CHRONIC DIETARY EXPOSURE WITH INTERMITTENT SPIKE DOSES OF CHLORPYRIFOS FAILS TO ALTER FLASH OR PATTERN REVERSAL EVOKED POTENTIALS IN RATS.

EPA Science Inventory

Human exposure to pesticides is often characterized by chronic low level exposure with intermittent spiked higher exposures. Visual disturbances are often reported following exposure to xenobiotics, and cholinesterase-inhibiting compounds have been reported to alter visual functi...

Increasing N200 Potentials Via Visual Stimulus Depicting Humanoid Robot Behavior.

PubMed

Li, Mengfan; Li, Wei; Zhou, Huihui

2016-02-01

Achieving recognizable visual event-related potentials plays an important role in improving the success rate in telepresence control of a humanoid robot via N200 or P300 potentials. The aim of this research is to intensively investigate ways to induce N200 potentials with obvious features by flashing robot images (images with meaningful information) and by flashing pictures containing only solid color squares (pictures with incomprehensible information). Comparative studies have shown that robot images evoke N200 potentials with recognizable negative peaks at approximately 260 ms in the frontal and central areas. The negative peak amplitudes increase, on average, from 1.2 μV, induced by flashing the squares, to 6.7 μV, induced by flashing the robot images. The data analyses support that the N200 potentials induced by the robot image stimuli exhibit recognizable features. Compared with the square stimuli, the robot image stimuli increase the average accuracy rate by 9.92%, from 83.33% to 93.25%, and the average information transfer rate by 24.56 bits/min, from 72.18 bits/min to 96.74 bits/min, in a single repetition. This finding implies that the robot images might provide the subjects with more information to understand the visual stimuli meanings and help them more effectively concentrate on their mental activities.

Cholinesterase Inhibition and Depression of the Photic After Discharge of Flash Evoked Potentials Following Acute or Repeated Exposures to a Mixture of Carbaryl and Propoxur

EPA Science Inventory

While information exists regarding inhibition of cholinesterase (ChE) activity, little is known about neurophysiological changes produced by a mixture of N-methyl carbamate pesticides. Previously, we reported that acute treatment with propoxur or carbaryl decreased the duration o...

The locus of origin of augmenting and reducing of visual evoked potentials in rat brain.

PubMed

Siegel, J; Gayle, D; Sharma, A; Driscoll, P

1996-07-01

Humans who are high sensation seekers and cats who demonstrate comparable behavioral traits show increasing amplitudes of the early components of the cortical visual evoked potential (VEP) to increasing intensities of light flash; low sensation seekers show VEP reducing. Roman high-avoidance (RHA) and Roman low-avoidance (RLA) rats have behavioral traits comparable to human and cat high and low sensation seekers, respectively. Previously, we showed that RHA and RLA rats are cortical VEP augmenters and reducers, respectively. The goal of this study was to determine if augmenting-reducing is in fact a property of the visual cortex or if it originates at the lateral geniculate nucleus and is merely reflected in recordings from the cortex. EPs to five flash intensities were recorded from the visual cortex and dorsal lateral geniculate of RHA and RLA rats. As in the previous study, the slope of the first cortical component as a function of flash intensity was greater in the RHA than in the RLA rats. The amplitude of the geniculate component that has a latency shorter than the first cortical component was no different in the two lines of rats. The finding from the cortex confirms the earlier finding of augmenting and reducing in RHA and RLA rats, respectively. The major new finding is that the augmenting-reducing difference recorded at the cortex does not occur at the thalamus, indicating that it is truly a cortical phenomenon.

[Visual evoked potentials produced by monocular flash stimuli in the cerebral cortex of the rabbit. I. Typography].

PubMed

Pérez-Cobo, J C; Ruiz-Beramendi, M; Pérez-Arroyo, M

1990-12-01

The visually evoked potentials in the hemisphere contralateral to the stimulated eye in rabbit, can be described topographically as follows. While a positive wave (P1) begins forming in the anterior zones and in the V I binocular zone, the N0 wave, at times very large, is produced in a more occipital zone, which corresponds to the visual streak. Immediately afterwards, the positivity, P1, practically invades the whole of the hemisphere. After this, the N1 wave which is produced in the most posterior parts of the V I, begins forming. The whole phenomenon comes to an end when the P2 wave is generated in the most occipital zones.

Lateral geniculate body evoked potentials elicited by visual and electrical stimulation.

PubMed

Choi, Chang Wook; Kim, Pan Sang; Shin, Sun Ae; Yang, Ji Yeon; Yang, Yun Sik

2014-08-01

Blind individuals who have photoreceptor loss are known to perceive phosphenes with electrical stimulation of their remaining retinal ganglion cells. We proposed that implantable lateral geniculate body (LGB) stimulus electrode arrays could be used to generate phosphene vision. We attempted to refine the basic reference of the electrical evoked potentials (EEPs) elicited by microelectrical stimulations of the optic nerve, optic tract and LGB of a domestic pig, and then compared it to visual evoked potentials (VEPs) elicited by short-flash stimuli. For visual function measurement, VEPs in response to short-flash stimuli on the left eye of the domestic pig were assessed over the visual cortex at position Oz with the reference electrode at Fz. After anesthesia, linearly configured platinum wire electrodes were inserted into the optic nerve, optic track and LGB. To determine the optimal stimulus current, EEPs were recorded repeatedly with controlling the pulse and power. The threshold of current and charge density to elicit EEPs at 0.3 ms pulse duration was about ±10 µA. Our experimental results showed that visual cortex activity can be effectively evoked by stimulation of the optic nerve, optic tract and LGB using penetrating electrodes. The latency of P1 was more shortened as the electrical stimulation was closer to LGB. The EEPs of two-channel in the visual cortex demonstrated a similar pattern with stimulation of different spots of the stimulating electrodes. We found that the LGB-stimulated EEP pattern was very similar to the simultaneously generated VEP on the control side, although implicit time deferred. EEPs and VEPs derived from visual-system stimulation were compared. The LGB-stimulated EEP wave demonstrated a similar pattern to the VEP waveform except implicit time, indicating prosthetic-based electrical stimulation of the LGB could be utilized for the blind to perceive vision of phosphenes.

Rabbit electroretinograms evoked by 632.8nm laser flash stimuli

NASA Astrophysics Data System (ADS)

Yang, Zai-Fu; Chen, Hong-Xia; Wang, Jia-Rui; Guan, Bo-Lin; Yu, Guang-Yuan; Zhang, Xiao-Na; Zhang, Wen-Yuan; Yang, Jing-Geng

2012-12-01

The flash electroretinography is a standard electrophysiological method and widely employed in basic research and ophthalmology clinics, of which the stimulus is usually white flash from dome stimulator. However, little is known about the electroretinograms (ERGs) evoked by monochromatic laser flash stimuli. The goal of this research effort is to quantify the ERGs of dark-adapted New Zealand rabbits elicited by He-Ne laser flash with wavelength 632.8 nm. The flash field was a Maxwellian viewing disc with angular subtense of 8.5°, 13.3° or 20.2°. The stimulus duration was 12 ms, 22 ms, 70 ms or 220 ms. The laser flash power incident on the cornea varied from 2.2 nW through 22 mW. Under the condition of 20 ms stimulus duration and 20.2° flash field, the ERG of New Zealand rabbit was compared with that of Chinchilla gray rabbit. Results showed that for the ERG b-wave, with the increase of laser energy, the amplitude first increased, then met a trough and finally increased again, the implicit time decreased first and then met a platform. While for the ERG a-wave, the amplitude increased and the implicit time decreased monotonically. Longer stimulus duration led to lower b-wave amplitude under equal flash power level. The flash field size showed limited effect on the ERG, especially on the low energy end. As compared with the pigmented rabbit, the albino rabbit was more sensitive and the threshold energy for b-wave excitation was about 10 times lower.

Effects of maternal inhalation of gasoline evaporative ...

EPA Pesticide Factsheets

In order to assess potential health effects resulting from exposure to ethanol-gasoline blend vapors, we previously conducted neurophysiological assessment of sensory function following gestational exposure to 100% ethanol vapor (Herr et al., Toxicologist, 2012). For comparison purposes, the current study investigated the same measures after gestational exposure to 100% gasoline evaporative condensates (GVC). Pregnant Long-Evans rats were exposed to 0, 3K, 6K, or 9K ppm GVC vapors for 6.5 h/day over GD9 – GD20. Sensory evaluations of male offspring began around PND106. Peripheral nerve function (compound action potentials, NCV), somatosensory (cortical and cerebellar evoked potentials), auditory (brainstem auditory evoked responses), and visual evoked responses were assessed. Visual function assessment included pattern elicited visual evoked potentials (VEP), VEP contrast sensitivity, and electroretinograms (ERG) recorded from dark-adapted (scotopic) and light-adapted (photopic) flashes, and UV and green flicker. Although some minor statistical differences were indicated for auditory and somatosensory responses, these changes were not consistently dose- or stimulus intensity-related. Scotopic ERGs had a statistically significant dose-related decrease in the b-wave implicit time. All other parameters of ERGs and VEPs were unaffected by treatment. All physiological responses showed changes related to stimulus intensity, and provided an estimate of detectable le

Non-linearity of visual evoked potentials in cerveau isolé and midpontine pretrigeminal cats.

PubMed

Shibagaki, M; Kiyono, S; Kawashima, T; Watanabe, S

1985-01-01

Characteristics of the visual evoked responses to the flickering flash stimulation were studied in the cerveau isolé and midpontine pretrigeminal cats. The flash stimulation frequency was changed stepwise between 1 and 30 Hz in increasing and decreasing order. In all cases of both preparations, with drawing of fixed sweep speed of 200 msec in whole length, P1 and N1 latencies in the successive response slightly prolonged progressively 1 to about 20 Hz and thereafter shortened about 20-30 Hz stimulus frequencies in the course of the increasing phase, and vice versa in the course of the decreasing phase. Moreover, no difference in each latency (P1, N1, P2, N2) was found at the same stimulus frequency during increasing and decreasing phases. In the amplitude taken from the P1-N1 component, the peak was found in 5-9 Hz frequency bands. This peak was higher during the decreasing phase than during the increasing phase, which indicated a hysteresis phenomenon. A peak of power for the 1st harmonics was found at 3-6 Hz driving frequency bands, and that of the 2nd harmonics at 6-10 Hz. In the state without flash stimulus, no peaks or valleys in the power spectrum were found in specific frequencies, for example 3-10 Hz. The peak in the amplitude and that in the power spectrum at 3-10 Hz stimulus frequency bands suggested an entrainment phenomenon induced by forced oscillation. The phenomena of entrainment and hysteresis suggest the existence of a non-linear structure in the oscillation generating systems of visual evoked response.

Paired-pulse flash-visual evoked potentials: new methods revive an old test.

PubMed

Cantello, Roberto; Strigaro, Gionata; Prandi, Paolo; Varrasi, Claudia; Mula, Marco; Monaco, Francesco

2011-08-01

We aimed at reviving with modern technology the paired flash-visual evoked potential (F-VEP) testing of the visual system excitability. In the 1960s, methodological problems hindered this test, which was expected to provide important physiologic information. We studied 22 consenting healthy subjects (10 men). We recorded F-VEPs from electrodes over occipital and central brain regions. We delivered single flashes, mixed at random to flash pairs at the interstimulus interval (ISI) of 333, 125, 62.5, 50, 33, and 16.5 ms, (i.e. an internal frequency (IF) of 3, 8, 16, 20, 30, and 60 Hz). Recordings were performed with the subject's eyes closed and opened. The F-VEP was split into a "main complex" and an "afterdischarge", which we analyzed statistically in relation to the eye state (closed or open) and to the changes due to paired stimulation. The eye state affected the single F-VEP size, latency and shape significantly (p<0.05). On paired stimulation, the test (second) F-VEP exhibited significant (p<0.05), ISI-dependent size changes, such as a progressive decrease for ISIs from 62.5 to 16.5 ms (IFs of 16-60 Hz), whose timing/amount varied significantly (p<0.05) according to the eye state and to the F-VEP epoch considered. Suppression of the test F-VEP was never complete, even for the shortest ISI (ISI=16.5 ms, IF=60 Hz). The eye state (closed or open) must be considered meticulously when studying F-VEPs. F-VEP changes on paired stimulation express neural inhibition within the visual system, which can be depicted as ISI-dependent curves. Modern equipment and simplified measures render this an easy test, with statistical validity, providing specific information on the excitability properties of the visual system. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Simultaneous diffuse near-infrared imaging of hemodynamic and oxygenation changes and electroencephalographic measurements of neuronal activity in the human brain

NASA Astrophysics Data System (ADS)

Noponen, Tommi; Kicic, Dubravko; Kotilahti, Kalle; Kajava, Timo; Kahkonen, Seppo; Nissila, Ilkka; Merilainen, Pekka; Katila, Toivo

2005-04-01

Visually evoked hemodynamic responses and potentials were simultaneously measured using a 16-channel optical imaging instrument and a 60-channel electroencephalography instrument during normo-, hypo- and hypercapnia from three subjects. Flashing and pattern-reversed checkerboard stimuli were used. The study protocol included two counterbalanced measurements during both normo- and hypocapnia and normo- and hypercapnia. Hypocapnia was produced by controlled hyperventilation and hypercapnia by breathing carbon dioxide enriched air. Near-infrared imaging was also used to monitor the concentration changes of oxy- and deoxyhaemoglobin due to hypo- and hypercapnia. Hemodynamic responses and evoked potentials were successfully detected for each subject above the visual cortex. The latencies of the hemodynamic responses during hypocapnia were shorter whereas during hypercapnia they were longer when compared to the latencies during normocapnia. Hypocapnia tended to decrease the latencies of visually evoked potentials compared to those during normocapnia while hypercapnia did not show any consistent effect to the potentials. The developed measurement setup and the study protocol provide the opportunity to investigate the neurovascular coupling and the links between the baseline level of blood flow, electrical activity and hemodynamic responses in the human brain.

[Design and implementation of controlling smart car systems using P300 brain-computer interface].

PubMed

Wang, Jinjia; Yang, Chengjie; Hu, Bei

2013-04-01

Using human electroencephalogram (EEG) to control external devices in order to achieve a variety of functions has been focus of the field of brain-computer interface (BCI) research. P300 is experiments which stimulate the eye to produce EEG by using letters flashing, and then identify the corresponding letters. In this paper, some improvements based on the P300 experiments were made??. Firstly, the matrix of flashing letters were modified into words which represent a certain sense. Secondly, the BCI2000 procedures were added with the corresponding source code. Thirdly, the smart car systems were designed using the radiofrequency signal. Finally it was realized that the evoked potentials were used to control the state of the smart car.

BRAIN CHOLINESTERASE INHIBITION AND DEPRESSION OF THE PHOTIC AFTER DISCHARGE (PHAD) OF FLASH EVOKED POTENTIALS (FEPS) IN LONG EVANS RATS FOLLOWING ACUTE OR REPEATED EXPOSURES TO A MIXTURE OF CARBARYL AND PROPOXUR.

EPA Science Inventory

Carbaryl and propoxur are N-methyl carbamate pesticides (NMCs) which are part of the EPA’s cumulative risk assessments for NMCs. These NMCs inhibit cholinesterase (ChE) activity and may lead to cholinergic disruption of CNS function. We used decreases in the PhAD of FEPs to indic...

Direct evidence for a position input to the smooth pursuit system.

PubMed

Blohm, Gunnar; Missal, Marcus; Lefèvre, Philippe

2005-07-01

When objects move in our environment, the orientation of the visual axis in space requires the coordination of two types of eye movements: saccades and smooth pursuit. The principal input to the saccadic system is position error, whereas it is velocity error for the smooth pursuit system. Recently, it has been shown that catch-up saccades to moving targets are triggered and programmed by using velocity error in addition to position error. Here, we show that, when a visual target is flashed during ongoing smooth pursuit, it evokes a smooth eye movement toward the flash. The velocity of this evoked smooth movement is proportional to the position error of the flash; it is neither influenced by the velocity of the ongoing smooth pursuit eye movement nor by the occurrence of a saccade, but the effect is absent if the flash is ignored by the subject. Furthermore, the response started around 85 ms after the flash presentation and decayed with an average time constant of 276 ms. Thus this is the first direct evidence of a position input to the smooth pursuit system. This study shows further evidence for a coupling between saccadic and smooth pursuit systems. It also suggests that there is an interaction between position and velocity error signals in the control of more complex movements.

Correlation of Visually Evoked Functional and Blood Flow Changes in the Rat Retina Measured With a Combined OCT+ERG System.

PubMed

Tan, Bingyao; Mason, Erik; MacLellan, Benjamin; Bizheva, Kostadinka K

2017-03-01

To correlate visually evoked functional and blood flow changes in the rat retina measured simultaneously with a combined optical coherence tomography and electroretinography system (OCT+ERG). Male Brown Norway (n = 6) rats were dark adapted and anesthetized with ketamine/xylazine. Visually evoked changes in the retinal blood flow (RBF) and functional response were measured simultaneously with an OCT+ERG system with 3-μm axial resolution in retinal tissue and 47-kHz image acquisition rate. Both single flash (10 and 200 ms) and flicker (10 Hz, 20% duty cycle, 1- and 2-second duration) stimuli were projected onto the retina with a custom visual stimulator, integrated into the OCT imaging probe. Total axial RBF was calculated from circular Doppler OCT scans by integrating over the arterial and venal flow. Temporary increase in the RBF was observed with the 10- and 200-ms continuous stimuli (∼1% and ∼4% maximum RBF change, respectively) and the 10-Hz flicker stimuli (∼8% for 1-second duration and ∼10% for 2-second duration). Doubling the flicker stimulus duration resulted in ∼25% increase in the RBF peak magnitude with no significant change in the peak latency. Single flash (200 ms) and flicker (10 Hz, 1 second) stimuli of the same illumination intensity and photon flux resulted in ∼2× larger peak RBF magnitude and ∼25% larger RBF peak latency for the flicker stimulus. Short, single flash and flicker stimuli evoked measureable RBF changes with larger RBF magnitude and peak latency observed for the flicker stimuli.

Temporal recalibration of motor and visual potentials in lag adaptation in voluntary movement.

PubMed

Cai, Chang; Ogawa, Kenji; Kochiyama, Takanori; Tanaka, Hirokazu; Imamizu, Hiroshi

2018-05-15

Adaptively recalibrating motor-sensory asynchrony is critical for animals to perceive self-produced action consequences. It is controversial whether motor- or sensory-related neural circuits recalibrate this asynchrony. By combining magnetoencephalography (MEG) and functional MRI (fMRI), we investigate the temporal changes in brain activities caused by repeated exposure to a 150-ms delay inserted between a button-press action and a subsequent flash. We found that readiness potentials significantly shift later in the motor system, especially in parietal regions (average: 219.9 ms), while visually evoked potentials significantly shift earlier in occipital regions (average: 49.7 ms) in the delay condition compared to the no-delay condition. Moreover, the shift in readiness potentials, but not in visually evoked potentials, was significantly correlated with the psychophysical measure of motor-sensory adaptation. These results suggest that although both motor and sensory processes contribute to the recalibration, the motor process plays the major role, given the magnitudes of shift and the correlation with the psychophysical measure. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Control of a nursing bed based on a hybrid brain-computer interface.

PubMed

Nengneng Peng; Rui Zhang; Haihua Zeng; Fei Wang; Kai Li; Yuanqing Li; Xiaobin Zhuang

2016-08-01

In this paper, we propose an intelligent nursing bed system which is controlled by a hybrid brain-computer interface (BCI) involving steady-state visual evoked potential (SSVEP) and P300. Specifically, the hybrid BCI includes an asynchronous brain switch based on SSVEP and P300, and a P300-based BCI. The brain switch is used to turn on/off the control system of the electric nursing bed through idle/control state detection, whereas the P300-based BCI is for operating the nursing bed. At the beginning, the user may focus on one group of flashing buttons in the graphic user interface (GUI) of the brain switch, which can simultaneously evoke SSVEP and P300, to switch on the control system. Here, the combination of SSVEP and P300 is used for improving the performance of the brain switch. Next, the user can control the nursing bed using the P300-based BCI. The GUI of the P300-based BCI includes 10 flashing buttons, which correspond to 10 functional operations, namely, left-side up, left-side down, back up, back down, bedpan open, bedpan close, legs up, legs down, right-side up, and right-side down. For instance, he/she can focus on the flashing button "back up" in the GUI of the P300-based BCI to activate the corresponding control such that the nursing bed is adjusted up. Eight healthy subjects participated in our experiment, and obtained an average accuracy of 93.75% and an average false positive rate (FPR) of 0.15 event/min. The effectiveness of our system was thus demonstrated.

A gaze independent hybrid-BCI based on visual spatial attention

NASA Astrophysics Data System (ADS)

Egan, John M.; Loughnane, Gerard M.; Fletcher, Helen; Meade, Emma; Lalor, Edmund C.

2017-08-01

Objective. Brain-computer interfaces (BCI) use measures of brain activity to convey a user’s intent without the need for muscle movement. Hybrid designs, which use multiple measures of brain activity, have been shown to increase the accuracy of BCIs, including those based on EEG signals reflecting covert attention. Our study examined whether incorporating a measure of the P3 response improved the performance of a previously reported attention-based BCI design that incorporates measures of steady-state visual evoked potentials (SSVEP) and alpha band modulations. Approach. Subjects viewed stimuli consisting of two bi-laterally located flashing white boxes on a black background. Streams of letters were presented sequentially within the boxes, in random order. Subjects were cued to attend to one of the boxes without moving their eyes, and they were tasked with counting the number of target-letters that appeared within. P3 components evoked by target appearance, SSVEPs evoked by the flashing boxes, and power in the alpha band are modulated by covert attention, and the modulations can be used to classify trials as left-attended or right-attended. Main Results. We showed that classification accuracy was improved by including a P3 feature along with the SSVEP and alpha features (the inclusion of a P3 feature lead to a 9% increase in accuracy compared to the use of SSVEP and Alpha features alone). We also showed that the design improves the robustness of BCI performance to individual subject differences. Significance. These results demonstrate that incorporating multiple neurophysiological indices of covert attention can improve performance in a gaze-independent BCI.

Neurophysiological assessment of auditory, peripheral nerve, somatosensory, and visual system functions after developmental exposure to ethanol vapors.

PubMed

Boyes, William K; Degn, Laura L; Martin, Sheppard A; Lyke, Danielle F; Hamm, Charles W; Herr, David W

2014-01-01

Ethanol-blended gasoline entered the market in response to demand for domestic renewable energy sources, and may result in increased inhalation of ethanol vapors in combination with other volatile gasoline constituents. It is important to understand potential risks of inhalation of ethanol vapors by themselves, and also as a baseline for evaluating the risks of ethanol combined with a complex mixture of hydrocarbon vapors. Because sensory dysfunction has been reported after developmental exposure to ethanol, we evaluated the effects of developmental exposure to ethanol vapors on neurophysiological measures of sensory function as a component of a larger project evaluating developmental ethanol toxicity. Pregnant Long-Evans rats were exposed to target concentrations 0, 5000, 10,000, or 21,000 ppm ethanol vapors for 6.5h/day over GD9-GD20. Sensory evaluations of male offspring began between PND106 and PND128. Peripheral nerve function (compound action potentials, nerve conduction velocity (NCV)), somatosensory (cortical and cerebellar evoked potentials), auditory (brainstem auditory evoked responses), and visual evoked responses were assessed. Visual function assessment included pattern elicited visual evoked potentials (VEPs), VEP contrast sensitivity, and electroretinograms recorded from dark-adapted (scotopic), light-adapted (photopic) flashes, and UV flicker and green flicker. No consistent concentration-related changes were observed for any of the physiological measures. The results show that gestational exposure to ethanol vapor did not result in detectable changes in peripheral nerve, somatosensory, auditory, or visual function when the offspring were assessed as adults. Published by Elsevier Inc.

Visually evoked changes in the rat retinal blood flow measured with Doppler optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tan, Bingyao; Mason, Erik; MacLellan, Ben; Bizheva, Kostadinka

2017-02-01

Visually evoked changes of retinal blood flow can serve as an important research tool to investigate eye disease such as glaucoma and diabetic retinopathy. In this study we used a combined, research-grade, high-resolution Doppler OCT+ERG system to study changes in the retinal blood flow (RBF) and retinal neuronal activity in response to visual stimuli of different intensities, durations and type (flicker vs single flash). Specifically, we used white light stimuli of 10 ms and 200 ms single flash, 1s and 2s for flickers stimuli of 20% duty cycle. The study was conducted in-vivo in pigmented rats. Both single flash (SF) and flicker stimuli caused increase in the RBF. The 10 ms SF stimulus did not generate any consistent measurable response, while the 200 ms SF of the same intensity generated 4% change in the RBF peaking at 1.5 s after the stimulus onset. Single flash stimuli introduced 2x smaller change in RBF and 30% earlier RBF peak response compared to flicker stimuli of the same intensity and duration. Doubling the intensity of SF or flicker stimuli increased the RBF peak magnitude by 1.5x. Shortening the flicker stimulus duration by 2x increased the RBF recovery rate by 2x, however, had no effect on the rate of RBF change from baseline to peak.

Implementation of Intraoperative Neurophysiological Monitoring during Endovascular Procedures in the Central Nervous System.

PubMed

Martinez Piñeiro, Alicia; Cubells, Carles; Garcia, Pablo; Castaño, Carlos; Dávalos, Antonio; Coll-Canti, Jaume

2015-03-01

Intraoperative monitoring (IOM) has been used in different surgical disciplines since the 1980s. Nonetheless, regular routine use of IOM in interventional neuroradiology units has only been reported in a few centers. The aim of this study is to report our experience, 1 year after deciding to implement standardized IOM during endovascular treatment of vascular abnormalities of the central nervous system. Basic recordings included somatosensory-evoked potentials (SEPs) and motor-evoked potentials (MEPs). Corticobulbar motor-evoked potentials and flash-visual-evoked potentials were also recorded depending on the topography of the lesion. Intra-arterial provocative tests (PTs) with amobarbital and lidocaine were also performed. All patients except 1 were under total intravenous anesthesia. Clinical outcome was assessed prospectively and correlated with IOM events. Twelve patients and 15 procedures were monitored during the inclusion period. Significant IOM events were detected during 3 of the 15 procedures (20%). We observed temporary MEP changes in 2 cases which resolved after interruption of the embolization or application of corrective measures, leaving no postoperative neurological deficits. In 1 case, persistent SEP and MEP deterioration was detected secondary to a frontal hematoma, resulting in mild sensory-motor deficit in the right upper extremity after the procedure. Overall, 12 PTs (4 spinal cord and 8 brain abnormalities) were performed using lidocaine and sodium amytal injections. One positive result occurred after the injection of lidocaine. No false negatives were detected. IOM may provide continuous real-time data about the functional status of eloquent areas and pathways of the central nervous system in patients under general anesthesia. It therefore allows us to detect early neurological damage in time to perform specific actions that may prevent irreversible neurological deficits.

Attentional enhancement during multiple-object tracking.

PubMed

Drew, Trafton; McCollough, Andrew W; Horowitz, Todd S; Vogel, Edward K

2009-04-01

What is the role of attention in multiple-object tracking? Does attention enhance target representations, suppress distractor representations, or both? It is difficult to ask this question in a purely behavioral paradigm without altering the very attentional allocation one is trying to measure. In the present study, we used event-related potentials to examine the early visual evoked responses to task-irrelevant probes without requiring an additional detection task. Subjects tracked two targets among four moving distractors and four stationary distractors. Brief probes were flashed on targets, moving distractors, stationary distractors, or empty space. We obtained a significant enhancement of the visually evoked P1 and N1 components (approximately 100-150 msec) for probes on targets, relative to distractors. Furthermore, good trackers showed larger differences between target and distractor probes than did poor trackers. These results provide evidence of early attentional enhancement of tracked target items and also provide a novel approach to measuring attentional allocation during tracking.

Origins of retinal intrinsic signals: a series of experiments on retinas of macaque monkeys.

PubMed

Tsunoda, Kazushige; Hanazono, Gen; Inomata, Koichi; Kazato, Yoko; Suzuki, Wataru; Tanifuji, Manabu

2009-07-01

Diffuse flash stimuli applied to the ocular fundus evoke light reflectance decreases of the fundus illuminated with infrared observation light. This phenomenon, which is independent of the photopigment bleaching observed as an increase in the reflectance of visible light, is called intrinsic signals. Intrinsic signals, in general, are stimulus-evoked light reflectance changes of neural tissues due to metabolic changes, and they have been extensively investigated in the cerebral cortex. This noninvasive objective technique of functional imaging has good potential as a tool for the early detection of retinal dysfunction. Once the signal properties were studied in detail, however, it became apparent that the intrinsic signals observed in the retina have uniquely interesting properties of their own due to the characteristic layered structure of the retina. Experiments on anesthetized macaque monkeys are reviewed, and the possible origins of the intrinsic signals of the retina are discussed.

Cardio-visual full body illusion alters bodily self-consciousness and tactile processing in somatosensory cortex.

PubMed

Heydrich, Lukas; Aspell, Jane Elizabeth; Marillier, Guillaume; Lavanchy, Tom; Herbelin, Bruno; Blanke, Olaf

2018-06-18

Prominent theories highlight the importance of bodily perception for self-consciousness, but it is currently not known whether this is based on interoceptive or exteroceptive signals or on integrated signals from these anatomically distinct systems, nor where in the brain such integration might occur. To investigate this, we measured brain activity during the recently described 'cardio-visual full body illusion' which combines interoceptive and exteroceptive signals, by providing participants with visual exteroceptive information about their heartbeat in the form of a periodically illuminated silhouette outlining a video image of the participant's body and flashing in synchrony with their heartbeat. We found, as also reported previously, that synchronous cardio-visual signals increased self-identification with the virtual body. Here we further investigated whether experimental changes in self-consciousness during this illusion are accompanied by activity changes in somatosensory cortex by recording somatosensory evoked potentials (SEPs). We show that a late somatosensory evoked potential component (P45) reflects the illusory self-identification with a virtual body. These data demonstrate that interoceptive and exteroceptive signals can be combined to modulate activity in parietal somatosensory cortex.

Visual evoked potentials in the horse.

PubMed

Ström, L; Ekesten, B

2016-06-21

Electrical potentials generated in the central nervous system in response to brief visual stimuli, flash visual evoked potentials (FVEPs), can be recorded non-invasively over the occipital cortex. FVEPs are used clinically in human medicine and also experimentally in a number of animal species, but the method has not yet been evaluated in the horse. The method would potentially allow the ophthalmologist and equine clinician to evaluate visual impairment caused by disorders affecting post-retinal visual pathways. The aim was to establish a method for recording of FVEPs in horses in a clinical setting and to evaluate the waveform morphology in the normal horse. Ten horses were sedated with a continuous detomidine infusion. Responses were recorded from electrodes placed on the scalp. Several positions were evaluated to determine suitable electrode placement. Flash electroretinograms (FERGs) were recorded simultaneously. To evaluate potential contamination of the FVEP from retinal potentials, a retrobulbar nerve block was performed in two horses and transection of the optic nerve was performed in one horse as a terminal procedure. A series of positive (P) and negative (N) peaks in response to light stimuli was recorded in all horses. Reproducible wavelets with mean times-to-peaks of 26 (N1), 55 (P2), 141 (N2) and 216 ms (P4) were seen in all horses in all recordings. Reproducible results were obtained when the active electrode was placed in the midline rostral to the nuchal crest. Recording at lateral positions gave more variable results, possibly due to ear muscle artifacts. Averaging ≥100 responses reduced the impact of noise and artifacts. FVEPs were reproducible in the same horse during the same recording session and between sessions, but were more variable between horses. Retrobulbar nerve block caused a transient loss of the VEP whereas transection of the optic nerve caused an irreversible loss. We describe the waveform of the equine FVEP and our results show that it is possible to record FVEPs in sedated horses in a clinical setting. The potentials recorded were shown to be of post-retinal origin. Further studies are needed to provide normative data and assess potential clinical use.

Detecting number processing and mental calculation in patients with disorders of consciousness using a hybrid brain-computer interface system.

