| 1. |
- Eklund, Anders, et al.
(författare)
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A Brain Computer Interface for Communication Using Real-Time fMRI
- 2010
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Ingår i: Proceedings of the 20th International Conference on Pattern Recognition. - Los Alamitos, CA, USA : IEEE Computer Society. - 9781424475421 ; , s. 3665-3669
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Konferensbidrag (refereegranskat)abstract
- We present the first step towards a brain computer interface (BCI) for communication using real-time functional magnetic resonance imaging (fMRI). The subject in the MR scanner sees a virtual keyboard and steers a cursor to select different letters that can be combined to create words. The cursor is moved to the left by activating the left hand, to the right by activating the right hand, down by activating the left toes and up by activating the right toes. To select a letter, the subject simply rests for a number of seconds. We can thus communicate with the subject in the scanner by for example showing questions that the subject can answer. Similar BCI for communication have been made with electroencephalography (EEG). The subject then focuses on a letter while different rows and columns of the virtual keyboard are flashing and the system tries to detect if the correct letter is flashing or not. In our setup we instead classify the brain activity. Our system is neither limited to a communication interface, but can be used for any interface where five degrees of freedom is necessary.
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| 2. |
- Eklund, Anders, et al.
(författare)
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Balancing an Inverted Pendulum by Thinking A Real-Time fMRI Approach
- 2009
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present a method for controlling a dynamical system using real-time fMRI. The objective for the subject in the MR scanner is to balance an inverse pendulum by activating the left or right hand or resting. The brain activity is classified each second by a neural network and the classification is sent to a pendulum simulator to change the force applied to the pendulum. The state of the inverse pendulum is shown to the subject in a pair of VR goggles. The subject was able to balance the inverse pendulum both with real activity and imagined activity. The developments here have a potential to aid people with communication disabilities e.g., locked in people. It might also be a tool for stroke patients to be ableto train the damaged brain area and get real-time feedback of when they do it right.
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| 3. |
- Eklund, Anders, et al.
(författare)
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Using Real-Time fMRI to Control a Dynamical System
- 2009
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Ingår i: ISMRM 17th Scientific Meeting & Exhibition. - Linköping : Linköping University Electronic Press.
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Konferensbidrag (refereegranskat)abstract
- We present e method for controlling a dynamical system using real-time fMRI. The objective for the subject in the MR scanner is to balance an inverse pendulum by activating the left or right hand or resting. The brain activity is clasified each second by a neural network and the classification is sent to a pendulum simulator to change the state of the pendulum. The state of the inverse pendulum is shown to the subject in a pair of VR goggles. The subject was able to balance the inverse pendulum during a 7 minute test run.
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| 4. |
- Eklund, Anders, 1981-, et al.
(författare)
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Using Real-Time fMRI to Control a Dynamical System by Brain Activity Classification
- 2009. - 1
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Ingår i: Medical Image Computing and Computer-Assisted Intervention – MICCAI 2009. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642042676 - 9783642042683 ; , s. 1000-1008
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Konferensbidrag (refereegranskat)abstract
- We present a method for controlling a dynamical system using real-time fMRI. The objective for the subject in the MR scanner is to balance an inverted pendulum by activating the left or right hand or resting. The brain activity is classified each second by a neural network and the classification is sent to a pendulum simulator to change the force applied to the pendulum. The state of the inverted pendulum is shown to the subject in a pair of VR goggles. The subject was able to balance the inverted pendulum during several minutes, both with real activity and imagined activity. In each classification 9000 brain voxels were used and the response time for the system to detect a change of activity was on average 2-4 seconds. The developments here have a potential to aid people with communication disabilities, such as locked in people. Another future potential application can be to serve as a tool for stroke and Parkinson patients to be able to train the damaged brain area and get real-time feedback for more efficient training.
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| 5. |
- Lundström, Claes, 1973-, et al.
(författare)
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The alpha-histogram: Using Spatial Coherence to Enhance Histograms and Transfer Function Design
- 2006
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Ingår i: Proceedings Eurographics/IEEE Symposium on Visualization 2006, Lisbon, Portugal. ; , s. 227-234
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The high complexity of Transfer Function (TF) design is a major obstacle to widespread routine use of Direct Volume Rendering, particularly in the case of medical imaging. Both manual and automatic TF design schemes would benefit greatly from a fast and simple method for detection of tissue value ranges. To this end, we introduce the a-histogram, an enhancement that amplifies ranges corresponding to spatially coherent materials. The properties of the a-histogram have been explored for synthetic data sets and then successfully used to detect vessels in 20 Magnetic Resonance angiographies, proving the potential of this approach as a fast and simple technique for histogram enhancement in general and for TF construction in particular.
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| 6. |
- Nguyen, Tan Khoa, et al.
