| 1. |
- Amat-Foraster, Maria, et al.
(författare)
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Modulation of thalamo-cortical activity by the NMDA receptor antagonists ketamine and phencyclidine in the awake freely-moving rat
- 2019
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Ingår i: Neuropharmacology. - : Elsevier BV. - 0028-3908. ; 158
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Tidskriftsartikel (refereegranskat)abstract
- Non-competitive N-methyl-D-aspartate receptor antagonists mimic schizophrenia symptoms and produce immediate and persistent antidepressant effects. We investigated the effects of ketamine and phencyclidine (PCP) on thalamo-cortical network activity in awake, freely-moving male Wistar rats to gain new insight into the neuronal populations and brain circuits involved in the effects of NMDA-R antagonists. Single unit and local field potential (LFP) recordings were conducted in mediodorsal/centromedial thalamus and in medial prefrontal cortex (mPFC) using microelectrode arrays. Ketamine and PCP moderately increased the discharge rates of principal neurons in both areas while not attenuating the discharge of mPFC GABAergic interneurons. They also strongly affected LFP activity, reducing beta power and increasing that of gamma and high-frequency oscillation bands. These effects were short-lasting following the rapid pharmacokinetic profile of the drugs, and consequently were not present at 24 h after ketamine administration. The temporal profile of both drugs was remarkably different, with ketamine effects peaking earlier than PCP effects. Although this study is compatible with the glutamate hypothesis for fast-acting antidepressant action, it does not support a local disinhibition mechanism as the source for the increased pyramidal neuron activity in mPFC. The short-lasting increase in thalamo-cortical activity is likely associated with the rapid psychotomimetic action of both agents but could also be part of a cascade of events ultimately leading to the persistent antidepressant effects of ketamine. Changes in spectral contents of high-frequency bands by the drugs show potential as translational biomarkers for target engagement of NMDA-R modulators.
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| 2. |
- Behjat, Hamid, et al.
(författare)
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Signal-Adapted Tight Frames on Graphs
- 2016
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Ingår i: IEEE Transactions on Signal Processing. - 1053-587X. ; 64:22, s. 6017-6029
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Tidskriftsartikel (refereegranskat)abstract
- The analysis of signals on complex topologies modeled by graphs is a topic of increasing importance. Decompositions play a crucial role in the representation and processing of such information. Here, we propose a new tight frame design that is adapted to a class of signals on a graph. The construction starts from a prototype Meyer-type system of kernels with uniform subbands. The ensemble energy spectral density is then defined for a given set of signals defined on the graph. The prototype design is then warped such that the resulting subbands capture the same amount of energy for the signal class. This approach accounts at the same time for graph topology and signal features. The proposed frames are constructed for three different graph signal sets and are compared with non-signal-adapted frames. Vertex localization of a set of resulting atoms is studied. The frames are then used to decompose a set of real graph signals and are also used in a setting of signal denoising. The results illustrate the superiority of the designed signal-adapted frames, over frames blind to signal characteristics, in representing data and in denoising.
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| 3. |
- Belic, Jovana, 1987-, et al.
(författare)
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Behavior Discrimination Using a Discrete Wavelet Based Approach for Feature Extraction on Local Field Potentials in the Cortex and Striatum
- 2015
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Ingår i: 7th International IEEE/EMBS Conference on Neural Engineering (NER). - : IEEE conference proceedings. - 9781467363891 ; , s. 964-967
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Konferensbidrag (refereegranskat)abstract
- Linkage between behavioral states and neural activity is one of the most important challenges in neuroscience. The network activity patterns in the awake resting state and in the actively behaving state in rodents are not well understood, and a better tool for differentiating these states can provide insights on healthy brain functions and its alteration with disease. Therefore, we simultaneously recorded local field potentials (LFPs) bilaterally in motor cortex and striatum, and measured locomotion from healthy, freely behaving rats. Here we analyze spectral characteristics of the obtained signals and present an algorithm for automatic discrimination of the awake resting and the behavioral states. We used the Support Vector Machine (SVM) classifier and utilized features obtained by applying discrete wavelet transform (DWT) on LFPs, which arose as a solution with high accuracy.
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| 4. |
- Belic, Jovana, et al.
(författare)
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Corticostriatal circuits and their role in disease
- 2015
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Ingår i: Frontiers in Neuroscience. - Cairns, Australia : Frontiers Media SA. - 1662-4548 .- 1662-453X. ; 8, s. 31-
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Tidskriftsartikel (refereegranskat)abstract
- The basal ganglia (BG) represent subcortical structures considered to be involved in action selection and decision making [1]. Dysfunction of the BG circuitry leads to many motor and cognitive disorders such as Parkinson’s disease (PD), Tourette syndrome, Huntington’s disease, obsessive compulsive disorder and many others. Therefore, we simultaneously recorded local field potentials (LFPs) in primary motor cortex and sensorimotor striatum to study features directly related to healthy versus pathological states such as Parkinson disease and levodopa-induced dyskinesia [2], [3]. The striatum, the input stage of the basal ganglia (BG), is an inhibitory network that contains several distinct cell types and receives massive excitatory inputs from the cortex. Cortex sends direct projections to the striatum, while striatum can affect cortex only indirectly through other BG nuclei and thalamus. Firstly we analyzed spectral characteristics of the obtained signals and observed that during dyskinesia, the most prominent feature was a relative power increase in the high gamma frequency range around 80 Hz, while for PD it was the beta frequency range. Secondly our preliminary results have shown that during both pathological states effective connectivity in terms of Granger causality is bidirectional with an accent on striatal influence on cortex. In the case of dyskinesia we have also found a specifically high increase in effective connectivity at 80 Hz. In order to further understand the 80-Hz phenomenon we have performed cross-frequency analysis across all states and both structures and observed characteristic patterns in the case of dyskinesia in both structures but not in the case of PD and healthy state. We have seen a large relative decrease in the modulation of the amplitude at 80Hz by the phase of low frequency oscillations (up to ~10Hz). It has been suggested that the activity of local neural populations is modulated according to the global neuronal dynamics in the way that populations oscillate and synchronize at lower frequencies and smaller ensembles are active at higher frequencies Our results suggest unexpectedly a lack of coupling between the low frequency activity of a larger population and the synchronized activity of a smaller group of neurons active at 80Hz.