PubMed

Li, Yuanqing; Pan, Jiahui; He, Yanbin; Wang, Fei; Laureys, Steven; Xie, Qiuyou; Yu, Ronghao

2015-12-15

For patients with disorders of consciousness such as coma, a vegetative state or a minimally conscious state, one challenge is to detect and assess the residual cognitive functions in their brains. Number processing and mental calculation are important brain functions but are difficult to detect in patients with disorders of consciousness using motor response-based clinical assessment scales such as the Coma Recovery Scale-Revised due to the patients' motor impairments and inability to provide sufficient motor responses for number- and calculation-based communication. In this study, we presented a hybrid brain-computer interface that combines P300 and steady state visual evoked potentials to detect number processing and mental calculation in Han Chinese patients with disorders of consciousness. Eleven patients with disorders of consciousness who were in a vegetative state (n = 6) or in a minimally conscious state (n = 3) or who emerged from a minimally conscious state (n = 2) participated in the brain-computer interface-based experiment. During the experiment, the patients with disorders of consciousness were instructed to perform three tasks, i.e., number recognition, number comparison, and mental calculation, including addition and subtraction. In each experimental trial, an arithmetic problem was first presented. Next, two number buttons, only one of which was the correct answer to the problem, flickered at different frequencies to evoke steady state visual evoked potentials, while the frames of the two buttons flashed in a random order to evoke P300 potentials. The patients needed to focus on the target number button (the correct answer). Finally, the brain-computer interface system detected P300 and steady state visual evoked potentials to determine the button to which the patients attended, further presenting the results as feedback. Two of the six patients who were in a vegetative state, one of the three patients who were in a minimally conscious state, and the two patients that emerged from a minimally conscious state achieved accuracies significantly greater than the chance level. Furthermore, P300 potentials and steady state visual evoked potentials were observed in the electroencephalography signals from the five patients. Number processing and arithmetic abilities as well as command following were demonstrated in the five patients. Furthermore, our results suggested that through brain-computer interface systems, many cognitive experiments may be conducted in patients with disorders of consciousness, although they cannot provide sufficient behavioral responses.

Evoked potentials recorded during routine EEG predict outcome after perinatal asphyxia.

PubMed

Nevalainen, Päivi; Marchi, Viviana; Metsäranta, Marjo; Lönnqvist, Tuula; Toiviainen-Salo, Sanna; Vanhatalo, Sampsa; Lauronen, Leena

2017-07-01

To evaluate the added value of somatosensory (SEPs) and visual evoked potentials (VEPs) recorded simultaneously with routine EEG in early outcome prediction of newborns with hypoxic-ischemic encephalopathy under modern intensive care. We simultaneously recorded multichannel EEG, median nerve SEPs, and flash VEPs during the first few postnatal days in 50 term newborns with hypoxic-ischemic encephalopathy. EEG background was scored into five grades and the worst two grades were considered to indicate poor cerebral recovery. Evoked potentials were classified as absent or present. Clinical outcome was determined from the medical records at a median age of 21months. Unfavorable outcome included cerebral palsy, severe mental retardation, severe epilepsy, or death. The accuracy of outcome prediction was 98% with SEPs compared to 90% with EEG. EEG alone always predicted unfavorable outcome when it was inactive (n=9), and favorable outcome when it was normal or only mildly abnormal (n=17). However, newborns with moderate or severe EEG background abnormality could have either favorable or unfavorable outcome, which was correctly predicted by SEP in all but one newborn (accuracy in this subgroup 96%). Absent VEPs were always associated with an inactive EEG, and an unfavorable outcome. However, presence of VEPs did not guarantee a favorable outcome. SEPs accurately predict clinical outcomes in newborns with hypoxic-ischemic encephalopathy and improve the EEG-based prediction particularly in those newborns with severely or moderately abnormal EEG findings. SEPs should be added to routine EEG recordings for early bedside assessment of newborns with hypoxic-ischemic encephalopathy. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Time course of influence on the allocation of attentional resources caused by unconscious fearful faces.

PubMed

Jiang, Yunpeng; Wu, Xia; Saab, Rami; Xiao, Yi; Gao, Xiaorong

2018-05-01

Emotionally affective stimuli have priority in our visual processing even in the absence of conscious processing. However, the influence of unconscious emotional stimuli on our attentional resources remains unclear. Using the continuous flash suppression (CFS) paradigm, we concurrently recorded and analyzed visual event-related potential (ERP) components evoked by the images of suppressed fearful and neutral faces, and the steady-state visual evoked potential (SSVEP) elicited by dynamic Mondrian pictures. Fearful faces, relative to neutral faces, elicited larger late ERP components on parietal electrodes, indicating emotional expression processing without consciousness. More importantly, the presentation of a suppressed fearful face in the CFS resulted in a significantly greater decrease in SSVEP amplitude which started about 1-1.2 s after the face images first appeared. This suggests that the time course of the attentional bias occurs at about 1 s after the appearance of the fearful face and demonstrates that unconscious fearful faces may influence attentional resource allocation. Moreover, we proposed a new method that could eliminate the interaction of ERPs and SSVEPs when recorded concurrently. Copyright © 2018 Elsevier Ltd. All rights reserved.

Neonatal and fetal response decrement of evoked responses – a MEG study

PubMed Central

Sheridan, Carolin J.; Preissl, Hubert; Siegel, Eric R.; Murphy, Pam; Ware, Maureen; Lowery, Curtis L.; Eswaran, Hari

2008-01-01

Objective To investigate the response decrements of visual evoked responses (VER) in newborns and assess the applicability of this paradigm to fetuses in magnetoencephalographic (MEG) recordings. Methods Twelve newborns with no known risks or complications participated at chronological ages between six and 22 days. They constituted the follow-up group to a prenatal study conducted on a sample of 25 fetuses whose gestational age (GA) varied between 29 and 37 weeks at the time of recording. Trains of four light flashes with an interstimulus interval of 2 s followed by 10 s without stimulation were delivered to record VER. Results Nine of the 12 newborns responded to the stimulation and showed response decrements in amplitude from the first to the last light flash. Furthermore, the response latency increased significantly from the first to the last stimulus. The remaining three recordings were discontinued early. Even though the prenatal visual evoked response rate was only 29%, the fetuses exhibited a response decrement after the first stimulus. Conclusions The amplitude of VERs can be used to elicit a response decrement in newborns and, with limitations, even in fetuses. This paradigm might be a useful tool for a direct non-invasive assessment of neonatal and prenatal brain development and CNS functioning. Significance The proposed method might be a first step towards an early detection of developmental deficits in newborns and fetuses. PMID:18226946

Restoration of visual response in aged dystrophic RCS rats using AAV-mediated channelopsin-2 gene transfer.

PubMed

Tomita, Hiroshi; Sugano, Eriko; Yawo, Hiromu; Ishizuka, Toru; Isago, Hitomi; Narikawa, Satoko; Kügler, Sebastian; Tamai, Makoto

2007-08-01

To investigate whether the channelopsin-2 (Chop2) gene would restore visual responses in 10-month-old dystrophic Royal College of Surgeons (aged RCS; rdy/rdy) rats, the authors transferred the Chop2 gene into the retinal cells of aged RCS rats using the adenoassociated virus (AAV) vector. The N-terminal fragment (residues 1-315) of Chop2 was fused to a fluorescent protein, Venus, in frame at the end of the Chop2 coding fragment. The viral vector construct (AAV-Chop2V) for the expression of the Chop2V in the retina was made by subcloning into an adenoassociated virus vector, including the CAG promoter. To evaluate the expression profile of Chop2V in the retina, the rats were killed and the eyes were removed and fixed with 4% paraformaldehyde in 0.1 M phosphate-buffered saline. Retinal wholemount specimens and cryosections were made. Under anesthetized conditions, electrodes for the recording of visually evoked potentials (VEPs) were implanted onto the visual cortex in aged-RCS (rdy/rdy) rats. AAV-Chop2V vectors were then injected into the vitreous cavity of the left eyes. As a control, AAV-Venus vectors were applied to the right eyes. VEPs were evoked by the flash of a blue, white, or red light-emitting diode (LED) and were recorded from the visual cortex of the rats at various time points after the AAV vector injection. Chop2V fluorescence was predominantly observed in retinal ganglion cells (RGCs). Some fluorescence was observed in the inner nuclear layer and the inner plexiform layer neurites. A tendency of recovery was observed in the VEPs of aged RCS (rdy/rdy) rats after the AAV-Chop2V injection but not after the AAV-Venus injection. The visual response of AAV-Chop2V-injected aged RCS (rdy/rdy) rats was less sensitive to the blue LED flash than that of nondystrophic RCS (+/+) rats. The AAV-Chop2V-injected aged RCS (rdy/rdy) rats were insensitive to the red LED flash, which evoked a robust VEP in the RCS (+/+) rats. The visual response of aged RCS (rdy/rdy) rats was partially restored by transduction of the Chop2 gene through AAV into the inner retinal neurons, mainly RGCs. These results suggest that the transduction of Chop2 would provide a new strategy to treat some retinitis pigmentosa (RP) symptoms independent of their etiology.

An optimized ERP brain-computer interface based on facial expression changes.

PubMed

Jin, Jing; Daly, Ian; Zhang, Yu; Wang, Xingyu; Cichocki, Andrzej

2014-06-01

Interferences from spatially adjacent non-target stimuli are known to evoke event-related potentials (ERPs) during non-target flashes and, therefore, lead to false positives. This phenomenon was commonly seen in visual attention-based brain-computer interfaces (BCIs) using conspicuous stimuli and is known to adversely affect the performance of BCI systems. Although users try to focus on the target stimulus, they cannot help but be affected by conspicuous changes of the stimuli (such as flashes or presenting images) which were adjacent to the target stimulus. Furthermore, subjects have reported that conspicuous stimuli made them tired and annoyed. In view of this, the aim of this study was to reduce adjacent interference, annoyance and fatigue using a new stimulus presentation pattern based upon facial expression changes. Our goal was not to design a new pattern which could evoke larger ERPs than the face pattern, but to design a new pattern which could reduce adjacent interference, annoyance and fatigue, and evoke ERPs as good as those observed during the face pattern. Positive facial expressions could be changed to negative facial expressions by minor changes to the original facial image. Although the changes are minor, the contrast is big enough to evoke strong ERPs. In this paper, a facial expression change pattern between positive and negative facial expressions was used to attempt to minimize interference effects. This was compared against two different conditions, a shuffled pattern containing the same shapes and colours as the facial expression change pattern, but without the semantic content associated with a change in expression, and a face versus no face pattern. Comparisons were made in terms of classification accuracy and information transfer rate as well as user supplied subjective measures. The results showed that interferences from adjacent stimuli, annoyance and the fatigue experienced by the subjects could be reduced significantly (p < 0.05) by using the facial expression change patterns in comparison with the face pattern. The offline results show that the classification accuracy of the facial expression change pattern was significantly better than that of the shuffled pattern (p < 0.05) and the face pattern (p < 0.05). The facial expression change pattern presented in this paper reduced interference from adjacent stimuli and decreased the fatigue and annoyance experienced by BCI users significantly (p < 0.05) compared to the face pattern.

An optimized ERP brain-computer interface based on facial expression changes

NASA Astrophysics Data System (ADS)

Jin, Jing; Daly, Ian; Zhang, Yu; Wang, Xingyu; Cichocki, Andrzej

2014-06-01

Objective. Interferences from spatially adjacent non-target stimuli are known to evoke event-related potentials (ERPs) during non-target flashes and, therefore, lead to false positives. This phenomenon was commonly seen in visual attention-based brain-computer interfaces (BCIs) using conspicuous stimuli and is known to adversely affect the performance of BCI systems. Although users try to focus on the target stimulus, they cannot help but be affected by conspicuous changes of the stimuli (such as flashes or presenting images) which were adjacent to the target stimulus. Furthermore, subjects have reported that conspicuous stimuli made them tired and annoyed. In view of this, the aim of this study was to reduce adjacent interference, annoyance and fatigue using a new stimulus presentation pattern based upon facial expression changes. Our goal was not to design a new pattern which could evoke larger ERPs than the face pattern, but to design a new pattern which could reduce adjacent interference, annoyance and fatigue, and evoke ERPs as good as those observed during the face pattern. Approach. Positive facial expressions could be changed to negative facial expressions by minor changes to the original facial image. Although the changes are minor, the contrast is big enough to evoke strong ERPs. In this paper, a facial expression change pattern between positive and negative facial expressions was used to attempt to minimize interference effects. This was compared against two different conditions, a shuffled pattern containing the same shapes and colours as the facial expression change pattern, but without the semantic content associated with a change in expression, and a face versus no face pattern. Comparisons were made in terms of classification accuracy and information transfer rate as well as user supplied subjective measures. Main results. The results showed that interferences from adjacent stimuli, annoyance and the fatigue experienced by the subjects could be reduced significantly (p < 0.05) by using the facial expression change patterns in comparison with the face pattern. The offline results show that the classification accuracy of the facial expression change pattern was significantly better than that of the shuffled pattern (p < 0.05) and the face pattern (p < 0.05). Significance. The facial expression change pattern presented in this paper reduced interference from adjacent stimuli and decreased the fatigue and annoyance experienced by BCI users significantly (p < 0.05) compared to the face pattern.

Neural basis of superior performance of action videogame players in an attention-demanding task.

PubMed

Mishra, Jyoti; Zinni, Marla; Bavelier, Daphne; Hillyard, Steven A

2011-01-19

Steady-state visual evoked potentials (SSVEPs) were recorded from action videogame players (VGPs) and from non-videogame players (NVGPs) during an attention-demanding task. Participants were presented with a multi-stimulus display consisting of rapid sequences of alphanumeric stimuli presented at rates of 8.6/12 Hz in the left/right peripheral visual fields, along with a central square at fixation flashing at 5.5 Hz and a letter sequence flashing at 15 Hz at an upper central location. Subjects were cued to attend to one of the peripheral or central stimulus sequences and detect occasional targets. Consistent with previous behavioral studies, VGPs detected targets with greater speed and accuracy than NVGPs. This behavioral advantage was associated with an increased suppression of SSVEP amplitudes to unattended peripheral sequences in VGPs relative to NVGPs, whereas the magnitude of the attended SSVEPs was equivalent in the two groups. Group differences were also observed in the event-related potentials to targets in the alphanumeric sequences, with the target-elicited P300 component being of larger amplitude in VGPS than NVGPs. These electrophysiological findings suggest that the superior target detection capabilities of the VGPs are attributable, at least in part, to enhanced suppression of distracting irrelevant information and more effective perceptual decision processes.

An electrocorticographic BCI using code-based VEP for control in video applications: a single-subject study

PubMed Central

Kapeller, Christoph; Kamada, Kyousuke; Ogawa, Hiroshi; Prueckl, Robert; Scharinger, Josef; Guger, Christoph

2014-01-01

A brain-computer-interface (BCI) allows the user to control a device or software with brain activity. Many BCIs rely on visual stimuli with constant stimulation cycles that elicit steady-state visual evoked potentials (SSVEP) in the electroencephalogram (EEG). This EEG response can be generated with a LED or a computer screen flashing at a constant frequency, and similar EEG activity can be elicited with pseudo-random stimulation sequences on a screen (code-based BCI). Using electrocorticography (ECoG) instead of EEG promises higher spatial and temporal resolution and leads to more dominant evoked potentials due to visual stimulation. This work is focused on BCIs based on visual evoked potentials (VEP) and its capability as a continuous control interface for augmentation of video applications. One 35 year old female subject with implanted subdural grids participated in the study. The task was to select one out of four visual targets, while each was flickering with a code sequence. After a calibration run including 200 code sequences, a linear classifier was used during an evaluation run to identify the selected visual target based on the generated code-based VEPs over 20 trials. Multiple ECoG buffer lengths were tested and the subject reached a mean online classification accuracy of 99.21% for a window length of 3.15 s. Finally, the subject performed an unsupervised free run in combination with visual feedback of the current selection. Additionally, an algorithm was implemented that allowed to suppress false positive selections and this allowed the subject to start and stop the BCI at any time. The code-based BCI system attained very high online accuracy, which makes this approach very promising for control applications where a continuous control signal is needed. PMID:25147509

The photocurrent, noise and spectral sensitivity of rods of the monkey Macaca fascicularis.

PubMed Central

Baylor, D A; Nunn, B J; Schnapf, J L

1984-01-01

Visual transduction in rods of the cynomolgus monkey, Macaca fascicularis, was studied by recording membrane current from single outer segments projecting from small pieces of retina. Light flashes evoked transient outward-going photocurrents with saturating amplitudes of up to 34 pA. A flash causing twenty to fifty photoisomerizations gave a response of half the saturating amplitude. The response-stimulus relation was of the form 1-e-x where x is flash strength. The response to a dim flash usually had a time to peak of 150-250 ms and resembled the impulse response of a series of six low-pass filters. From the average spectral sensitivity of ten rods the rhodopsin was estimated to have a peak absorption near 491 nm. The spectral sensitivity of the rods was in good agreement with the average human scotopic visibility curve determined by Crawford (1949), when the human curve was corrected for lens absorption and self-screening of rhodopsin. Fluctuations in the photocurrent evoked by dim lights were consistent with a quantal event about 0.7 pA in peak amplitude. A steady light causing about 100 photoisomerizations s-1 reduced the flash sensitivity to half the dark-adapted value. At higher background levels the rod rapidly saturated. These results support the idea that dim background light desensitizes human scotopic vision by a mechanism central to the rod outer segments while scotopic saturation may occur within the outer segments. Recovery of the photocurrent after bright flashes was marked by quantized step-like events. The events had the properties expected if bleached rhodopsin in the disks occasionally caused an abrupt blockage of the dark current over about one-twentieth of the length of the outer segment. It is suggested that superposition of these events after bleaching may contribute to the threshold elevation measured psychophysically. The current in darkness showed random fluctuations which disappeared in bright light. The continuous component of the noise had a variance of about 0.03 pA2 and a power spectrum that fell to half near 3 Hz. A second component, consisting of discrete events resembling single-photon responses, was estimated to occur at a rate of 0.006 s-1. It is suggested that the continuous component of the noise may be removed from scotopic vision by a thresholding operation near the rod output. PMID:6512705

The photocurrent, noise and spectral sensitivity of rods of the monkey Macaca fascicularis.

PubMed

Baylor, D A; Nunn, B J; Schnapf, J L

1984-12-01

Visual transduction in rods of the cynomolgus monkey, Macaca fascicularis, was studied by recording membrane current from single outer segments projecting from small pieces of retina. Light flashes evoked transient outward-going photocurrents with saturating amplitudes of up to 34 pA. A flash causing twenty to fifty photoisomerizations gave a response of half the saturating amplitude. The response-stimulus relation was of the form 1-e-x where x is flash strength. The response to a dim flash usually had a time to peak of 150-250 ms and resembled the impulse response of a series of six low-pass filters. From the average spectral sensitivity of ten rods the rhodopsin was estimated to have a peak absorption near 491 nm. The spectral sensitivity of the rods was in good agreement with the average human scotopic visibility curve determined by Crawford (1949), when the human curve was corrected for lens absorption and self-screening of rhodopsin. Fluctuations in the photocurrent evoked by dim lights were consistent with a quantal event about 0.7 pA in peak amplitude. A steady light causing about 100 photoisomerizations s-1 reduced the flash sensitivity to half the dark-adapted value. At higher background levels the rod rapidly saturated. These results support the idea that dim background light desensitizes human scotopic vision by a mechanism central to the rod outer segments while scotopic saturation may occur within the outer segments. Recovery of the photocurrent after bright flashes was marked by quantized step-like events. The events had the properties expected if bleached rhodopsin in the disks occasionally caused an abrupt blockage of the dark current over about one-twentieth of the length of the outer segment. It is suggested that superposition of these events after bleaching may contribute to the threshold elevation measured psychophysically. The current in darkness showed random fluctuations which disappeared in bright light. The continuous component of the noise had a variance of about 0.03 pA2 and a power spectrum that fell to half near 3 Hz. A second component, consisting of discrete events resembling single-photon responses, was estimated to occur at a rate of 0.006 s-1. It is suggested that the continuous component of the noise may be removed from scotopic vision by a thresholding operation near the rod output.

Greater magnocellular saccadic suppression in high versus low autistic tendency suggests a causal path to local perceptual style.

PubMed

Crewther, David P; Crewther, Daniel; Bevan, Stephanie; Goodale, Melvyn A; Crewther, Sheila G

2015-12-01

Saccadic suppression-the reduction of visual sensitivity during rapid eye movements-has previously been proposed to reflect a specific suppression of the magnocellular visual system, with the initial neural site of that suppression at or prior to afferent visual information reaching striate cortex. Dysfunction in the magnocellular visual pathway has also been associated with perceptual and physiological anomalies in individuals with autism spectrum disorder or high autistic tendency, leading us to question whether saccadic suppression is altered in the broader autism phenotype. Here we show that individuals with high autistic tendency show greater saccadic suppression of low versus high spatial frequency gratings while those with low autistic tendency do not. In addition, those with high but not low autism spectrum quotient (AQ) demonstrated pre-cortical (35-45 ms) evoked potential differences (saccade versus fixation) to a large, low contrast, pseudo-randomly flashing bar. Both AQ groups showed similar differential visual evoked potential effects in later epochs (80-160 ms) at high contrast. Thus, the magnocellular theory of saccadic suppression appears untenable as a general description for the typically developing population. Our results also suggest that the bias towards local perceptual style reported in autism may be due to selective suppression of low spatial frequency information accompanying every saccadic eye movement.

Inhalational exposure to carbonyl sulfide produces altered brainstem auditory and somatosensory-evoked potentials in Fischer 344N rats.

PubMed

Herr, David W; Graff, Jaimie E; Moser, Virginia C; Crofton, Kevin M; Little, Peter B; Morgan, Daniel L; Sills, Robert C

2007-01-01

Carbonyl sulfide (COS), a chemical listed by the original Clean Air Act, was tested for neurotoxicity by a National Institute of Environmental Health Sciences/National Toxicology Program and U.S. Environmental Protection Agency collaborative investigation. Previous studies demonstrated that COS produced cortical and brainstem lesions and altered auditory neurophysiological responses to click stimuli. This paper reports the results of expanded neurophysiological examinations that were an integral part of the previously published experiments (Morgan et al., 2004, Toxicol. Appl. Pharmacol. 200, 131-145; Sills et al., 2004, Toxicol. Pathol. 32, 1-10). Fisher 334N rats were exposed to 0, 200, 300, or 400 ppm COS for 6 h/day, 5 days/week for 12 weeks, or to 0, 300, or 400 ppm COS for 2 weeks using whole-body inhalation chambers. After treatment, the animals were studied using neurophysiological tests to examine: peripheral nerve function, somatosensory-evoked potentials (SEPs) (tail/hindlimb and facial cortical regions), brainstem auditory-evoked responses (BAERs), and visual flash-evoked potentials (2-week study). Additionally, the animals exposed for 2 weeks were examined using a functional observational battery (FOB) and response modification audiometry (RMA). Peripheral nerve function was not altered for any exposure scenario. Likewise, amplitudes of SEPs recorded from the cerebellum were not altered by treatment with COS. In contrast, amplitudes and latencies of SEPs recorded from cortical areas were altered after 12-week exposure to 400 ppm COS. The SEP waveforms were changed to a greater extent after forelimb stimulation than tail stimulation in the 2-week study. The most consistent findings were decreased amplitudes of BAER peaks associated with brainstem regions after exposure to 400 ppm COS. Additional BAER peaks were affected after 12 weeks, compared to 2 weeks of treatment, indicating that additional regions of the brainstem were damaged with longer exposures. The changes in BAERs were observed in the absence of altered auditory responsiveness in FOB or RMA. This series of experiments demonstrates that COS produces changes in brainstem auditory and cortical somatosensory neurophysiological responses that correlate with previously described histopathological damage.

Pupil light reflex evoked by light-emitting diode and computer screen: Methodology and association with need for recovery in daily life.

PubMed

Wang, Yang; Zekveld, Adriana A; Wendt, Dorothea; Lunner, Thomas; Naylor, Graham; Kramer, Sophia E

2018-01-01

Pupil light reflex (PLR) has been widely used as a method for evaluating parasympathetic activity. The first aim of the present study is to develop a PLR measurement using a computer screen set-up and compare its results with the PLR generated by a more conventional setup using light-emitting diode (LED). The parasympathetic nervous system, which is known to control the 'rest and digest' response of the human body, is considered to be associated with daily life fatigue. However, only few studies have attempted to test the relationship between self-reported daily fatigue and physiological measurement of the parasympathetic nervous system. Therefore, the second aim of this study was to investigate the relationship between daily-life fatigue, assessed using the Need for Recovery scale, and parasympathetic activity, as indicated by the PLR parameters. A pilot study was conducted first to develop a PLR measurement set-up using a computer screen. PLRs evoked by light stimuli with different characteristics were recorded to confirm the influence of light intensity, flash duration, and color on the PLRs evoked by the system. In the subsequent experimental study, we recorded the PLR of 25 adult participants to light flashes generated by the screen set-up as well as by a conventional LED set-up. PLR parameters relating to parasympathetic and sympathetic activity were calculated from the pupil responses. We tested the split-half reliability across two consecutive blocks of trials, and the relationships between the parameters of PLRs evoked by the two set-ups. Participants rated their need for recovery prior to the PLR recordings. PLR parameters acquired in the screen and LED set-ups showed good reliability for amplitude related parameters. The PLRs evoked by both set-ups were consistent, but showed systematic differences in absolute values of all parameters. Additionally, higher need for recovery was associated with faster and larger constriction of the PLR. This study assessed the PLR generated by a computer screen and the PLR generated by a LED. The good reliability within set-ups and the consistency between the PLRs evoked by the set-ups indicate that both systems provides a valid way to evoke the PLR. A higher need for recovery was associated with faster and larger constricting PLRs, suggesting increased levels of parasympathetic nervous system activity in people experiencing higher levels of need for recovery on a daily basis.

Spatiotemporal mapping of scalp potentials.

PubMed

Fender, D H; Santoro, T P

1977-11-01

Computerized analysis and display techniques are applied to the problem of identifying the origins of visually evoked scalped potentials (VESP's). A new stimulus for VESP work, white noise, is being incorporated in the solution of this problem. VESP's for white-noise stimulation exhibit time domain behavior similar to the classical response for flash stimuli but with certain significant differences. Contour mapping algorithms are used to display the time behavior of equipotential surfaces on the scalp during the VESP. The electrical and geometrical parameters of the head are modeled. Electrical fields closely matching those obtained experimentally are generated on the surface of the model head by optimally selecting the location and strength parameters of one or two dipole current sources contained within the model. Computer graphics are used to display as a movie the actual and model scalp potential field and the parameters of the dipole generators whithin the model head during the time course of the VESP. These techniques are currently used to study retinotopic mapping, fusion, and texture perception in the human.

Transesophageal versus transcranial motor evoked potentials to monitor spinal cord ischemia.

PubMed

Tsuda, Kazumasa; Shiiya, Norihiko; Takahashi, Daisuke; Ohkura, Kazuhiro; Yamashita, Katsushi; Kando, Yumi; Arai, Yoshifumi

2016-02-01

We have previously reported that transesophageal motor evoked potential is feasible and more stable than transcranial motor evoked potential. This study aimed to investigate the efficacy of transesophageal motor evoked potential to monitor spinal cord ischemia. Transesophageal and transcranial motor evoked potentials were recorded in 13 anesthetized dogs at the bilateral forelimbs, anal sphincters, and hindlimbs. Spinal cord ischemia was induced by aortic balloon occlusion at the 8th to 10th thoracic vertebra level. In the 12 animals with motor evoked potential disappearance, occlusion was maintained for 10 minutes (n = 6) or 40 minutes (n = 6) after motor evoked potential disappearance. Neurologic function was evaluated by Tarlov score at 24 and 48 hours postoperatively. Time to disappearance of bilateral motor evoked potentials was quicker in transesophageal motor evoked potentials than in transcranial motor evoked potentials at anal sphincters (6.9 ± 3.1 minutes vs 8.3 ± 3.4 minutes, P = .02) and hindlimbs (5.7 ± 1.9 minutes vs 7.1 ± 2.7 minutes, P = .008). Hindlimb function was normal in all dogs in the 10-minute occlusion group, and motor evoked potentials recovery (>75% on both sides) after reperfusion was quicker in transesophageal motor evoked potentials than transcranial motor evoked potentials at hindlimbs (14.8 ± 5.6 minutes vs 24.7 ± 8.2 minutes, P = .001). At anal sphincters, transesophageal motor evoked potentials always reappeared (>25%), but transcranial motor evoked potentials did not in 3 of 6 dogs. In the 40-minute occlusion group, hindlimb motor evoked potentials did not reappear in 4 dogs with paraplegia. Among the 2 remaining dogs, 1 with paraparesis (Tarlov 3) showed delayed recovery (>75%) of hindlimb motor evoked potentials without reappearance of anal sphincter motor evoked potentials. In another dog with spastic paraplegia, transesophageal motor evoked potentials from the hindlimbs remained less than 20%, whereas transcranial motor evoked potentials showed recovery (>75%). Transesophageal motor evoked potentials may be superior to transcranial motor evoked potentials in terms of quicker response to spinal cord ischemia and better prognostic value. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Neurophysiological intraoperative monitoring during an optic nerve schwannoma removal.

PubMed

San-Juan, Daniel; Escanio Cortés, Manuel; Tena-Suck, Martha; Orozco Garduño, Adolfo Josué; López Pizano, Jesús Alejandro; Villanueva Domínguez, Jonathan; Fernández Gónzalez-Aragón, Maricarmen; Gómez-Amador, Juan Luis

2017-10-01

This paper reports the case of a patient with optic nerve schwannoma and the first use of neurophysiological intraoperative monitoring of visual evoked potentials during the removal of such tumor with no postoperative visual damage. Schwannomas are benign neoplasms of the peripheral nervous system arising from the neural crest-derived Schwann cells, these tumors are rarely located in the optic nerve and the treatment consists on surgical removal leading to high risk of damage to the visual pathway. Case report of a thirty-year-old woman with an optic nerve schwannoma. The patient underwent surgery for tumor removal on the left optic nerve through a left orbitozygomatic approach with intraoperative monitoring of left II and III cranial nerves. We used Nicolet Endeavour CR IOM (Carefusion, Middleton WI, USA) to performed visual evoked potentials stimulating binocularly with LED flash goggles with the patient´s eyes closed and direct epidural optic nerve stimulation delivering rostral to the tumor a rectangular current pulse. At follow up examinations 7 months later, the left eye visual acuity was 20/60; Ishihara score was 8/8 in both eyes; the right eye photomotor reflex was normal and left eye was mydriatic and arreflectic; optokinetic reflex and ocular conjugate movements were normal. In this case, the epidural direct electrical stimulation of optic nerve provided stable waveforms during optic nerve schwannoma resection without visual loss.

Greater magnocellular saccadic suppression in high versus low autistic tendency suggests a causal path to local perceptual style

PubMed Central

Crewther, David P.; Crewther, Daniel; Bevan, Stephanie; Goodale, Melvyn A.; Crewther, Sheila G.

2015-01-01

Saccadic suppression—the reduction of visual sensitivity during rapid eye movements—has previously been proposed to reflect a specific suppression of the magnocellular visual system, with the initial neural site of that suppression at or prior to afferent visual information reaching striate cortex. Dysfunction in the magnocellular visual pathway has also been associated with perceptual and physiological anomalies in individuals with autism spectrum disorder or high autistic tendency, leading us to question whether saccadic suppression is altered in the broader autism phenotype. Here we show that individuals with high autistic tendency show greater saccadic suppression of low versus high spatial frequency gratings while those with low autistic tendency do not. In addition, those with high but not low autism spectrum quotient (AQ) demonstrated pre-cortical (35–45 ms) evoked potential differences (saccade versus fixation) to a large, low contrast, pseudo-randomly flashing bar. Both AQ groups showed similar differential visual evoked potential effects in later epochs (80–160 ms) at high contrast. Thus, the magnocellular theory of saccadic suppression appears untenable as a general description for the typically developing population. Our results also suggest that the bias towards local perceptual style reported in autism may be due to selective suppression of low spatial frequency information accompanying every saccadic eye movement. PMID:27019719

Effect of ethanol on the visual-evoked potential in rat: dynamics of ON and OFF responses.

PubMed

Dulinskas, Redas; Buisas, Rokas; Vengeliene, Valentina; Ruksenas, Osvaldas

2017-01-01

The effect of acute ethanol administration on the flash visual-evoked potential (VEP) was investigated in numerous studies. However, it is still unclear which brain structures are responsible for the differences observed in stimulus onset (ON) and offset (OFF) responses and how these responses are modulated by ethanol. The aim of our study was to investigate the pattern of ON and OFF responses in the visual system, measured as amplitude and latency of each VEP component following acute administration of ethanol. VEPs were recorded at the onset and offset of a 500 ms visual stimulus in anesthetized male Wistar rats. The effect of alcohol on VEP latency and amplitude was measured for one hour after injection of 2 g/kg ethanol dose. Three VEP components - N63, P89 and N143 - were analyzed. Our results showed that, except for component N143, ethanol increased the latency of both ON and OFF responses in a similar manner. The latency of N143 during OFF response was not affected by ethanol but its amplitude was reduced. Our study demonstrated that the activation of the visual system during the ON response to a 500 ms visual stimulus is qualitatively different from that during the OFF response. Ethanol interfered with processing of the stimulus duration at the level of the visual cortex and reduced the activation of cortical regions.

