31 results on '"Schneiderman, Justin F."'
Search Results
2. From MEG to clinical EEG: evaluating a promising non-invasive estimator of defense-related muscle sympathetic nerve inhibition
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Eskelin, John J., Lundblad, Linda C., Wallin, B. Gunnar, Karlsson, Tomas, Riaz, Bushra, Lundqvist, Daniel, Schneiderman, Justin F., and Elam, Mikael
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- 2023
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3. Globally elevated excitation–inhibition ratio in children with autism spectrum disorder and below-average intelligence
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Manyukhina, Viktoriya O., Prokofyev, Andrey O., Galuta, Ilia A., Goiaeva, Dzerassa E., Obukhova, Tatiana S., Schneiderman, Justin F., Altukhov, Dmitrii I., Stroganova, Tatiana A., and Orekhova, Elena V.
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- 2022
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4. Brain structural and functional correlates to defense-related inhibition of muscle sympathetic nerve activity in man
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Riaz, Bushra, Eskelin, John J., Lundblad, Linda C., Wallin, B. Gunnar, Karlsson, Tomas, Starck, Göran, Lundqvist, Daniel, Oostenveld, Robert, Schneiderman, Justin F., and Elam, Mikael
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- 2022
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5. On-scalp MEG SQUIDs are sensitive to early somatosensory activity unseen by conventional MEG
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Andersen, Lau M., Pfeiffer, Christoph, Ruffieux, Silvia, Riaz, Bushra, Winkler, Dag, Schneiderman, Justin F., and Lundqvist, Daniel
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- 2020
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6. Spatial suppression in visual motion perception is driven by inhibition: Evidence from MEG gamma oscillations
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Orekhova, Elena V., Rostovtseva, Ekaterina N., Manyukhina, Viktoriya O., Prokofiev, Andrey O., Obukhova, Tatiana S., Nikolaeva, Anastasia Yu., Schneiderman, Justin F., and Stroganova, Tatiana A.
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- 2020
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7. On-scalp MEG sensor localization using magnetic dipole-like coils: A method for highly accurate co-registration
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Pfeiffer, Christoph, Ruffieux, Silvia, Andersen, Lau M., Kalabukhov, Alexei, Winkler, Dag, Oostenveld, Robert, Lundqvist, Daniel, and Schneiderman, Justin F.
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- 2020
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8. Visual gamma oscillations predict sensory sensitivity in females as they do in males
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Manyukhina, Viktoriya O., Rostovtseva, Ekaterina N., Prokofyev, Andrey O., Obukhova, Tatiana S., Schneiderman, Justin F., Stroganova, Tatiana A., and Orekhova, Elena V.
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- 2021
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9. Input-dependent modulation of MEG gamma oscillations reflects gain control in the visual cortex
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Orekhova, Elena V., Sysoeva, Olga V., Schneiderman, Justin F., Lundström, Sebastian, Galuta, Ilia A., Goiaeva, Dzerasa E., Prokofyev, Andrey O., Riaz, Bushra, Keeler, Courtney, Hadjikhani, Nouchine, Gillberg, Christopher, and Stroganova, Tatiana A.
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- 2018
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10. Gamma oscillations point to the role of primary visual cortex in atypical motion processing in autism.
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Orekhova, Elena V., Manyukhina, Viktoriya O., Galuta, Ilia A., Prokofyev, Andrey O., Goiaeva, Dzerassa E., Obukhova, Tatiana S., Fadeev, Kirill A., Schneiderman, Justin F., and Stroganova, Tatiana A.
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VISUAL cortex ,AUTISM spectrum disorders ,NEURAL inhibition ,VISUAL perception ,AUTISM ,OSCILLATIONS ,MOTION - Abstract
Neurophysiological studies suggest that abnormal neural inhibition may explain a range of sensory processing differences in autism spectrum disorders (ASD). In particular, the impaired ability of people with ASD to visually discriminate the motion direction of small-size objects and their reduced perceptual suppression of background-like visual motion may stem from deficient surround inhibition within the primary visual cortex (V1) and/or its atypical top-down modulation by higher-tier cortical areas. In this study, we estimate the contribution of abnormal surround inhibition to the motion-processing deficit in ASD. For this purpose, we used a putative correlate of surround inhibition–suppression of the magnetoencephalographic (MEG) gamma response (GR) caused by an increase in the drift rate of a large annular high-contrast grating. The motion direction discrimination thresholds for the gratings of different angular sizes (1° and 12°) were assessed in a separate psychophysical paradigm. The MEG data were collected in 42 boys with ASD and 37 typically developing (TD) boys aged 7–15 years. Psychophysical data were available in 33 and 34 of these participants, respectively. The results showed that the GR suppression in V1 was reduced in boys with ASD, while their ability to detect the direction of motion was compromised only in the case of small stimuli. In TD boys, the GR suppression directly correlated with perceptual suppression caused by increasing stimulus size, thus suggesting the role of the top-down modulations of V1 in surround inhibition. In ASD, weaker GR suppression was associated with the poor directional sensitivity to small stimuli, but not with perceptual suppression. These results strongly suggest that a local inhibitory deficit in V1 plays an important role in the reduction of directional sensitivity in ASD and that this perceptual deficit cannot be explained exclusively by atypical top-down modulation of V1 by higher-tier cortical areas. [ABSTRACT FROM AUTHOR]