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| 5. |
- Belic, Jovana, 1987-, et al.
(författare)
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Untangling cortico-striatal connectivity and cross-frequency coupling in L-DOPA-induced dyskinesia
- 2016
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Ingår i: Frontiers in Systems Neuroscience. - : Frontiers. - 1662-5137. ; 10:26, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- We simultaneously recorded local field potentials in the primary motor cortex and sensorimotor striatum in awake, freely behaving, 6-OHDA lesioned hemi-parkinsonian rats in order to study the features directly related to pathological states such as parkinsonian state and levodopa-induced dyskinesia. We analysed the spectral characteristics of the obtained signals and observed that during dyskinesia the most prominent feature was a relative power increase in the high gamma frequency range at around 80 Hz, while for the parkinsonian state it was in the beta frequency range. Here we show that during both pathological states effective connectivity in terms of Granger causality is bidirectional with an accent on the striatal influence on the cortex. In the case of dyskinesia, we also found a high increase in effective connectivity at 80 Hz. In order to further understand the 80- Hz phenomenon, we performed cross-frequency analysis and observed characteristic patterns in the case of dyskinesia but not in the case of the parkinsonian state or the healthy state. We noted a large decrease in the modulation of the amplitude at 80 Hz by the phase of low frequency oscillations (up to ~10 Hz) across both structures in the case of dyskinesia. This may suggest a lack of coupling between the low frequency activity of the recorded network and the group of neurons active at ~80 Hz.
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| 6. |
- Budczies, Jan, et al.
(författare)
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Remodeling of central metabolism in invasive breast cancer compared to normal breast tissue - a GC-TOFMS based metabolomics study
- 2012
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Changes in energy metabolism of the cells are common to many kinds of tumors and are considered a hallmark of cancer. Gas chromatography followed by time-of-flight mass spectrometry (GC-TOFMS) is a well-suited technique to investigate the small molecules in the central metabolic pathways. However, the metabolic changes between invasive carcinoma and normal breast tissues were not investigated in a large cohort of breast cancer samples so far.RESULTS: A cohort of 271 breast cancer and 98 normal tissue samples was investigated using GC-TOFMS-based metabolomics. A total number of 468 metabolite peaks could be detected; out of these 368 (79%) were significantly changed between cancer and normal tissues (p<0.05 in training and validation set). Furthermore, 13 tumor and 7 normal tissue markers were identified that separated cancer from normal tissues with a sensitivity and a specificity of >80%. Two-metabolite classifiers, constructed as ratios of the tumor and normal tissues markers, separated cancer from normal tissues with high sensitivity and specificity. Specifically, the cytidine-5-monophosphate / pentadecanoic acid metabolic ratio was the most significant discriminator between cancer and normal tissues and allowed detection of cancer with a sensitivity of 94.8% and a specificity of 93.9%.CONCLUSIONS: For the first time, a comprehensive metabolic map of breast cancer was constructed by GC-TOF analysis of a large cohort of breast cancer and normal tissues. Furthermore, our results demonstrate that spectrometry-based approaches have the potential to contribute to the analysis of biopsies or clinical tissue samples complementary to histopathology.
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| 7. |
- Börjesson, Per Ola, et al.
(författare)
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Free-riding in Group Work - Mechanisms and Countermeasures
- 2006
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- Studies have shown that group work offers great possibilities for deeper learning compared to some more traditional teaching formats [1], but it can also lead to some new problems such as free-riding. Different aspects of group psychology and behaviour as well as impropriate group sizes can be used to explain why and how free-riding develops in groups. With careful course planning teachers can seriously discourage students from free-riding. Especially the grading system should be carefully chosen not to promote free-riding but to stimulate deeper learning
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| 8. |
- de Jong, R. S., et al.
(författare)
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4MOST : Project overview and information for the First Call for Proposals
- 2019
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Ingår i: The Messenger. - : European Southern Observatory. - 0722-6691. ; 175, s. 3-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations.
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| 9. |
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| 10. |
- Halje, Pär, et al.
(författare)
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Levodopa-induced dyskinesia is strongly associated with resonant cortical oscillations.
- 2012
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Ingår i: The Journal of Neuroscience : the official journal of the Society for Neuroscience. - 1529-2401. ; 32:47, s. 16541-16551
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Tidskriftsartikel (refereegranskat)abstract
- The standard pharmacological treatment for Parkinson's disease using the dopamine precursor levodopa is unfortunately limited by gradual development of disabling involuntary movements for which the underlying causes are poorly understood. Here we show that levodopa-induced dyskinesia in hemiparkinsonian rats is strongly associated with pronounced 80 Hz local field potential oscillations in the primary motor cortex following levodopa treatment. When this oscillation is interrupted by application of a dopamine antagonist onto the cortical surface the dyskinetic symptoms disappear. The finding that abnormal cortical oscillations are a key pathophysiological mechanism calls for a revision of the prevailing hypothesis that links levodopa-induced dyskinesia to an altered sensitivity to dopamine only in the striatum. Apart from having important implications for the treatment of Parkinson's disease, the discovered pathophysiological mechanism may also play a role in several other psychiatric and neurological conditions involving cortical dysfunction.
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