Enhancing Soldier Performance: A Nonlinear Model of Performance to Improve Selection Testing and Training

DTIC Science & Technology

1994-07-01

psychological refractory period 15. Two-flash threshold 16. Critical flicker fusion (CFF) 17. Steady state visually evoked response 18. Auditory brain stem...States of awareness I: Subliminal erceoption relationships to situational awareness (AL-TR-1992-0085). Brooks Air Force BaSe, TX: Armstrong...the signals required different inputs (e.g., visual versus auditory ) (Colley & Beech, 1989). Despite support of this theory from such experiments

Habituation of visual evoked responses in neonates and fetuses: A MEG study

PubMed Central

Matuz, Tamara; Govindan, Rathinaswamy B.; Preissl, Hubert; Siegel, Eric R.; Muenssinger, Jana; Murphy, Pamela; Ware, Maureen; Lowery, Curtis L.; Eswaran, Hari

2013-01-01

In this study we aimed to develop a habituation paradigm that allows the investigation of response decrement and response recovery and examine its applicability for measuring the habituation of the visually evoked responses (VERs) in neonatal and fetal magnetoencephalographic recordings. Two paradigms, one with a long and one with a short inter-train interval (ITI), were developed and tested in separate studies. Both paradigms consisted of a train of four light flashes; each train being followed by a 500 Hz burst tone. Healthy pregnant women underwent two prenatal measurements and returned with their babies for a neonatal investigation. The amplitudes of the neonatal VERs in the long-ITI condition showed within-train response decrement. An increased response to the auditory dishabituator was found confirming response recovery. In the short-ITI condition, neonatal amplitude decrement could not be demonstrated while response recovery was present. In both ITI conditions, the response rate of the cortical responses was much lower in the fetuses than in the neonates. Fetal VERs in the long-ITI condition indicate amplitude decline from the first to the second flash with no further decrease. The long-ITI paradigm might be useful to investigate habituation of the VERs in neonates and fetuses, although the latter requires precaution. PMID:22483416

Interactions of Prosthetic and Natural Vision in Animals With Local Retinal Degeneration

PubMed Central

Lorach, Henri; Lei, Xin; Galambos, Ludwig; Kamins, Theodore; Mathieson, Keith; Dalal, Roopa; Huie, Philip; Harris, James; Palanker, Daniel

2015-01-01

Purpose Prosthetic restoration of partial sensory loss leads to interactions between artificial and natural inputs. Ideally, the rehabilitation should allow perceptual fusion of the two modalities. Here we studied the interactions between normal and prosthetic vision in a rodent model of local retinal degeneration. Methods Implantation of a photovoltaic array in the subretinal space of normally sighted rats induced local degeneration of the photoreceptors above the chip, and the inner retinal neurons in this area were electrically stimulated by the photovoltaic implant powered by near-infrared (NIR) light. We studied prosthetic and natural visually evoked potentials (VEP) in response to simultaneous stimulation by NIR and visible light patterns. Results We demonstrate that electrical and natural VEPs summed linearly in the visual cortex, and both responses decreased under brighter ambient light. Responses to visible light flashes increased over 3 orders of magnitude of contrast (flash/background), while for electrical stimulation the contrast range was limited to 1 order of magnitude. The maximum amplitude of the prosthetic VEP was three times lower than the maximum response to a visible flash over the same area on the retina. Conclusions Ambient light affects prosthetic responses, albeit much less than responses to visible stimuli. Prosthetic representation of contrast in the visual scene can be encoded, to a limited extent, by the appropriately calibrated stimulus intensity, which also depends on the ambient light conditions. Such calibration will be important for patients combining central prosthetic vision with natural peripheral sight, such as in age-related macular degeneration. PMID:26618643

The membrane current of single rod outer segments.

PubMed

Baylor, D A; Lamb, T D; Yau, K W

1979-03-01

1. Outer segments of individual rods in the retina of the toad, Bufo marinus, were drawn into a glass pipette to record the membrane current. 2. Light flashes evoked transient outward currents. The peak response amplitude was related to flash intensity by a Michaelis equation with half-saturating intensity about 1 photon mum-2. 3. The saturating response amplitude ranged up to 27 pA and corresponded closely to complete suppression of the steady inward current present in darkness. 4. For a given cell the saturating response amplitude varied linearly with the length of outer segment within the pipette. This is consistent with a uniform density of light-sensitive channels and negligible gradient of membrane potential along the outer segment. 5. Responses to bright flashes never showed the relaxation from an initial peak seen previously in intracellular voltage recordings, suggesting that the conductance change responsible for the relaxation does not occur in the outer segment. 6. Responses to local illumination of only the recorded outer segment were very similar to those obtained with diffuse light at the same intensity, indicating that peripheral rods made little contribution to the responses. 7. The spectral sensitivity of 'red' rods was consistent with a retinal1-based pigment with lambda max = 498 +/- 2 nm. 8. The kinetics of the response were consistent with four stages of delay affecting action of the internal transmitter. Responses were faster at the basal end of the outer segment than at the distal tip. 9. Background light reduced the sensitivity to a superposed dim test flash and shortened the time course of the response, indicating that adapting light modifies the kinetics and gain of the transduction mechanism within the outer segment. 10. Responses to dim lights exhibited pronounced fluctuations which are attributed in the succeeding paper (Baylor, Lamb & Yau, 1979) to the quantal nature of light.

Hemispheric asymmetry of macroscopic and elementary calcium signals mediated by InsP3 in Xenopus oocytes.

PubMed

Callamaras, N; Sun, X P; Ivorra, I; Parker, I

1998-09-01

1. The mechanisms underlying hemispheric asymmetry of the inositol 1, 4,5-trisphosphate (InsP3)-calcium signalling pathway in Xenopus oocytes were examined by fluorescence imaging of calcium signals and recording calcium-activated Cl- currents (ICl,Ca) evoked by intracellular calcium injections and photorelease of InsP3. 2. The maximal ICl,Ca evoked by strong photorelease of InsP3 was 8 times greater in the animal than the vegetal hemisphere, but the average threshold amounts of InsP3 required to evoke detectable currents were similar in each hemisphere. 3. Currents evoked by injections of calcium were about 2.5 times greater near the animal pole than near the vegetal pole, whereas fluorescence signals evoked by injections were similar in each hemisphere. 4. Calcium waves were evoked by photolysis flashes of similar strengths in both hemispheres of albino oocytes, but peak calcium levels evoked by supramaximal stimuli were 70 % greater in the animal hemisphere. 5. Elementary calcium release events (puffs) in the animal hemisphere had amplitudes about double that in the vegetal hemisphere, and more often involved coupled release from adjacent sites. Calcium release sites were more closely packed in the animal hemisphere, with a mean spacing of about 1.5 micro m compared with 2.25 micro m in the vegetal hemisphere. 6. The larger amplitude of currents mediated by InsP3 in the animal hemisphere, therefore, involves an increased flux of calcium at individual release units, a more dense packing of release units and a higher density of Cl- channels.

Hemispheric asymmetry of macroscopic and elementary calcium signals mediated by InsP3 in Xenopus oocytes

PubMed Central

Callamaras, Nick; Sun, Xiao-Ping; Ivorra, Isabel; Parker, Ian

1998-01-01

The mechanisms underlying hemispheric asymmetry of the inositol 1,4,5-trisphosphate (InsP3)-calcium signalling pathway in Xenopus oocytes were examined by fluorescence imaging of calcium signals and recording calcium-activated Cl− currents (ICl,Ca) evoked by intracellular calcium injections and photorelease of InsP3. The maximal ICl,Ca evoked by strong photorelease of InsP3 was 8 times greater in the animal than the vegetal hemisphere, but the average threshold amounts of InsP3 required to evoke detectable currents were similar in each hemisphere. Currents evoked by injections of calcium were about 2.5 times greater near the animal pole than near the vegetal pole, whereas fluorescence signals evoked by injections were similar in each hemisphere. Calcium waves were evoked by photolysis flashes of similar strengths in both hemispheres of albino oocytes, but peak calcium levels evoked by supramaximal stimuli were 70% greater in the animal hemisphere. Elementary calcium release events (puffs) in the animal hemisphere had amplitudes about double that in the vegetal hemisphere, and more often involved coupled release from adjacent sites. Calcium release sites were more closely packed in the animal hemisphere, with a mean spacing of about 1.5 μm compared with 2.25 μm in the vegetal hemisphere. The larger amplitude of currents mediated by InsP3 in the animal hemisphere, therefore, involves an increased flux of calcium at individual release units, a more dense packing of release units and a higher density of Cl− channels. PMID:9706018

Potentiation of inositol trisphosphate-induced Ca2+ mobilization in Xenopus oocytes by cytosolic Ca2+.

PubMed Central

Yao, Y; Parker, I

1992-01-01

1. The ability of cytosolic Ca2+ ions to modulate inositol 1,4,5-trisphosphate (Insp3)-induced Ca2+ liberation from intracellular stores was studied in Xenopus oocytes using light flash photolysis of caged InsP3. Changes in cytosolic free Ca2+ level were effected by inducing Ca2+ entry through ionophore and voltage-gated plasma membrane channels and by injection of Ca2+ through a micropipette. Their effects on Ca2+ liberation were monitored by video imaging of Fluo-3 fluorescence and by voltage clamp recording of Ca(2+)-activated membrane Cl- currents. 2. Treatment of oocytes with the Ca2+ ionophores A23187 and ionomycin caused a transient elevation of cytosolic Ca2+ level when cells were bathed in Ca(2+)-free solution, which probably arose because of release of Ca2+ from intracellular stores. 3. Membrane current and Fluo-3 Ca2+ signals evoked by photoreleased InsP3 in ionophore-treated oocytes were potentiated when the intracellular Ca2+ level was elevated by raising the Ca2+ level in the bathing solution. 4. Responses to photoreleased InsP3 were similarly potentiated following activation of Ca2+ entry through voltage-gated Ca2+ channels expressed in the plasma membrane. 5. Ca(2+)-activated membrane currents evoked by depolarization developed a delayed 'hump' component during sustained photorelease of InsP3, probably because Ca2+ ions entering through the membrane channels triggered liberation of Ca2+ from intracellular stores. 6. Ba2+ and Sr2+ ions were able to substitute for Ca2+ in potentiating InsP3-mediated Ca2+ liberation. 7. Gradual photorelease of InsP3 by weak photolysis light evoked Ca2+ liberation that began at particular foci and then propagated throughout, but not beyond that area of the oocyte exposed to the light. Local elevations of intracellular Ca2+ produced by microinjection of Ca2+ acted as new foci for the initiation of Ca2+ liberation by InsP3. 8. In resting oocytes, intracellular injections of Ca2+ resulted only in localized elevation of intracellular Ca2+, and did not evoke propagating waves. 9. The results show that cytosolic Ca2+ ions potentiate the ability of InsP3 to liberate Ca2+ from intracellular stores. This process may be important for the positive feedback mechanism underlying the generation of Ca2+ spikes and waves, and for interactions between the InsP3 pathway and Ca2+ ions entering cells through voltage- and ligand-gated channels. Images Fig. 5 PMID:1284567

Square or sine: finding a waveform with high success rate of eliciting SSVEP.

PubMed

Teng, Fei; Chen, Yixin; Choong, Aik Min; Gustafson, Scott; Reichley, Christopher; Lawhead, Pamela; Waddell, Dwight

2011-01-01

Steady state visual evoked potential (SSVEP) is the brain's natural electrical potential response for visual stimuli at specific frequencies. Using a visual stimulus flashing at some given frequency will entrain the SSVEP at the same frequency, thereby allowing determination of the subject's visual focus. The faster an SSVEP is identified, the higher information transmission rate the system achieves. Thus, an effective stimulus, defined as one with high success rate of eliciting SSVEP and high signal-noise ratio, is desired. Also, researchers observed that harmonic frequencies often appear in the SSVEP at a reduced magnitude. Are the harmonics in the SSVEP elicited by the fundamental stimulating frequency or by the artifacts of the stimuli? In this paper, we compare the SSVEP responses of three periodic stimuli: square wave (with different duty cycles), triangle wave, and sine wave to find an effective stimulus. We also demonstrate the connection between the strength of the harmonics in SSVEP and the type of stimulus.

Visual processing during recovery from vegetative state to consciousness: comparing behavioral indices to brain responses.

PubMed

Wijnen, V J M; Eilander, H J; de Gelder, B; van Boxtel, G J M

2014-11-01

Auditory stimulation is often used to evoke responses in unresponsive patients who have suffered severe brain injury. In order to investigate visual responses, we examined visual evoked potentials (VEPs) and behavioral responses to visual stimuli in vegetative patients during recovery to consciousness. Behavioral responses to visual stimuli (visual localization, comprehension of written commands, and object manipulation) and flash VEPs were repeatedly examined in eleven vegetative patients every two weeks for an average period of 2.6months, and patients' VEPs were compared to a healthy control group. Long-term outcome of the patients was assessed 2-3years later. Visual response scores increased during recovery to consciousness for all scales: visual localization, comprehension of written commands, and object manipulation. VEP amplitudes were smaller, and latencies were longer in the patient group relative to the controls. VEPs characteristics at first measurement were related to long-term outcome up to three years after injury. Our findings show the improvement of visual responding with recovery from the vegetative state to consciousness. Elementary visual processing is present, yet according to VEP responses, poorer in vegetative and minimally conscious state than in healthy controls, and remains poorer when patients recovered to consciousness. However, initial VEPs are related to long-term outcome. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Effects of pharmacological agents on subcortical resistance shifts

NASA Technical Reports Server (NTRS)

Klivington, K. A.

1975-01-01

Microliter quantities of tetrodotoxin, tetraethylammonium chloride, and picrotoxin injected into the inferior colliculus and superior olive of unanesthetized cats differentially affect the amplitude and waveform of click-evoked potentials and evoked resistance shifts. Tetrodotoxin simultaneously reduces the negative phase of the evoked potential and eliminates the evoked resistance shift. Tetraethylammonium enhances the negative evoked potential component, presumably of postsynaptic origin, without significantly altering evoked resistance shift amplitude. Picrotoxin also enhances the negative evoked potential wave but increases evoked resistance shift amplitude. These findings implicate events associated with postsynaptic membrane depolarization in the production of the evoked resistance shift.

Retinal cross talk in the mammalian visual system

PubMed Central

Tang, Xiaolan; Tzekov, Radouil

2016-01-01

The existence and functional relevance of efferent optic nerve fibers in mammals have long been debated. While anatomical evidence for cortico-retinal and retino-retinal projections is substantial, physiological evidence is lacking, as efferent fibers are few in number and are severed in studies of excised retinal tissue. Here we show that interocular connections contribute to retinal bioelectrical activity in adult mammals. Full-field flash electroretinograms (ERGs) were recorded from one or both eyes of Brown-Norway rats under dark-adapted (n = 16) and light-adapted (n = 11) conditions. Flashes were confined to each eye by an opaque tube that blocked stray light. Monocular flashes evoked a small (5–15 μV) signal in the nonilluminated eye, which was named “crossed ERG” (xERG). The xERG began under dark-adapted conditions with a positive (xP1) wave that peaked at 70–90 ms and ended with slower negative (xN1) and positive (xP2) waves from 200 to 400 ms. xN1 was absent under light-adapted conditions. Injection of tetrodotoxin in either eye (n = 15) eliminated the xERG. Intraocular pressure elevation of the illuminated eye (n = 6) had the same effect. The treatments also altered the ERG b-wave in both eyes, and the alterations correlated with xERG disappearance. Optic nerve stimulation (n = 3) elicited a biphasic compound action potential in the nonstimulated nerve with 10- to 13-ms latency, implying that the xERG comes from slow-conducting (W type) fibers. Monocular dye application (n = 7) confirmed the presence of retino-retinal ganglion cells in adult rats. We conclude that mammalian eyes communicate directly with each other via a handful of optic nerve fibers. The cross talk alters retinal activity in rats, and perhaps other animals. PMID:26984426

Initial neuro-ophthalmological manifestations in Churg–Strauss syndrome

PubMed Central

Vallet, Anne-Evelyne; Didelot, Adrien; Guebre-Egziabher, Fitsum; Bernard, Martine; Mauguière, François

2010-01-01

Churg–Strauss syndrome (CSS) is a systemic vasculitis with frequent respiratory tract involvement. It can also affect the nervous system, notably the optic tract. The present work reports the case of a 65-year-old man diagnosed as having CSS in the context of several acute onset neurological symptoms including muscle weakness and signs of temporal arteritis, including bilateral anterior ischaemic optic neuropathy (ON). Electroretinograms (ERGs) and visual evoked potentials (VEPs) were performed. Flash ERGs were normal whereas VEPs were highly abnormal, showing a dramatic voltage reduction, thus confirming the ON. The vision outcome was poor. Ophthalmological presentations of CSS have rarely been reported, but no previous case of sudden blindness documented by combined ERG and VEP investigations were found in the literature. The present case strongly suggests that the occurrence of visual loss in the context of systemic inflammation with hypereosinophilia should lead to considering the diagnosis of CSS. PMID:22789694

Real-time mobile phone dialing system based on SSVEP

NASA Astrophysics Data System (ADS)

Wang, Dongsheng; Kobayashi, Toshiki; Cui, Gaochao; Watabe, Daishi; Cao, Jianting

2017-03-01

Brain computer interface (BCI) systems based on the steady state visual evoked potential (SSVEP) provide higher information transfer rates and require shorter training time than BCI systems using other brain signals. It has been widely used in brain science, rehabilitation engineering, biomedical engineering and intelligent information processing. In this paper, we present a real-time mobile phone dialing system based on SSVEP, and it is more portable than other dialing system because the flashing dial interface is set on a small tablet. With this online BCI system, we can take advantage of this system based on SSVEP to identify the specific frequency on behalf of a number using canonical correlation analysis (CCA) method and dialed out successfully without using any physical movements such as finger tapping. This phone dialing system will be promising to help disable patients to improve the quality of lives.

Deconstructing continuous flash suppression

PubMed Central

Yang, Eunice; Blake, Randolph

2012-01-01

In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular “Mondrian” CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS. PMID:22408039

Deconstructing continuous flash suppression.

PubMed

Yang, Eunice; Blake, Randolph

2012-03-08

In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular "Mondrian" CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS.

Blue light filtered white light induces depression-like responses and temporary spatial learning deficits in rats.

PubMed

Meng, Qinghe; Lian, Yuzheng; Jiang, Jianjun; Wang, Wei; Hou, Xiaohong; Pan, Yao; Chu, Hongqian; Shang, Lanqin; Wei, Xuetao; Hao, Weidong

2018-04-18

Ambient light has a vital impact on mood and cognitive functions. Blue light has been previously reported to play a salient role in the antidepressant effect via melanopsin. Whether blue light filtered white light (BFW) affects mood and cognitive functions remains unclear. The present study aimed to investigate whether BFW led to depression-like symptoms and cognitive deficits including spatial learning and memory abilities in rats, and whether they were associated with the light-responsive function in retinal explants. Male Sprague-Dawley albino rats were randomly divided into 2 groups (n = 10) and treated with a white light-emitting diode (LED) light source and BFW light source, respectively, under a standard 12 : 12 h L/D condition over 30 days. The sucrose consumption test, forced swim test (FST) and the level of plasma corticosterone (CORT) were employed to evaluate depression-like symptoms in rats. Cognitive functions were assessed by the Morris water maze (MWM) test. A multi-electrode array (MEA) system was utilized to measure electro-retinogram (ERG) responses induced by white or BFW flashes. The effect of BFW over 30 days on depression-like responses in rats was indicated by decreased sucrose consumption in the sucrose consumption test, an increased immobility time in the FST and an elevated level of plasma CORT. BFW led to temporary spatial learning deficits in rats, which was evidenced by prolonged escape latency and swimming distances in the spatial navigation test. However, no changes were observed in the short memory ability of rats treated with BFW. The micro-ERG results showed a delayed implicit time and reduced amplitudes evoked by BFW flashes compared to the white flash group. BFW induces depression-like symptoms and temporary spatial learning deficits in rats, which might be closely related to the impairment of light-evoked output signals in the retina.

A joint sparse representation-based method for double-trial evoked potentials estimation.

PubMed

Yu, Nannan; Liu, Haikuan; Wang, Xiaoyan; Lu, Hanbing

2013-12-01

In this paper, we present a novel approach to solving an evoked potentials estimating problem. Generally, the evoked potentials in two consecutive trials obtained by repeated identical stimuli of the nerves are extremely similar. In order to trace evoked potentials, we propose a joint sparse representation-based double-trial evoked potentials estimation method, taking full advantage of this similarity. The estimation process is performed in three stages: first, according to the similarity of evoked potentials and the randomness of a spontaneous electroencephalogram, the two consecutive observations of evoked potentials are considered as superpositions of the common component and the unique components; second, making use of their characteristics, the two sparse dictionaries are constructed; and finally, we apply the joint sparse representation method in order to extract the common component of double-trial observations, instead of the evoked potential in each trial. A series of experiments carried out on simulated and human test responses confirmed the superior performance of our method. © 2013 Elsevier Ltd. Published by Elsevier Ltd. All rights reserved.

A simple model for the generation of the vestibular evoked myogenic potential (VEMP).

PubMed

Wit, Hero P; Kingma, Charlotte M

2006-06-01

To describe the mechanism by which the vestibular evoked myogenic potential is generated. Vestibular evoked myogenic potential generation is modeled by adding a large number of muscle motor unit action potentials. These action potentials occur randomly in time along a 100 ms long time axis. But because between approximately 15 and 20 ms after a loud short sound stimulus (almost) no action potentials are generated during VEMP measurements in human subjects, no action potentials are present in the model during this time. The evoked potential is the result of the lack of amplitude cancellation in the averaged surface electromyogram at the edges of this 5 ms long time interval. The relatively simple model describes generation and some properties of the vestibular evoked myogenic potential very well. It is shown that, in contrast with other evoked potentials (BAEPs, VERs), the vestibular evoked myogenic potential is the result of an interruption of activity and not that of summed synchronized neural action potentials.

Time-varying bispectral analysis of visually evoked multi-channel EEG

NASA Astrophysics Data System (ADS)

Chandran, Vinod

2012-12-01

Theoretical foundations of higher order spectral analysis are revisited to examine the use of time-varying bicoherence on non-stationary signals using a classical short-time Fourier approach. A methodology is developed to apply this to evoked EEG responses where a stimulus-locked time reference is available. Short-time windowed ensembles of the response at the same offset from the reference are considered as ergodic cyclostationary processes within a non-stationary random process. Bicoherence can be estimated reliably with known levels at which it is significantly different from zero and can be tracked as a function of offset from the stimulus. When this methodology is applied to multi-channel EEG, it is possible to obtain information about phase synchronization at different regions of the brain as the neural response develops. The methodology is applied to analyze evoked EEG response to flash visual stimulii to the left and right eye separately. The EEG electrode array is segmented based on bicoherence evolution with time using the mean absolute difference as a measure of dissimilarity. Segment maps confirm the importance of the occipital region in visual processing and demonstrate a link between the frontal and occipital regions during the response. Maps are constructed using bicoherence at bifrequencies that include the alpha band frequency of 8Hz as well as 4 and 20Hz. Differences are observed between responses from the left eye and the right eye, and also between subjects. The methodology shows potential as a neurological functional imaging technique that can be further developed for diagnosis and monitoring using scalp EEG which is less invasive and less expensive than magnetic resonance imaging.

Are evoked potentials in patients with adult-onset pompe disease indicative of clinically relevant central nervous system involvement?

PubMed

Wirsching, Andreas; Müller-Felber, Wolfgang; Schoser, Benedikt

2014-08-01

Pompe disease is a multisystem autosomal recessive glycogen storage disease. Autoptic findings in patients with classic infantile and late-onset Pompe disease have proven that accumulation of glycogen can also be found in the peripheral and central nervous system. To assess the functional role of these pathologic findings, multimodal sensory evoked potentials were analyzed. Serial recordings for brainstem auditory, visual, and somatosensory evoked potentials of 11 late-onset Pompe patients were reviewed. Data at the onset of the enzyme replacement therapy with alglucosidase alfa were compared with follow-up recordings at 12 and 24 months. Brainstem auditory evoked potentials showed a delayed peak I in 1/10 patients and an increased I-III and I-V interpeak latency in 1/10 patients, respectively. The III-V interpeak latencies were in the normal range. Visual evoked potentials were completely normal. Median somatosensory evoked potentials showed an extended interpeak latency in 3/9 patients. Wilcoxon tests comparing age-matched subgroups found significant differences in brainstem auditory evoked potentials and visual evoked potentials. We found that the majority of recordings for evoked potentials were within the ranges for standard values, therefore reflecting the lack of clinically relevant central nervous system involvement. Regular surveillance by means of evoked potentials does not seem to be appropriate in late-onset Pompe patients.

Analysis of Spontaneous and Nerve-Evoked Calcium Transients in Intact Extraocular Muscles in Vitro

PubMed Central

Feng, Cheng-Yuan; Hennig, Grant W.; Corrigan, Robert D.; Smith, Terence K.; von Bartheld, Christopher S.

2012-01-01

Extraocular muscles (EOMs) have unique calcium handling properties, yet little is known about the dynamics of calcium events underlying ultrafast and tonic contractions in myofibers of intact EOMs. Superior oblique EOMs of juvenile chickens were dissected with their nerve attached, maintained in oxygenated Krebs buffer, and loaded with fluo-4. Spontaneous and nerve stimulation-evoked calcium transients were recorded and, following calcium imaging, some EOMs were double-labeled with rhodamine-conjugated alpha-bungarotoxin (rhBTX) to identify EOM myofiber types. EOMs showed two main types of spontaneous calcium transients, one slow type (calcium waves with 1/2max duration of 2–12 s, velocity of 25–50 μm/s) and two fast “flash-like” types (Type 1, 30–90 ms; Type 2, 90–150 ms 1/2max duration). Single pulse nerve stimulation evoked fast calcium transients identical to the fast (Type 1) calcium transients. Calcium waves were accompanied by a local myofiber contraction that followed the calcium transient wavefront. The magnitude of calcium-wave induced myofiber contraction far exceeded those of movement induced by nerve stimulation and associated fast calcium transients. Tetrodotoxin eliminated nerve-evoked transients, but not spontaneous transients. Alpha-bungarotoxin eliminated both spontaneous and nerve-evoked fast calcium transients, but not calcium waves, and caffeine increased wave activity. Calcium waves were observed in myofibers lacking spontaneous or evoked fast transients, suggestive of multiply-innervated myofibers, and this was confirmed by double-labeling with rhBTX. We propose that the abundant spontaneous calcium transients and calcium waves with localized contractions that do not depend on innervation may contribute to intrinsic generation of tonic functions of EOMs. PMID:22579493

Loss of lower limb motor evoked potentials and spinal cord injury during the initial exposure in scoliosis surgery.

PubMed

Legatt, Alan D; Fried, Stephen J; Amaral, Terry D; Sarwahi, Vishal; Moguilevitch, Marina

2014-04-01

To report a case of motor evoked potential changes and spinal cord injury during the initial dissection in scoliosis surgery. Motor evoked potentials to transcranial electrical stimulation were recorded from multiple muscles. Somatosensory evoked potentials to limb nerve stimulation were recorded from the scalp. Clear motor evoked potentials were initially present in all monitored muscles. The patient was then pharmacologically paralyzed for the initial dissection. More than usual bleeding was encountered during that dissection, prompting transfusion. As the neuromuscular blockade subsided, motor evoked potentials persisted in the hand muscles but disappeared and remained absent in all monitored leg muscles. The spine had not been instrumented. A wake-up test demonstrated paraplegia; the surgery was aborted. There were no adverse somatosensory evoked potential changes. MRI showed an anterior spinal cord infarct. Copious soft tissue bleeding during the initial dissection might have lowered pressures in critical segmental arteries enough to cause spinal cord infarction through a steal phenomenon. The lack of somatosensory evoked potential changes reflected sparing of the dorsal columns. When neuromuscular blockade is used during the initial soft tissue dissection, motor evoked potentials should be assessed after this, but before spinal instrumentation, to determine whether there had been any spinal cord compromise during the initial dissection.

A user-friendly SSVEP-based brain-computer interface using a time-domain classifier.

PubMed

Luo, An; Sullivan, Thomas J

2010-04-01

We introduce a user-friendly steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) system. Single-channel EEG is recorded using a low-noise dry electrode. Compared to traditional gel-based multi-sensor EEG systems, a dry sensor proves to be more convenient, comfortable and cost effective. A hardware system was built that displays four LED light panels flashing at different frequencies and synchronizes with EEG acquisition. The visual stimuli have been carefully designed such that potential risk to photosensitive people is minimized. We describe a novel stimulus-locked inter-trace correlation (SLIC) method for SSVEP classification using EEG time-locked to stimulus onsets. We studied how the performance of the algorithm is affected by different selection of parameters. Using the SLIC method, the average light detection rate is 75.8% with very low error rates (an 8.4% false positive rate and a 1.3% misclassification rate). Compared to a traditional frequency-domain-based method, the SLIC method is more robust (resulting in less annoyance to the users) and is also suitable for irregular stimulus patterns.

Emotion-Related Consciousness Detection in Patients With Disorders of Consciousness Through an EEG-Based BCI System

PubMed Central

Pan, Jiahui; Xie, Qiuyou; Huang, Haiyun; He, Yanbin; Sun, Yuping; Yu, Ronghao; Li, Yuanqing

2018-01-01

For patients with disorders of consciousness (DOC), such as vegetative state (VS) and minimally conscious state (MCS), detecting and assessing the residual cognitive functions of the brain remain challenging. Emotion-related cognitive functions are difficult to detect in patients with DOC using motor response-based clinical assessment scales such as the Coma Recovery Scale-Revised (CRS-R) because DOC patients have motor impairments and are unable to provide sufficient motor responses for emotion-related communication. In this study, we proposed an EEG-based brain-computer interface (BCI) system for emotion recognition in patients with DOC. Eight patients with DOC (5 VS and 3 MCS) and eight healthy controls participated in the BCI-based experiment. During the experiment, two movie clips flashed (appearing and disappearing) eight times with a random interstimulus interval between flashes to evoke P300 potentials. The subjects were instructed to focus on the crying or laughing movie clip and to count the flashes of the corresponding movie clip cued by instruction. The BCI system performed online P300 detection to determine which movie clip the patients responsed to and presented the result as feedback. Three of the eight patients and all eight healthy controls achieved online accuracies based on P300 detection that were significantly greater than chance level. P300 potentials were observed in the EEG signals from the three patients. These results indicated the three patients had abilities of emotion recognition and command following. Through spectral analysis, common spatial pattern (CSP) and differential entropy (DE) features in the delta, theta, alpha, beta, and gamma frequency bands were employed to classify the EEG signals during the crying and laughing movie clips. Two patients and all eight healthy controls achieved offline accuracies significantly greater than chance levels in the spectral analysis. Furthermore, stable topographic distribution patterns of CSP and DE features were observed in both the healthy subjects and these two patients. Our results suggest that cognitive experiments may be conducted using BCI systems in patients with DOC despite the inability of such patients to provide sufficient behavioral responses. PMID:29867421

Emotion-Related Consciousness Detection in Patients With Disorders of Consciousness Through an EEG-Based BCI System.

PubMed

Pan, Jiahui; Xie, Qiuyou; Huang, Haiyun; He, Yanbin; Sun, Yuping; Yu, Ronghao; Li, Yuanqing

2018-01-01

For patients with disorders of consciousness (DOC), such as vegetative state (VS) and minimally conscious state (MCS), detecting and assessing the residual cognitive functions of the brain remain challenging. Emotion-related cognitive functions are difficult to detect in patients with DOC using motor response-based clinical assessment scales such as the Coma Recovery Scale-Revised (CRS-R) because DOC patients have motor impairments and are unable to provide sufficient motor responses for emotion-related communication. In this study, we proposed an EEG-based brain-computer interface (BCI) system for emotion recognition in patients with DOC. Eight patients with DOC (5 VS and 3 MCS) and eight healthy controls participated in the BCI-based experiment. During the experiment, two movie clips flashed (appearing and disappearing) eight times with a random interstimulus interval between flashes to evoke P300 potentials. The subjects were instructed to focus on the crying or laughing movie clip and to count the flashes of the corresponding movie clip cued by instruction. The BCI system performed online P300 detection to determine which movie clip the patients responsed to and presented the result as feedback. Three of the eight patients and all eight healthy controls achieved online accuracies based on P300 detection that were significantly greater than chance level. P300 potentials were observed in the EEG signals from the three patients. These results indicated the three patients had abilities of emotion recognition and command following. Through spectral analysis, common spatial pattern (CSP) and differential entropy (DE) features in the delta, theta, alpha, beta, and gamma frequency bands were employed to classify the EEG signals during the crying and laughing movie clips. Two patients and all eight healthy controls achieved offline accuracies significantly greater than chance levels in the spectral analysis. Furthermore, stable topographic distribution patterns of CSP and DE features were observed in both the healthy subjects and these two patients. Our results suggest that cognitive experiments may be conducted using BCI systems in patients with DOC despite the inability of such patients to provide sufficient behavioral responses.

Vestibular evoked potentials (VsEPs) of cortical origin produced by impulsive acceleration applied at the nasion.