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- 2023
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11. A new approach for bioassays based on frequency- and time-domain measurements of magnetic nanoparticles
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Öisjöen, Fredrik, Schneiderman, Justin F., Astalan, Andrea Prieto, Kalabukhov, Alexey, Johansson, Christer, and Winkler, Dag
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- 2010
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12. TH-169. Brain responses to stress reflect individual blood pressure reactivity
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Eskelin, John J., Riaz, Bushra, Lundblad, Linda C., Gunnar Wallin, B., Karlsson, Tomas, Starck, Göran, Lundqvist, Daniel, Oostenveld, Robert, Schneiderman, Justin F., and Elam, Mikael
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- 2022
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13. A liquid nitrogen-cooled cryostat for multichannel HTS magnetoencephalography
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Pfeiffer, Christoph, Ruffieux, Silvia, Schneiderman, Justin F., Chukharkin, Maxim L., Kalaboukhov, Alexei, Xie, Minshu, and Winkler, Dag
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Physics ,ddc:530 - Abstract
Magnetoencephalography (MEG) is a functional neuroimaging technology used in neuroscience as well as in the diagnosis and treatment of brain disorders like epilepsy and for surgical planning. In MEG neural activity is measured by sensing the weak magnetic fields (~10s to 100s of femtotesla) that are generated by neural currents in the brain. Highly sensitive magnetic field sensors are required for MEG. Today’s commercial systems therefore employ liquid helium-cooled low-Tc SQUIDs. With advances in high-temperature superconducting (HTS) technology high-Tc SQUIDs have become a serious alternative. Due to the higher operating temperature they can be placed closer to the head and therefore measure higher magnitude signals than low-Tc SQUIDs that must record from further away – thus enabling them to overcome the typically higher noise compared to their commercial counterparts [1]. We have developed a liquid nitrogen-cooled cryostat for a 7-channel HTS MEG system. The cryostat is designed for minimum distance between the cold (~77 K) SQUIDs and the head of a subject at room temperature. With superinsulation around the nitrogen vessel and a small vacuum space between the sensors and a thin window, we can achieve minimum sensor-to-head distances of less than 3 mm. The magnetometers are arranged in a dense hexagonal pattern for high spatial sampling of a small area of the head (≈ 15 cm2). The outer sensors are tilted towards the middle to align them to the average adult head’s curvature. The sensor tilt combined with a thin, curved window ensures minimal distance to the head for all sensors. The system employs 10 mm × 10 mm bicrystal dc SQUIDs made from YBa2Cu3O7-x with direct injection feedback (to minimize crosstalk [2]). The SQUIDs are thermally connected to liquid nitrogen via a sapphire fixture. To control temperature the nitrogen reservoir can be pumped on. The cryostat achieves high temperature stability (18h with a single filling). We will present the design and performance of the cryostat and show results from measurements on a head phantom. [1] Schneiderman, J. Neurosci. Methods 222, 42-46 (2014) [2] Ruffieux, Supercond. Sci. Technol. 30, 054006 (2017)
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- 2017
14. A 7-Channel High-${T}_\text{c}$ SQUID-Based On-Scalp MEG System.
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Pfeiffer, Christoph, Ruffieux, Silvia, Jonsson, Lars, Chukharkin, Maxim L., Kalaboukhov, Alexei, Xie, Minshu, Winkler, Dag, and Schneiderman, Justin F.
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VISUAL cortex ,SUPERCONDUCTING quantum interference devices ,AUDITORY evoked response ,AUDITORY perception ,WHITE noise ,CRITICAL temperature - Abstract
Objective: To present the technical design and demonstrate the feasibility of a multi-channel on-scalp magnetoencephalography (MEG) system based on high critical temperature (high- ${T}_\text{c}$) superconducting quantum interference devices (SQUIDs). Methods: We built a liquid nitrogen-cooled cryostat that houses seven YBCO SQUID magnetometers arranged in a dense, head-aligned array with minimal distance to the room-temperature environment for all sensors. We characterize the performance of this 7-channel system in terms of on-scalp MEG utilization and present recordings of spontaneous and evoked brain activity. Results: The center-to-center spacing between adjacent SQUIDs is 12.0 and 13.4 mm and all SQUIDs are in the range of 1-3 mm of the head surface. The cryostat reaches a base temperature of $\sim$ 70 K and stays cold for $>$ 16 h with a single 0.9 L filling. The white noise levels of the magnetometers is 50–130 fT/Hz1/2 at 10 Hz and they show low sensor-to-sensor feedback flux crosstalk ($< $ 0.6%). We demonstrate evoked fields from auditory stimuli and single-shot sensitivity to alpha modulation from the visual cortex. Conclusion: All seven channels in the system sensitively sample neuromagnetic fields with mm-scale scalp standoff distances. The hold time of the cryostat furthermore is sufficient for a day of recordings. As such, our multi-channel high- ${T}_\text{c}$ SQUID-based system meets the demands of on-scalp MEG. Significance: The system presented here marks the first high- ${T}_\text{c}$ SQUID-based on-scalp MEG system with more than two channels. It enables us to further explore the benefits of on-scalp MEG in future recordings. [ABSTRACT FROM AUTHOR]
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- 2020
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15. Additive effect of contrast and velocity suggests the role of strong excitatory drive in suppression of visual gamma response.
