Abstract
Introduction
Recent advances in micro-electromechanical system (MEMS) technology have promoted the development of microelectrode arrays (MEA) that allow high resolution recordings in ...neuroscience research. However, applying MEA in studies in freely moving mice remains very challenging due to the large number of electrical connections required in this type of studies. The use of commutators for a large number of connections is not practical, and headmounts/loggers placed on the animal head are too heavy for small animals such as mice. Therefore, there is a need for a better compact system for using MEA in mice. Herein, we designed such a system and successfully recorded high-density-EEG in freely moving mice.
Methods
We designed a system in which forty flexible ultrathin wires are connected to the headstage enclosed in a container held close to the mouse. The container also houses a logger and battery connected to the headstage. This recording system allows minimizing weighted pressure on the animal using a counterbalance, so that the animal can freely move in the cage.
Results
We tested the system using a signal generator and mouse EEG arrays (NeuroNexus). When potentials produced by the signal generator were recorded via the wires, recorded traces were indistinguishable from the traces that were recorded when the signal generator was connected directly to the logger. We then implanted mice with EEG electrode arrays under surgical anesthesia. The high-density EEG recordings were performed one and four weeks after the surgery. High-quality EEG signals were observed in all the channels of the 32-channel logger (SpikeGadgets) in freely moving mice.
Conclusion
We successfully developed and tested a novel system for enabling high-density EEG recordings in freely moving mice. We expect that this system will be useful for recording biopotentials from different types of MEA in freely moving mice.
Support
NIH 1R43OD023231 (LG), NIH 1RF1AG061774 (DG), and NIH 5R21NS106406 (DG)
Keywords: alpha rhythm; gamma rhythm; somatosensory cortex; spatial orientation; tactile perception; transcranial alternating current stimulation Introduction Spontaneous oscillations in the ...somatosensory cortex, especially of the alpha (8 - 14 Hz) and gamma (60 - 80 Hz) frequencies, affect tactile perception; moreover, these oscillations can be selectively modulated by frequency-matched transcranial alternating current stimulation (tACS) on the basis of ongoing oscillatory brain activity. To examine whether tACS can actually improve tactile perception via alpha and gamma modulation, we measured the effects of 10-Hz and 70-Hz tACS (alpha- and gamma-tACS) on the left somatosensory cortex on right-finger tactile spatial orientation discrimination, and the associations between performance changes and individual alpha and gamma activities. Methods Fifteen neurologically healthy subjects were recruited into this study. Electroencephalography (EEG) was performed before the first day, to assess the normal alpha- and gamma-activity levels. A grating orientation discrimination task was performed before and during 10-Hz and 70-Hz tACS. Results The 10-Hz tACS protocol decreased the grating orientation discrimination threshold, primarily in subjects with low alpha event-related synchronization (ERS). In contrast, the 70-Hz tACS had no effect on the grating orientation discrimination threshold. Conclusions This study showed that 10-Hz tACS can improve tactile orientation discrimination in subjects with low alpha activity. Alpha-frequency tACS may help identify the contributions of these oscillations to other neurophysiological and pathological processes. Byline: Kei Saito, Naofumi Otsuru, Hirotake Yokota, Yasuto Inukai, Shota Miyaguchi, Sho Kojima, Hideaki Onishi
With the recent development of new technology and practices in the field of ambulatory EEG (aEEG), the time is right for a practical reference on the application of aEEG in clinical practice. This ...authoritative guide to prolonged EEG recording outside the hospital or clinic is a valuable resource for anyone involved in long-term EEG monitoring and interpretation. Bridging the gap between routine scalp EEG and in-patient video EEG monitoring, aEEG has evolved to provide cost-effective, high-yield, high-tech recording for evaluation of epilepsy diagnoses, nonepileptic attacks, quantification of seizures or epileptiform burden, and other issues requiring extended EEG observation for paroxysmal neurological events in any environment. Bringing together top experts from leading epilepsy centers, the book covers equipment, technical aspects of recording, instrumentation and polygraphic event monitoring, artifacts, clinical use in adult and pediatric patients, sleep recording, short-term and chronic ambulatory EEG, and reimbursement. The concluding chapter offers representative case presentations with relevant findings to further enhance the reader's understanding and implementation of key concepts. This "start to stop" survey of current applications is essential reading for a wide range of clinicians practicing in the field of clinical neurophysiology and epilepsy management, whether seasoned or in training.Key Features:Fills the void of when and how to use aEEG in evaluating patients with paroxysmal neurological events and epilepsyIncorporates aEEG into clinical management at all stages of diagnosis and treatmentContains numerous aEEG illustrations and graphics to emphasize key pointsIncludes a chapter on common artifacts that can complicate the interpretation of an aEEGDetails the evolving use of chronic intracranial aEEG and wearable devicesIllustrative case studies provide pearls and reinforce best practices in aEEG monitoring
Summary
Objective
To examine the true incidence of hemorrhage related to stereo‐electroencephalography (SEEG) procedures. To analyze risk factors associated with the presence of different types of ...hemorrhage in SEEG procedures.
Methods
This was a retrospective, single‐center observational study examining every SEEG implantation performed at our center from 2009 to 2017. This consisted of 549 consecutive SEEG implantations using a variety of stereotactic and imaging techniques. A hemorrhage grading system was applied by a blinded neuroradiologist to every postimplant and postexplant computed tomography (CT) scan. Hemorrhages were classified as asymptomatic or symptomatic based on neurologic deficit seen on examination. Statistical analysis included multivariate regression using relevant preoperative variables to predict the presence of hemorrhage.
Results
One hundred five implantations (19.1%) had any type of hemorrhage seen on postimplant CT. Of these, 93 (16.9%) were asymptomatic and 12 (2.2%) were symptomatic, with 3 implantations (0.6%) resulting in either a permanent deficit (2, 0.4%) or death (1, 0.2%). Male sex, increased number of electrodes, and increasing age were associated with increased risk of postimplant hemorrhage on multivariate analysis. Increasing score in the grading system was related to a statistically significant increase in the likelihood of a symptomatic hemorrhage.
Significance
Detailed examination of every postimplant CT reveals that the total hemorrhage rate appears higher than previously reported. Most of these hemorrhages are small and asymptomatic. Our grading system may be useful to risk stratify these hemorrhages and awaits prospective validation.
PDF
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