PubMed

Todd, Neil P M; McLean, Aisha; Paillard, Aurore; Kluk, Karolina; Colebatch, James G

2014-12-01

We report the results of a study to record vestibular evoked potentials (VsEPs) of cortical origin produced by impulsive acceleration (IA). In a sample of 12 healthy participants, evoked potentials recorded by 70 channel electroencephalography were obtained by IA stimulation at the nasion and compared with evoked potentials from the same stimulus applied to the forefingers. The nasion stimulation gave rise to a series of positive and negative deflections in the latency range of 26-72 ms, which were dependent on the polarity of the applied IA. In contrast, evoked potentials from the fingers were characterised by a single N50/P50 deflection at about 50 ms and were polarity invariant. Source analysis confirmed that the finger evoked potentials were somatosensory in origin, i.e. were somatosensory evoked potentials, and suggested that the nasion evoked potentials plausibly included vestibular midline and frontal sources, as well as contributions from the eyes, and thus were likely VsEPs. These results show considerable promise as a new method for assessment of the central vestibular system by means of VsEPs produced by IA applied to the head.

Calcium regulates vesicle replenishment at the cone ribbon synapse

PubMed Central

Babai, Norbert; Bartoletti, Theodore M.; Thoreson, Wallace B.

2010-01-01

Cones release glutamate-filled vesicles continuously in darkness and changing illumination modulates this release. Because sustained release in darkness is governed by vesicle replenishment rates, we analyzed how cone membrane potential regulates replenishment. Synaptic release from cones was measured by recording post-synaptic currents in Ambystoma tigrinum horizontal or OFF bipolar cells evoked by depolarization of simultaneously voltage-clamped cones. We measured replenishment after attaining a steady-state between vesicle release and replenishment using trains of test pulses. Increasing Ca2+ currents (ICa) by changing the test step from −30 to −10 mV increased replenishment. Lengthening −30 mV test pulses to match the Ca2+ influx during 25 ms test pulses to −10 mV produced similar replenishment rates. Reducing Ca2+ driving force by using test steps to +30 mV slowed replenishment. Using UV flashes to reverse inhibition of ICa by nifedipine accelerated replenishment. Increasing [Ca2+]i by flash photolysis of caged Ca2+ also accelerated replenishment. Replenishment, but not the initial burst of release, was enhanced by using an intracellular Ca2+ buffer of 0.5 mM EGTA rather than 5 mM EGTA, and diminished by 1 mM BAPTA. This suggests that although release and replenishment and release exhibited similar Ca2+-dependencies, release sites are <200 nm from Ca2+ channels but replenishment sites are >200 nm away. Membrane potential thus regulates replenishment by controlling Ca2+ influx, principally by effects on replenishment mechanisms but also by altering releasable pool size. This in turn provides a mechanism for converting changes in light intensity into changes in sustained release at the cone ribbon synapse. PMID:21106825

Skin denervation does not alter cortical potentials to surface concentric electrode stimulation: A comparison with laser evoked potentials and contact heat evoked potentials.

PubMed

La Cesa, S; Di Stefano, G; Leone, C; Pepe, A; Galosi, E; Alu, F; Fasolino, A; Cruccu, G; Valeriani, M; Truini, A

2018-01-01

In the neurophysiological assessment of patients with neuropathic pain, laser evoked potentials (LEPs), contact heat evoked potentials (CHEPs) and the evoked potentials by the intraepidermal electrical stimulation via concentric needle electrode are widely agreed as nociceptive specific responses; conversely, the nociceptive specificity of evoked potentials by surface concentric electrode (SE-PREPs) is still debated. In this neurophysiological study we aimed at verifying the nociceptive specificity of SE-PREPs. We recorded LEPs, CHEPs and SE-PREPs in eleven healthy participants, before and after epidermal denervation produced by prolonged capsaicin application. We also used skin biopsy to verify the capsaicin-induced nociceptive nerve fibre loss in the epidermis. We found that whereas LEPs and CHEPs were suppressed after capsaicin-induced epidermal denervation, the surface concentric electrode stimulation of the same denervated skin area yielded unchanged SE-PREPs. The suppression of LEPs and CHEPs after nociceptive nerve fibre loss in the epidermis indicates that these techniques are selectively mediated by nociceptive system. Conversely, the lack of SE-PREP changes suggests that SE-PREPs do not provide selective information on nociceptive system function. Capsaicin-induced epidermal denervation abolishes laser evoked potentials (LEPs) and contact heat evoked potentials (CHEPs), but leaves unaffected pain-related evoked potentials by surface concentric electrode (SE-PREPs). These findings suggest that unlike LEPs and CHEPs, SE-PREPs are not selectively mediated by nociceptive system. © 2017 European Pain Federation - EFIC®.

Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials.

PubMed

Jones, Matthew D; Taylor, Janet L; Booth, John; Barry, Benjamin K

2016-01-01

Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant's maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1-SEPs; Experiment 2-LEPs) by increased pressure pain thresholds at biceps brachii (24.3 and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p < 0.001) and first dorsal interosseous (18.8 and 21.5% increase in Experiment 1 and 2, respectively; both d > 0.57 and p < 0.001). In contrast, heat pain thresholds were not significantly different after exercise (forearm: 10.8% increase, d = 0.35, p = 0.10; hand: 3.6% increase, d = 0.06, p = 0.74). Contrasting effects of exercise on the amplitude of laser evoked potentials (14.6% decrease, d = -0.42, p = 0.004) and somatosensory evoked potentials (10.9% increase, d = -0.02, p = 1) were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = -0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = -0.32, p = 0.006). The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia.

On Stellar Flash Echoes from Circular Rings

NASA Astrophysics Data System (ADS)

Nemiroff, Robert; Mukherjee, Oindabi

2018-01-01

A flash -- or any episode of variability -- that occurs in the vicinity of a circular ring might be seen several times later, simultaneously, as echoes on the ring. Effective images of the flash are created and annihilated in pairs, with as many as four flash images visible concurrently. Videos detailing sequences of image pair creation, tandem motion, and subsequent image annihilation are shown, given simple opacity and scattering assumptions. It is proven that, surprisingly, images from a second pair creation event always annihilate with images from the first. Caustic surfaces between flash locations yielding two and four images are computed. Although such ring echos surely occur, their practical detection might be difficult as it could require dedicated observing programs involving sensitive photometry of extended objects. Potential flash sources include planetary and interstellar gas and dust rings near and around variable stars, flare stars, novae, supernovae, and GRBs. Potentially recoverable information includes size, distance, temporal history, and angular isotropy of both the ring and flash.

Synaptic physiology of the flow of information in the cat's visual cortex in vivo

PubMed Central

Hirsch, Judith A; Martinez, Luis M; Alonso, José-Manuel; Desai, Komal; Pillai, Cinthi; Pierre, Carhine

2002-01-01

Each stage of the striate cortical circuit extracts novel information about the visual environment. We asked if this analytic process reflected laminar variations in synaptic physiology by making whole-cell recording with dye-filled electrodes from the cat's visual cortex and thalamus; the stimuli were flashed spots. Thalamic afferents terminate in layer 4, which contains two types of cell, simple and complex, distinguished by the spatial structure of the receptive field. Previously, we had found that the postsynaptic and spike responses of simple cells reliably followed the time course of flash-evoked thalamic activity. Here we report that complex cells in layer 4 (or cells intermediate between simple and complex) similarly reprised thalamic activity (response/trial, 99 ± 1.9 %; response duration 159 ± 57 ms; latency 25 ± 4 ms; average ± standard deviation; n = 7). Thus, all cells in layer 4 share a common synaptic physiology that allows secure integration of thalamic input. By contrast, at the second cortical stage (layer 2+3), where layer 4 directs its output, postsynaptic responses did not track simple patterns of antecedent activity. Typical responses to the static stimulus were intermittent and brief (response/trial, 31 ± 40 %; response duration 72 ± 60 ms, latency 39 ± 7 ms; n = 11). Only richer stimuli like those including motion evoked reliable responses. All told, the second level of cortical processing differs markedly from the first. At that later stage, ascending information seems strongly gated by connections between cortical neurons. Inputs must be combined in newly specified patterns to influence intracortical stages of processing. PMID:11927691

A linear model fails to predict orientation selectivity of cells in the cat visual cortex.

PubMed Central

Volgushev, M; Vidyasagar, T R; Pei, X

1996-01-01

1. Postsynaptic potentials (PSPs) evoked by visual stimulation in simple cells in the cat visual cortex were recorded using in vivo whole-cell technique. Responses to small spots of light presented at different positions over the receptive field and responses to elongated bars of different orientations centred on the receptive field were recorded. 2. To test whether a linear model can account for orientation selectivity of cortical neurones, responses to elongated bars were compared with responses predicted by a linear model from the receptive field map obtained from flashing spots. 3. The linear model faithfully predicted the preferred orientation, but not the degree of orientation selectivity or the sharpness of orientation tuning. The ratio of optimal to non-optimal responses was always underestimated by the model. 4. Thus non-linear mechanisms, which can include suppression of non-optimal responses and/or amplification of optimal responses, are involved in the generation of orientation selectivity in the primary visual cortex. PMID:8930828

Whole-brain diffusion tensor imaging in correlation to visual-evoked potentials in multiple sclerosis: a tract-based spatial statistics analysis.

PubMed

Lobsien, D; Ettrich, B; Sotiriou, K; Classen, J; Then Bergh, F; Hoffmann, K-T

2014-01-01

Functional correlates of microstructural damage of the brain affected by MS are incompletely understood. The purpose of this study was to evaluate correlations of visual-evoked potentials with microstructural brain changes as determined by DTI in patients with demyelinating central nervous disease. Sixty-one patients with clinically isolated syndrome or MS were prospectively recruited. The mean P100 visual-evoked potential latencies of the right and left eyes of each patient were calculated and used for the analysis. For DTI acquisition, a single-shot echo-planar imaging pulse sequence with 80 diffusion directions was performed at 3T. Fractional anisotropy, radial diffusivity, and axial diffusivity were calculated and correlated with mean P100 visual-evoked potentials by tract-based spatial statistics. Significant negative correlations between mean P100 visual-evoked potentials and fractional anisotropy and significant positive correlations between mean P100 visual-evoked potentials and radial diffusivity were found widespread over the whole brain. The highest significance was found in the optic radiation, frontoparietal white matter, and corpus callosum. Significant positive correlations between mean P100 visual-evoked potentials and axial diffusivity were less widespread, notably sparing the optic radiation. Microstructural changes of the whole brain correlated significantly with mean P100 visual-evoked potentials. The distribution of the correlations showed clear differences among axial diffusivity, fractional anisotropy, and radial diffusivity, notably in the optic radiation. This finding suggests a stronger correlation of mean P100 visual-evoked potentials to demyelination than to axonal damage. © 2014 by American Journal of Neuroradiology.

Electrophysiological studies of the nervous system

NASA Technical Reports Server (NTRS)

Galambos, R.

1972-01-01

The electrophysiology of the nervous system is studied using cats and human subjects. Data cover effects of chlorolose on evoked potential, the evoked resistance shift that accompanies evoked potentials, and the relationship of eye movements to potentials aroused by visual stimulation.

A Perturbation Based Decomposition of Compound-Evoked Potentials for Characterization of Nerve Fiber Size Distributions.

PubMed

Szlavik, Robert B

2016-02-01

The characterization of peripheral nerve fiber distributions, in terms of diameter or velocity, is of clinical significance because information associated with these distributions can be utilized in the differential diagnosis of peripheral neuropathies. Electro-diagnostic techniques can be applied to the investigation of peripheral neuropathies and can yield valuable diagnostic information while being minimally invasive. Nerve conduction velocity studies are single parameter tests that yield no detailed information regarding the characteristics of the population of nerve fibers that contribute to the compound-evoked potential. Decomposition of the compound-evoked potential, such that the velocity or diameter distribution of the contributing nerve fibers may be determined, is necessary if information regarding the population of contributing nerve fibers is to be ascertained from the electro-diagnostic study. In this work, a perturbation-based decomposition of compound-evoked potentials is proposed that facilitates determination of the fiber diameter distribution associated with the compound-evoked potential. The decomposition is based on representing the single fiber-evoked potential, associated with each diameter class, as being perturbed by contributions, of varying degree, from all the other diameter class single fiber-evoked potentials. The resultant estimator of the contributing nerve fiber diameter distribution is valid for relatively large separations in diameter classes. It is also useful in situations where the separation between diameter classes is small and the concomitant single fiber-evoked potentials are not orthogonal.

Auditory- and visual-evoked potentials in Mexican infants are not affected by maternal supplementation with 400 mg/d docosahexaenoic acid in the second half of pregnancy.

PubMed

Stein, Aryeh D; Wang, Meng; Rivera, Juan A; Martorell, Reynaldo; Ramakrishnan, Usha

2012-08-01

The evidence relating prenatal supplementation with DHA to offspring neurological development is limited. We investigated the effect of prenatal DHA supplementation on infant brainstem auditory-evoked responses and visual- evoked potentials in a double-blind, randomized controlled trial in Cuernavaca, Mexico. Pregnant women were supplemented daily with 400 mg DHA or placebo from gestation wk 18-22 through delivery. DHA and placebo groups did not differ in maternal characteristics at randomization or infant characteristics at birth. Brainstem auditory-evoked responses were measured at 1 and 3 mo in 749 and 664 infants, respectively, and visual-evoked potentials were measured at 3 and 6 mo in 679 and 817 infants, respectively. Left-right brainstem auditory-evoked potentials were moderately correlated (range, 0.26-0.43; all P < 0.001) and left-right visual-evoked potentials were strongly correlated (range, 0.79-0.94; all P < 0.001) within any assessment. Correlations across visits were modest to moderate (range, 0.09-0.38; all P < 0.01). The offspring of DHA-supplemented women did not differ from those of control women with respect to any outcome measure (all comparisons P > 0.10). We conclude that DHA supplementation during pregnancy did not influence brainstem auditory-evoked responses at 1 and 3 mo or visual-evoked potentials at 3 and 6 mo.

ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.

EPA Science Inventory

This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats

" NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo.

" The pattern evok...

A novel hybrid BCI speller based on the incorporation of SSVEP into the P300 paradigm

NASA Astrophysics Data System (ADS)

Yin, Erwei; Zhou, Zongtan; Jiang, Jun; Chen, Fanglin; Liu, Yadong; Hu, Dewen

2013-04-01

Objective. Although extensive studies have shown improvement in spelling accuracy, the conventional P300 speller often exhibits errors, which occur in almost the same row or column relative to the target. To address this issue, we propose a novel hybrid brain-computer interface (BCI) approach by incorporating the steady-state visual evoked potential (SSVEP) into the conventional P300 paradigm. Approach. We designed a periodic stimuli mechanism and superimposed it onto the P300 stimuli to increase the difference between the symbols in the same row or column. Furthermore, we integrated the random flashings and periodic flickers to simultaneously evoke the P300 and SSVEP, respectively. Finally, we developed a hybrid detection mechanism based on the P300 and SSVEP in which the target symbols are detected by the fusion of three-dimensional, time-frequency features. Main results. The results obtained from 12 healthy subjects show that an online classification accuracy of 93.85% and information transfer rate of 56.44 bit/min were achieved using the proposed BCI speller in only a single trial. Specifically, 5 of the 12 subjects exhibited an information transfer rate of 63.56 bit/min with an accuracy of 100%. Significance. The pilot studies suggested that the proposed BCI speller could achieve a better and more stable system performance compared with the conventional P300 speller, and it is promising for achieving quick spelling in stimulus-driven BCI applications.

Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials

PubMed Central

Jones, Matthew D.; Taylor, Janet L.; Booth, John; Barry, Benjamin K.

2016-01-01

Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant's maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1–SEPs; Experiment 2–LEPs) by increased pressure pain thresholds at biceps brachii (24.3 and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p < 0.001) and first dorsal interosseous (18.8 and 21.5% increase in Experiment 1 and 2, respectively; both d > 0.57 and p < 0.001). In contrast, heat pain thresholds were not significantly different after exercise (forearm: 10.8% increase, d = 0.35, p = 0.10; hand: 3.6% increase, d = 0.06, p = 0.74). Contrasting effects of exercise on the amplitude of laser evoked potentials (14.6% decrease, d = −0.42, p = 0.004) and somatosensory evoked potentials (10.9% increase, d = −0.02, p = 1) were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = −0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = −0.32, p = 0.006). The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia. PMID:27965587

Properties of visual evoked potentials to onset of movement on a television screen.

PubMed

Kubová, Z; Kuba, M; Hubacek, J; Vít, F

1990-08-01

In 80 subjects the dependence of movement-onset visual evoked potentials on some measures of stimulation was examined, and these responses were compared with pattern-reversal visual evoked potentials to verify the effectiveness of pattern movement application for visual evoked potential acquisition. Horizontally moving vertical gratings were generated on a television screen. The typical movement-onset reactions were characterized by one marked negative peak only, with a peak time between 140 and 200 ms. In all subjects the sufficient stimulus duration for acquisition of movement-onset-related visual evoked potentials was 100 ms; in some cases it was only 20 ms. Higher velocity (5.6 degree/s) produced higher amplitudes of movement-onset visual evoked potentials than did the lower velocity (2.8 degrees/s). In 80% of subjects, the more distinct reactions were found in the leads from lateral occipital areas (in 60% from the right hemisphere), with no correlation to handedness of subjects. Unlike pattern-reversal visual evoked potentials, the movement-onset responses tended to be larger to extramacular stimulation (annular target of 5 degrees-9 degrees) than to macular stimulation (circular target of 5 degrees diameter).

Neurophysiological detection of impending spinal cord injury during scoliosis surgery.

PubMed

Schwartz, Daniel M; Auerbach, Joshua D; Dormans, John P; Flynn, John; Drummond, Denis S; Bowe, J Andrew; Laufer, Samuel; Shah, Suken A; Bowen, J Richard; Pizzutillo, Peter D; Jones, Kristofer J; Drummond, Denis S

2007-11-01

Despite the many reports attesting to the efficacy of intraoperative somatosensory evoked potential monitoring in reducing the prevalence of iatrogenic spinal cord injury during corrective scoliosis surgery, these afferent neurophysiological signals can provide only indirect evidence of injury to the motor tracts since they monitor posterior column function. Early reports on the use of transcranial electric motor evoked potentials to monitor the corticospinal motor tracts directly suggested that the method holds great promise for improving detection of emerging spinal cord injury. We sought to compare the efficacy of these two methods of monitoring to detect impending iatrogenic neural injury during scoliosis surgery. We reviewed the intraoperative neurophysiological monitoring records of 1121 consecutive patients (834 female and 287 male) with adolescent idiopathic scoliosis (mean age, 13.9 years) treated between 2000 and 2004 at four pediatric spine centers. The same group of experienced surgical neurophysiologists monitored spinal cord function in all patients with use of a standardized multimodality technique with the patient under total intravenous anesthesia. A relevant neurophysiological change (an alert) was defined as a reduction in amplitude (unilateral or bilateral) of at least 50% for somatosensory evoked potentials and at least 65% for transcranial electric motor evoked potentials compared with baseline. Thirty-eight (3.4%) of the 1121 patients had recordings that met the criteria for a relevant signal change (i.e., an alert). Of those thirty-eight patients, seventeen showed suppression of the amplitude of transcranial electric motor evoked potentials in excess of 65% without any evidence of changes in somatosensory evoked potentials. In nine of the thirty-eight patients, the signal change was related to hypotension and was corrected with augmentation of the blood pressure. The remaining twenty-nine patients had an alert that was related directly to a surgical maneuver. Three alerts occurred following segmental vessel clamping, and the remaining twenty-six were related to posterior instrumentation and correction. Nine (35%) of these twenty-six patients with an instrumentation-related alert, or 0.8% of the cohort, awoke with a transient motor and/or sensory deficit. Seven of these nine patients presented solely with a motor deficit, which was detected by intraoperative monitoring of transcranial electric motor evoked potentials in all cases, and two patients had only sensory symptoms. Somatosensory evoked potential monitoring failed to identify a motor deficit in four of the seven patients with a confirmed motor deficit. Furthermore, when changes in somatosensory evoked potentials occurred, they lagged behind the changes in transcranial electric motor evoked potentials by an average of approximately five minutes. With an appropriate response to the alert, the motor or sensory deficit resolved in all nine patients within one to ninety days. This study underscores the advantage of monitoring the spinal cord motor tracts directly by recording transcranial electric motor evoked potentials in addition to somatosensory evoked potentials. Transcranial electric motor evoked potentials are exquisitely sensitive to altered spinal cord blood flow due to either hypotension or a vascular insult. Moreover, changes in transcranial electric motor evoked potentials are detected earlier than are changes in somatosensory evoked potentials, thereby facilitating more rapid identification of impending spinal cord injury.

Rhesus Monkeys Behave As If They Perceive the Duncker Illusion

PubMed Central

Zivotofsky, A. Z.; Goldberg, M. E.; Powell, K. D.

2008-01-01

The visual system uses the pattern of motion on the retina to analyze the motion of objects in the world, and the motion of the observer him/herself. Distinguishing between retinal motion evoked by movement of the retina in space and retinal motion evoked by movement of objects in the environment is computationally difficult, and the human visual system frequently misinterprets the meaning of retinal motion. In this study, we demonstrate that the visual system of the Rhesus monkey also misinterprets retinal motion. We show that monkeys erroneously report the trajectories of pursuit targets or their own pursuit eye movements during an epoch of smooth pursuit across an orthogonally moving background. Furthermore, when they make saccades to the spatial location of stimuli that flashed early in an epoch of smooth pursuit or fixation, they make large errors that appear to take into account the erroneous smooth eye movement that they report in the first experiment, and not the eye movement that they actually make. PMID:16102233

[A Case of Left Vertebral Artery Aneurysm Showing Evoked Potentials on Bilateral Electrode by the Left Vagus Nerve Stimulation to Electromyographic Tracheal Tube].

PubMed

Kadoya, Tatsuo; Uehara, Hirofumi; Yamamoto, Toshinori; Shiraishi, Munehiro; Kinoshita, Yuki; Joyashiki, Takeshi; Enokida, Kengo

2016-02-01

Previously, we reported a case of brainstem cavernous hemangioma showing false positive responses to electromyographic tracheal tube (EMG tube). We concluded that the cause was spontaneous respiration accompanied by vocal cord movement. We report a case of left vertebral artery aneurysm showing evoked potentials on bilateral electrodes by the left vagus nerve stimulation to EMG tube. An 82-year-old woman underwent clipping of a left unruptured vertebral artery-posterior inferior cerebellar artery aneurysm. General anesthesia was induced with remifentanil, propofol and suxamethonium, and was maintained with oxygen, air, remifentanil and propofol. We monitored somatosensory evoked potentials, motor evoked potentials, and electromyogram of the vocal cord. When the manipulation reached brainstem and the instrument touched the left vagus nerve, evoked potentials appeared on bilateral electrodes. EMG tube is equipped with two electrodes on both sides. We concluded that the left vagus nerve stimulation generated evoked potentials of the left laryngeal muscles, and they were simultaneously detected as potential difference between two electrodes on both sides. EMG tube is used to identify the vagus nerve. However, it is necessary to bear in mind that each vagus nerve stimulation inevitably generates evoked potentials on bilateral electrodes.

Combined evoked potentials in co-occuring attention deficit hyperactivity disorder and epilepsy.

PubMed

Major, Zoltán Zsigmond

2011-07-30

Evoked potentials, both stimulus related and event related, show disturbances in attention deficit-hyperactivity disorder and epilepsies, too. This study was designed to evaluate if these potentials are characteristically influenced by the presence of the two diseases, individually, and in the case of co-occurrence. Forty children were included, and four groups were formed, control group, ADHD group, epilepsy group and a group with the comorbidity of epilepsy and ADHD. Epilepsy patients were under proper antiepileptic treatment; ADHD patients were free of specific therapy. Brainstem auditory evoked potentials, visual evoked potentials and auditory P300 evaluation were performed. The latency of the P100 and N135 visual evoked potential components was significantly extended by the presence of epilepsy. If ADHD was concomitantly present, this effect was attenuated. Brainstem auditory evoked potential components were prolonged in the presence of the comorbidity, considering the waves elicited in the brainstem. P300 latencies were prolonged by the presence of co-occurring ADHD and epilepsy. Feedback parameters showed overall reduction of the tested cognitive performances in the ADHD group. Disturbances produced by the presence of ADHD-epilepsy comorbidity reveal hypothetically a linked physiopathological path for both diseases, and offers an approach with possible diagnostic importance, combined evoked potential recordings.

Monitoring somatosensory evoked potentials in spinal cord ischemia-reperfusion injury

PubMed Central

Ji, Yiming; Meng, Bin; Yuan, Chenxi; Yang, Huilin; Zou, Jun

2013-01-01

It remains unclear whether spinal cord ischemia-reperfusion injury caused by ischemia and other non-mechanical factors can be monitored by somatosensory evoked potentials. Therefore, we monitored spinal cord ischemia-reperfusion injury in rabbits using somatosensory evoked potential detection technology. The results showed that the somatosensory evoked potential latency was significantly prolonged and the amplitude significantly reduced until it disappeared during the period of spinal cord ischemia. After reperfusion for 30–180 minutes, the amplitude and latency began to gradually recover; at 360 minutes of reperfusion, the latency showed no significant difference compared with the pre-ischemic value, while the somatosensory evoked potential amplitude in-creased, and severe hindlimb motor dysfunctions were detected. Experimental findings suggest that changes in somatosensory evoked potential latency can reflect the degree of spinal cord ischemic injury, while the amplitude variations are indicators of the late spinal cord reperfusion injury, which provide evidence for the assessment of limb motor function and avoid iatrogenic spinal cord injury. PMID:25206629

Daily Physical Activity and Hot Flashes in the Study of Women's Health Across the Nation FLASHES Study

PubMed Central

Gibson, Carolyn; Matthews, Karen; Thurston, Rebecca

2014-01-01

Objective To examine the role of physical activity in menopausal hot flashes. Competing models conceptualize physical activity as a risk or protective factor for hot flashes. Few studies have examined this relationship prospectively using physiologic measures of hot flashes and physical activity. Design Over two 48 hour-periods, 51 participants wore a physiologic hot flash monitor and activity monitor, and reported their hot flashes in an electronic diary. Physiologic hot flashes, reported hot flashes and reported hot flashes without physiological corroboration were related to activity changes using hierarchical generalized linear modeling, adjusting for potential confounders. Setting Community. Patients Midlife women. Interventions None. Main Outcome Measures Physiologically-detected hot flashes and reported hot flashes with and without physiologic corroboration. Results Hot flash reports without physiologic corroboration were more likely after activity increases (OR 1.04, 95% CI: 1.00-1.10, p=.01), particularly among women with higher levels of depressive symptoms (interaction p=.02). No other types of hot flashes were related to physical activity. Conclusion Acute increases in physical activity were associated with increased reporting of hot flashes lacking physiologic corroboration, particularly among women with depressive symptoms. Clinicians should consider the role of symptom perception and reporting in relations between physical activity and hot flashes. PMID:24491454

Auditory- and Visual-Evoked Potentials in Mexican Infants Are Not Affected by Maternal Supplementation with 400 mg/d Docosahexaenoic Acid in the Second Half of Pregnancy1234

PubMed Central

Stein, Aryeh D.; Wang, Meng; Rivera, Juan A.; Martorell, Reynaldo; Ramakrishnan, Usha

2012-01-01

The evidence relating prenatal supplementation with DHA to offspring neurological development is limited. We investigated the effect of prenatal DHA supplementation on infant brainstem auditory-evoked responses and visual- evoked potentials in a double-blind, randomized controlled trial in Cuernavaca, Mexico. Pregnant women were supplemented daily with 400 mg DHA or placebo from gestation wk 18–22 through delivery. DHA and placebo groups did not differ in maternal characteristics at randomization or infant characteristics at birth. Brainstem auditory-evoked responses were measured at 1 and 3 mo in 749 and 664 infants, respectively, and visual-evoked potentials were measured at 3 and 6 mo in 679 and 817 infants, respectively. Left-right brainstem auditory-evoked potentials were moderately correlated (range, 0.26–0.43; all P < 0.001) and left-right visual-evoked potentials were strongly correlated (range, 0.79–0.94; all P < 0.001) within any assessment. Correlations across visits were modest to moderate (range, 0.09–0.38; all P < 0.01). The offspring of DHA-supplemented women did not differ from those of control women with respect to any outcome measure (all comparisons P > 0.10). We conclude that DHA supplementation during pregnancy did not influence brainstem auditory-evoked responses at 1 and 3 mo or visual-evoked potentials at 3 and 6 mo. PMID:22739364

Evoked potentials in multiple sclerosis.

PubMed

Kraft, George H

2013-11-01

Before the development of magnetic resonance imaging (MRI), evoked potentials (EPs)-visual evoked potentials, somatosensory evoked potentials, and brain stem auditory evoked responses-were commonly used to determine a second site of disease in patients being evaluated for possible multiple sclerosis (MS). The identification of an area of the central nervous system showing abnormal conduction was used to supplement the abnormal signs identified on the physical examination-thus identifying the "multiple" in MS. This article is a brief overview of additional ways in which central nervous system (CNS) physiology-as measured by EPs-can still contribute value in the management of MS in the era of MRIs. Copyright © 2013 Elsevier Inc. All rights reserved.

Combined ocular and cervical vestibular evoked myogenic potential in individuals with vestibular hyporeflexia and in patients with Ménière's disease.

PubMed

Silva, Tatiana Rocha; de Resende, Luciana Macedo; Santos, Marco Aurélio Rocha

The vestibular evoked myogenic potential is a potential of mean latency that measures the muscle response to auditory stimulation. This potential can be generated from the contraction of the sternocleidomastoid muscle and also from the contraction of extraocular muscles in response to high-intensity sounds. This study presents a combined or simultaneous technique of cervical and ocular vestibular evoked myogenic potential in individuals with changes in the vestibular system, for use in otoneurologic diagnosis. To characterize the records and analyze the results of combined cervical and ocular VEMP in individuals with vestibular hyporeflexia and in those with Ménière's disease. The study included 120 subjects: 30 subjects with vestibular hyporeflexia, 30 with Ménière's disease, and 60 individuals with normal hearing. Data collection was performed by simultaneously recording the cervical and ocular vestibular evoked myogenic potential. There were differences between the study groups (individuals with vestibular hyporeflexia and individuals with Ménière's disease) and the control group for most of wave parameters in combined cervical and ocular vestibular evoked myogenic potential. For cervical vestibular evoked myogenic potential, it was observed that the prolongation of latency of the P13 and N23 waves was the most frequent finding in the group with vestibular hyporeflexia and in the group with Ménière's disease. For ocular vestibular evoked myogenic potential, prolonged latency of N10 and P15 waves was the most frequent finding in the study groups. Combined cervical and ocular vestibular evoked myogenic potential presented relevant results for individuals with vestibular hyporeflexia and for those with Ménière's disease. There were differences between the study groups and the control group for most of the wave parameters in combined cervical and ocular vestibular evoked myogenic potential. Copyright © 2016 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

The effect of ingested sulfite on visual evoked potentials, lipid peroxidation, and antioxidant status of brain in normal and sulfite oxidase-deficient aged rats.

PubMed

Ozsoy, Ozlem; Aras, Sinem; Ozkan, Ayse; Parlak, Hande; Aslan, Mutay; Yargicoglu, Piraye; Agar, Aysel

2016-07-01

Sulfite, commonly used as a preservative in foods, beverages, and pharmaceuticals, is a very reactive and potentially toxic molecule which is detoxified by sulfite oxidase (SOX). Changes induced by aging may be exacerbated by exogenous chemicals like sulfite. The aim of this study was to investigate the effects of ingested sulfite on visual evoked potentials (VEPs) and brain antioxidant statuses by measuring superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities. Brain lipid oxidation status was also determined via thiobarbituric acid reactive substances (TBARS) in normal- and SOX-deficient aged rats. Rats do not mimic the sulfite responses seen in humans because of their relatively high SOX activity level. Therefore this study used SOX-deficient rats since they are more appropriate models for studying sulfite toxicity. Forty male Wistar rats aged 24 months were randomly assigned to four groups: control (C), sulfite (S), SOX-deficient (D) and SOX-deficient + sulfite (DS). SOX deficiency was established by feeding rats with low molybdenum (Mo) diet and adding 200 ppm tungsten (W) to their drinking water. Sulfite in the form of sodium metabisulfite (25 mg kg(-1) day(-1)) was given by gavage. Treatment continued for 6 weeks. At the end of the experimental period, flash VEPs were recorded. Hepatic SOX activity was measured to confirm SOX deficiency. SOX-deficient rats had an approximately 10-fold decrease in hepatic SOX activity compared with the normal rats. The activity of SOX in deficient rats was thus in the range of humans. There was no significant difference between control and treated groups in either latence or amplitude of VEP components. Brain SOD, CAT, and GPx activities and brain TBARS levels were similar in all experimental groups compared with the control group. Our results indicate that exogenous administration of sulfite does not affect VEP components and the antioxidant/oxidant status of aged rat brains. © The Author(s) 2014.

Brainstem auditory and somatosensory evoked potentials in relation to clinical and neuroimaging findings in Chiari type 1 malformation.