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Orekhova, Elena V., Prokofyev, Andrey O., Nikolaeva, Anastasia Yu., Schneiderman, Justin F., and Stroganova, Tatiana A.
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CONTRAST effect ,VELOCITY ,OSCILLATIONS - Abstract
It is commonly acknowledged that gamma-band oscillations arise from interplay between neural excitation and inhibition; however, the neural mechanisms controlling the power of stimulus-induced gamma responses (GR) in the human brain remain poorly understood. A moderate increase in velocity of drifting gratings results in GR power enhancement, while increasing the velocity beyond some 'transition point' leads to GR power attenuation. We tested two alternative explanations for this nonlinear input-output dependency in the GR power. First, the GR power can be maximal at the preferable velocity/temporal frequency of motion-sensitive V1 neurons. This 'velocity tuning' hypothesis predicts that lowering contrast either will not affect the transition point or shift it to a lower velocity. Second, the GR power attenuation at high velocities of visual motion can be caused by changes in excitation/inhibition balance with increasing excitatory drive. Since contrast and velocity both add to excitatory drive, this 'excitatory drive' hypothesis predicts that the 'transition point' for low-contrast gratings would be reached at a higher velocity, as compared to high-contrast gratings. To test these alternatives, we recorded magnetoencephalography during presentation of low (50%) and high (100%) contrast gratings drifting at four velocities. We found that lowering contrast led to a highly reliable shift of the GR suppression transition point to higher velocities, thus supporting the excitatory drive hypothesis. No effects of contrast or velocity were found in the alpha-beta range. The results have implications for understanding the mechanisms of gamma oscillations and developing gamma-based biomarkers of disturbed excitation/inhibition balance in brain disorders. [ABSTRACT FROM AUTHOR]
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- 2020
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16. SQUIDs in biomagnetism
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Körber, Rainer, Storm, Jan Hendrik, Seton, Hugh, Makela, Jyrki P., Paetau, Ritva, Parkkonen, Lauri, Pfeiffer, Christoph, Riaz, Bushra, Schneiderman, Justin F., Dong, Hui, Hwang, Seong Min, You, Lixing, Inglis, Ben, Clarke, John, Espy, Michelle A., Ilmoniemi, Risto J., Magnelind, Per E., Matlashov, Andrei N., Nieminen, Jaakko O., Volegov, Petr L., Zevenhoven, Koos C J, Höfner, Nora, Burghoff, Martin, Enpuku, Keiji, Yang, S. Y., Chieh, Jen Jei, Knuutila, Jukka, Laine, Petteri, Nenonen, Jukka, Physikalisch-Technische Bundesanstalt, University of Aberdeen, University of Helsinki, Department of Neuroscience and Biomedical Engineering, Chalmers University of Technology, University of Gothenburg, Chinese Academy of Sciences, Korea Research Institute of Standards and Science, University of California Berkeley, Los Alamos National Laboratory, Kyushu University, MagQu Co. Ltd., National Taiwan Normal University, Elekta Oy, Aalto-yliopisto, and Aalto University
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magnetic nanoparticles ,MEG ,MEG-MRI ,ULF MRI ,Biomagnetism ,SQUID ,MRI - Abstract
Globally, the demand for improved health care delivery while managing escalating costs is a major challenge. Measuring the biomagnetic fields that emanate from the human brain already impacts the treatment of epilepsy, brain tumours and other brain disorders. This roadmap explores how superconducting technologies are poised to impact health care. Biomagnetism is the study of magnetic fields of biological origin. Biomagnetic fields are typically very weak, often in the femtotesla range, making their measurement challenging. The earliest in vivo human measurements were made with room-temperature coils. In 1963, Baule and McFee (1963 Am. Heart J. 55 95-6) reported the magnetic field produced by electric currents in the heart ('magnetocardiography'), and in 1968, Cohen (1968 Science 161 784-6) described the magnetic field generated by alpha-rhythm currents in the brain ('magnetoencephalography'). Subsequently, in 1970, Cohen et al (1970 Appl. Phys. Lett. 16 278-80) reported the recording of a magnetocardiogram using a Superconducting QUantum Interference Device (SQUID). Just two years later, in 1972, Cohen (1972 Science 175 664-6) described the use of a SQUID in magnetoencephalography. These last two papers set the scene for applications of SQUIDs in biomagnetism, the subject of this roadmap. The SQUID is a combination of two fundamental properties of superconductors. The first is flux quantization - the fact that the magnetic flux Φ in a closed superconducting loop is quantized in units of the magnetic flux quantum, Φ0 ≡ h/2e, ≈ 2.07 × 10-15 Tm2 (Deaver and Fairbank 1961 Phys. Rev. Lett. 7 43-6, Doll R and Nabauer M 1961 Phys. Rev. Lett. 7 51-2). Here, h is the Planck constant and e the elementary charge. The second property is the Josephson effect, predicted in 1962 by Josephson (1962 Phys. Lett. 1 251-3) and observed by Anderson and Rowell (1963 Phys. Rev. Lett. 10 230-2) in 1963. The Josephson junction consists of two weakly coupled superconductors separated by a tunnel barrier or other weak link. A tiny electriccurrent is able to flow between the superconductors as a supercurrent, without developing a voltage across them. At currents above the 'critical current' (maximum supercurrent), however, a voltage is developed. In 1964, Jaklevic et al (1964 Phys. Rev. Lett. 12 159-60) observed quantum interference between two Josephson junctions connected in series on a superconducting loop, giving birth to the dc SQUID. The essential property of the SQUID is that a steady increase in the magnetic flux threading the loop causes