlear implant (CI) success in
the future. Its therapeutic goals include the improvement of hearing preservation by
reduction of insertion trauma and intra-cochlear tissue growth. Other benefits of intracochlear
drug delivery include improvements of the auditory nerve status and of the
electrode/nerve interface. A number of potential drug delivery devices are currently
under development including drug release using electrode arrays.
Among the drugs involved, dexamethasone has been shown to reduce the hearing loss
due to mild cochlear implant insertion trauma (Kiefer et al 2010). Based on this evidence
we evaluated the effects of intratympanic insertion of 10% dexamethasone-eluting
silicone rods in animal models of both minimal and severe insertion trauma.
With the purpose of verifying the hearing protection, the effect on tissue growth and the
cochleostomy healing, we used 2 different types of electrode array designed to create
either minimal or severe insertion trauma. In one group guinea pigs were gently
implanted with soft rods constructed only from silicone, while in the other animals were
implanted with a stiffer array containing stiff wire and causing mechanical trauma. In
each case, 10% dexamethasone-eluting rods were evaluated for therapeutic benefit and
non-eluting rods were implanted as controls.
Implantations were performed through a 0.7mm cochleostomy, followed by 3-mm deep
rod insertion. Hearing threshold audiograms were acquired prior to implantation and
during the next two/four/eight weeks by recording compound action potentials with
electrodes near the round window. After these periods the cochlea was removed,
decalcified, embedded in paraffin and longitudinally cut into 5-μm thick sections. For
each sample we examined the Scala Tympani occlusion in the cochlear basal turn, and
the cochleostomy healing.
Audiological and histological results showed no significant differences in hearing
protection between non-eluting or 10% dexamethasone-eluting rods within 60 days. No
bacterial contamination was detected in the implant rods. However, in presence of 10%
dexamethasone-eluting tubes, the average tissue growth was always lower in
comparison to non eluting ones, in particular we observed a significant reduction in the
new bone.
This data supports the use of steroid eluting rods with slow-release as an antiinflammatory
additive in cochlear implants. The poor hearing preservation obtained
under these conditions is under further histological investigation
Social neuroscience and hyperscanning techniques: Past, present and future
No full textThis paper reviews the published literature on the hyperscanning methodologies using hemodynamic or neuro-electric modalities. In particular, we describe how different brain recording devices have been employed in different experimental paradigms to gain information about the subtle nature of human interactions. This review also included papers based on single-subject recordings in which a correlation was found between the activities of different (non-simultaneously recorded) participants in the experiment. The descriptions begin with the methodological issues related to the simultaneous measurements and the descriptions of the results generated by such approaches will follow. Finally, a discussion of the possible future uses of such new approaches to explore human social interactions will be presented. © 2012 Elsevier Ltd. All rights reserved
OC-k3 cells, an in vitro model for cochlear implant biocompatibility
No full textObjective: In patients with severe or deep hypoacousis, the cochlear implant represents the only way to recover the ability to hear. Nevertheless, the insertion of a silicone-embedded electrode in the cochlea may produce damage through pressure, shock, bleeding and tissue perforation, which could cause apoptosis and necrosis in the organ of Corti. Another variable is the use of different silicone materials. Although all embedding silicone compounds are medical grade biocompatible, their effects in the inner ear environment have never been tested. Our aim was to assess whether polydimethylsiloxane (PDMS) compounds employed in cochlear implants could be cytotoxic to inner ear cells, by exposing an in vitro organ of Corti cell line (OC-k3) to four PMDS compounds (three fluid and one elastomere) and verifying whether or not any one of these compounds could lead to cell death by apoptosis or necrosis. Study design: To obtain a toxicity curve, OC-k3 cells were exposed to PDMS compounds (octadimethylsiloxane, hexadimethylsiloxane, decamethylcyclopentasiloxane and a silicon rod) at different dilutions and time of exposure, testing vitality by flux cytofluorometry and fluorescence microscopy. Investigations were extended to molecular interactions between OC-k3 cells and PDMS, testing cell death markers by immunocytochemistry and real-Time PCR. Results: Among the fluid PDMS compounds, decamethylcyclopentasiloxane induced the highest significant cell mortality (at 1:100 dilution) after 48 h of treatment, followed by octadimethylsiloxane (1:10) and hexadimethylsiloxane (1:5) at 24 h. The silicon rod did not show any inner ear cell toxicity. Conclusion: In our experimental conditions, the observed cell mortality was not caused by release of cytotoxic molecules by PDMS on OC-k3 cells, but by the formation by PMDS of a surface film preventing air exchange. From a biomolecular point of view, PDMS compounds appear suitable for electrode coating in cochlear implants. © 2015 International Association of Physicians in Audiology
Effetti di ischemia, rumore e cisplatino sull'orecchio interno-Ipoacusia da danno neurosensoriale: uno studio sperimentale sul ratto
No full textElectromagnetical Neuroimaging
Full text linkNeuroimaging is becoming increasingly multimodal, and the integration of hemodynamic, electromagnetic, structural and behavioral data is offering insights unavailable to a single method alone. For conclusions to converge across modalities, the analysis strategies must however contain sufficient conceptual and statistical vigor. Aim of this educational course is to give a critical introduction to the available theories, models and methods to analyze multichannel electromagnetic data recorded from the human scalp in an unambiguous, explicit and coherent way. Particular care is given to present methods that offer explicit junctions to other imaging modalities, allowing converging and/or complementary conclusions.
In addition, there is a rapidly increasing demand for non-invasive human neuroimaging tools to be applicable in translational research. Electromagnetic signals, and in particular the EEG, are exceptionally suitable to be used at the patients' bedside, in critical clinical conditions, or outside hospitals, and their low cost also makes them a prime instrument under economically constrained conditions. The teachers of the course and the content of their presentations will promote a sound methodological basis for the global audience attracted to the OHBM meeting to conduct neuroimaging where the usage of large and expensive scanners is not feasible
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