PubMed

Moncho, Dulce; Poca, Maria-Antonia; Minoves, Teresa; Ferré, Alejandro; Rahnama, Kimia; Sahuquillo, Juan

2015-04-01

The aim of this study was to describe the abnormalities found in the recordings of evoked potentials (EPs), in particular those of brainstem auditory evoked potentials and somatosensory evoked potentials, in a homogeneous series of patients with Chiari type 1 malformation (CM-1) and study their relationship with clinical symptoms and malformation severity. CM-1 is characterized by cerebellar tonsils that descend below the foramen magnum and may be associated with EP alterations. However, only a small number of authors have described these tests in CM-1, and the patient groups studied to date have been small and heterogeneous. The clinical findings, neuroimages, and EP findings were retrospectively studied in a cohort of 50 patients with CM-1. Seventy percent of patients had EP abnormalities (brainstem auditory evoked potential: 52%, posterior tibial nerve somatosensory evoked potential: 42%, and median nerve somatosensory evoked potential: 34%). The most frequent alteration was an increased central conduction time. Morphometric measurements differed between the normal and pathological groups, although no statistical significance was found when comparing these groups. A high percentage of patients with CM-1 show EP alterations regardless of their clinical or radiological findings, thus highlighting the necessity of performing these tests, especially in patients with few or no symptoms.

Quasi-steady-state analysis of coupled flashing ratchets.

PubMed

Levien, Ethan; Bressloff, Paul C

2015-10-01

We perform a quasi-steady-state (QSS) reduction of a flashing ratchet to obtain a Brownian particle in an effective potential. The resulting system is analytically tractable and yet preserves essential dynamical features of the full model. We first use the QSS reduction to derive an explicit expression for the velocity of a simple two-state flashing ratchet. In particular, we determine the relationship between perturbations from detailed balance, which are encoded in the transitions rates of the flashing ratchet, and a tilted-periodic potential. We then perform a QSS analysis of a pair of elastically coupled flashing ratchets, which reduces to a Brownian particle moving in a two-dimensional vector field. We suggest that the fixed points of this vector field accurately approximate the metastable spatial locations of the coupled ratchets, which are, in general, impossible to identify from the full system.

Evaluating Non-In-Place Update Techniques for Flash-Based Transaction Processing Systems

NASA Astrophysics Data System (ADS)

Wang, Yongkun; Goda, Kazuo; Kitsuregawa, Masaru

Recently, flash memory is emerging as the storage device. With price sliding fast, the cost per capacity is approaching to that of SATA disk drives. So far flash memory has been widely deployed in consumer electronics even partly in mobile computing environments. For enterprise systems, the deployment has been studied by many researchers and developers. In terms of the access performance characteristics, flash memory is quite different from disk drives. Without the mechanical components, flash memory has very high random read performance, whereas it has a limited random write performance because of the erase-before-write design. The random write performance of flash memory is comparable with or even worse than that of disk drives. Due to such a performance asymmetry, naive deployment to enterprise systems may not exploit the potential performance of flash memory at full blast. This paper studies the effectiveness of using non-in-place-update (NIPU) techniques through the IO path of flash-based transaction processing systems. Our deliberate experiments using both open-source DBMS and commercial DBMS validated the potential benefits; x3.0 to x6.6 performance improvement was confirmed by incorporating non-in-place-update techniques into file system without any modification of applications or storage devices.

Targeting an efficient target-to-target interval for P300 speller brain–computer interfaces

PubMed Central

Sellers, Eric W.; Wang, Xingyu

2013-01-01

Longer target-to-target intervals (TTI) produce greater P300 event-related potential amplitude, which can increase brain–computer interface (BCI) classification accuracy and decrease the number of flashes needed for accurate character classification. However, longer TTIs requires more time for each trial, which will decrease the information transfer rate of BCI. In this paper, a P300 BCI using a 7 × 12 matrix explored new flash patterns (16-, 18- and 21-flash pattern) with different TTIs to assess the effects of TTI on P300 BCI performance. The new flash patterns were designed to minimize TTI, decrease repetition blindness, and examine the temporal relationship between each flash of a given stimulus by placing a minimum of one (16-flash pattern), two (18-flash pattern), or three (21-flash pattern) non-target flashes between each target flashes. Online results showed that the 16-flash pattern yielded the lowest classification accuracy among the three patterns. The results also showed that the 18-flash pattern provides a significantly higher information transfer rate (ITR) than the 21-flash pattern; both patterns provide high ITR and high accuracy for all subjects. PMID:22350331

SUMO regulates proteasome-dependent degradation of FLASH/Casp8AP2

PubMed Central

Vennemann, Astrid; Hofmann, Thomas G.

2013-01-01

FLASH/Casp8AP2 is a huge multifunctional protein involved in multiple cellular processes, reaching from death receptor signaling to regulation of histone gene transcription and histone mRNA processing. Previous work has shown that FLASH localizes to Cajal bodies and promyelocytic leukemia (PML) bodies. However, the function of its nuclear body association remains unclear. Here we demonstrate that murine FLASH is covalently modified by SUMO at Lys residue 1792. Interestingly, ectopic expression of SUMO results in proteasome-dependent degradation of FLASH. A point mutant of FLASH with a mutated SUMO acceptor lysine residue, FLASHK1792R, is resistant to SUMO-induced degradation. Finally, we show that arsenic trioxide, a drug known to potentiate SUMO modification and degradation of PML, triggers recruitment of FLASH to PML bodies and concomitant loss of FLASH protein. Our data suggest that SUMO targets FLASH for proteasome-dependent degradation, which is associated with recruitment of FLASH to PML bodies. PMID:23673342

Assessment and Development of Oculomotor Flying Skills by the Application of the Channel Theory of Vision.

DTIC Science & Technology

1983-11-04

visual acuity in amblyopia , using steady-state visual evoked potentials. In J. E. Desmedt (Ed.), Visual evoked potentials in man: new developments... amblyopia by the evoked potential method. Ophthalmologica, 1977s 175, 159-164. 61. Regan, D. & Spekreijse, H. Auditory-visual interactions and the

Postoperative neurological deficits may occur despite unchanged intraoperative somatosensory evoked potentials.

PubMed

Lesser, R P; Raudzens, P; Lüders, H; Nuwer, M R; Goldie, W D; Morris, H H; Dinner, D S; Klem, G; Hahn, J F; Shetter, A G

1986-01-01

We describe 6 patients who demonstrated postoperative neurological deficits despite unchanged somatosensory evoked potentials during intraoperative monitoring. Although there is both experimental and clinical evidence that somatosensory evoked potentials are sensitive to some types of intraoperative mishap, the technique should be employed with an awareness of its possible limitations.

Neurotoxic effects of n-hexane on the human central nervous system: evoked potential abnormalities in n-hexane polyneuropathy.

PubMed Central

Chang, Y C

1987-01-01

An outbreak of n-hexane polyneuropathy as a result of industrial exposure occurred in printing factories in Taipei area from December 1983 to February 1985. Multimodality evoked potentials study was performed on 22 of the polyneuropathy cases, five of the subclinical cases, and seven of the unaffected workers. The absolute and interpeak latencies of patterned visual evoked potential (pVEP) in both the polyneuropathy and subclinical groups were longer than in the normal controls. The pVEP interpeak amplitude was also decreased in the polyneuropathy cases. Brainstem auditory evoked potentials (BAEP), showed no difference of wave I latency between factory workers and normal controls, but prolongation of the wave I-V interpeak latencies was noted, corresponding with the severity of the polyneuropathy. In somatosensory evoked potentials (SEPs), both the absolute latencies and central conduction time (CCT) were longer in subclinical and polyneuropathy cases than in the unaffected workers and normal controls. From this evoked potentials study, chronic toxic effects of n-hexane on the central nervous system were shown. PMID:3031221

Brainstem Auditory Evoked Potential in HIV-Positive Adults.

PubMed

Matas, Carla Gentile; Samelli, Alessandra Giannella; Angrisani, Rosanna Giaffredo; Magliaro, Fernanda Cristina Leite; Segurado, Aluísio C

2015-10-20

To characterize the findings of brainstem auditory evoked potential in HIV-positive individuals exposed and not exposed to antiretroviral treatment. This research was a cross-sectional, observational, and descriptive study. Forty-five HIV-positive individuals (18 not exposed and 27 exposed to the antiretroviral treatment - research groups I and II, respectively - and 30 control group individuals) were assessed through brainstem auditory evoked potential. There were no significant between-group differences regarding wave latencies. A higher percentage of altered brainstem auditory evoked potential was observed in the HIV-positive groups when compared to the control group. The most common alteration was in the low brainstem. HIV-positive individuals have a higher percentage of altered brainstem auditory evoked potential that suggests central auditory pathway impairment when compared to HIV-negative individuals. There was no significant difference between individuals exposed and not exposed to antiretroviral treatment.

Cortico-cortical evoked potentials for sites of early versus late seizure spread in stereoelectroencephalography.

PubMed

Lega, Bradley; Dionisio, Sasha; Flanigan, Patrick; Bingaman, William; Najm, Imad; Nair, Dileep; Gonzalez-Martinez, Jorge

2015-09-01

Cortico-cortical evoked potentials offer the possibility of understanding connectivity within seizure networks to improve diagnosis and more accurately identify candidates for seizure surgery. We sought to determine if cortico-cortical evoked potentials and post-stimulation oscillatory changes differ for sites of EARLY versus LATE ictal spread. 37 patients undergoing stereoelectroencephalography were tested using a cortico-cortical evoked potential paradigm. All electrodes were classified according to the speed of ictal spread. EARLY spread sites were matched to a LATE spread site equidistant from the onset zone. Root-mean-square was used to quantify evoked responses and post-stimulation gamma band power and coherence were extracted and compared. Sites of EARLY spread exhibited significantly greater evoked responses after stimulation across all patients (t(36)=2.973, p=0.004). Stimulation elicited enhanced gamma band activity at EARLY spread sites (t(36)=2.61, p=0.03, FDR corrected); this gamma band oscillation was highly coherent with the onset zone. Cortico-cortical evoked potentials and post-stimulation changes in gamma band activity differ between sites of EARLY versus LATE ictal spread. The oscillatory changes can help visualize connectivity within the seizure network. Copyright © 2015 Elsevier B.V. All rights reserved.

The Forensic Potential of Flash Memory

DTIC Science & Technology

2009-09-01

limit range of 10 to 100 years before data is lost [12]. 5. Flash Memory Logical Structure The logical structure of flash memory from least to...area is not standardized and is manufacturer specific. This information will be used by the wear leveling algorithms and as such will be proprietary...memory cells, the manufacturers of the flash implement a wear leveling algorithm . In contrast, a magnetic disk in an overwrite operation will reuse the

Cervical sympathetic block prolongs the latency and reduces the amplitude of trigeminal somatosensory evoked potentials on the contralateral side.

PubMed

Kawaguchi, Jun; Matsuura, Nobuyuki; Kasahara, Masataka; Ichinohe, Tatsuya

2015-02-01

The purpose of this study was to investigate the latency and amplitude of trigeminal somatosensory evoked potentials to clarify how nerve function on the contralateral side is affected after cervical sympathetic block (CSB). Subjects comprised 16 volunteers. For CSB, the tip of a needle was contacted with the transverse process of the sixth cervical vertebra on the right side, and lidocaine was injected. Trigeminal somatosensory evoked potentials were recorded bilaterally from C5/C6 scalp positions. Pupil diameters were also measured. Electrical stimulations were applied to the left-side lower lip, and trigeminal somatosensory evoked potentials waveforms derived from both sides of the scalp were recorded. Then, electrical stimulations were applied to the right-side of the lower lip, and recording was again performed. Recordings were performed at 5, 15, and 30 minutes after CSB. On the CSB side, pupil diameter decreased at 5 and 15 minutes after CSB. Trigeminal somatosensory evoked potentials at contralateral stimulation showed a prolongation of the latency in both P20 and N25 components on bilateral recording sites 5 and 15 minutes after CSB. Trigeminal somatosensory evoked potentials' amplitude at contralateral stimulation was smaller than at ipsilateral stimulation 5 minutes after CSB. Cervical sympathetic block prolongs the latency and reduces the amplitude of trigeminal somatosensory evoked potentials on the contralateral side.

Click- and chirp-evoked human compound action potentials

PubMed Central

Chertoff, Mark; Lichtenhan, Jeffery; Willis, Marie

2010-01-01

In the experiments reported here, the amplitude and the latency of human compound action potentials (CAPs) evoked from a chirp stimulus are compared to those evoked from a traditional click stimulus. The chirp stimulus was created with a frequency sweep to compensate for basilar membrane traveling wave delay using the O-Chirp equations from Fobel and Dau [(2004). J. Acoust. Soc. Am. 116, 2213–2222] derived from otoacoustic emission data. Human cochlear traveling wave delay estimates were obtained from derived compound band action potentials provided by Eggermont [(1979). J. Acoust. Soc. Am. 65, 463–470]. CAPs were recorded from an electrode placed on the tympanic membrane (TM), and the acoustic signals were monitored with a probe tube microphone attached to the TM electrode. Results showed that the amplitude and latency of chirp-evoked N1 of the CAP differed from click-evoked CAPs in several regards. For the chirp-evoked CAP, the N1 amplitude was significantly larger than the click-evoked N1s. The latency-intensity function was significantly shallower for chirp-evoked CAPs as compared to click-evoked CAPs. This suggests that auditory nerve fibers respond with more unison to a chirp stimulus than to a click stimulus. PMID:21117748

Conformational detection of p53's oligomeric state by FlAsH Fluorescence.

PubMed

Webber, Tawnya M; Allen, Andrew C; Ma, Wai Kit; Molloy, Rhett G; Kettelkamp, Charisse N; Dow, Caitlin A; Gage, Matthew J

2009-06-19

The p53 tumor suppressor protein is a critical checkpoint in prevention of tumor formation, and the function of p53 is dependent on proper formation of the active tetramer. In vitro studies have shown that p53 binds DNA most efficiently as a tetramer, though inactive p53 is predicted to be monomeric in vivo. We demonstrate that FlAsH binding can be used to distinguish between oligomeric states of p53, providing a potential tool to explore p53 oligomerization in vivo. The FlAsH tetra-cysteine binding motif has been incorporated along the dimer and tetramer interfaces in the p53 tetramerization domain to create reporters for the dimeric and tetrameric states of p53, though the geometry of the four cysteines is critical for efficient FlAsH binding. Furthermore, we demonstrate that FlAsH binding can be used to monitor tetramer formation in real-time. These results demonstrate the potential for using FlAsH fluorescence to monitor protein-protein interactions in vivo.

Conformational detection of p53's oligomeric state by FlAsH Fluorescence

PubMed Central

Webber, Tawnya M.; Allen, Andrew C.; Ma, Wai Kit; Molloy, Rhett G.; Kettelkamp, Charisse N.; Dow, Caitlin A.; Gage, Matthew J.

2009-01-01

The p53 tumor suppressor protein is a critical checkpoint in prevention of tumor formation, and the function of p53 is dependent on proper formation of the active tetramer. In vitro studies have shown that p53 binds DNA most efficiently as a tetramer, though inactive p53 is predicted to be monomeric in vivo. We demonstrate that FlAsH binding can be used to distinguish between oligomeric states of p53, providing a potential tool to explore p53 oligomerization in vivo. The FlAsH tetra-cysteine binding motif has been incorporated along the dimer and tetramer interfaces in the p53 tetramerization domain to create reporters for the dimeric and tetrameric states of p53, though the geometry of the four cysteines is critical for efficient FlAsH binding. Furthermore, we demonstrate that FlAsH binding can be used to monitor tetramer formation in real-time. These results demonstrate the potential for using FlAsH fluorescence to monitor protein-protein interactions in vivo. PMID:19393630

[The algorithms and development for the extraction of evoked potentials].

PubMed

Niu, Jie; Qiu, Tianshuang

2004-06-01

The extraction of evoked potentials is a main subject in the area of brain signal processing. In recent years, the single-trial extraction of evoked potentials has been focused on by many studies. In this paper, the approaches based on the wavelet transform, the neural network, the high order acumulants and the independent component analysis are briefly reviewed.

Human cerebral potentials evoked by moving dynamic random dot stereograms.

PubMed

Herpers, M J; Caberg, H B; Mol, J M

1981-07-01

In 11 normal healthy human subjects an evoked potential was elicited by moving dynamic random dot stereograms. The random dots were generated by a minicomputer. An average of each of 8 EEG channels of the subjects tested was made. The maximum of the cerebral evoked potentials thus found was localized in the central and parietal region. No response earlier than 130--150 msec after the stimulus could be proved. The influence of fixation, the number of dots provided, an interocular interstimulus interval in the presentation of the dots, and lense accommodation movements on the evoked stereoptic potentials was investigated and discussed. An interocular interstimulus interval (left eye leading) in the presentation of the dots caused an increase in latency of the response much longer than the imposed interstimulus interval itself. It was shown that no accommodation was needed to perceive the depth impression, and to evoke the cerebral response with random dot stereograms. There are indications of an asymmetry between the two hemispheres in the handling of depth perception after 250 msec. The potential distribution of the evoked potentials strongly suggests that they are not generated in the occipital region.

[Application of evoked potentials monitoring in total thoracoabdominal aorta aneurysm repair].

PubMed

Duan, Y Y; Zheng, J; Pan, X D; Zhu, J M; Liu, Y M; Ge, Y P; Cheng, L J; Sun, L Z

2016-04-05

To evaluate the application value of evoked potentials (EP) monitoring in patients undergoing aorta-iliac bypass for total thoracoabdominal aorta aneurysm repair (tTAAAR). A prospective study, with a total of 31 patients undergoing tTAAAR and intraoperative EP monitoring from June 2014 to April 2015 was carried out. The results of intraoperative evoked potentials, clinical outcomes and follow-up data of patients were collected for further evaluation. The EP wave disappeared [motor evoked potentials for (55.6±18.1) min, somatosensory evoked potentials for (50.3±18.7) min] after proximal descending aorta being clamped, and gradually recovered after the segment arteries of spine cord were reconstructed. The EP wave was restored to normal level at the end of operation in all the cases. The somatosensory evoked potentials remained unchanged in 2 cases (false negative). One case died after operation. No spinal cord injury occurred. The median follow-up after operation was 10 months (5-14 months). There was no delayed neurological deficit. EP provided an on-line monitoring of the condition of spinal cord function, which become an intraoperative protocol to avoid the irreversible injury of spinal cord.

Objective correlate of subjective pain perception by contact heat-evoked potentials.

PubMed

Granovsky, Yelena; Granot, Michal; Nir, Rony-Reuven; Yarnitsky, David

2008-01-01

The method of pain-evoked potentials has gained considerable acceptance over the last 3 decades regarding its objectivity, repeatability, and quantifiability. The present study explored whether the relationship between pain-evoked potentials and pain psychophysics obtained by contact heat stimuli is similar to those observed for the conventionally used laser stimulation. Evoked potentials (EPs) were recorded in response to contact heat stimuli at different body sites in 24 healthy volunteers. Stimuli at various temperatures were applied to the forearm (43 degrees C, 46 degrees C, 49 degrees C, and 52 degrees C) and leg (46 degrees C and 49 degrees C). The amplitudes of both components (N2 and P2) were strongly associated with the intensity of the applied stimuli and with subjective pain perception. Yet, regression analysis revealed pain perception and not stimulus intensity as the major contributing factor. A significant correlation was found between the forearm and the leg for both psychophysics and EPs amplitude. Contact heat can generate readily distinguishable evoked potentials on the scalp, consistent between upper and lower limbs. Although these potentials bear positive correlation with both stimulus intensity and pain magnitude, the latter is the main contributor to the evoked brain response.

Contact Heat Evoked Potentials (CHEPs) in Patients with Mild-Moderate Alzheimer's Disease and Matched Control--A Pilot Study.

PubMed

Jensen-Dahm, Christina; Madsen, Caspar Skau; Waldemar, Gunhild; Ballegaard, Martin; Hejl, Anne-Mette; Johnsen, Birger; Jensen, Troels Staehelin

2016-04-01

Clinical studies have found that patients with Alzheimer's disease report pain of less intensity and with a lower affective response, which has been thought to be due to altered pain processing. The authors wished to examine the cerebral processing of non-painful and painful stimuli using somatosensory evoked potentials and contact heat evoked potentials in patients with Alzheimer's disease and in healthy elderly controls. Case-control study Twenty outpatients with mild-moderate Alzheimer's disease and in 17 age- and gender-matched healthy controls were included Contact heat evoked potentials and somatosensory evoked potentials were recorded in all subjects. Furthermore, warmth detection threshold and heat pain threshold were assessed. Patients and controls also rated quality and intensity of the stimuli. The authors found no difference on contact heat evoked potential amplitude (P = 0.59) or latency of N2 or P2 wave (P = 0.62 and P = 0.75, respectively) between patients and controls. In addition, there was no difference in regard to pain intensity scores or pain quality. The patients and controls had similar warmth detection threshold and heat pain threshold. Somatosensory evoked potentials, amplitude, and latency were within normal range and similar for the two groups. The findings suggest that the processing of non-painful and painful stimuli is preserved in patients with mild to moderate Alzheimer's disease. © 2015 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Sunlight irradiance and habituation of visual evoked potentials in migraine: The environment makes its mark.

PubMed

Lisicki, Marco; D'Ostilio, Kevin; Erpicum, Michel; Schoenen, Jean; Magis, Delphine

2017-01-01

Background Migraine is a complex multifactorial disease that arises from the interaction between a genetic predisposition and an enabling environment. Habituation is considered as a fundamental adaptive behaviour of the nervous system that is often impaired in migraine populations. Given that migraineurs are hypersensitive to light, and that light deprivation is able to induce functional changes in the visual cortex recognizable through visual evoked potentials habituation testing, we hypothesized that regional sunlight irradiance levels could influence the results of visual evoked potentials habituation studies performed in different locations worldwide. Methods We searched the literature for visual evoked potentials habituation studies comparing healthy volunteers and episodic migraine patients and correlated their results with levels of local solar radiation. Results After reviewing the literature, 26 studies involving 1291 participants matched our inclusion criteria. Deficient visual evoked potentials habituation in episodic migraine patients was reported in 19 studies. Mean yearly sunlight irradiance was significantly higher in locations of studies reporting deficient habituation. Correlation analyses suggested that visual evoked potentials habituation decreases with increasing sunlight irradiance in migraine without aura patients. Conclusion Results from this hypothesis generating analysis suggest that variations in sunlight irradiance may induce adaptive modifications in visual processing systems that could be reflected in visual evoked potentials habituation, and thus partially account for the difference in results between studies performed in geographically distant centers. Other causal factors such as genetic differences could also play a role, and therefore well-designed prospective trials are warranted.

Spinal NMDA-receptor dependent amplification of nociceptive transmission to rat primary somatosensory cortex (SI).

PubMed

Kalliomäki, Jarkko; Granmo, Marcus; Schouenborg, Jens

2003-07-01

The role of NMDA mechanisms in spinal pathways mediating acute nociceptive input to the somatosensory cortex is not clear. In this study, the effect of NMDA-antagonists on nociceptive C fibre transmission to the primary somatosensory cortex (SI) was investigated. Cortical field potentials evoked by CO(2)-laser stimulation of the skin were recorded in the halothane/nitrous oxide anaesthetized rat. The SI nociceptive evoked potential (EP) amplitudes were dependent on the frequency of noxious heat stimulation. The amplitudes of SI potentials evoked by CO(2)-laser pulses (duration 15-20 ms, stimulation energy 21-28 mJ/mm(2)) delivered at a frequency of 0.1 Hz were approximately 40% of the amplitudes of potentials evoked by 1.0 Hz stimulation. After intrathecal lumbar application of either of the NMDA-antagonists CPP or MK-801, the amplitudes of nociceptive SI potentials, evoked by 1.0 Hz stimulation of the contralateral hindpaw, were reduced to approximately 40% of controls. By contrast, field potentials evoked by 0.1 Hz stimulation of the hindpaw were unaffected by MK-801. SI potentials evoked by 1.0 Hz stimulation of the contralateral forepaw did not change after lumbar application of CPP or MK-801, indicating that the depression of hindpaw EPs was due to a segmental effect in the spinal cord. It is concluded that spinal NMDA-receptor mechanisms amplify the acute transmission of nociceptive C fiber input to SI in a frequency-dependent way.

Biochemical markers for cardiovascular disease in recently postmenopausal women with or without hot flashes.

PubMed

Tuomikoski, Pauliina; Mikkola, Tomi S; Hämäläinen, Esa; Tikkanen, Matti J; Turpeinen, Ursula; Ylikorkala, Olavi

2010-01-01

Menopausal hot flashes may affect vascular function and perhaps explain conflicting data on cardiovascular disease (CVD) between observational and randomized hormone therapy (HT) studies. We prospectively assessed hot flash status in recently postmenopausal women and related it to a number of biochemical vascular surrogate markers for CVD. Healthy, nonsmoking women (n = 150) exhibiting a broad range (no, mild, moderate, severe) of hot flashes and an onset of menopause within the previous 0.5 to 3 years were studied with laboratory tests for lipids, lipoproteins, apolipoproteins, high-sensitivity C-reactive protein, and sex hormone-binding globulin. Apart from marked differences in hot flashes, the groups showed comparable levels of estrone, estradiol, or free estradiol index. The levels of total cholesterol (3.7-9.1 mmol/L) were similar between the groups (P = 0.744), and hypercholesterolemia (>6.5 mmol/L) was encountered equally often (P = 0.699). No difference was seen in high-, low-, or very low-density lipoproteins, triglycerides, apolipoprotein A-1, apolipoprotein B (or their ratio), or lipoprotein(a) between the groups. The levels of sex hormone-binding globulin and high-sensitivity C-reactive protein correlated negatively with each other (r = -0.204; P = 0.013) but showed no dependence on hot flashes (P = 0.531 and P = 0.215, respectively). No baseline difference in lipid or nonlipid CVD risk factors was observed between women with hot flashes (potential HT users) and women with no or mild hot flashes (potential HT nonusers). This may imply that hot flash status per se cannot explain the difference between observational and randomized trials.

Clinical Applications for EPs in the ICU.

PubMed

Koenig, Matthew A; Kaplan, Peter W

2015-12-01

In critically ill patients, evoked potential (EP) testing is an important tool for measuring neurologic function, signal transmission, and secondary processing of sensory information in real time. Evoked potential measures conduction along the peripheral and central sensory pathways with longer-latency potentials representing more complex thalamocortical and intracortical processing. In critically ill patients with limited neurologic exams, EP provides a window into brain function and the potential for recovery of consciousness. The most common EP modalities in clinical use in the intensive care unit include somatosensory evoked potentials, brainstem auditory EPs, and cortical event-related potentials. The primary indications for EP in critically ill patients are prognostication in anoxic-ischemic or traumatic coma, monitoring for neurologic improvement or decline, and confirmation of brain death. Somatosensory evoked potentials had become an important prognostic tool for coma recovery, especially in comatose survivors of cardiac arrest. In this population, the bilateral absence of cortical somatosensory evoked potentials has nearly 100% specificity for death or persistent vegetative state. Historically, EP has been regarded as a negative prognostic test, that is, the absence of cortical potentials is associated with poor outcomes while the presence cortical potentials are prognostically indeterminate. In recent studies, the presence of middle-latency and long-latency potentials as well as the amplitude of cortical potentials is more specific for good outcomes. Event-related potentials, particularly mismatch negativity of complex auditory patterns, is emerging as an important positive prognostic test in patients under comatose. Multimodality predictive algorithms that combine somatosensory evoked potentials, event-related potentials, and clinical and radiographic factors are gaining favor for coma prognostication.

Neurobehavioral and neurometabolic (SPECT) correlates of paranormal information: involvement of the right hemisphere and its sensitivity to weak complex magnetic fields.

PubMed

Roll, W G; Persinger, M A; Webster, D L; Tiller, S G; Cook, C M

2002-02-01

Experiments were designed to help elucidate the neurophysiological correlates for the experiences reported by Sean Harribance. For most of his life he has routinely experienced "flashes of images" of objects that were hidden and of accurate personal information concerning people with whom he was not familiar. The specificity of details for target pictures of people was correlated positively with the proportion of occipital alpha activity. Results from a complete neuropsychological assessment, Single Photon Emission Computed Tomography (SPECT), and screening electroencephalography suggested that his experiences were associated with increased activity within the parietal lobe and occipital regions of the right hemisphere. Sensed presences (subjectively localized to his left side) were evoked when weak, magnetic fields, whose temporal structure simulated long-term potentiation in the hippocampus, were applied over his right temporoparietal lobes. These results suggest that the phenomena attributed to paranormal or "extrasensory" processes are correlated quantitatively with morphological and functional anomalies involving the right parietotemporal cortices (or its thalamic inputs) and the hippocampal formation.

Virus-mediated EpoR76E Therapy Slows Optic Nerve Axonopathy in Experimental Glaucoma.

PubMed

Bond, Wesley S; Hines-Beard, Jessica; GoldenMerry, YPaul L; Davis, Mara; Farooque, Alma; Sappington, Rebecca M; Calkins, David J; Rex, Tonia S

2016-02-01

Glaucoma, a common cause of blindness, is currently treated by intraocular pressure (IOP)-lowering interventions. However, this approach is insufficient to completely prevent vision loss. Here, we evaluate an IOP-independent gene therapy strategy using a modified erythropoietin, EPO-R76E, which has reduced erythropoietic function. We used two models of glaucoma, the murine microbead occlusion model and the DBA/2J mouse. Systemic recombinant adeno-associated virus-mediated gene delivery of EpoR76E (rAAV.EpoR76E) was performed concurrent with elevation of IOP. Axon structure and active anterograde transport were preserved in both models. Vision, as determined by the flash visual evoked potential, was preserved in the DBA/2J. These results show that systemic EpoR76E gene therapy protects retinal ganglion cells from glaucomatous degeneration in two different models. This suggests that EPO targets a component of the neurodegenerative pathway that is common to both models. The efficacy of rAAV.EpoR76E delivered at onset of IOP elevation supports clinical relevance of this treatment.

The Relationship of Visual Evoked Potential Asymmetries to the Performance of Sonar Operators

DTIC Science & Technology

1981-08-11

also been related to EP variability. Schizophrenic adults and patients with Korsakoff’s Syndrome have shown higher evoked potential variability than...average evoked response in Korsakoff patients. J. Psychiatry Res. 6: 253-260, 1969. Santoro, T. and D. Fender. Rules for the perception of

Differences in the Optical Characteristics of Continental US Ground and Cloud Flashes as Observed from Space

NASA Technical Reports Server (NTRS)

Koshak, William

2007-01-01

Continental US lightning flashes observed by the Optical Transient Detector (OTD) are categorized according to flash type (ground or cloud flash) using US National Lightning Detection Network (TM) (NLDN) data. The statistics of the ground and cloud flash optical parameters (e.g., radiance, area, duration, number of optical groups, and number of optical events) are inter-compared. On average, the ground flash cloud-top emissions are more radiant, illuminate a larger area, are longer lasting, and have more optical groups and optical events than those cloud-top emissions associated with cloud flashes. Given these differences, it is suggested that the methods of Bayesian Inference could be used to help discriminate between ground and cloud flashes. The ability to discriminate flash type on-orbit is highly desired since such information would help researchers and operational decision makers better assess the intensification, evolutionary state, and severe weather potential of thunderstorms. This work supports risk reduction activities presently underway for the future launch of the GOES-R Geostationary Lightning Mapper (GLM).

The association between later cortical potentials and later phases of postural reactions evoked by perturbations to upright stance.

PubMed

Quant, Sylvia; Maki, Brian E; McIlroy, William E

2005-06-24

Previous studies have suggested that early cortical potentials (e.g. N1) that are evoked by perturbations to upright stance are associated with sensory processing of the initial perturbation and that later potentials may represent cognitive processing of this perturbation. However, it has also been suggested that later cortical potentials could reflect sensory and motor processing of later phases of the postural reaction. The current study set out to provide additional insight into the association between perturbation-evoked cortical potentials and postural reactions evoked by whole-body perturbations. By altering the deceleration onset of the perturbation, which altered the timing of later postural responses, we determined whether changes in later postural responses were associated with changes in later potentials. Based on previous work, we hypothesized that later potentials would not be associated with changes in later postural responses. During stance, seven healthy young adults were instructed to maintain their balance following two types of perturbations: (1) acceleration phase immediately followed by a deceleration phase (TASK 1), and (2) acceleration phase followed by a delayed deceleration phase (TASK 2). In spite of profound task differences in later postural responses, results revealed no significant differences in later potentials. This work provides additional support for the idea that latter elements of perturbation-evoked cortical responses are likely independent of evoked motor reactions required to maintain stability.

Auditory evoked potentials in two short-finned pilot whales (Globicephala macrorhynchus).