the critical current to oscillate with a period of one flux quantum. In today's SQUIDs, using conventional semiconductor readout electronics, one can typically detect a change in Φ corresponding to 10-6 Φ0 in one second. Although early practical SQUIDs were usually made from bulk superconductors, for example, niobium or Pb-Sn solder blobs, today's devices are invariably made from thin superconducting films patterned with photolithography or even electron lithography. An extensive description of SQUIDsand their applications can be found in the SQUID Handbooks (Clarke and Braginski 2004 Fundamentals and Technology of SQUIDs and SQUID Systems vol I (Weinheim, Germany: Wiley-VCH), Clarke and Braginski 2006 Applications of SQUIDs and SQUID Systems vol II (Weinheim, Germany: Wiley-VCH)). The roadmap begins (chapter 1) with a brief review of the state-of-the-art of SQUID-based magnetometers and gradiometers for biomagnetic measurements. The magnetic field noise referred to the pick-up loop is typically a few fT Hz-1/2, often limited by noise in the metallized thermal insulation of the dewar rather than by intrinsic SQUID noise. The authors describe a pathway to achieve an intrinsic magnetic field noise as low as 0.1 fT Hz-1/2, approximately the Nyquist noise of the human body. They also descibe a technology to defeat dewar noise. Chapter 2 reviews the neuroscientific and clinical use of magnetoencephalography (MEG), by far the most widespread application of biomagnetism with systems containing typically 300 sensors cooled to liquid-helium temperature, 4.2 K. Two important clinical applications are presurgical mapping of focal epilepsy and of eloquent cortex in brain-tumor patients. Reducing the sensor-to-brain separation and the system noise level would both improve spatial resolution. The very recent commercial innovation that replaces the need for frequent manual transfer of liquid helium with an automated system that collects and liquefies the gas and transfers the liquid to the dewar will make MEG systems more accessible. A highly promising means of placing the sensors substantially closer to the scalp for MEG is to use high-transition-temperature (high-T c) SQUID sensors and flux transformers (chapter 3). Operation of these devices at liquid-nitrogen temperature, 77 K, enables one to minimize or even omit metallic thermal insulation between the sensors and the dewar. Noise levels of a few fT Hz-1/2 have already been achieved, and lower values are likely. The dewars can be made relatively flexible, and thus able to be placed close to the skull irrespective of the size of the head, potentially providing higher spatial resolution than liquid-helium based systems. The successful realization of a commercial high-T c MEG system would have a major commercial impact. Chapter 4 introduces the concept of SQUID-based ultra-low-field magnetic resonance imaging (ULF MRI) operating at typically several kHz, some four orders of magnitude lower than conventional, clinical MRI machines. Potential advantages of ULF MRI include higher image contrast than for conventional MRI, enabling methodologies not currently available. Examples include screening for cancer without a contrast agent, imaging traumatic brain injury (TBI) and degenerative diseases such as Alzheimer's, and determining the elapsed time since a stroke. The major current problem with ULF MRI is that its signal-to-noise ratio (SNR) is low compared with high-field MRI. Realistic solutions to this problem are proposed, including implementing sensors with a noise level of 0.1 fT Hz-1/2. A logical and exciting prospect (chapter 5) is to combine MEG and ULF MRI into a single system in which both signal sources are detected with the same array of SQUIDs. A prototype system is described. The combination of MEG and ULF MRI allows one to obtain structural images of the head concurrently with the recording of brain activity. Since all MEG images require an MRI to determine source locations underlying the MEG signal, the combined modality would give a precise registration of the two images; the combination of MEG with high-field MRI can produce registration errors as large as 5 mm. The use of multiple sensors for ULF MRI increases both the SNR and the field of view. Chapter 6 describes another potentially far-reaching application of ULF MRI, namely neuronal current imaging (NCI) of the brain. Currently available neuronal imaging techniques include MEG, which is fast but has relatively poor spatial resolution, perhaps 10 mm, and functional MRI (fMRI) which has a millimeter resolution but is slow, on the order of seconds, and furthermore does not directly measure neuronal signals. NCI combines the ability of direct measurement of MEG with the spatial precision of MRI. In essence, the magnetic fields generated by neural currents shift the frequency of the magnetic resonance signal at a location that is imaged by the three-dimensional magnetic field gradients that form the basis of MRI. The currently achieved sensitivity of NCI is not quite sufficient to realize its goal, but it is close. The realization of NCI would represent a revolution in functional brain imaging. Improved techniques for immunoassay are always being sought, and chapter 7 introduces an entirely new topic, magnetic nanoparticles for immunoassay. These particles are bio-funtionalized, for example with a specific antibody which binds to its corresponding antigen, if it is present. Any resulting changes in the properties of the nanoparticles are detected with a SQUID. For liquid-phase detection, there are three basic methods: AC susceptibility, magnetic relaxation and remanence measurement. These methods, which have been successfully implemented for both in vivo and ex vivo applications, are highly sensitive and, although further development is required, it appears highly likely that at least some of them will be commercialized.
