1,217 research outputs found
OH + Isoprene: A Direct Dynamics Study
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137441/1/bkcs11145.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137441/2/bkcs11145_am.pd
Brain Source Imaging in Preclinical Rat Models of Focal Epilepsy using High-Resolution EEG Recordings
Electroencephalogram (EEG) has been traditionally used to determine which brain regions are the most likely candidates for resection in patients with focal epilepsy. This methodology relies on the assumption that seizures originate from the same regions of the brain from which interictal epileptiform discharges (IEDs) emerge. Preclinical models are very useful to find correlates between IED locations and the actual regions underlying seizure initiation in focal epilepsy. Rats have been commonly used in preclinical studies of epilepsy1; hence, there exist a large variety of models for focal epilepsy in this particular species. However, it is challenging to record multichannel EEG and to perform brain source imaging in such a small animal. To overcome this issue, we combine a patented-technology to obtain 32-channel EEG recordings from rodents2 and an MRI probabilistic atlas for brain anatomical structures in Wistar rats to perform brain source imaging. In this video, we introduce the procedures to acquire multichannel EEG from Wistar rats with focal cortical dysplasia, and describe the steps both to define the volume conductor model from the MRI atlas and to uniquely determine the IEDs. Finally, we validate the whole methodology by obtaining brain source images of IEDs and compare them with those obtained at different time frames during the seizure onset
Senior Recital: Lindsay Peterson, mezzo-soprano
This recital is presented in partial fulfillment of requirements for the degree Bachelor of Music in Music Education. Ms. Peterson studies voice with Todd Wedge.https://digitalcommons.kennesaw.edu/musicprograms/2207/thumbnail.jp
Understanding the Formation and Evolution of Dark Galaxies in a Simulated Universe
We study the formation and evolution of dark galaxies using the IllustrisTNG
cosmological hydrodynamical simulation. We first identify dark galaxies with
stellar-to-total mass ratios, , smaller than ,
which differ from luminous galaxies with .
We then select the galaxies with dark matter halo mass of for mass completeness, and compare their physical
properties with those of luminous galaxies. We find that at the present epoch
(), dark galaxies are predominantly located in void regions without
star-forming gas. We also find that dark galaxies tend to have larger sizes and
higher spin parameters than luminous galaxies. In the early universe, dark and
luminous galaxies show small differences in the distributions of spin and local
environment estimates, and the difference between the two samples becomes more
significant as they evolve. Our results suggest that dark galaxies tend to be
initially formed in less dense regions, and could not form stars because of
heating from cosmic reionization and of few interactions and mergers with other
systems containing stars unlike luminous galaxies. This study based on
numerical simulations can provide important hints for validating dark galaxy
candidates in observations and for constraining galaxy formation models.Comment: 15 pages, 10 figures, accepted for publication in Ap
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Dysfunction of neurovascular/metabolic coupling in chronic focal epilepsy
In this study, we aim to evaluate the mechanisms underlying the neuro-vascular/metabolic coupling in the epileptogenic cortices of rats with chronic focal epilepsy. To that end, we first analyzed intracranial recordings (electrophysiology, laser Doppler flowmetry and optical imaging) obtained from the seizure onset zones during ictal periods and then used these data to fit a metabolically-coupled balloon model. This biophysical model is an extension of the standard balloon model with modulatory effects of changes in tissue oxygenation, capillary dynamics and variable O2 extraction fraction. As previously reported using acute seizure models, we found that there is a significant higher contribution from high local field potential frequency bands to the cerebral blood flow (CBF) responses in the epileptogenic cortices during ictal neuronal activities. The hemodynamic responses associated with ictal activities were distance-dependent with regard to the seizure focus, though varied in profiles from those obtained from acute seizure models. Parameters linking the CBF and relative concentration of deoxy-hemoglobin to neuronal activity in the biophysical model were significantly different between epileptic and normal rats. In particular, we found that the coefficient associated with the strength of the functional hyperemic response was significantly larger in the epileptogenic cortices, although changes in hemoglobin concentration associated with ictal activity reflected the existence of a significantly higher baseline for oxygen metabolism in the epileptogenic cortices
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