PubMed

Schlundt, Carolyn E; Dear, Randall L; Houser, Dorian S; Bowles, Ann E; Reidarson, Tom; Finneran, James J

2011-02-01

The hearing sensitivities of two short-finned pilot whales (Globicephala macrorhynchus) were investigated by measuring auditory evoked potentials generated in response to clicks and sinusoidal amplitude modulated (SAM) tones. The first whale tested, an adult female, was a long-time resident at SeaWorld San Diego with a known health history. Click-evoked responses in this animal were similar to those measured in other echolocating odontocetes. Auditory thresholds were comparable to dolphins of similar age determined with similar evoked potential methods. The region of best sensitivity was near 40 kHz and the upper limit of functional hearing was between 80 and 100 kHz. The second whale tested, a juvenile male, was recently stranded and deemed non-releasable. Click-evoked potentials were not detected in this animal and testing with SAM tones suggested severe hearing loss above 10 kHz.

Use of the Stockwell Transform in the Detection of P300 Evoked Potentials with Low-Cost Brain Sensors.

PubMed

Pérez-Vidal, Alan F; Garcia-Beltran, Carlos D; Martínez-Sibaja, Albino; Posada-Gómez, Rubén

2018-05-09

The evoked potential is a neuronal activity that originates when a stimulus is presented. To achieve its detection, various techniques of brain signal processing can be used. One of the most studied evoked potentials is the P300 brain wave, which usually appears between 300 and 500 ms after the stimulus. Currently, the detection of P300 evoked potentials is of great importance due to its unique properties that allow the development of applications such as spellers, lie detectors, and diagnosis of psychiatric disorders. The present study was developed to demonstrate the usefulness of the Stockwell transform in the process of identifying P300 evoked potentials using a low-cost electroencephalography (EEG) device with only two brain sensors. The acquisition of signals was carried out using the Emotiv EPOC ® device—a wireless EEG headset. In the feature extraction, the Stockwell transform was used to obtain time-frequency information. The algorithms of linear discriminant analysis and a support vector machine were used in the classification process. The experiments were carried out with 10 participants; men with an average age of 25.3 years in good health. In general, a good performance (75⁻92%) was obtained in identifying P300 evoked potentials.

Visual and brainstem auditory evoked potentials in infants with severe vitamin B12 deficiency.

PubMed

Demir, Nihat; Koç, Ahmet; Abuhandan, Mahmut; Calik, Mustafa; Işcan, Akin

2015-01-01

Vitamin B12 plays an important role in the development of mental, motor, cognitive, and social functions via its role in DNA synthesis and nerve myelination. Its deficiency in infants might cause neuromotor retardation as well as megaloblastic anemia. The objective of this study was to investigate the effects of infantile vitamin B12 deficiency on evoked brain potentials and determine whether improvement could be obtained with vitamin B12 replacement at appropriate dosages. Thirty patients with vitamin B12 deficiency and 30 age-matched healthy controls were included in the study. Hematological parameters, visual evoked potentials, and brainstem auditory evoked potentials tests were performed prior to treatment, 1 week after treatment, and 3 months after treatment. Visual evoked potentials (VEPs) and brainstem auditory evoked potentials (BAEPs) were found to be prolonged in 16 (53.3%) and 15 (50%) patients, respectively. Statistically significant improvements in VEP and BAEP examinations were determined 3 months after treatment. Three months after treatment, VEP and BAEP examinations returned to normal in 81.3% and 53.3% of subjects with prolonged VEPs and BAEPs, respectively. These results demonstrate that vitamin B12 deficiency in infants causes significant impairment in the auditory and visual functioning tests of the brain, such as VEP and BAEP.

Middle Latency Auditory Evoked Potential (MLAEP) in Workers with and without Tinnitus who are Exposed to Occupational Noise.

PubMed

dos Santos Filha, Valdete Alves Valentins; Samelli, Alessandra Giannella; Matas, Carla Gentile

2015-09-11

Tinnitus is an important occupational health concern, but few studies have focused on the central auditory pathways of workers with a history of occupational noise exposure. Thus, we analyzed the central auditory pathways of workers with a history of occupational noise exposure who had normal hearing threshold, and compared middle latency auditory evoked potential in those with and without noise-induced tinnitus. Sixty individuals (30 with and 30 without tinnitus) underwent the following procedures: anamnesis, immittance measures, pure-tone air conduction thresholds at all frequencies between 0.25-8 kHz, and middle latency auditory evoked potentials. Quantitative analysis of latencies and amplitudes of middle latency auditory evoked potential showed no significant differences between the groups with and without tinnitus. In the qualitative analysis, we found that both groups showed increased middle latency auditory evoked potential latencies. The study group had more alterations of the "both" type regarding the Na-Pa amplitude, while the control group had more "electrode effect" alterations, but these alterations were not significantly different when compared to controls. Individuals with normal hearing with or without tinnitus who are exposed to occupational noise have altered middle latency auditory evoked potential, suggesting impairment of the auditory pathways in cortical and subcortical regions. Although differences did not reach significance, individuals with tinnitus seemed to have more abnormalities in components of the middle latency auditory evoked potential when compared to individuals without tinnitus, suggesting alterations in the generation and transmission of neuroelectrical impulses along the auditory pathway.

Refractory episodic vertigo: role of intratympanic gentamicin and vestibular evoked myogenic potentials.

PubMed

Celis-Aguilar, Erika; Hinojosa-González, Ramon; Vales-Hidalgo, Olivia; Coutinho-Toledo, Heloisa

Even today, the treatment of intractable vertigo remains a challenge. Vestibular ablation with intratympanic gentamicin stands as a good alternative in the management of refractory vertigo patients. To control intractable vertigo through complete saccular and horizontal canal vestibular ablation with intratympanic gentamicin treatment. Patients with refractory episodic vertigo were included. The inclusion criteria were: unilateral ear disease, moderate to profound sensorineural hearing loss, and failure to other treatments. Included patients underwent 0.5-0.8mL of gentamicin intratympanic application at a 30mg/mL concentration. Vestibular ablation was confirmed by the absence of response on cervical vestibular evoked myogenic potentials and no response on caloric tests. Audiometry, electronystagmography with iced water, and vestibular evoked myogenic potentials were performed in all patients. Ten patients were included; nine patients with Meniere's disease and one patient with (late onset) delayed hydrops. Nine patients showed an absent response on vestibular evoked myogenic potentials and no response on caloric tests. The only patient with low amplitude on cervical vestibular evoked myogenic potentials had vertigo recurrence. Vertigo control was achieved in 90% of the patients. One patient developed hearing loss >30dB. Cervical vestibular evoked myogenic potentials confirmed vestibular ablation in patients treated with intratympanic gentamicin. High-grade vertigo control was due to complete saccular and horizontal canal ablation (no response to iced water in electronystagmography and no response on cervical vestibular evoked myogenic potentials). Copyright © 2016 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Evoked potentials in immobilized cats to a combination of clicks with painful electrocutaneous stimuli

NASA Technical Reports Server (NTRS)

Gilinskiy, M. A.; Korsakov, I. A.

1979-01-01

Averaged evoked potentials in the auditory, somatosensory, and motor cortical zones, as well as in the mesencephalic reticular formation were recorded in acute experiments on nonanesthetized, immobilized cats. Omission of the painful stimulus after a number of pairings resulted in the appearance of a delayed evoked potential, often resembling the late phases of the response to the painful stimulus. The characteristics of this response are discussed in comparison with conditioned changes of the sensory potential amplitudes.

Chirp-modulated visual evoked potential as a generalization of steady state visual evoked potential

NASA Astrophysics Data System (ADS)

Tu, Tao; Xin, Yi; Gao, Xiaorong; Gao, Shangkai

2012-02-01

Visual evoked potentials (VEPs) are of great concern in cognitive and clinical neuroscience as well as in the recent research field of brain-computer interfaces (BCIs). In this study, a chirp-modulated stimulation was employed to serve as a novel type of visual stimulus. Based on our empirical study, the chirp stimuli visual evoked potential (Chirp-VEP) preserved frequency features of the chirp stimulus analogous to the steady state evoked potential (SSVEP), and therefore it can be regarded as a generalization of SSVEP. Specifically, we first investigated the characteristics of the Chirp-VEP in the time-frequency domain and the fractional domain via fractional Fourier transform. We also proposed a group delay technique to derive the apparent latency from Chirp-VEP. Results on EEG data showed that our approach outperformed the traditional SSVEP-based method in efficiency and ease of apparent latency estimation. For the recruited six subjects, the average apparent latencies ranged from 100 to 130 ms. Finally, we implemented a BCI system with six targets to validate the feasibility of Chirp-VEP as a potential candidate in the field of BCIs.

Active Flash: Out-of-core Data Analytics on Flash Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boboila, Simona; Kim, Youngjae; Vazhkudai, Sudharshan S

2012-01-01

Next generation science will increasingly come to rely on the ability to perform efficient, on-the-fly analytics of data generated by high-performance computing (HPC) simulations, modeling complex physical phenomena. Scientific computing workflows are stymied by the traditional chaining of simulation and data analysis, creating multiple rounds of redundant reads and writes to the storage system, which grows in cost with the ever-increasing gap between compute and storage speeds in HPC clusters. Recent HPC acquisitions have introduced compute node-local flash storage as a means to alleviate this I/O bottleneck. We propose a novel approach, Active Flash, to expedite data analysis pipelines bymore » migrating to the location of the data, the flash device itself. We argue that Active Flash has the potential to enable true out-of-core data analytics by freeing up both the compute core and the associated main memory. By performing analysis locally, dependence on limited bandwidth to a central storage system is reduced, while allowing this analysis to proceed in parallel with the main application. In addition, offloading work from the host to the more power-efficient controller reduces peak system power usage, which is already in the megawatt range and poses a major barrier to HPC system scalability. We propose an architecture for Active Flash, explore energy and performance trade-offs in moving computation from host to storage, demonstrate the ability of appropriate embedded controllers to perform data analysis and reduction tasks at speeds sufficient for this application, and present a simulation study of Active Flash scheduling policies. These results show the viability of the Active Flash model, and its capability to potentially have a transformative impact on scientific data analysis.« less

Vestibular receptors contribute to cortical auditory evoked potentials.

PubMed

Todd, Neil P M; Paillard, Aurore C; Kluk, Karolina; Whittle, Elizabeth; Colebatch, James G

2014-03-01

Acoustic sensitivity of the vestibular apparatus is well-established, but the contribution of vestibular receptors to the late auditory evoked potentials of cortical origin is unknown. Evoked potentials from 500 Hz tone pips were recorded using 70 channel EEG at several intensities below and above the vestibular acoustic threshold, as determined by vestibular evoked myogenic potentials (VEMPs). In healthy subjects both auditory mid- and long-latency auditory evoked potentials (AEPs), consisting of Na, Pa, N1 and P2 waves, were observed in the sub-threshold conditions. However, in passing through the vestibular threshold, systematic changes were observed in the morphology of the potentials and in the intensity dependence of their amplitude and latency. These changes were absent in a patient without functioning vestibular receptors. In particular, for the healthy subjects there was a fronto-central negativity, which appeared at about 42 ms, referred to as an N42, prior to the AEP N1. Source analysis of both the N42 and N1 indicated involvement of cingulate cortex, as well as bilateral superior temporal cortex. Our findings are best explained by vestibular receptors contributing to what were hitherto considered as purely auditory evoked potentials and in addition tentatively identify a new component that appears to be primarily of vestibular origin. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

An SSVEP-actuated brain computer interface using phase-tagged flickering sequences: a cursor system.

PubMed

Lee, Po-Lei; Sie, Jyun-Jie; Liu, Yu-Ju; Wu, Chi-Hsun; Lee, Ming-Huan; Shu, Chih-Hung; Li, Po-Hung; Sun, Chia-Wei; Shyu, Kuo-Kai

2010-07-01

This study presents a new steady-state visual evoked potential (SSVEP)-based brain computer interface (BCI). SSVEPs, induced by phase-tagged flashes in eight light emitting diodes (LEDs), were used to control four cursor movements (up, right, down, and left) and four button functions (on, off, right-, and left-clicks) on a screen menu. EEG signals were measured by one EEG electrode placed at Oz position, referring to the international EEG 10-20 system. Since SSVEPs are time-locked and phase-locked to the onsets of SSVEP flashes, EEG signals were bandpass-filtered and segmented into epochs, and then averaged across a number of epochs to sharpen the recorded SSVEPs. Phase lags between the measured SSVEPs and a reference SSVEP were measured, and targets were recognized based on these phase lags. The current design used eight LEDs to flicker at 31.25 Hz with 45 degrees phase margin between any two adjacent SSVEP flickers. The SSVEP responses were filtered within 29.25-33.25 Hz and then averaged over 60 epochs. Owing to the utilization of high-frequency flickers, the induced SSVEPs were away from low-frequency noises, 60 Hz electricity noise, and eye movement artifacts. As a consequence, we achieved a simple architecture that did not require eye movement monitoring or other artifact detection and removal. The high-frequency design also achieved a flicker fusion effect for better visualization. Seven subjects were recruited in this study to sequentially input a command sequence, consisting of a sequence of eight cursor functions, repeated three times. The accuracy and information transfer rate (mean +/- SD) over the seven subjects were 93.14 +/- 5.73% and 28.29 +/- 12.19 bits/min, respectively. The proposed system can provide a reliable channel for severely disabled patients to communicate with external environments.

NLP-12 engages different UNC-13 proteins to potentiate tonic and evoked release.

PubMed

Hu, Zhitao; Vashlishan-Murray, Amy B; Kaplan, Joshua M

2015-01-21

A neuropeptide (NLP-12) and its receptor (CKR-2) potentiate tonic and evoked ACh release at Caenorhabditis elegans neuromuscular junctions. Increased evoked release is mediated by a presynaptic pathway (egl-30 Gαq and egl-8 PLCβ) that produces DAG, and by DAG binding to short and long UNC-13 proteins. Potentiation of tonic ACh release persists in mutants deficient for egl-30 Gαq and egl-8 PLCβ and requires DAG binding to UNC-13L (but not UNC-13S). Thus, NLP-12 adjusts tonic and evoked release by distinct mechanisms. Copyright © 2015 the authors 0270-6474/15/351038-05$15.00/0.

Generalized alternating stimulation: a novel method to reduce stimulus artifact in electrically evoked compound action potentials.

PubMed

Alvarez, Isaac; de la Torre, Angel; Sainz, Manuel; Roldan, Cristina; Schoesser, Hansjoerg; Spitzer, Philipp

2007-09-15

Stimulus artifact is one of the main limitations when considering electrically evoked compound action potential for clinical applications. Alternating stimulation (average of recordings obtained with anodic-cathodic and cathodic-anodic bipolar stimulation pulses) is an effective method to reduce stimulus artifact when evoked potentials are recorded. In this paper we extend the concept of alternating stimulation by combining anodic-cathodic and cathodic-anodic recordings with a weight in general different to 0.5. We also provide an automatic method to obtain an estimation of the optimal weights. Comparison with conventional alternating, triphasic stimulation and masker-probe paradigm shows that the generalized alternating method improves the quality of electrically evoked compound action potential responses.

Development of visual evoked potentials in neonates. A study using light emitting diode goggles.

PubMed Central

Chin, K C; Taylor, M J; Menzies, R; Whyte, H

1985-01-01

We used a signal averager with light emitting diode goggles as the photostimulator to study the development of the visual evoked potentials in 40 normal neonates of between 23 and 42 weeks' gestation. All except two infants of less than 24 weeks' gestation had replicable visual evoked potentials. A negative peak of latency (mean (SD), 308 (21) msec) was present in all infants, but the development of the primary positive peak depended on maturity. Only infants of 37 weeks or more had a consistent positive peak of latency (mean (SD), 220 (22) msec). The practical simplicity and reliability of this technique has distinct advantages over previous conventional recording systems. Neonatal visual evoked potentials are shown to change with maturity. PMID:4091582

The flashing right turn signal with pedestrian indication : human factors studies to understand the potential of a new signal to increase awareness of and attention to crossing pedestrians.

DOT National Transportation Integrated Search

2015-12-01

The flashing pedestrian indicator (FPI) is intended to alert turning drivers to the potential presence of : pedestrians in the roadway, facilitate scanning in the likely direction of pedestrians, and encourage caution and : yielding behavior in respo...

Effect of intrathecal baclofen on evoked pain perception: an evoked potentials and quantitative thermal testing study.

PubMed

Kumru, H; Kofler, M; Flores, M C; Portell, E; Robles, V; Leon, N; Vidal, J

2013-08-01

Somatic antinociceptive effects of baclofen have been demonstrated in animal models. We hypothesized that if enhanced thermal or pain sensitivity is produced by loss of gamma-aminobutyric acid (GABA)-ergic tone in the central nervous system, spinal administration of GABA agonists might be predicted to be effective in thermal and/or pain perception changes and pain-related evoked potentials in candidates for intrathecal baclofen (ITB) treatment. Eleven patients with severe spinal cord injury (SCI) who suffered from severe spasticity were evaluated during a 50-μg ITB bolus test. Warm and heat pain thresholds, evoked heat pain perception, and contact heat-evoked potentials (CHEPs) were determined above SCI level from the right and left sides. Nine age- and gender-matched healthy volunteers undergoing repeat testing without any placebo injection served as control group. In patients, heat pain perception threshold increased, and evoked pain perception and amplitude of CHEPs decreased significantly after ITB bolus application in comparison with baseline (p < 0.005), with no change in warm perception threshold. In controls, no significant changes were observed in repeat testing over time. Our findings indicate that ITB modulates heat pain perception threshold, evoked heat pain perception and heat pain-related evoked potentials without inducing warm perception threshold changes in SCI patients. This phenomenon should be taken into account in the clinical evaluation and management of pain in patients receiving baclofen. © 2012 European Federation of International Association for the Study of Pain Chapters.

Synchronized Electronic Shutter System (SESS) for Thermal Nondestructive Evaluation

NASA Technical Reports Server (NTRS)

Zalameda, Joseph N.

2001-01-01

The purpose of this paper is to describe a new method for thermal nondestructive evaluation. This method uses a synchronized electronic shutter system (SESS) to remove the heat lamp's influence on the thermal data during and after flash heating. There are two main concerns when using flash heating. The first concern is during the flash when the photons are reflected back into the camera. This tends to saturate the detectors and potentially introduces unknown and uncorrectable errors when curve fitting the data to a model. To address this, an electronically controlled shutter was placed over the infrared camera lens. Before firing the flash lamps, the shutter is opened to acquire the necessary background data for offset calibration. During flash heating, the shutter is closed to prevent the photons from the high intensity flash from saturating the camera's detectors. The second concern is after the flash heating where the lamps radiate heat after firing. This residual cooling introduces an unwanted transient thermal response into the data. To remove this residual effect, a shutter was placed over the flash lamps to block the infrared heat radiating from the flash head after heating. This helped to remove the transient contribution of the flash. The flash lamp shutters were synchronized electronically with the camera shutter. Results are given comparing the use of the thermal inspection with and without the shutter system.

Pain-related somatosensory evoked potentials and functional brain magnetic resonance in the evaluation of neurologic recovery after cardiac arrest: a case study of three patients.

PubMed

Zanatta, Paolo; Messerotti Benvenuti, Simone; Baldanzi, Fabrizio; Bendini, Matteo; Saccavini, Marsilio; Tamari, Wadih; Palomba, Daniela; Bosco, Enrico

2012-03-31

This case series investigates whether painful electrical stimulation increases the early prognostic value of both somatosensory-evoked potentials and functional magnetic resonance imaging in comatose patients after cardiac arrest. Three single cases with hypoxic-ischemic encephalopathy were considered. A neurophysiological evaluation with an electroencephalogram and somatosensory-evoked potentials during increased electrical stimulation in both median nerves was performed within five days of cardiac arrest. Each patient also underwent a functional magnetic resonance imaging evaluation with the same neurophysiological protocol one month after cardiac arrest. One patient, who completely recovered, showed a middle latency component at a high intensity of stimulation and the activation of all brain areas involved in cerebral pain processing. One patient in a minimally conscious state only showed the cortical somatosensory response and the activation of the primary somatosensory cortex. The last patient, who was in a vegetative state, did not show primary somatosensory evoked potentials; only the activation of subcortical brain areas occurred. These preliminary findings suggest that the pain-related somatosensory evoked potentials performed to increase the prognosis of comatose patients after cardiac arrest are associated with regional brain activity showed by functional magnetic resonance imaging during median nerves electrical stimulation. More importantly, this cases report also suggests that somatosensory evoked potentials and functional magnetic resonance imaging during painful electrical stimulation may be sensitive and complementary methods to predict the neurological outcome in the acute phase of coma. Thus, pain-related somatosensory-evoked potentials may be a reliable and a cost-effective tool for planning the early diagnostic evaluation of comatose patients.

Characterization of Motor and Somatosensory Evoked Potentials in the Yucatan Micropig Using Transcranial and Epidural Stimulation.

PubMed

Benavides, Francisco D; Santamaria, Andrea J; Bodoukhin, Nikita; Guada, Luis G; Solano, Juan P; Guest, James D

2017-09-15

Yucatan micropigs have brain and spinal cord dimensions similar to humans and are useful for certain spinal cord injury (SCI) translational studies. Micropigs are readily trained in behavioral tasks, allowing consistent testing of locomotor loss and recovery. However, there has been little description of their motor and sensory pathway neurophysiology. We established methods to assess motor and sensory cortical evoked potentials in the anesthetized, uninjured state. We also evaluated epidurally evoked motor and sensory stimuli from the T6 and T9 levels, spanning the intended contusion injury epicenter. Response detection frequency, mean latency and amplitude values, and variability of evoked potentials were determined. Somatosensory evoked potentials were reliable and best detected during stimulation of peripheral nerve and epidural stimulation by referencing the lateral cortex to midline Fz. The most reliable hindlimb motor evoked potential (MEP) occurred in tibialis anterior. We found MEPs in forelimb muscles in response to thoracic epidural stimulation likely generated from propriospinal pathways. Cranially stimulated MEPs were easier to evoke in the upper limbs than in the hindlimbs. Autopsy studies revealed substantial variations in cortical morphology between animals. This electrophysiological study establishes that neurophysiological measures can be reliably obtained in micropigs in a time frame compatible with other experimental procedures, such as SCI and transplantation. It underscores the need to better understand the motor control pathways, including the corticospinal tract, to determine which therapeutics are suitable for testing in the pig model.

The Nature and Process of Development in Averaged Visually Evoked Potentials: Discussion on Pattern Structure.

ERIC Educational Resources Information Center

Izawa, Shuji; Mizutani, Tohru

This paper examines the development of visually evoked EEG patterns in retarded and normal subjects. The paper focuses on the averaged visually evoked potentials (AVEP) in the central and occipital regions of the brain in eyes closed and eyes open conditions. Wave pattern, amplitude, and latency are examined. The first section of the paper reviews…

Phantom somatosensory evoked potentials following selective intraneural electrical stimulation in two amputees.

PubMed

Granata, Giuseppe; Di Iorio, Riccardo; Romanello, Roberto; Iodice, Francesco; Raspopovic, Stanisa; Petrini, Francesco; Strauss, Ivo; Valle, Giacomo; Stieglitz, Thomas; Čvančara, Paul; Andreu, David; Divoux, Jean-Louis; Guiraud, David; Wauters, Loic; Hiairrassary, Arthur; Jensen, Winnie; Micera, Silvestro; Rossini, Paolo Maria

2018-06-01

The aim of the paper is to objectively demonstrate that amputees implanted with intraneural interfaces are truly able to feel a sensation in the phantom hand by recording "phantom" somatosensory evoked potentials from the corresponding brain areas. We implanted four transverse intrafascicular multichannel electrodes, available with percutaneous connections to a multichannel electrical stimulator, in the median and ulnar nerves of two left trans-radial amputees. Two channels of the implants that were able to elicit sensations during intraneural nerve stimulation were chosen, in both patients, for recording somatosensory evoked potentials. We recorded reproducible evoked responses by stimulating the median and the ulnar nerves in both cases. Latencies were in accordance with the arrival of somatosensory information to the primary somatosensory cortex. Our results provide evidence that sensations generated by intraneural stimulation are truly perceived by amputees and located in the phantom hand. Moreover, our results strongly suggest that sensations perceived in different parts of the phantom hand result in different evoked responses. Somatosensory evoked potentials obtained by selective intraneural electrical stimulation in amputee patients are a useful tool to provide an objective demonstration of somatosensory feedback in new generation bidirectional prostheses. Copyright © 2018. Published by Elsevier B.V.

Effects of single cycle binaural beat duration on auditory evoked potentials.

PubMed

Mihajloski, Todor; Bohorquez, Jorge; Özdamar, Özcan

2014-01-01

Binaural beat (BB) illusions are experienced as continuous central pulsations when two sounds with slightly different frequencies are delivered to each ear. It has been shown that steady-state auditory evoked potentials (AEPs) to BBs can be captured and investigated. The authors recently developed a new method of evoking transient AEPs to binaural beats using frequency modulated stimuli. This methodology was able to create single BBs in predetermined intervals with varying carrier frequencies. This study examines the effects of the BB duration and the frequency modulating component of the stimulus on the binaural beats and their evoked potentials. Normal hearing subjects were tested with a set of four durations (25, 50, 100, and 200 ms) with two stimulation configurations, binaural dichotic (binaural beats) and diotic (frequency modulation). The results obtained from the study showed that out of the given durations, the 100 ms beat, was capable of evoking the largest amplitude responses. The frequency modulation effect showed a decrease in peak amplitudes with increasing beat duration until their complete disappearance at 200 ms. Even though, at 200 ms, the frequency modulation effects were not present, the binaural beats were still perceived and captured as evoked potentials.

Helium runaways in white dwarfs

NASA Technical Reports Server (NTRS)

Taam, R. E.

1979-01-01

The long term evolution of an accreting carbon white dwarf was studied from the onset of accretion to the ignition of helium. The variations in the details of the helium shell flash examined with respect to variations in mass accretion rate. For intermediate rates the helium flash is potentially explosive whereas for high rates the shell flash is relatively weak. The results are discussed in the context of the long term evolution of novae.

Diagnostic accuracy of evoked potentials for functional impairment after contusive spinal cord injury in adult rats.

PubMed

Thirumala, Parthasarathy; Zhou, James; Krishnan, Rohan; Manem, Nihita; Umredkar, Shreya; Hamilton, D K; Balzer, Jeffrey R; Oudega, Martin

2016-03-01

Iatrogenic spinal cord injury (SCI) is a cause of potentially debilitating post-operative neurologic complications. Currently, intra-operative neurophysiological monitoring (IONM) via somatosensory evoked potentials and motor-evoked potentials is used to detect and prevent impending SCI. However, no empirically validated interventions exist to halt the progression of iatrogenic SCI once it is detected. This is in part due to the lack of a suitable translational model that mimics the circumstances surrounding iatrogenic SCI detected via IONM. Here, we evaluate a model of simulated contusive iatrogenic SCI detected via IONM in adult female Sprague-Dawley rats. We show that transient losses of somatosensory evoked potentials responses are 88.24% sensitive (95% confidence interval [CI] 63.53-98.20) and 80% specific (95% CI 51.91-95.43) for significant functional impairment following simulated iatrogenic SCI. Similarly, we show that transient losses in motor-evoked potentials responses are 70.83% sensitive (95% CI 48.91-87.33) and 100% specific (95% CI 62.91-100.00) for significant functional impairment following simulated iatrogenic SCI. These results indicate that our model is a suitable replica of the circumstances surrounding clinical iatrogenic SCI. Copyright © 2015 Elsevier Ltd. All rights reserved.

Unknown Pseudocholinesterase Deficiency in a Patient Undergoing TIVA with Planned Motor Evoked Potential Monitoring: A Case Report.

PubMed

Binkley, Candace

2016-06-01

Pseudocholinesterase abnormalities are a genetic cause of aberrant metabolism of the depolarizing muscle relaxant succinylcholine. This article examines a case where succinylcholine was chosen to facilitate intubation due to its ultra short duration and the request of the surgeon to monitor motor evoked potentials. Following succinylcholine administration the neurophysiologist was unable to obtain motor evoked potentials. This case study highlights the intraoperative and postoperative management of an elderly patient with an unknown pseudocholinesterase deficiency.

Human auditory evoked potentials in the assessment of brain function during major cardiovascular surgery.

PubMed

Rodriguez, Rosendo A

2004-06-01

Focal neurologic and intellectual deficits or memory problems are relatively frequent after cardiac surgery. These complications have been associated with cerebral hypoperfusion, embolization, and inflammation that occur during or after surgery. Auditory evoked potentials, a neurophysiologic technique that evaluates the function of neural structures from the auditory nerve to the cortex, provide useful information about the functional status of the brain during major cardiovascular procedures. Skepticism regarding the presence of artifacts or difficulty in their interpretation has outweighed considerations of its potential utility and noninvasiveness. This paper reviews the evidence of their potential applications in several aspects of the management of cardiac surgery patients. The sensitivity of auditory evoked potentials to the effects of changes in brain temperature makes them useful for monitoring cerebral hypothermia and rewarming during cardiopulmonary bypass. The close relationship between evoked potential waveforms and specific anatomic structures facilitates the assessment of the functional integrity of the central nervous system in cardiac surgery patients. This feature may also be relevant in the management of critical patients under sedation and coma or in the evaluation of their prognosis during critical care. Their objectivity, reproducibility, and relative insensitivity to learning effects make auditory evoked potentials attractive for the cognitive assessment of cardiac surgery patients. From a clinical perspective, auditory evoked potentials represent an additional window for the study of underlying cerebral processes in healthy and diseased patients. From a research standpoint, this technology offers opportunities for a better understanding of the particular cerebral deficits associated with patients who are undergoing major cardiovascular procedures.

Cost calculation for a flash glucose monitoring system for UK adults with type 1 diabetes mellitus receiving intensive insulin treatment.

PubMed

Hellmund, Richard; Weitgasser, Raimund; Blissett, Deirdre

2018-04-01

To estimate the costs associated with a flash glucose monitoring system as a replacement for routine self-monitoring of blood glucose (SMBG) in patients with type 1 diabetes mellitus (T1DM) using intensive insulin, from a UK National Health Service (NHS) perspective. The base-case cost calculation was created using the maximum frequency of glucose monitoring recommended by the 2015 National Institute for Health and Care Excellence guidelines (4-10 tests per day). Scenario analyses considered SMBG at the frequency observed in the IMPACT clinical trial (5.6 tests per day) and at the frequency of flash monitoring observed in a real-world analysis (16 tests per day). A further scenario included potential costs associated with severe hypoglycaemia. In the base case, the annual cost per patient using flash monitoring was £234 (19%) lower compared with routine SMBG (10 tests per day). In scenario analyses, the annual cost per patient of flash monitoring compared with 5.6 and 16 SMBG tests per day was £296 higher and £957 lower, respectively. The annual cost of severe hypoglycaemia for flash monitoring users was estimated to be £221 per patient, compared with £428 for routine SMBG users (based on 5.6 tests/day), corresponding to a reduction in costs of £207. The flash monitoring system has a modest impact on glucose monitoring costs for the UK NHS for patients with T1DM using intensive insulin. For people requiring frequent tests, flash monitoring may be cost saving, especially when taking into account potential reductions in the rate of severe hypoglycaemia. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Hot flashes and midlife symptoms in relation to levels of salivary cortisol.

PubMed

Gerber, Linda M; Sievert, Lynnette L; Schwartz, Joseph E

2017-02-01

This study examined the relationship between salivary cortisol levels and hot flashes during midlife. Previous studies have shown that cortisol levels increase with hot flashes in the laboratory, and higher cortisol levels have been associated with more severe hot flashes. Salivary cortisol levels were also examined in relation to total number of midlife symptoms. Women aged 40-60 years (n=109) reported the presence or absence of 23 symptoms, including hot flashes, during the previous 2 weeks. Salivary samples were collected at waking, 30min after waking, 1h before bedtime, and at bedtime. The cortisol awakening response (CAR), cortisol daily decline (CDD), log transformed salivary cortisol levels at each time point, and mean cortisol levels were compared by hot flash report using t-tests. Logistic regression analyses were performed to assess the association between each cortisol measure and the presence or absence of hot flashes, after controlling for potential covariates. Salivary cortisol levels were not significantly associated with hot flashes or sum of symptoms. Hot flash report did not differentiate women who had a positive CAR from those who did not, or women who showed strong CDD from those who did not. Symptomatic women - defined by hot flash report or symptom total - were not found to have higher salivary cortisol levels. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Two types of flash drought over China and their connections with sub-seasonal to seasonal soil moisture drought

NASA Astrophysics Data System (ADS)

Wang, L.; Yuan, X.; Xie, Z.