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- 2016
17. Homogeneous Differential Magnetic Assay.
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Sepehri, Sobhan, Zardán Gómez de la Torre, Teresa, Schneiderman, Justin F., Blomgren, Jakob, Jesorka, Aldo, Johansson, Christer, Nilsson, Mats, Albert, Jan, Strømme, Maria, Winkler, Dag, and Kalaboukhov, Alexei
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- 2019
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18. Neural gain control measured through cortical gamma oscillations is associated with sensory sensitivity.
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Orekhova, Elena V., Stroganova, Tatiana A., Schneiderman, Justin F., Lundström, Sebastian, Riaz, Bushra, Sarovic, Darko, Sysoeva, Olga V., Brant, Georg, Gillberg, Christopher, and Hadjikhani, Nouchine
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Gamma oscillations facilitate information processing by shaping the excitatory input/output of neuronal populations. Recent studies in humans and nonhuman primates have shown that strong excitatory drive to the visual cortex leads to suppression of induced gamma oscillations, which may reflect inhibitory‐based gain control of network excitation. The efficiency of the gain control measured through gamma oscillations may in turn affect sensory sensitivity in everyday life. To test this prediction, we assessed the link between self‐reported sensitivity and changes in magneto‐encephalographic gamma oscillations as a function of motion velocity of high‐contrast visual gratings. The induced gamma oscillations increased in frequency and decreased in power with increasing stimulation intensity. As expected, weaker suppression of the gamma response correlated with sensory hypersensitivity. Robustness of this result was confirmed by its replication in the two samples: neurotypical subjects and people with autism, who had generally elevated sensory sensitivity. We conclude that intensity‐related suppression of gamma response is a promising biomarker of homeostatic control of the excitation–inhibition balance in the visual cortex. [ABSTRACT FROM AUTHOR]
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- 2019
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19. Characterizing hippocampal dynamics with MEG: A systematic review and evidence‐based guidelines.
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Ruzich, Emily, Crespo‐García, Maité, Dalal, Sarang S., and Schneiderman, Justin F.
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The hippocampus, a hub of activity for a variety of important cognitive processes, is a target of increasing interest for researchers and clinicians. Magnetoencephalography (MEG) is an attractive technique for imaging spectro‐temporal aspects of function, for example, neural oscillations and network timing, especially in shallow cortical structures. However, the decrease in MEG signal‐to‐noise ratio as a function of source depth implies that the utility of MEG for investigations of deeper brain structures, including the hippocampus, is less clear. To determine whether MEG can be used to detect and localize activity from the hippocampus, we executed a systematic review of the existing literature and found successful detection of oscillatory neural activity originating in the hippocampus with MEG. Prerequisites are the use of established experimental paradigms, adequate coregistration, forward modeling, analysis methods, optimization of signal‐to‐noise ratios, and protocol trial designs that maximize contrast for hippocampal activity while minimizing those from other brain regions. While localizing activity to specific sub‐structures within the hippocampus has not been achieved, we provide recommendations for improving the reliability of such endeavors. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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20. Localizing on-scalp MEG sensors using an array of magnetic dipole coils.
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Pfeiffer, Christoph, Andersen, Lau M., Lundqvist, Daniel, Hämäläinen, Matti, Schneiderman, Justin F., and Oostenveld, Robert
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MAGNETOENCEPHALOGRAPHY ,MAGNETIC dipoles ,MAGNETOMETERS ,A priori ,ELECTROMAGNETS - Abstract
Accurate estimation of the neural activity underlying magnetoencephalography (MEG) signals requires co-registration i.e., determination of the position and orientation of the sensors with respect to the head. In modern MEG systems, an array of hundreds of low-T
c SQUID sensors is used to localize a set of small, magnetic dipole-like (head-position indicator, HPI) coils that are attached to the subject’s head. With accurate prior knowledge of the positions and orientations of the sensors with respect to one another, the HPI coils can be localized with high precision, and thereby the positions of the sensors in relation to the head. With advances in magnetic field sensing technologies, e.g., high-Tc SQUIDs and optically pumped magnetometers (OPM), that require less extreme operating temperatures than low-Tc SQUID sensors, on-scalp MEG is on the horizon. To utilize the full potential of on-scalp MEG, flexible sensor arrays are preferable. Conventional co-registration is impractical for such systems as the relative positions and orientations of the sensors to each other are subject-specific and hence not known a priori. Herein, we present a method for co-registration of on-scalp MEG sensors. We propose to invert the conventional co-registration approach and localize the sensors relative to an array of HPI coils on the subject’s head. We show that given accurate prior knowledge of the positions of the HPI coils with respect to one another, the sensors can be localized with high precision. We simulated our method with realistic parameters and layouts for sensor and coil arrays. Results indicate co-registration is possible with sub-millimeter accuracy, but the performance strongly depends upon a number of factors. Accurate calibration of the coils and precise determination of the positions and orientations of the coils with respect to one another are crucial. Finally, we propose methods to tackle practical challenges to further improve the method. [ABSTRACT FROM AUTHOR]- Published
- 2018
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21. Similarities and differences between on-scalp and conventional in-helmet magnetoencephalography recordings.