(författare)
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Concurrent Volume Visualization of Real-Time fMRI
- 2010
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Ingår i: Proceedings of the 8th IEEE/EG International Symposium on Volume Graphics. - Goslar, Germany : Eurographics - European Association for Computer Graphics. - 9783905674231 ; , s. 53-60
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Konferensbidrag (refereegranskat)abstract
- We present a novel approach to interactive and concurrent volume visualization of functional Magnetic Resonance Imaging (fMRI). While the patient is in the scanner, data is extracted in real-time using state-of-the-art signal processing techniques. The fMRI signal is treated as light emission when rendering a patient-specific high resolution reference MRI volume, obtained at the beginning of the experiment. As a result, the brain glows and emits light from active regions. The low resolution fMRI signal is thus effectively fused with the reference brain with the current transfer function settings yielding an effective focus and context visualization. The delay from a change in the fMRI signal to the visualization is approximately 2 seconds. The advantage of our method over standard 2D slice based methods is shown in a user study. We demonstrate our technique through experiments providing interactive visualization to the fMRI operator and also to the test subject in the scanner through a head mounted display.
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| 7. |
- Ohlsson, Henrik, 1981-, et al.
(författare)
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Enabling Bio-Feedback using Real-Time fMRI
- 2008
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Ingår i: 47th IEEE Conference on Decision and Control, 2008, CDC 2008. - Linköping : IEEE. - 9781424431236 ; , s. 3336-3341
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Konferensbidrag (refereegranskat)abstract
- Despite the enormous complexity of the human mind, fMRI techniques are able to partially observe the state of a brain in action. In this paper we describe an experimental setup for real-time fMRI in a bio-feedback loop. One of the main challenges in the project is to reach a detection speed, accuracy and spatial resolution necessary to attain sufficient bandwidth of communication to close the bio-feedback loop. To this end we have banked on our previous work on real-time filtering for fMRI and system identification, which has been tailored for use in the experiment setup. In the experiments presented the system is trained to estimate where a person in the MRI scanner is looking from signals derived from the visual cortex only. We have been able to demonstrate that the user can induce an action and perform simple tasks with her mind sensed using real-time fMRI. The technique may have several clinical applications, for instance to allow paralyzed and "locked in" people to communicate with the outside world. In the meanwhile, the need for improved fMRI performance and brain state detection poses a challenge to the signal processing community. We also expect that the setup will serve as an invaluable tool for neuro science research in general.
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| 8. |
- Sjödin, Fredrik, et al.
(författare)
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Minimizing speech contribution using different microphone noise dosimeter positions
- 2012
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Ingår i: Proceedings of BNAM 2012. - Odense : University of Southern Denmark. - 9788799540006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Use of noise dosimeter recordings in low sound level environments is often problematic due to the voice contribution from the carrier. The aim of the study was to find a microphone position with low speech contribution while still providing an accurate sound level recording. An experiment with different microphone positions was conducted in a low sound reverberation room. Two types of noise dosimeters were used (Brüel & Kjaer 4445 and Larson Davis Spark 706-Atex). In repeated measurements the carrier was instructed to read a text chapter during 60 seconds and at a speech of level about 60 dB(A), acquired by practice, with different background noise and noise levels. White noise and preschool noise was used at sound levels 50, 60, 70 and 80 dB(A). The voice contribution to the background noise level was then measured. Three microphone positions were tested; on the shoulder, above the ear and on the back of the head. The position with the microphone placed behind the head of the carrier had the lowest speech contribution, less than 2 dB(A) to the background noise at 70 dB(A). This compared to positions right above the ear 6 dB(A and on the shoulder 12 dB(A).
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| 9. |
- Sjödin, Fredrik, et al.
(författare)
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Tinnitus, noise and health effects in preschool environments
- 2012
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Ingår i: Proceedings of BNAM 2012. - Odense : University of Southern Denmark. - 9788799540006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The study included 93 employees at 17 preschools in the county of Umeå located in northern part ofSweden. Personal daily noise dosimeter recordings were made at five representative work days.Stationary noise recordings were made during the same days at two departments of each preschool, in theplaying halls and in the dining rooms. Besides audiometric tests, the employees rated their experiences ofthe noise, hearing and tinnitus as well as well as different health effects, on validated questionnaires.Tinnitus was reported among 31 per cent of the participants. The study group was dichotomized intoemployees with or without tinnitus. Employees with tinnitus reported higher prevalence of subjectivehearing loss, higher experiences of elevated sound levels at work, anxiety of the noise at work, chestpressure/pain, burn out symptoms, depression and reduced sleep quality. Significant differences wereseen for shoulder tension/pain. No group differences were seen for the objective personal or stationarynoise measures or the number of children present at the department. The results of the study are discussedin terms of underlying causes and the way in which the symptom interfere with experiences and healtheffects of the employees.
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| 10. |
- Abramian, David, 1992-, et al.
(författare)
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Anatomically Informed Bayesian Spatial Priors for FMRI Analysis
- 2020
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Ingår i: ISBI 2020. - : IEEE. - 9781538693308
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Konferensbidrag (refereegranskat)abstract
- Existing Bayesian spatial priors for functional magnetic resonance imaging (fMRI) data correspond to stationary isotropic smoothing filters that may oversmooth at anatomical boundaries. We propose two anatomically informed Bayesian spatial models for fMRI data with local smoothing in each voxel based on a tensor field estimated from a T1-weighted anatomical image. We show that our anatomically informed Bayesian spatial models results in posterior probability maps that follow the anatomical structure.
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