2017-12-01

Flash drought has been receiving attention recently due to its rapid development and vast damage on crops in the growing season. Accompanied with heatwave and rainfall deficit, the soil moisture decreased rapidly in a short time and may lead to the failure of root water uptake and large-scale crops wither. There are two types of flash droughts according to the causes (Mo and Lettenmaier, 2016), i.e., heat wave flash drought and rainfall deficit flash drought. Here, based on pentad-mean surface air temperature and precipitation observations from over two thousand meteorological stations as well as soil moisture and ET estimations from three global reanalysis products, the characteristics and evolution of the two types of flash droughts over China are being explored. Heat wave flash drought is more likely to occur in humid and semi-humid areas, such as southern China, while rainfall deficit flash drought is more likely to occur in northern China. Unlike the traditional drought that persists for a few months to decades, the mean durations of both types of flash droughts are very short. We use monthly mean soil moisture to calculate sub-seasonal to seasonal (S2S) soil moisture drought, and compare its characteristics and preferred conditions such as the large-scale atmospheric circulation and oceanic anomaly for both types of flash droughts. The percentages of flash drought in different periods of S2S drought are also being explored to see the potential relationship between flash drought and S2S drought over different regions.

Assessment of Vulnerability to Extreme Flash Floods in Design Storms

PubMed Central

Kim, Eung Seok; Choi, Hyun Il

2011-01-01

There has been an increase in the occurrence of sudden local flooding of great volume and short duration caused by heavy or excessive rainfall intensity over a small area, which presents the greatest potential danger threat to the natural environment, human life, public health and property, etc. Such flash floods have rapid runoff and debris flow that rises quickly with little or no advance warning to prevent flood damage. This study develops a flash flood index through the average of the same scale relative severity factors quantifying characteristics of hydrographs generated from a rainfall-runoff model for the long-term observed rainfall data in a small ungauged study basin, and presents regression equations between rainfall characteristics and the flash flood index. The aim of this study is to develop flash flood index-duration-frequency relation curves by combining the rainfall intensity-duration-frequency relation and the flash flood index from probability rainfall data in order to evaluate vulnerability to extreme flash floods in design storms. This study is an initial effort to quantify the flash flood severity of design storms for both existing and planned flood control facilities to cope with residual flood risks due to extreme flash floods that have ocurred frequently in recent years. PMID:21845165

Assessment of vulnerability to extreme flash floods in design storms.

PubMed

Kim, Eung Seok; Choi, Hyun Il

2011-07-01

There has been an increase in the occurrence of sudden local flooding of great volume and short duration caused by heavy or excessive rainfall intensity over a small area, which presents the greatest potential danger threat to the natural environment, human life, public health and property, etc. Such flash floods have rapid runoff and debris flow that rises quickly with little or no advance warning to prevent flood damage. This study develops a flash flood index through the average of the same scale relative severity factors quantifying characteristics of hydrographs generated from a rainfall-runoff model for the long-term observed rainfall data in a small ungauged study basin, and presents regression equations between rainfall characteristics and the flash flood index. The aim of this study is to develop flash flood index-duration-frequency relation curves by combining the rainfall intensity-duration-frequency relation and the flash flood index from probability rainfall data in order to evaluate vulnerability to extreme flash floods in design storms. This study is an initial effort to quantify the flash flood severity of design storms for both existing and planned flood control facilities to cope with residual flood risks due to extreme flash floods that have ocurred frequently in recent years.

Flash Floods Simulation using a Physical-Based Hydrological Model at Different Hydroclimatic Regions

NASA Astrophysics Data System (ADS)

Saber, Mohamed; Kamil Yilmaz, Koray

2016-04-01

Currently, flash floods are seriously increasing and affecting many regions over the world. Therefore, this study will focus on two case studies; Wadi Abu Subeira, Egypt as arid environment, and Karpuz basin, Turkey as Mediterranean environment. The main objective of this work is to simulate flash floods at both catchments considering the hydrometeorological differences between them which in turn effect their flash flood behaviors. An integrated methodology incorporating Hydrological River Basin Environmental Assessment Model (Hydro-BEAM) and remote sensing observations was devised. Global Satellite Mapping of Precipitation (GSMAP) were compared with the rain gauge network at the target basins to estimate the bias in an effort to further use it effectively in simulation of flash floods. Based on the preliminary results of flash floods simulation on both basins, we found that runoff behaviors of flash floods are different due to the impacts of climatology, hydrological and topographical conditions. Also, the simulated surface runoff hydrographs are reasonably coincide with the simulated ones. Consequently, some mitigation strategies relying on this study could be introduced to help in reducing the flash floods disasters at different climate regions. This comparison of different climatic basins would be a reasonable implication for the potential impact of climate change on the flash floods frequencies and occurrences.

A place-based model for assessing the coherence of the flash floods and socio-economic vulnerability across the Contiguous United States (CONUS)

NASA Astrophysics Data System (ADS)

Khajehei, S.; Moradkhani, H.

2017-12-01

Understanding socio-economic characteristics involving natural hazards potential, vulnerability, and resilience is necessary to address the damages to economy and loss of life from extreme natural hazards. The vulnerability to flash floods is dependent on both biophysical and socio-economic factors. Although the biophysical characteristics (e.g. climate, vegetation, and land use) are informative and useful for predicting spatial and temporal extent of flash floods, they have minimal bearing on predicting when and where flash floods are likely to influence people or damage valuable assets and resources. The socio-economic factors determine spatial and temporal scales of the regions affected by flash floods. In this study, we quantify the socio-economic vulnerability to flash floods across the Contiguous United States (CONUS). A socio-economic vulnerability index was developed, employing Bayesian principal components for each state in the CONUS. For this purpose, extensive sets of social and economic variables from US Census and the Bureau of Economic Analysis were used. We developed maps presenting the coincidence of socio-economic vulnerability and the flash floods records. This product can help inform flash flood prevention, mitigation and recovery planning, as well as reducing the flash flood hazards affecting vulnerable places and population.

A new method for registration of kinesthetic evoked potentials for studies of proprioceptive sensitivity in normal subjects and patients with organic lesions in the brain.

PubMed

Gordeev, S A; Voronin, S G

2015-01-01

The proprioceptive sensitivity of healthy volunteers and convalescents after acute cerebrovascular episodes was studied by a new neurophysiological method for registration of kinesthetic evoked potentials emerging in response to passive 50(o) bending of the hand in the wrist joint with the angular acceleration of 350 rad/sec(2). Kinesthetic evoked potentials were recorded above the somatosensory cortex projection areas in the hemispheres contra- and ipsilateral to the stimulated limb. The patients exhibited significantly longer latencies and lesser amplitudes of the early components of response in the involved hemisphere in comparison with normal subjects. The method for registration of the kinesthetic evoked potentials allows a more detailed study of the mechanisms of kinesthetic sensitivity in health and in organic involvement of the brain.

Vertex evoked potentials in a rating-scale detection task: Relation to signal probability

NASA Technical Reports Server (NTRS)

Squires, K. C.; Squires, N. K.; Hillyard, S. A.

1974-01-01

Vertex evoked potentials were recorded from human subjects performing in an auditory detection task with rating scale responses. Three values of a priori probability of signal presentation were tested. The amplitudes of the N1 and P3 components of the vertex potential associated with correct detections of the signal were found to be systematically related to the strictness of the response criterion and independent of variations in a priori signal probability. No similar evoked potential components were found associated with signal absent judgements (misses and correct rejections) regardless of the confidence level of the judgement or signal probability. These results strongly support the contention that the form of the vertex evoked response is closely correlated with the subject's psychophysical decision regarding the presence or absence of a threshold level signal.

Effects of core body temperature on changes in spinal somatosensory-evoked potential in acute spinal cord compression injury: an experimental study in the rat.

PubMed

Jou, I M

2000-08-01

Acute spinal cord injury was induced by a clip compression model in rats to approximate spinal cord injury encountered in spinal surgery. Spinal somatosensory-evoked potential neuromonitoring was used to study the electrophysiologic change. To compare and correlate changes in evoked potential after acute compression at different core temperatures with postoperative neurologic function and histologic change, to evaluate current intraoperative neuromonitoring warning criteria for neural damage, and to confirm the protective effect of hypothermia in acute spinal cord compression injury by electrophysiologic, histologic, and clinical observation. With the increase in aggressive correction of spinal deformities, and the invasiveness of surgical instruments, the incidence of neurologic complication appears to have increased despite the availability of sensitive intraoperative neuromonitoring techniques designed to alert surgeons to impending neural damage. Many reasons have been given for the frequent failures of neuromonitoring, but the influence of temperature-a very important and frequently encountered factor-on evoked potential has not been well documented. Specifically, decrease in amplitude and elongation of latency seem not to have been sufficiently taken into account when intraoperative neuromonitoring levels were interpreted and when acceptable intraoperative warning criteria were determined. Experimental acute spinal cord injury was induced in rats by clip compression for two different intervals and at three different core temperatures. Spinal somatosensory-evoked potential, elicited by stimulating the median nerve and recorded from the cervical interspinous C2-C3, was monitored immediately before and after compression, and at 15-minute intervals for 1 hour. Spinal somatosensory-evoked potential change is almost parallel to temperature-based amplitude reduction and latency elongation. Significant neurologic damage induced by acute compression of the cervical spinal cord produced a degree of effect on the amplitude of spinal somatosensory-evoked potential in normothermic conditions that differed from the effect in moderately hypothermic conditions. Using the same electromonitoring criteria,moderately hypothermic groups showed a significantly higher false-negative rate statistically (35%) than normothermic groups (10%). Systemic cooling may protect against the detrimental effects of aggressive spinal surgical procedures. There is still not enough published information available to establish statistically and ethically acceptable intraoperative neuromonitoring warning and intervention criteria conclusively. Therefore, an urgent need exists for further investigation. Although a reduction of more than 50% in evoked potential still seems acceptable as an indicator of impending neural function loss, maintenance of more than 50% of baseline evoked potential is no guarantee of normal postoperative neural function, especially at lower than normal temperatures.

Report on in-situ studies of flash sintering of uranium dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raftery, Alicia Marie

Flash sintering is a novel type of field assisted sintering that uses an electric field and current to provide densification of materials on very short time scales. The potential for field assisted sintering techniques to be used in producing nuclear fuel is gaining recognition due to the potential economic benefits and improvements in material properties. The flash sintering behavior has so far been linked to applied and material parameters, but the underlying mechanisms active during flash sintering have yet to be identified. This report summarizes the efforts to investigate flash sintering of uranium dioxide using dilatometer studies at Los Alamosmore » National Laboratory and two separate sets of in-situ studies at Brookhaven National Laboratory’s NSLS-II XPD-1 beamline. The purpose of the dilatometer studies was to understand individual parameter (applied and material) effects on the flash behavior and the purpose of the in-situ studies was to better understand the mechanisms active during flash sintering. As far as applied parameters, it was found that stoichiometry, or oxygen-to-metal ratio, has a significant effect on the flash behavior (time to flash and speed of flash). Composite systems were found to have degraded sintering behavior relative to pure UO 2. The critical field studies are complete for UO 2.00 and will be analyzed against an existing model for comparison. The in-situ studies showed that the strength of the field and current are directly related to the sample temperature, with temperature-driven phase changes occurring at high values. The existence of an ‘incubation time’ has been questioned, due to a continuous change in lattice parameter values from the moment that the field is applied. Some results from the in-situ experiments, which should provide evidence regarding ion migration, are still being analyzed. Some preliminary conclusions can be made from these results with regard to using field assisted sintering to fabricate nuclear fuel. First, the pure UO 2-based system shows promising behavior with flash sintering, but composite systems are likely to show better sintering behavior with spark plasma sintering. Efforts to develop these methods should therefore be tailored towards the likelihood of success. Additionally, modeling is a rapidly developing aspect of current flash sintering research and should be used in parallel with experiments. Ultimately, ongoing flash sintering studies on various materials, like those summarized in this report, are rapidly contributing to the feasibility of controlling this method for use in the future.« less

Coupling Radar Rainfall Estimation and Hydrological Modelling For Flash-flood Hazard Mitigation

NASA Astrophysics Data System (ADS)

Borga, M.; Creutin, J. D.

Flood risk mitigation is accomplished through managing either or both the hazard and vulnerability. Flood hazard may be reduced through structural measures which alter the frequency of flood levels in the area. The vulnerability of a community to flood loss can be mitigated through changing or regulating land use and through flood warning and effective emergency response. When dealing with flash-flood hazard, it is gener- ally accepted that the most effective way (and in many instances the only affordable in a sustainable perspective) to mitigate the risk is by reducing the vulnerability of the involved communities, in particular by implementing flood warning systems and community self-help programs. However, both the inherent characteristics of the at- mospheric and hydrologic processes involved in flash-flooding and the changing soci- etal needs provide a tremendous challenge to traditional flood forecasting and warning concepts. In fact, the targets of these systems are traditionally localised like urbanised sectors or hydraulic structures. Given the small spatial scale that characterises flash floods and the development of dispersed urbanisation, transportation, green tourism and water sports, human lives and property are exposed to flash flood risk in a scat- tered manner. This must be taken into consideration in flash flood warning strategies and the investigated region should be considered as a whole and every section of the drainage network as a potential target for hydrological warnings. Radar technology offers the potential to provide information describing rain intensities almost contin- uously in time and space. Recent research results indicate that coupling radar infor- mation to distributed hydrologic modelling can provide hydrologic forecasts at all potentially flooded points of a region. Nevertheless, very few flood warning services use radar data more than on a qualitative basis. After a short review of current under- standing in this area, two issues are examined: advantages and caveats of using radar rainfall estimates in operational flash flood forecasting, methodological problems as- sociated to the use of hydrological models for distributed flash flood forecasting with rainfall input estimated from radar.

[The modified method registration of kinesthetic evoked potentials and its application for research of proprioceptive sensitivity disorders at spondylogenic cervical myelopathy].

PubMed

Gordeev, S A; Voronin, S G

2016-01-01

To analyze the efficacy of modified (passive radiocarpal articulation flexion/extension) and «standard» (passive radiocarpal articulation flexion) methods of kinesthetic evoked potentials for proprioceptive sensitivity assessment in healthy subjects and patients with spondylotic cervical myelopathy. The study included 14 healthy subjects (4 women and 10 men, mean age 54.1±10.5 years) and 8 patients (2 women and 6 men, mean age 55.8±10.9 years) with spondylotic cervical myelopathy. Muscle-joint sensation was examined during the clinical study. A modified method of kinesthetic evoked potentials was developed. This method differed from the "standard" one by the organization of a cycle including several passive movements,where each new movement differed from the preceding one by the direction. The modified method of kinesthetic evoked potentials ensures more reliable kinesthetic sensitivity assessment due to movement variability. Asignificant increaseof the latent periods of the early components of the response was found in patients compared to healthy subjects. The modified method of kinesthetic evoked potentials can be used for objective diagnosis of proprioceptive sensitivity disorders in patients with spondylotic cervical myelopathy.

Feasibility and performance evaluation of generating and recording visual evoked potentials using ambulatory Bluetooth based system.

PubMed

Ellingson, Roger M; Oken, Barry

2010-01-01

Report contains the design overview and key performance measurements demonstrating the feasibility of generating and recording ambulatory visual stimulus evoked potentials using the previously reported custom Complementary and Alternative Medicine physiologic data collection and monitoring system, CAMAS. The methods used to generate visual stimuli on a PDA device and the design of an optical coupling device to convert the display to an electrical waveform which is recorded by the CAMAS base unit are presented. The optical sensor signal, synchronized to the visual stimulus emulates the brain's synchronized EEG signal input to CAMAS normally reviewed for the evoked potential response. Most importantly, the PDA also sends a marker message over the wireless Bluetooth connection to the CAMAS base unit synchronized to the visual stimulus which is the critical averaging reference component to obtain VEP results. Results show the variance in the latency of the wireless marker messaging link is consistent enough to support the generation and recording of visual evoked potentials. The averaged sensor waveforms at multiple CPU speeds are presented and demonstrate suitability of the Bluetooth interface for portable ambulatory visual evoked potential implementation on our CAMAS platform.

Detecting activity-evoked pH changes in human brain

PubMed Central

Magnotta, Vincent A.; Heo, Hye-Young; Dlouhy, Brian J.; Dahdaleh, Nader S.; Follmer, Robin L.; Thedens, Daniel R.; Welsh, Michael J.; Wemmie, John A.

2012-01-01

Localized pH changes have been suggested to occur in the brain during normal function. However, the existence of such pH changes has also been questioned. Lack of methods for noninvasively measuring pH with high spatial and temporal resolution has limited insight into this issue. Here we report that a magnetic resonance imaging (MRI) strategy, T1 relaxation in the rotating frame (T1ρ), is sufficiently sensitive to detect widespread pH changes in the mouse and human brain evoked by systemically manipulating carbon dioxide or bicarbonate. Moreover, T1ρ detected a localized acidosis in the human visual cortex induced by a flashing checkerboard. Lactate measurements and pH-sensitive 31P spectroscopy at the same site also identified a localized acidosis. Consistent with the established role for pH in blood flow recruitment, T1ρ correlated with blood oxygenation level-dependent contrast commonly used in functional MRI. However, T1ρ was not directly sensitive to blood oxygen content. These observations indicate that localized pH fluctuations occur in the human brain during normal function. Furthermore, they suggest a unique functional imaging strategy based on pH that is independent of traditional functional MRI contrast mechanisms. PMID:22566645

Experimental Platform for Ultra-high Dose Rate FLASH Irradiation of Small Animals Using a Clinical Linear Accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schüler, Emil; Trovati, Stefania; King, Gregory

Purpose: A key factor limiting the effectiveness of radiation therapy is normal tissue toxicity, and recent preclinical data have shown that ultra-high dose rate irradiation (>50 Gy/s, “FLASH”) potentially mitigates this effect. However, research in this field has been strongly limited by the availability of FLASH irradiators suitable for small animal experiments. We present a simple methodologic approach for FLASH electron small animal irradiation with a clinically available linear accelerator (LINAC). Methods and Materials: We investigated the FLASH irradiation potential of a Varian Clinac 21EX in both clinical mode and after tuning of the LINAC. We performed detailed FLUKA Monte Carlomore » and experimental dosimetric characterization at multiple experimental locations within the LINAC head. Results: Average dose rates of ≤74 Gy/s were achieved in clinical mode, and the dose rate after tuning exceeded 900 Gy/s. We obtained 220 Gy/s at 1-cm depth for a >4-cm field size with 90% homogeneity throughout a 2-cm-thick volume. Conclusions: We present an approach for using a clinical LINAC for FLASH irradiation. We obtained dose rates exceeding 200 Gy/s after simple tuning of the LINAC, with excellent dosimetric properties for small animal experiments. This will allow for increased availability of FLASH irradiation to the general research community.« less

Local classifiers for evoked potentials recorded from behaving rats.

PubMed

Jakuczun, Wit; Kublik, Ewa; Wójcik, Daniel K; Wróbel, Andrzej

2005-01-01

Dynamic states of the brain determine the way information is processed in local neural networks. We have applied classical conditioning paradigm in order to study whether habituated and aroused states can be differentiated in single barrel column of rat's somatosensory cortex by means of analysis of field potentials evoked by stimulation of a single vibrissa. A new method using local classifiers is presented which allows for reliable and meaningful classification of single evoked potentials which might be consequently attributed to different functional states of the cortical column.

Absence of both auditory evoked potentials and auditory percepts dependent on timing cues.

PubMed

Starr, A; McPherson, D; Patterson, J; Don, M; Luxford, W; Shannon, R; Sininger, Y; Tonakawa, L; Waring, M

1991-06-01

An 11-yr-old girl had an absence of sensory components of auditory evoked potentials (brainstem, middle and long-latency) to click and tone burst stimuli that she could clearly hear. Psychoacoustic tests revealed a marked impairment of those auditory perceptions dependent on temporal cues, that is, lateralization of binaural clicks, change of binaural masked threshold with changes in signal phase, binaural beats, detection of paired monaural clicks, monaural detection of a silent gap in a sound, and monaural threshold elevation for short duration tones. In contrast, auditory functions reflecting intensity or frequency discriminations (difference limens) were only minimally impaired. Pure tone audiometry showed a moderate (50 dB) bilateral hearing loss with a disproportionate severe loss of word intelligibility. Those auditory evoked potentials that were preserved included (1) cochlear microphonics reflecting hair cell activity; (2) cortical sustained potentials reflecting processing of slowly changing signals; and (3) long-latency cognitive components (P300, processing negativity) reflecting endogenous auditory cognitive processes. Both the evoked potential and perceptual deficits are attributed to changes in temporal encoding of acoustic signals perhaps occurring at the synapse between hair cell and eighth nerve dendrites. The results from this patient are discussed in relation to previously published cases with absent auditory evoked potentials and preserved hearing.

Flash floods warning technique based on wireless communication networks data

NASA Astrophysics Data System (ADS)

David, Noam; Alpert, Pinhas; Messer, Hagit

2010-05-01

Flash floods can occur throughout or subsequent to rainfall events, particularly in cases where the precipitation is of high-intensity. Unfortunately, each year these floods cause severe property damage and heavy casualties. At present, there are no sufficient real time flash flood warning facilities found to cope with this phenomenon. Here we show the tremendous potential of flash floods advanced warning based on precipitation measurements of commercial microwave links. As was recently shown, wireless communication networks supply high resolution precipitation measurements at ground level while often being situated in flood prone areas, covering large parts of these hazardous regions. We present the flash flood warning potential of the wireless communication system for two different cases when floods occurred at the Judean desert and at the northern Negev in Israel. In both cases, an advanced warning regarding the hazard could have been announced based on this system. • This research was supported by THE ISRAEL SCIENCE FOUNDATION (grant No. 173/08). This work was also supported by a grant from the Yeshaya Horowitz Association, Jerusalem. Additional support was given by the PROCEMA-BMBF project and by the GLOWA-JR BMBF project.

[Recurrent cortical blindness after LSD-intake].

PubMed

Bernhard, M K; Ulrich, K

2009-02-01

Recurrent disturbances of vision associated with headaches are typical signs of a migraine. A 15-year-old girl suffered from common migraine. The patient had a headache and nausea five days after a first and proved intake of LSD. Shortly later, a complete blindness of both eyes developed within seconds. These symptoms continued for 48 hours. As the pupillar reactions were intact the findings were consistent with cortical blindness. MRI and MR-angiography of the brain, analysis of the cerebrospinal fluid and blood investigations for thrombophilia were normal. The EEG showed a bilateral symmetrical delta wave slowing over the occipital areas. Within the following three months the girl had three more episodes with complete blindness over a period of 12-36 hours. There have never been any visual disturbances in between the episodes and afterwards. Extended diagnosis with long term blood pressure measurement, Doppler sonography and visual evoked potentials were normal. The occipital slowing in the EEG persisted for 18 months. As the symptoms were unusually long and severe for a complicated migraine it is possible that the temporary blindness was the correlate of flash backs caused by the LSD. LSD intake could trigger additional, local cortical dysfunction (e. g. in the occipital areas) in preexisting migraine.

Informing hot flash treatment decisions for breast cancer survivors: a systematic review of randomized trials comparing active interventions.

PubMed

Johns, Claire; Seav, Susan M; Dominick, Sally A; Gorman, Jessica R; Li, Hongying; Natarajan, Loki; Mao, Jun James; Irene Su, H

2016-04-01

Patient-centered decision making about hot flash treatments often incorporates a balance of efficacy and side effects in addition to patient preference. This systematic review examines randomized controlled trials (RCTs) comparing at least two non-hormonal hot flash treatments in breast cancer survivors. In July 2015, PubMed, SCOPUS, CINAHL, Cochrane, and Web of Science databases were searched for RCTs comparing active, non-hormonal hot flash treatments in female breast cancer survivors. Thirteen trials were included after identifying 906 potential studies. Four trials were dose comparison studies of pharmacologic treatments citalopram, venlafaxine, gabapentin, and paroxetine. Hot flash reduction did not differ by tamoxifen or aromatase inhibitor use. Citalopram 10, 20, and 30 mg daily had comparable outcomes. Venlafaxine 75 mg daily improved hot flashes without additional side effects from higher dosing. Gabapentin 900 mg daily improved hot flashes more than 300 mg. Paroxetine 10 mg daily had fewer side effects than 20 mg. Among four trials comparing different pharmacologic treatments, venlafaxine alleviated hot flash symptoms faster than clonidine; participants preferred venlafaxine over gabapentin. Five trials compared pharmacologic to non-pharmacologic treatments. Acupuncture had similar efficacy to venlafaxine and gabapentin but may have longer durability after completing treatment and fewer side effects. We could not perform a pooled meta-analysis because outcomes were not reported in comparable formats. Clinical trial data on non-hormonal hot flash treatments provide comparisons of hot flash efficacy and other patient important outcomes to guide clinical management. Clinicians can use the information to help patients select hot flash interventions.

Intraoperative Functional Mapping and Monitoring during Glioma Surgery

PubMed Central

SAITO, Taiichi; MURAGAKI, Yoshihiro; MARUYAMA, Takashi; TAMURA, Manabu; NITTA, Masayuki; OKADA, Yoshikazu

2015-01-01

Glioma surgery represents a significant advance with respect to improving resection rates using new surgical techniques, including intraoperative functional mapping, monitoring, and imaging. Functional mapping under awake craniotomy can be used to detect individual eloquent tissues of speech and/or motor functions in order to prevent unexpected deficits and promote extensive resection. In addition, monitoring the patient’s neurological findings during resection is also very useful for maximizing the removal rate and minimizing deficits by alarming that the touched area is close to eloquent regions and fibers. Assessing several types of evoked potentials, including motor evoked potentials (MEPs), sensory evoked potentials (SEPs) and visual evoked potentials (VEPs), is also helpful for performing surgical monitoring in patients under general anesthesia (GA). We herein review the utility of intraoperative mapping and monitoring the assessment of neurological findings, with a particular focus on speech and the motor function, in patients undergoing glioma surgery. PMID:25744346

Transcranial electric motor evoked potential monitoring during spine surgery: is it safe?

PubMed

Schwartz, Daniel M; Sestokas, Anthony K; Dormans, John P; Vaccaro, Alexander R; Hilibrand, Alan S; Flynn, John M; Li, P Mark; Shah, Suken A; Welch, William; Drummond, Denis S; Albert, Todd J

2011-06-01

Retrospective review. To report on the safety of repetitive transcranial electric stimulation (RTES) for eliciting motor-evoked potentials during spine surgery. Theoretical concerns over the safety of RTES have hindered broader acceptance of transcranial electric motor-evoked potentials (tceMEP), despite successful implementation of spinal cord monitoring with tceMEPs in many large spine centers, as well as their apparent superiority over mixed-nerve somatosensory-evoked potentials (SSEP) for detection of spinal cord injury. The records of 18,862 consecutive patients who met inclusion criteria and underwent spine surgery with tceMEP monitoring were reviewed for RTES-related complications. This large retrospective review identified only 26 (0.14%) cases with RTES-related complications; all but one of these were tongue lacerations, most of which were self-limiting. The results demonstrate that RTES is a highly safe modality for monitoring spinal cord motor tract function intraoperatively.

Innovative neurophysiological methods in itch research: long-latency evoked potentials after electrical and thermal stimulation in patients with atopic dermatitis.

PubMed

Yudina, Marina M; Toropina, Galina G; Lvov, Andrey; Gieler, Uwe

2011-10-01

The aim of this study was to examine the findings of innovative neurophysiological methods of itch research. Short-latency and pain-related somatosensory-evoked potentials after electrical stimulation, as well as long-latency evoked potentials after thermal stimulation were studied in 38 patients with atopic dermatitis (AD) and 26 healthy volunteers. Quantitative Sensory Testing of thermal perception was performed in 22 patients with AD from the main AD group and in 15 healthy volunteers. Brain hyperactivity to electrical stimuli, delayed thermal-evoked potentials and elevated thermal thresholds were revealed in patients with AD compared with healthy controls. The data indicate small nerve fibre dysfunction in patients with AD, which may contribute to the pathogenesis of AD and chronic itch. The study demonstrates objective approaches to assess the function of small nerve fibres in patients with chronic itch.

Recording Visual Evoked Potentials and Auditory Evoked P300 at 9.4T Static Magnetic Field

PubMed Central

Hahn, David; Boers, Frank; Shah, N. Jon

2013-01-01

Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4T were not different from those recorded at 0T. The amplitudes of ERPs were higher at 9.4T when compared to recordings at 0T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses. PMID:23650538

Recording visual evoked potentials and auditory evoked P300 at 9.4T static magnetic field.

PubMed

Arrubla, Jorge; Neuner, Irene; Hahn, David; Boers, Frank; Shah, N Jon

2013-01-01

Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4 T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4 T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4 T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4 T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4 T were not different from those recorded at 0 T. The amplitudes of ERPs were higher at 9.4 T when compared to recordings at 0 T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses.

Anatomy of a Flash Flood in the Amargosa Desert, U.S.A.

NASA Astrophysics Data System (ADS)

Stonestrom, D. A.; Prudic, D. E.; Glancy, P. A.; Beck, D. A.

2004-12-01

In August 2004, intense convective rainstorms caused flash flooding throughout the Amargosa River drainage network, temporarily closing Death Valley National Park and causing two fatalities when runoff from Furnace Creek and other channels overtopped roadways in the Park. In 1998, we began installing streambed temperature loggers, pressure transducers, and scour chains in the normally dry channel and selected tributaries of the river in the Amargosa Desert and Oasis Valley. The primary objective of this work is to improve understanding of ground-water recharge from ephemeral streamflows under current climatic conditions. Two weeks after the flash flooding, we visited instrumented sites and estimated peak flows by surveying high-water marks and corresponding channel geometries. Time series of temperatures and stages, together with peak-flow estimates, reveal the routing and evolution of distinct flood pulses in the upper Amargosa River basin. The data also reveal previously undocumented details of individual flash-flood hydrographs, including initial and subsequent flood pulses at two sites. Arid environments are prone to flash flooding not only because vegetation is sparse, but also because the surface-water network is decoupled from underlying ground water by a thick unsaturated zone. Nonlinear interactions between runoff (with energy potentials on the order of a meter of head) and the unsaturated zone (with energy potentials on the order of negative hundreds of meters of head) keep advancing fronts of flood pulses sharp. Profiles of water content beneath the main channel before and after the passage of a flood pulse, together with down-channel attenuation of flow volume within individual pulses, show the leaky nature of dry alluvial channels and the efficiency at which flash floods become potential recharge.

Surgical monitoring with auditory evoked potentials.

PubMed

Lüders, H

1988-07-01

This comprehensive review of surgical monitoring with auditory evoked potentials (AEPs) includes a detailed discussion of techniques used for recording brainstem auditory evoked potentials, direct eight-nerve potentials, and electrocochleograms. The normal waveform of these different potentials is discussed, and the typical patterns of abnormalities seen with different insults to the peripheral or central auditory pathways are presented. The mechanisms most probably responsible for changes in AEPs during surgical procedures are analyzed. A critical analysis is made of what represents a significant change in AEPs. Also considered is the predictive value of intrasurgical changes of AEPs. Finally, attempts are made to determine whether AEPs monitoring can assist the surgeon in the prevention of postsurgical complications.

New stimulation pattern design to improve P300-based matrix speller performance at high flash rate

NASA Astrophysics Data System (ADS)

Polprasert, Chantri; Kukieattikool, Pratana; Demeechai, Tanee; Ritcey, James A.; Siwamogsatham, Siwaruk

2013-06-01

Objective. We propose a new stimulation pattern design for the P300-based matrix speller aimed at increasing the minimum target-to-target interval (TTI). Approach. Inspired by the simplicity and strong performance of the conventional row-column (RC) stimulation, the proposed stimulation is obtained by modifying the RC stimulation through alternating row and column flashes which are selected based on the proposed design rules. The second flash of the double-flash components is then delayed for a number of flashing instants to increase the minimum TTI. The trade-off inherited in this approach is the reduced randomness within the stimulation pattern. Main results. We test the proposed stimulation pattern and compare its performance in terms of selection accuracy, raw and practical bit rates with the conventional RC flashing paradigm over several flash rates. By increasing the minimum TTI within the stimulation sequence, the proposed stimulation has more event-related potentials that can be identified compared to that of the conventional RC stimulations, as the flash rate increases. This leads to significant performance improvement in terms of the letter selection accuracy, the raw and practical bit rates over the conventional RC stimulation. Significance. These studies demonstrate that significant performance improvement over the RC stimulation is obtained without additional testing or training samples to compensate for low P300 amplitude at high flash rate. We show that our proposed stimulation is more robust to reduced signal strength due to the increased flash rate than the RC stimulation.

Risk factors for hot flashes among women undergoing the menopausal transition: baseline results from the Midlife Women's Health Study

PubMed Central

Gallicchio, Lisa; Miller, Susan R.; Kiefer, Judith; Greene, Teresa; Zacur, Howard A.; Flaws, Jodi A.