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Andersen, Lau M., Oostenveld, Robert, Pfeiffer, Christoph, Ruffieux, Silvia, Jousmäki, Veikko, Hämäläinen, Matti, Schneiderman, Justin F., and Lundqvist, Daniel
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MAGNETOENCEPHALOGRAPHY ,MAGNETIC sensors ,LOW temperatures ,MAGNETIC recorders & recording ,NEURAL stimulation - Abstract
The development of new magnetic sensor technologies that promise sensitivities approaching that of conventional MEG technology while operating at far lower operating temperatures has catalysed the growing field of on-scalp MEG. The feasibility of on-scalp MEG has been demonstrated via benchmarking of new sensor technologies performing neuromagnetic recordings in close proximity to the head surface against state-of-the-art in-helmet MEG sensor technology. However, earlier work has provided little information about how these two approaches compare, or about the reliability of observed differences. Herein, we present such a comparison, based on recordings of the N20m component of the somatosensory evoked field as elicited by electric median nerve stimulation. As expected from the proximity differences between the on-scalp and in-helmet sensors, the magnitude of the N20m activation as recorded with the on-scalp sensor was higher than that of the in-helmet sensors. The dipole pattern of the on-scalp recordings was also more spatially confined than that of the conventional recordings. Our results furthermore revealed unexpected temporal differences in the peak of the N20m component. An analysis protocol was therefore developed for assessing the reliability of this observed difference. We used this protocol to examine our findings in terms of differences in sensor sensitivity between the two types of MEG recordings. The measurements and subsequent analysis raised attention to the fact that great care has to be taken in measuring the field close to the zero-line crossing of the dipolar field, since it is heavily dependent on the orientation of sensors. Taken together, our findings provide reliable evidence that on-scalp and in-helmet sensors measure neural sources in mostly similar ways. [ABSTRACT FROM AUTHOR]
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- 2017
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22. Benchmarking for On-Scalp MEG Sensors.
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Xie, Minshu, Schneiderman, Justin F., Chukharkin, Maxim L., Kalabukhov, Alexei, Riaz, Bushra, Lundqvist, Daniel, Whitmarsh, Stephen, Hamalainen, Matti, Jousmaki, Veikko, Oostenveld, Robert, and Winkler, Dag
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MAGNETOENCEPHALOGRAPHY , *MAGNETIC sensors , *SOMATOSENSORY evoked potentials , *SUPERCONDUCTING quantum interference devices , *MAGNETOMETERS , *SUPERCONDUCTORS - Abstract
Objective: We present a benchmarking protocol for quantitatively comparing emerging on-scalp magnetoencephalography (MEG) sensor technologies to their counterparts in state-of-the-art MEG systems. Methods: As a means of validation, we compare a high-critical-temperature superconducting quantum interference device (high $T_{{c}}$ SQUID) with the low-$T_{{c}}$ SQUIDs of an Elekta Neuromag TRIUX system in MEG recordings of auditory and somatosensory evoked fields (SEFs) on one human subject. Results: We measure the expected signal gain for the auditory-evoked fields (deeper sources) and notice some unfamiliar features in the on-scalp sensor-based recordings of SEFs (shallower sources). Conclusion: The experimental results serve as a proof of principle for the benchmarking protocol. This approach is straightforward, general to various on-scalp MEG sensors, and convenient to use on human subjects. The unexpected features in the SEFs suggest on-scalp MEG sensors may reveal information about neuromagnetic sources that is otherwise difficult to extract from state-of-the-art MEG recordings. Significance: As the first systematically established on-scalp MEG benchmarking protocol, magnetic sensor developers can employ this method to prove the utility of their technology in MEG recordings. Further exploration of the SEFs with on-scalp MEG sensors may reveal unique information about their sources. [ABSTRACT FROM AUTHOR]
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- 2017
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23. Novel HTS DC Squid Solutions for NMR Applications.
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Chukharkin, Maxim L., Kalabukhov, Alexey S., Schneiderman, Justin F., Öisjöen, Fredrik, Jönsson, Magnus, Xie, Minshu, Snigirev, Oleg V., and Winkler, Dag
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- 2014
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24. Information content with low- vs. high-T c SQUID arrays in MEG recordings: The case for high-T c SQUID-based MEG.
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Schneiderman, Justin F.
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SUPERCONDUCTING quantum interference devices , *MAGNETOENCEPHALOGRAPHY , *RECORDING & registration , *COGNITIVE ability , *BRAIN physiology , *COMPARATIVE studies - Abstract
Highlights: [•] We model low- and high-T c SQUID arrays in MEG recordings of neural activity in the brain. [•] We compare the total information available to these SQUID arrays. [•] An MEG system based on high-T c technology is capable of producing at least 40% more information than the state-of-the-art in low-T c MEG systems. [•] The gain in information provided by high-T c MEG technology is a result of the closer source-to-sensor standoff distance. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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25. Characterization of Binding of Magnetic Nanoparticles to Rolling Circle Amplification Products by Turn-On Magnetic Assay.
