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- Iurilli, Giuliano, et al.
(författare)
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Sound-Driven Synaptic Inhibition in Primary Visual Cortex
- 2012
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Ingår i: Neuron. - : Elsevier BV. - 0896-6273 .- 1097-4199. ; 73:4, s. 814-28
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Tidskriftsartikel (refereegranskat)abstract
- Multimodal objects and events activate many sensory cortical areas simultaneously. This is possibly reflected in reciprocal modulations of neuronal activity, even at the level of primary cortical areas. However, the synaptic character of these interareal interactions, and their impact on synaptic and behavioral sensory responses are unclear. Here, we found that activation of auditory cortex by a noise burst drove local GABAergic inhibition on supragranular pyramids of the mouse primary visual cortex, via cortico-cortical connections. This inhibition was generated by sound-driven excitation of a limited number of cells in infragranular visual cortical neurons. Consequently, visually driven synaptic and spike responses were reduced upon bimodal stimulation. Also, acoustic stimulation suppressed conditioned behavioral responses to a dim flash, an effect that was prevented by acute blockade of GABAergic transmission in visual cortex. Thus, auditory cortex activation by salient stimuli degrades potentially distracting sensory processing in visual cortex by recruiting local, translaminar, inhibitory circuits.
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| 3. |
- Jakešová, Marie, 1991-
(författare)
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Wireless Bioelectronic Devices Driven by Deep Red Light
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of electronic devices in medical care is one of the main targets of precision medicine. The field of bioelectronic medicine uses electronic devices to diagnose or treat diseases and disorders in a complementary or alternative way to chemical drugs. It has been more than sixty years since the world’s first implantable battery-driven cardiac pacemaker was implanted here in Sweden. Since then, electronic therapies have been implemented for neurological disorders such as Parkinson’s disease, epilepsy, sensory and motor function restoration, and many more. However, electronics can also be used for delivery of conventional drugs in a more controlled, localized, and specific fashion.Therapeutic utility and patient comfort are maximized when the devices are as minimally invasive as possible. The most important milestone in the development of the cardiac stimulator was making it wireless. The early versions of the device required bulky parts to be placed outside of the body with transcutaneous electrical leads to the target site which led to high infection risk and frequent failures. To date, batteries remain the most common way to power implantable electronics. However, their large size and the necessity for replacement surgeries makes the technology relatively invasive. Alternative approaches to wireless power transfer are thus sought after. The most promising technologies are based on electromagnetic, ultrasound, or light-coupling methods. The aim of this thesis is to utilize tissue-penetrating deep red light for powering implantable devices. The overarching concept is an organic photovoltaic based on small molecule donor-acceptor bilayer junctions, which allows for ultrathin, flexible, minimally-invasive devices. Within this thesis, the photovoltaic device was utilized in two ways. Firstly, the photovoltaics are fabricated to act as an integrated driver for other implantable electronic components: 1) an organic electronic ion pump for acetylcholine delivery; 2) a depth-probe microelectrode stimulation device for epilepsy applications. Secondly, an alternative device, the organic electrolytic photocapacitor, is formed by replacing one of the solid electrodes by an electrolytic contact, thus yielding a minimalistic device acting as a direct photoelectrical stimulator. Within the thesis, the photocapacitive stimulation mechanism is validated by studying voltage-gated ion channels in a frog oocyte model. Next, two lithography-based patterning techniques are developed for fabricating these devices with better resolution and on flexible substrates suitable for in vivo operation. Finally, a chronic implant is demonstrated for in vivo sciatic nerve stimulation in rodents. The end result of this thesis is a series of novel device concepts and methods for stimulation of the nervous system using deep red light.
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- Lienemann, Samuel Lukas, 1988-
(författare)
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Materials and Devices for Stretchable Electronic Nerve Interfaces
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Within our body, there is a large network of nerves that facilitates communication between the brain and the body’s organs. This network is called our peripheral nervous system, consisting of soft and stretchable nerve bundles that gradually increase in their functional specificity as they split and branch out the closer they get to their target organ. Communication within the nerve is based on action potentials, fast fluctuations in electric trans-membrane potential along the neurons within the nerve. These action potentials can be recorded and artificially triggered by interfacing electronically with peripheral nerves. In doing so, modern medicine is able to elucidate the mechanisms behind disorders related to the nervous system and even applies novel electronic therapies to treat them. Over the last decade, the field of biomedical engineering has therefore seen a surge of interest in electronic devices that interface with the peripheral nervous system, such as cuff electrodes. The device function is based on electrodes that are implanted in close proximity of the nerves they intend to record or stimulate. A cuff electrode, specifically, is wrapped around a peripheral nerve and applies stimulation pulses at electrodes located on the inside of the cuff to evoke action potentials within the nerve. Our body is not welcoming to foreign objects though. Any implant within our body triggers a foreign body reaction with an intensity dependent on the biocompatibility of the implant. Recent studies have found that one of the major factors governing the foreign body reaction is the mechanical mismatch of the implant to the interfacing tissue, with softer, more mechanically similar implants, exhibiting reduced foreign body response. This has prompted an ongoing push for thin and soft peripheral nerve interfaces. However, to truly match the mechanical properties of peripheral nerves, peripheral nerve interfaces need not only to be soft and flexible, they need to become as elastic and stretchable as the nerve themselves. A common strategy to achieve stretchable conductors is by incorporating highly conductive filler materials in an elastomeric matrix. The resulting composite remains conductive even when stretched due to the ability of the filler material to dislocate with the elastomeric matrix while retaining its interconnectivity and thus conductivity. Electronic composites based on gold nanowires and silicones are promising candidates for stretchable peripheral nerve interfaces, due to their material-based biocompatibility, good stretchability, and versatile patterning possibilities.Based on this, the thesis at hand investigated stretchable electronic composite materials and devices to interface with the peripheral nervous system. Publication I and II develop gold-nanowire/polydimethylsiloxane-based cuff electrodes, which are functional even at 50% strain, as peripheral nerve interfaces in vivo. These publications highlight the beneficial conformability of stretchable devices, with a stretchable bi-polar cuff for low-voltage stimulation of the rat sciatic nerve in publication I and a stretchable multi-electrode cuff for selective stimulation of the pig sciatic nerve in publication II. Publication III investigates stretchable gold-nanowire composites based on a variety of elastomers, therein, elucidating the influence of the varying elastomer properties on the electromechanical performance of gold-nanowire composites. Lastly, publication IV establishes a stretchable ion delivery device with potential use for the peripheral nervous system. The device is based on an ionically conductive membrane as the conductive filler, and the device can be reversibly stretched to 100% strain. Overall, this thesis presents stretchable materials and devices that advance the possibilities for peripheral nerve interfaces.
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| 5. |
- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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