- Author
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Sepehri, Sobhan, Agnarsson, Björn, Zardán Gómez de la Torre, Teresa, Schneiderman, Justin F., Blomgren, Jakob, Jesorka, Aldo, Johansson, Christer, Nilsson, Mats, Albert, Jan, Strømme, Maria, Winkler, Dag, and Kalaboukhov, Alexei
- Subjects
MAGNETIC susceptibility ,CIRCLE ,MANUFACTURED products ,THYRISTORS ,MAGNETIC nanoparticles - Abstract
The specific binding of oligonucleotide-tagged 100 nm magnetic nanoparticles (MNPs) to rolling circle products (RCPs) is investigated using our newly developed differential homogenous magnetic assay (DHMA). The DHMA measures ac magnetic susceptibility from a test and a control samples simultaneously and eliminates magnetic background signal. Therefore, the DHMA can reveal details of binding kinetics of magnetic nanoparticles at very low concentrations of RCPs. From the analysis of the imaginary part of the DHMA signal, we find that smaller MNPs in the particle ensemble bind first to the RCPs. When the RCP concentration increases, we observe the formation of agglomerates, which leads to lower number of MNPs per RCP at higher concentrations of RCPs. The results thus indicate that a full frequency range of ac susceptibility observation is necessary to detect low concentrations of target RCPs and a long amplification time is not required as it does not significantly increase the number of MNPs per RCP. The findings are critical for understanding the underlying microscopic binding process for improving the assay performance. They furthermore suggest DHMA is a powerful technique for dynamically characterizing the binding interactions between MNPs and biomolecules in fluid volumes. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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26. Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils.
- Author
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Ahrentorp, Fredrik, Blomgren, Jakob, Jonasson, Christian, Sarwe, Anna, Sepehri, Sobhan, Eriksson, Emil, Kalaboukhov, Alexei, Jesorka, Aldo, Winkler, Dag, Schneiderman, Justin F., Nilsson, Mats, Albert, Jan, de la Torre, Teresa Zardán Gómez, Strømme, Maria, and Johansson, Christer
- Subjects
- *
MAGNETIC nanoparticles , *IRON oxides , *HYDRODYNAMICS , *DETECTION limit , *ELECTRIC properties of DNA - Abstract
We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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27. A 7-Channel High-[Formula: see text] SQUID-Based On-Scalp MEG System.
- Author
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Pfeiffer C, Ruffieux S, Jonsson L, Chukharkin ML, Kalaboukhov A, Xie M, Winkler D, and Schneiderman JF
- Subjects
- Animals, Brain, Decapodiformes, Magnetoencephalography, Scalp
- Abstract
Objective: To present the technical design and demonstrate the feasibility of a multi-channel on-scalp magnetoencephalography (MEG) system based on high critical temperature (high-[Formula: see text]) superconducting quantum interference devices (SQUIDs)., Methods: We built a liquid nitrogen-cooled cryostat that houses seven YBCO SQUID magnetometers arranged in a dense, head-aligned array with minimal distance to the room-temperature environment for all sensors. We characterize the performance of this 7-channel system in terms of on-scalp MEG utilization and present recordings of spontaneous and evoked brain activity., Results: The center-to-center spacing between adjacent SQUIDs is 12.0 and 13.4 mm and all SQUIDs are in the range of 1-3 mm of the head surface. The cryostat reaches a base temperature of ∼ 70 K and stays cold for 16 h with a single 0.9 L filling. The white noise levels of the magnetometers is 50-130 fT/Hz
1/2 at 10 Hz and they show low sensor-to-sensor feedback flux crosstalk ( 0.6%). We demonstrate evoked fields from auditory stimuli and single-shot sensitivity to alpha modulation from the visual cortex., Conclusion: All seven channels in the system sensitively sample neuromagnetic fields with mm-scale scalp standoff distances. The hold time of the cryostat furthermore is sufficient for a day of recordings. As such, our multi-channel high-[Formula: see text] SQUID-based system meets the demands of on-scalp MEG., Significance: The system presented here marks the first high-[Formula: see text] SQUID-based on-scalp MEG system with more than two channels. It enables us to further explore the benefits of on-scalp MEG in future recordings.- Published
- 2020
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28. Volume-amplified magnetic bioassay integrated with microfluidic sample handling and high- T c SQUID magnetic readout.
- Author
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Sepehri S, Eriksson E, Kalaboukhov A, Zardán Gómez de la Torre T, Kustanovich K, Jesorka A, Schneiderman JF, Blomgren J, Johansson C, Strømme M, and Winkler D
- Abstract
A bioassay based on a high- T
c superconducting quantum interference device (SQUID) reading out functionalized magnetic nanoparticles (fMNPs) in a prototype microfluidic platform is presented. The target molecule recognition is based on volume amplification using padlock-probe-ligation followed by rolling circle amplification (RCA). The MNPs are functionalized with single-stranded oligonucleotides, which give a specific binding of the MNPs to the large RCA coil product, resulting in a large change in the amplitude of the imaginary part of the ac magnetic susceptibility. The RCA products from amplification of synthetic Vibrio cholera target DNA were investigated using our SQUID ac susceptibility system in microfluidic channel with an equivalent sample volume of 3 μ l. From extrapolation of the linear dependence of the SQUID signal versus concentration of the RCA coils, it is found that the projected limit of detection for our system is about 1.0 × 105 RCA coils (0.2 × 10-18 mol), which is equivalent to 66 fM in the 3 μ l sample volume. This ultra-high magnetic sensitivity and integration with microfluidic sample handling are critical steps towards magnetic bioassays for rapid detection of DNA and RNA targets at the point of care.- Published
- 2017
- Full Text
- View/download PDF
29. Evaluation of realistic layouts for next generation on-scalp MEG: spatial information density maps.
- Author
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Riaz B, Pfeiffer C, and Schneiderman JF
- Abstract
While commercial magnetoencephalography (MEG) systems are the functional neuroimaging state-of-the-art in terms of spatio-temporal resolution, MEG sensors have not changed significantly since the 1990s. Interest in newer sensors that operate at less extreme temperatures, e.g., high critical temperature (high-T
c ) SQUIDs, optically-pumped magnetometers, etc., is growing because they enable significant reductions in head-to-sensor standoff (on-scalp MEG). Various metrics quantify the advantages of on-scalp MEG, but a single straightforward one is lacking. Previous works have furthermore been limited to arbitrary and/or unrealistic sensor layouts. We introduce spatial information density (SID) maps for quantitative and qualitative evaluations of sensor arrays. SID-maps present the spatial distribution of information a sensor array extracts from a source space while accounting for relevant source and sensor parameters. We use it in a systematic comparison of three practical on-scalp MEG sensor array layouts (based on high-Tc SQUIDs) and the standard Elekta Neuromag TRIUX magnetometer array. Results strengthen the case for on-scalp and specifically high-Tc SQUID-based MEG while providing a path for the practical design of future MEG systems. SID-maps are furthermore general to arbitrary magnetic sensor technologies and source spaces and can thus be used for design and evaluation of sensor arrays for magnetocardiography, magnetic particle imaging, etc.- Published
- 2017
- Full Text
- View/download PDF
30. Information content with low- vs. high-T(c) SQUID arrays in MEG recordings: the case for high-T(c) SQUID-based MEG.
- Author
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Schneiderman JF
- Subjects
- Algorithms, Brain physiology, Computer Simulation, Head, Humans, Information Theory, Magnetometry, Brain Mapping instrumentation, Magnetoencephalography instrumentation
- Abstract
Background: Magnetoencephalography (MEG) is a method of studying brain activity via recordings of the magnetic field generated by neural activity. Modern MEG systems employ an array of low critical-temperature superconducting quantum interference devices (low-Tc SQUIDs) that surround the head. The geometric distribution of these arrays is optimized by maximizing the information content available to the system in brain activity recordings according to Shannon's theory of noisy channel capacity., New Method: Herein, we present a theoretical comparison of the performance of low- and high-Tc SQUID-based multichannel systems in recordings of brain activity., Results: We find a high-Tc SQUID magnetometer-based multichannel system is capable of extracting at least 40% more information than an equivalent low-Tc SQUID system. The results suggest more information can be extracted from high-Tc SQUID MEG recordings (despite higher sensor noise levels than their low-Tc counterparts) because of the closer proximity to neural sources in the brain., Comparison With Existing Methods: We have duplicated previous results in terms of total information of multichannel low-Tc SQUID arrays for MEG. High-Tc SQUID technology theoretically outperforms its conventional low-Tc counterpart in MEG recordings., Conclusions: A full-head high-Tc SQUID-based MEG system's potential for extraction of more information about neural activity can be used to, e.g., develop better diagnostic and monitoring techniques for brain disease and enhance our understanding of the working human brain., (Copyright © 2013 Elsevier B.V. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
31. Towards an electrowetting-based digital microfluidic platform for magnetic immunoassays.
- Author
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Schaller V, Sanz-Velasco A, Kalabukhov A, Schneiderman JF, Oisjöen F, Jesorka A, Astalan AP, Krozer A, Rusu C, Enoksson P, and Winkler D
- Subjects
- Equipment Design, Nanoparticles chemistry, Electrowetting instrumentation, Immunoassay trends, Magnetics, Microfluidic Analytical Techniques instrumentation
- Abstract
We demonstrate ElectroWetting-On-Dielectric (EWOD) transport and SQUID gradiometer detection of magnetic nanoparticles (MNPs) suspended in a 2 microl de-ionized water droplet. This proof-of-concept methodology constitutes the first development step towards a highly sensitive magnetic immunoassay platform with SQUID readout and droplet-based sample handling. Magnetic AC-susceptibility measurements were performed on MNPs with a hydrodynamic diameter of 100 nm using a high-Tc dc Superconducting Quantum Interference Device (SQUID) gradiometer as detector. We observed that the signal amplitude per unit volume is 2.5 times higher for a 2 microl sample droplet compared to a 30 microl sample volume.
- Published
- 2009
- Full Text
- View/download PDF
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