2015-01-01

Objective The aim of this study was to examine the associations between demographic characteristics, health behaviors, hormone concentrations, and the experiencing of any, current, more severe, and more frequent midlife hot flashes. Methods Baseline data were analyzed from 732 women aged 45 to 54 years enrolled in the Midlife Women's Health Study. A clinic visit was conducted to collect blood samples for hormone assays and to measure ovarian volume using transvaginal ultrasound. A self-administered questionnaire ascertained information on demographic factors, health habits, and hot flashes history. Multivariable logistic regression was conducted to examine the associations between potential risk factors and the hot flashes outcomes. Results Approximately 45% of participants reported experiencing midlife hot flashes. In the covariate-adjusted models, older age, peri-menopausal status, current and former cigarette smoking, and depressive symptoms were significantly associated with increased odds of all of the hot flashes outcomes. In addition, history of oral contraceptive use was associated with increased odds of any hot flashes. In contrast, higher current alcohol intake was significantly associated with decreased odds of any, current, and more severe hot flashes. Higher estradiol and progesterone concentrations were significantly associated with decreased odds of all hot flashes outcomes. Conclusions Although the temporalities of such associations are not known due to the cross-sectional nature of the data, these observed relationships can help to identify women at risk for hot flashes. PMID:25783472

Micro-field evoked potentials recorded from the porcine sub-dural cortical surface utilizing a microelectrode array.

PubMed

Kitzmiller, Joseph P; Hansford, Derek J; Fortin, Linda D; Obrietan, Karl H; Bergdall, Valerie K; Beversdorf, David Q

2007-05-15

A sub-dural surface microelectrode array designed to detect micro-field evoked potentials has been developed. The device is comprised of an array of 350-microm square gold contacts, with bidirectional spacing of 150 microm, contained within a polyimide Kapton material. Cytotoxicity testing suggests that the device is suitable for use with animal and human patients. Implementation of the device in animal studies revealed that reliable evoked potentials could be acquired. Further work will be needed to determine how these micro-field potentials, which demonstrate selectivity for one eye, relate to the distribution of the ocular dominance columns of the occipital cortex.

Micro-Field Evoked Potentials Recorded from the Porcine Sub-Dural Cortical Surface Utilizing a Microelectrode Array

PubMed Central

Kitzmiller, Joseph P.; Hansford, Derek J.; Fortin, Linda D.; Obrietan, Karl H.; Bergdall, Valerie K.

2007-01-01

A sub-dural surface microelectrode array designed to detect microfield evoked potentials has been developed. The device is comprised of an array of 350-micron square gold contacts, with bi-directional spacing of 150 microns, contained within a polyimide Kapton material. Cytotoxicity testing suggests that the device is suitable for use with animal and human patients. Implementation of the device in animal studies revealed that reliable evoked potentials could be acquired. Further work will be needed to determine how these microfield potentials, which demonstrate selectivity for one eye, relate to the distribution of the ocular dominance columns of the occipital cortex. PMID:17298849

Interside Latency Differences in Brainstem Auditory and Somatosensory Evoked Potentials. Defining Upper Limits to Determine Asymmetry.

PubMed

Moncho, Dulce; Poca, Maria A; Minoves, Teresa; Ferré, Alejandro; Sahuquillo, Juan

2015-10-01

Limits of the interside differences are invaluable when interpreting asymmetry in brainstem auditory evoked potentials and somatosensory evoked potentials (SEP) recordings. The aim of this study was to analyze the normal upper limits of interside latency differences of brainstem auditory evoked potentials and SEP from the posterior tibial nerve and median nerve to determine asymmetry. The authors performed a prospective study in 56 healthy subjects aged 15 to 64 years with no neurological or hearing disorders. They analyzed (1) the latencies of I, III, and V waves and I-III, III-V, and I-V intervals and the amplitude ratios V/I and IV/I for brainstem auditory evoked potentials bilaterally; (2) the latencies of N8, N22, N28, and P37 waves and the interval N22-P37 and the amplitude P37 for posterior tibial nerve SEP bilaterally; and (3) the latencies and amplitudes of N9, N13, and N20 waves and N9-N13 and N13-N20 intervals for median nerve SEP bilaterally. The interside differences for these parameters were calculated and analyzed. The authors obtained an upper limit for the interside latency differences from brainstem auditory evoked potentials that was significantly lower than the previously published data. However, the upper limits of interside latency differences for SEP were similar to those previously reported. The findings of this study should be considered when laboratories analyze asymmetry using the normative data published by another center, however temporarily, in organizing new laboratories.

Deep brain stimulation of the ventral hippocampus restores deficits in processing of auditory evoked potentials in a rodent developmental disruption model of schizophrenia.

PubMed

Ewing, Samuel G; Grace, Anthony A

2013-02-01

Existing antipsychotic drugs are most effective at treating the positive symptoms of schizophrenia but their relative efficacy is low and they are associated with considerable side effects. In this study deep brain stimulation of the ventral hippocampus was performed in a rodent model of schizophrenia (MAM-E17) in an attempt to alleviate one set of neurophysiological alterations observed in this disorder. Bipolar stimulating electrodes were fabricated and implanted, bilaterally, into the ventral hippocampus of rats. High frequency stimulation was delivered bilaterally via a custom-made stimulation device and both spectral analysis (power and coherence) of resting state local field potentials and amplitude of auditory evoked potential components during a standard inhibitory gating paradigm were examined. MAM rats exhibited alterations in specific components of the auditory evoked potential in the infralimbic cortex, the core of the nucleus accumbens, mediodorsal thalamic nucleus, and ventral hippocampus in the left hemisphere only. DBS was effective in reversing these evoked deficits in the infralimbic cortex and the mediodorsal thalamic nucleus of MAM-treated rats to levels similar to those observed in control animals. In contrast stimulation did not alter evoked potentials in control rats. No deficits or stimulation-induced alterations were observed in the prelimbic and orbitofrontal cortices, the shell of the nucleus accumbens or ventral tegmental area. These data indicate a normalization of deficits in generating auditory evoked potentials induced by a developmental disruption by acute high frequency, electrical stimulation of the ventral hippocampus. Copyright © 2012 Elsevier B.V. All rights reserved.

Deep brain stimulation of the ventral hippocampus restores deficits in processing of auditory evoked potentials in a rodent developmental disruption model of schizophrenia

PubMed Central

Ewing, Samuel G.; Grace, Anthony A.

2012-01-01

Existing antipsychotic drugs are most effective at treating the positive symptoms of schizophrenia, but their relative efficacy is low and they are associated with considerable side effects. In this study deep brain stimulation of the ventral hippocampus was performed in a rodent model of schizophrenia (MAM-E17) in an attempt to alleviate one set of neurophysiological alterations observed in this disorder. Bipolar stimulating electrodes were fabricated and implanted, bilaterally, into the ventral hippocampus of rats. High frequency stimulation was delivered bilaterally via a custom-made stimulation device and both spectral analysis (power and coherence) of resting state local field potentials and amplitude of auditory evoked potential components during a standard inhibitory gating paradigm were examined. MAM rats exhibited alterations in specific components of the auditory evoked potential in the infralimbic cortex, the core of the nucleus accumbens, mediodorsal thalamic nucleus, and ventral hippocampus in the left hemisphere only. DBS was effective in reversing these evoked deficits in the infralimbic cortex and the mediodorsal thalamic nucleus of MAM-treated rats to levels similar to those observed in control animals. In contrast stimulation did not alter evoked potentials in control rats. No deficits or stimulation-induced alterations were observed in the prelimbic and orbitofrontal cortices, the shell of the nucleus accumbens or ventral tegmental area. These data indicate a normalization of deficits in generating auditory evoked potentials induced by a developmental disruption by acute high frequency, electrical stimulation of the ventral hippocampus. PMID:23269227

Evoked potentials are useful for diagnosis of neuromyelitis optica spectrum disorder.

PubMed

Ohnari, Keiko; Okada, Kazumasa; Takahashi, Toshiyuki; Mafune, Kosuke; Adachi, Hiroaki

2016-05-15

Neuromyelitis optica spectrum disorder (NMOSD) has been differentiated from relapsing-remitting multiple sclerosis (RRMS) by clinical, laboratory, and pathological findings, including the presence of the anti-aquaporin 4 antibody. Measurement of evoked potentials (EPs) is often used for the diagnosis of RRMS, although the possibility of applying EPs to the diagnosis of NMOSD has not been investigated in detail. Eighteen patients with NMOSD and 28 patients with RRMS were included in this study. The patients' neurological symptoms and signs were examined and their EPs were recorded. Characteristic findings were absence of visual evoked potentials and absence of motor evoked potentials in the lower extremities in patients with NMOSD, and a delay in these potentials in patients with RRMS. Most patients with NMOSD did not present abnormal subclinical EPs, whereas many patients with RRMS did. None of the patients with NMOSD showed abnormalities in auditory brainstem responses. NMOSD can be differentiated from RRMS by EP data obtained in the early stages of these diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

SOMATOSENSORY EVOKED POTENTIALS

EPA Science Inventory

Somatosensory evoked potentials (SEPs) have been used by neuroscientists for many years. The versatility of the method is attested to be the differing purposes to which it has been applied. Initially, SEPs were used to uncover basic principles of sensory processing. A casual glan...

Hydrogen postconditioning promotes survival of rat retinal ganglion cells against ischemia/reperfusion injury through the PI3K/Akt pathway.

PubMed

Wu, Jiangchun; Wang, Ruobing; Yang, Dianxu; Tang, Wenbin; Chen, Zeli; Sun, Qinglei; Liu, Lin; Zang, Rongyu

2018-01-22

Retinal ischemia/reperfusion injury (IRI) plays a crucial role in the pathophysiology of various ocular diseases. Our previous study have shown that postconditioning with inhaled hydrogen (H 2 ) (HPC) can protect retinal ganglion cells (RGCs) in a rat model of retinal IRI. Our further study aims to investigate potential mechanisms underlying HPC-induced protection. Retinal IRI was performed on the right eyes of rats and was followed by inhalation of 67% H 2 mixed with 33% oxygen immediately after ischemia for 1 h daily for one week. RGC density was counted using haematoxylin and eosin (HE) staining, retrograde labelling with cholera toxin beta (CTB) and TUNEL staining, respectively. Visual function was assessed using flash visual evoked potentials (FVEP) and pupillary light reflex (PLR). The phosphorylated Akt was analysed by RT-PCR and western blot. The results showed that administration of HPC significantly inhibited the apoptosis of RGCs and protected the visual function. Simultaneously, HPC treatment markedly increased the phosphorylations of Akt. Blockade of PI3K activity by inhibitors (LY294002) dramatically abolished its anti-apoptotic effect and lowered both visual function and Akt phosphorylation levels. Taken together, our results demonstrate that HPC appears to confer neuroprotection against retinal IRI via the PI3K/Akt pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

The flashing Brownian ratchet and Parrondo's paradox.

PubMed

Ethier, S N; Lee, Jiyeon

2018-01-01

A Brownian ratchet is a one-dimensional diffusion process that drifts towards a minimum of a periodic asymmetric sawtooth potential. A flashing Brownian ratchet is a process that alternates between two regimes, a one-dimensional Brownian motion and a Brownian ratchet, producing directed motion. These processes have been of interest to physicists and biologists for nearly 25 years. The flashing Brownian ratchet is the process that motivated Parrondo's paradox, in which two fair games of chance, when alternated, produce a winning game. Parrondo's games are relatively simple, being discrete in time and space. The flashing Brownian ratchet is rather more complicated. We show how one can study the latter process numerically using a random walk approximation.

A comparison of auditory evoked potentials to acoustic beats and to binaural beats.

PubMed

Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

2010-04-01

The purpose of this study was to compare cortical brain responses evoked by amplitude modulated acoustic beats of 3 and 6 Hz in tones of 250 and 1000 Hz with those evoked by their binaural beats counterparts in unmodulated tones to indicate whether the cortical processes involved differ. Event-related potentials (ERPs) were recorded to 3- and 6-Hz acoustic and binaural beats in 2000 ms duration 250 and 1000 Hz tones presented with approximately 1 s intervals. Latency, amplitude and source current density estimates of ERP components to beats-evoked oscillations were determined and compared across beat types, beat frequencies and base (carrier) frequencies. All stimuli evoked tone-onset components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude in response to acoustic than to binaural beats, to 250 than to 1000 Hz base frequency and to 3 Hz than to 6 Hz beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left temporal lobe areas. Differences between estimated sources of potentials to acoustic and binaural beats were not significant. The perceptions of binaural beats involve cortical activity that is not different than acoustic beats in distribution and in the effects of beat- and base frequency, indicating similar cortical processing. Copyright 2010 Elsevier B.V. All rights reserved.

Interactions of cervico-ocular and vestibulo-ocular fast-phase signals in the control of eye position in rabbits.

PubMed Central

Barmack, N H; Errico, P; Ferraresi, A; Pettorossi, V E

1989-01-01

1. Eye movements in unanaesthetized rabbits were studied during horizontal neck-proprioceptive stimulation (movement of the body with respect to the fixed head), when this stimulation was given alone and when it was given simultaneously with vestibular stimulation (rotation of the head-body). The effect of neck-proprioceptive stimulation on modifying the anticompensatory fast-phase eye movements (AFPs) evoked by vestibular stimulation was studied with a 'conditioning-test' protocol; the 'conditioning' stimulus was a neck-proprioceptive signal evoked by a step-like change in body position with respect to the head and the 'test' stimulus was a vestibular signal evoked by a step rotation of the head-body. 2. The influence of eye position and direction of slow eye movements on the occurrence of compensatory fast-phase eye movements (CFPs) evoked by neck-proprioceptive stimulation was also examined. 3. The anticompensatory fast phase (AFP) evoked by vestibular stimulation was attenuated by a preceding neck-proprioceptive stimulus which when delivered alone evoked compensatory slow-phase eye movements (CSP) in the same direction as the CSP evoked by vestibular stimulation. Conversely, the vestibularly evoked AFP was potentiated by a neck-proprioceptive stimulus which evoked CSPs opposite to that of vestibularly evoked CSPs. 4. Eccentric initial eye positions increased the probability of occurrence of midline-directed compensatory fast-phase eye movements (CFPs) evoked by appropriate neck-proprioceptive stimulation. 5. The gain of the horizontal cervico-ocular reflex (GHCOR) was measured from the combined changes in eye position resulting from AFPs and CSPs. GHCOR was potentiated during simultaneous vestibular stimulation. This enhancement of GHCOR occurred at neck-proprioceptive stimulus frequencies which, in the absence of conjoint vestibular stimulation, do not evoke CSPs. PMID:2795479

Influence of rotating shift work on visual reaction time and visual evoked potential.

PubMed

R V, Hemamalini; N, Krishnamurthy; A, Saravanan

2014-10-01

The present day life style is changing the circadian rhythm of the body especially in rotating night shift workers. The impact of this prolongs their reaction time. Night shift also interferes with the circadian variation of pupil size which may affect the visual evoked potential. To compare the visual reaction time, visual evoked potential (VEP) in rotating night shift workers & day workers and also to correlate the changes in visual reaction time with visual evoked potential. Forty healthy male security guards & staff (25 - 35 y) who did rotating night shifts at least for six months & 40 d workers (25 - 35 y) who did not do night shift in last two years were involved in the study. Visual reaction time and the latency & amplitude of VEP were recorded. Kolmogorov- Smirnov test for normalcy showed the latencies & amplitude of VEP to be normally distributed. Student's unpaired t test showed significant difference (p<0.05) in the visual time and in the latencies of VEP between night shift & day workers. There was no significant difference in the amplitude of VEP. Night shift workers who are prone to circadian rhythm alteration will have prolonged visual reaction time & visual evoked potential abnormalities. Implementation of Bright Light Therapy would be beneficial to the night shift worker.

Evaluation of afferent pain pathways in adrenomyeloneuropathic patients.

PubMed

Yagüe, Sara; Veciana, Misericordia; Casasnovas, Carlos; Ruiz, Montserrat; Pedro, Jordi; Valls-Solé, Josep; Pujol, Aurora

2018-03-01

Patients with adrenomyeloneuropathy may have dysfunctions of visual, auditory, motor and somatosensory pathways. We thought on examining the nociceptive pathways by means of laser evoked potentials (LEPs), to obtain additional information on the pathophysiology of this condition. In 13 adrenomyeloneuropathic patients we examined LEPs to leg, arm and face stimulation. Normative data were obtained from 10 healthy subjects examined in the same experimental conditions. We also examined brainstem auditory evoked potentials (BAEPs), pattern reversal full-field visual evoked potentials (VEPs), motor evoked potentials (MEPs) and somatosensory evoked potentials (SEPs). Upper and lower limb MEPs and SEPs, as well as BAEPs, were abnormal in all patients, while VEPs were abnormal in 3 of them (23.1%). LEPs revealed abnormalities to stimulation of the face in 4 patients (30.7%), the forearm in 4 patients (30.7%) and the leg in 10 patients (76.9%). The pathologic process of adrenomyeloneuropathy is characterized by a preferential involvement of auditory, motor and somatosensory tracts and less severely of the visual and nociceptive pathways. This non-inflammatory distal axonopathy preferably damages large myelinated spinal tracts but there is also partial involvement of small myelinated fibres. LEPs studies can provide relevant information about afferent pain pathways involvement in adrenomyeloneuropathic patients. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Electropysiologic evaluation of the visual pathway in patients with multiple sclerosis.

PubMed

Rodriguez-Mena, Diego; Almarcegui, Carmen; Dolz, Isabel; Herrero, Raquel; Bambo, Maria P; Fernandez, Javier; Pablo, Luis E; Garcia-Martin, Elena

2013-08-01

To evaluate the ability of visual evoked potentials and pattern electroretinograms (PERG) to detect subclinical axonal damage in patients during the early diagnostic stage of multiple sclerosis (MS). The authors also compared the ability of optical coherence tomography (OCT), PERG, and visual evoked potentials to detect axonal loss in MS patients and correlated the functional and structural properties of the retinal nerve fiber layer. Two hundred twenty-eight eyes of 114 subjects (57 MS patients and 57 age- and sex-matched healthy controls) were included. The visual pathway was evaluated based on functional and structural assessments. All patients underwent a complete ophthalmic examination that included assessment of visual acuity, ocular motility, intraocular pressure, visual field, papillary morphology, OCT, visual evoked potentials, and PERG. Visual evoked potentials (P100 latency and amplitude), PERG (N95 amplitude and N95/P50 ratio), and OCT parameters differed significantly between MS patients and healthy subjects. Moderate significant correlations were found between visual evoked potentials or PERG parameters and OCT measurements. Axonal damage in ganglion cells of the visual pathway can be detected based on structural measures provided by OCT in MS patients and by the N95 component and N95/P50 index of PERG, thus providing good correlation between function and structure.

Premature infants display increased noxious-evoked neuronal activity in the brain compared to healthy age-matched term-born infants.

PubMed

Slater, Rebeccah; Fabrizi, Lorenzo; Worley, Alan; Meek, Judith; Boyd, Stewart; Fitzgerald, Maria

2010-08-15

This study demonstrates that infants who are born prematurely and who have experienced at least 40days of intensive or special care have increased brain neuronal responses to noxious stimuli compared to healthy newborns at the same postmenstrual age. We have measured evoked potentials generated by noxious clinically-essential heel lances in infants born at term (8 infants; born 37-40weeks) and in infants born prematurely (7 infants; born 24-32weeks) who had reached the same postmenstrual age (mean age at time of heel lance 39.2+/-1.2weeks). These noxious-evoked potentials are clearly distinguishable from shorter latency potentials evoked by non-noxious tactile sensory stimulation. While the shorter latency touch potentials are not dependent on the age of the infant at birth, the noxious-evoked potentials are significantly larger in prematurely-born infants. This enhancement is not associated with specific brain lesions but reflects a functional change in pain processing in the brain that is likely to underlie previously reported changes in pain sensitivity in older ex-preterm children. Our ability to quantify and measure experience-dependent changes in infant cortical pain processing will allow us to develop a more rational approach to pain management in neonatal intensive care. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Functional brain development in growth-restricted and constitutionally small fetuses: a fetal magnetoencephalography case-control study.

PubMed

Morin, E C; Schleger, F; Preissl, H; Braendle, J; Eswaran, H; Abele, H; Brucker, S; Kiefer-Schmidt, I

2015-08-01

Fetal magnetoencephalography records fetal brain activity non-invasively. Delayed brain responses were reported for fetuses weighing below the tenth percentile. To investigate whether this delay indicates delayed brain maturation resulting from placental insufficiency, this study distinguished two groups of fetuses below the tenth percentile: growth-restricted fetuses with abnormal umbilical artery Doppler velocity (IUGR) and constitutionally small-for-gestational-age fetuses with normal umbilical artery Doppler findings (SGA) were compared with fetuses of adequate weight for gestational age (AGA), matched for age and behavioural state. A case-control study of matched pairs. Fetal magnetoencephalography-Center at the University Hospital of Tuebingen. Fourteen IUGR fetuses and 23 SGA fetuses were matched for gestational age and fetal behavioural state with 37 healthy, normal-sized fetuses. A 156-channel fetal magentoencephalography system was used to record fetal brain activity. Light flashes as visual stimulation were applied to the fetus. The Student's t-test for paired groups was performed. Latency of fetal visual evoked magnetic responses (VER). The IUGR fetuses showed delayed VERs compared with controls (IUGR, 233.1 ms; controls, 184.6 ms; P = 0.032). SGA fetuses had similar evoked response latencies compared with controls (SGA, 216.1 ms; controls, 219.9 ms; P = 0.828). Behavioural states were similarly distributed. Visual evoked responses are delayed in IUGR fetuses, but not in SGA. Fetal behavioural state as an influencing factor of brain response latency was accounted for in the comparison. This reinforces that delayed brain maturation is the result of placental insufficiency. © 2015 Royal College of Obstetricians and Gynaecologists.

Recording and assessment of evoked potentials with electrode arrays.

PubMed

Miljković, N; Malešević, N; Kojić, V; Bijelić, G; Keller, T; Popović, D B

2015-09-01

In order to optimize procedure for the assessment of evoked potentials and to provide visualization of the flow of action potentials along the motor systems, we introduced array electrodes for stimulation and recording and developed software for the analysis of the recordings. The system uses a stimulator connected to an electrode array for the generation of evoked potentials, an electrode array connected to the amplifier, A/D converter and computer for the recording of evoked potentials, and a dedicated software application. The method has been tested for the assessment of the H-reflex on the triceps surae muscle in six healthy humans. The electrode array with 16 pads was positioned over the posterior aspect of the thigh, while the recording electrode array with 16 pads was positioned over the triceps surae muscle. The stimulator activated all the pads of the stimulation electrode array asynchronously, while the signals were recorded continuously at all the recording sites. The results are topography maps (spatial distribution of evoked potentials) and matrices (spatial visualization of nerve excitability). The software allows the automatic selection of the lowest stimulation intensity to achieve maximal H-reflex amplitude and selection of the recording/stimulation pads according to predefined criteria. The analysis of results shows that the method provides rich information compared with the conventional recording of the H-reflex with regard the spatial distribution.

Flash sintering of ceramic materials

NASA Astrophysics Data System (ADS)

Dancer, C. E. J.

2016-10-01

During flash sintering, ceramic materials can sinter to high density in a matter of seconds while subjected to electric field and elevated temperature. This process, which occurs at lower furnace temperatures and in shorter times than both conventional ceramic sintering and field-assisted methods such as spark plasma sintering, has the potential to radically reduce the power consumption required for the densification of ceramic materials. This paper reviews the experimental work on flash sintering methods carried out to date, and compares the properties of the materials obtained to those produced by conventional sintering. The flash sintering process is described for oxides of zirconium, yttrium, aluminium, tin, zinc, and titanium; silicon and boron carbide, zirconium diboride, materials for solid oxide fuel applications, ferroelectric materials, and composite materials. While experimental observations have been made on a wide range of materials, understanding of the underlying mechanisms responsible for the onset and latter stages of flash sintering is still elusive. Elements of the proposed theories to explain the observed behaviour include extensive Joule heating throughout the material causing thermal runaway, arrested by the current limitation in the power supply, and the formation of defect avalanches which rapidly and dramatically increase the sample conductivity. Undoubtedly, the flash sintering process is affected by the electric field strength, furnace temperature and current density limit, but also by microstructural features such as the presence of second phase particles or dopants and the particle size in the starting material. While further experimental work and modelling is still required to attain a full understanding capable of predicting the success of the flash sintering process in different materials, the technique non-etheless holds great potential for exceptional control of the ceramic sintering process.

High frequency bone conduction auditory evoked potentials in the guinea pig: Assessing cochlear injury after ossicular chain manipulation.

PubMed

Bergin, M J; Bird, P A; Vlajkovic, S M; Thorne, P R

2015-12-01

Permanent high frequency (>4 kHz) sensorineural hearing loss following middle ear surgery occurs in up to 25% of patients. The aetiology of this loss is poorly understood and may involve transmission of supra-physiological forces down the ossicular chain to the cochlea. Investigating the mechanisms of this injury using animal models is challenging, as evaluating cochlear function with evoked potentials is confounded when ossicular manipulation disrupts the normal air conduction (AC) pathway. Bone conduction (BC) using clinical bone vibrators in small animals is limited by poor transducer output at high frequencies sensitive to trauma. The objectives of the present study were firstly to evaluate a novel high frequency bone conduction transducer with evoked auditory potentials in a guinea pig model, and secondly to use this model to investigate the impact of middle ear surgical manipulation on cochlear function. We modified a magnetostrictive device as a high frequency BC transducer and evaluated its performance by comparison with a calibrated AC transducer at frequencies up to 32 kHz using the auditory brainstem response (ABR), compound action potential (CAP) and summating potential (SP). To mimic a middle ear traumatising stimulus, a rotating bur was brought in to contact with the incudomalleal complex and the effect on evoked cochlear potentials was observed. BC-evoked potentials followed the same input-output function pattern as AC potentials for all ABR frequencies. Deterioration in CAP and SP thresholds was observed after ossicular manipulation. It is possible to use high frequency BC to evoke responses from the injury sensitive basal region of the cochlea and so not rely on AC with the potential confounder of conductive hearing loss. Ongoing research explores how these findings evolve over time, and ways in which injury may be reduced and the cochlea protected during middle ear surgery. Copyright © 2015 Elsevier B.V. All rights reserved.

Hypnotherapy to Reduce Hot Flashes: Examination of Response Expectancies as a Mediator of Outcomes

PubMed Central

Sliwinski, Jim R.; Elkins, Gary R.

2017-01-01

The mechanism of action responsible for hypnotherapy’s effect in reducing hot flashes is not yet known. The purpose of this study was to examine the role of response expectancies as a potential mediator. Hypnotizability was also tested as an effect moderator. Data were collected from a sample of 172 postmenopausal women, who had been randomized to receive either a 5-week hypnosis intervention or structured attention counseling. Measures of response expectancies were analyzed to determine if the relationship between group assignment and hot flashes frequency was mediated by expectancies for treatment efficacy. A series of simple mediation and conditional process analyses did not support mediation of the relationship between treatment condition and hot flash frequency through response expectancy. The effect of hypnotherapy in reducing hot flashes does not appear to be due to placebo effects as determined by response expectancies. Implications for clinical practice and future research are discussed. PMID:28528570

Severe craniocerebral trauma with sequelae caused by Flash-Ball® shot, a less-lethal weapon: Report of one case and review of the literature.

PubMed

Hiquet, Jean; Gromb-Monnoyeur, Sophie

2016-07-01

The use of Flash-Ball® as a non-lethal weapon by several special units within the police and police forces started in France in 1995. Little literature is available concerning injuries caused by Flash-Ball® shooting. However, we report the case of a healthy 34-year-old male victim of a Flash-Ball® shooting during a riot following a sports event. This young man presented serious craniocerebral injuries with a left temporal fracture, moderate cerebral oedema, fronto-temporal haemorrhagic contusion along with an extra-dural hematoma and subarachnoid hemorrhage requiring neurological and rehabilitation care for two months leaving important sequelae. Although the risk is obviously lower than with firearms, Flash-Ball® is nonetheless potentially lethal and may cause serious physical injuries, particularly after a shot to the head. © The Author(s) 2015.

Mitochondrial Flash: Integrative Reactive Oxygen Species and pH Signals in Cell and Organelle Biology

PubMed Central

Gong, Guohua; Wang, Xianhua; Wei-LaPierre, Lan; Cheng, Heping; Dirksen, Robert

2016-01-01

Abstract Significance: Recent breakthroughs in mitochondrial research have advanced, reshaped, and revolutionized our view of the role of mitochondria in health and disease. These discoveries include the development of novel tools to probe mitochondrial biology, the molecular identification of mitochondrial functional proteins, and the emergence of new concepts and mechanisms in mitochondrial function regulation. The discovery of “mitochondrial flash” activity has provided unique insights not only into real-time visualization of individual mitochondrial redox and pH dynamics in live cells but has also advanced understanding of the excitability, autonomy, and integration of mitochondrial function in vivo. Recent Advances: The mitochondrial flash is a transient and stochastic event confined within an individual mitochondrion and is observed in a wide range of organisms from plants to Caenorhabditis elegans to mammals. As flash events involve multiple transient concurrent changes within the mitochondrion (e.g., superoxide, pH, and membrane potential), a number of different mitochondrial targeted fluorescent indicators can detect flash activity. Accumulating evidence indicates that flash events reflect integrated snapshots of an intermittent mitochondrial process arising from mitochondrial respiration chain activity associated with the transient opening of the mitochondrial permeability transition pore. Critical Issues: We review the history of flash discovery, summarize current understanding of flash biology, highlight controversies regarding the relative roles of superoxide and pH signals during a flash event, and bring forth the integration of both signals in flash genesis. Future Directions: Investigations using flash as a biomarker and establishing its role in cell signaling pathway will move the field forward. Antioxid. Redox Signal. 25, 534–549. PMID:27245241

The effects of neck flexion on cerebral potentials evoked by visual, auditory and somatosensory stimuli and focal brain blood flow in related sensory cortices

PubMed Central

2012-01-01

Background A flexed neck posture leads to non-specific activation of the brain. Sensory evoked cerebral potentials and focal brain blood flow have been used to evaluate the activation of the sensory cortex. We investigated the effects of a flexed neck posture on the cerebral potentials evoked by visual, auditory and somatosensory stimuli and focal brain blood flow in the related sensory cortices. Methods Twelve healthy young adults received right visual hemi-field, binaural auditory and left median nerve stimuli while sitting with the neck in a resting and flexed (20° flexion) position. Sensory evoked potentials were recorded from the right occipital region, Cz in accordance with the international 10–20 system, and 2 cm posterior from C4, during visual, auditory and somatosensory stimulations. The oxidative-hemoglobin concentration was measured in the respective sensory cortex using near-infrared spectroscopy. Results Latencies of the late component of all sensory evoked potentials significantly shortened, and the amplitude of auditory evoked potentials increased when the neck was in a flexed position. Oxidative-hemoglobin concentrations in the left and right visual cortices were higher during visual stimulation in the flexed neck position. The left visual cortex is responsible for receiving the visual information. In addition, oxidative-hemoglobin concentrations in the bilateral auditory cortex during auditory stimulation, and in the right somatosensory cortex during somatosensory stimulation, were higher in the flexed neck position. Conclusions Visual, auditory and somatosensory pathways were activated by neck flexion. The sensory cortices were selectively activated, reflecting the modalities in sensory projection to the cerebral cortex and inter-hemispheric connections. PMID:23199306

Transcranial Motor-Evoked Potentials Are More Readily Acquired Than Somatosensory-Evoked Potentials in Children Younger Than 6 Years.

PubMed

McIntyre, Ian W; Francis, Lisa; McAuliffe, John J

2016-01-01

There is a general belief that somatosensory-evoked potentials (SSEPs) are more easily obtained than transcranial motor-evoked potentials (TcMEPs) in children younger than 6 years. We tested this assumption and the assumption that motor-evoked potentials are rarely obtained in children younger than 2 years. The records of all patients who were monitored during surgical procedures between April 1, 2010, and June 30, 2013, were reviewed and those who were younger than 72 months at the time of surgery were identified and analyzed for the rate of obtaining clinically useful SSEPs and motor-evoked potentials. Subgroup analysis was performed by age. A total of 146 patients were identified, 9 had SSEPs without TcMEPs monitored, 117 had both TcMEPs and SSEPs monitored, and the remainder had only electromyographic monitoring. All patients who were to have TcMEPs recorded received a total IV anesthetic. Among the 117 patients who had both SSEPs and TcMEPs monitored, clinically relevant TcMEPs were obtained more frequently than SSEPs (110/117 vs 89/117; χ = 14.82; P = 0.00012). There were significant differences between the rates of obtaining SSEPs and TcMEPs in the 0- to 23-month (P = 0.0038) and 24- to 47-month (P = 0.0056) age groups. Utilization of a double-train stimulation technique facilitated obtaining TcMEPs in the youngest patients. TcMEPs can be obtained more easily than SSEPs in patients younger than 72 months if a permissive anesthetic technique is used. The success rate for obtaining TcMEPs can be further enhanced by the use of a temporal facilitation (double-train) stimulation technique.

Utility of Brainstem Trigeminal Evoked Potentials in Patients With Primary Trigeminal Neuralgia Treated by Microvascular Decompression.

PubMed

Zhu, Jin; Zhang, Xin; Zhao, Hua; Tang, Yin-Da; Ying, Ting-Ting; Li, Shi-Ting

2017-09-01

To investigate the characteristics of brainstem trigeminal evoked potentials (BTEP) waveform in patients with and without trigeminal neuralgia (TN), and to discuss the utility of BTEP in patients with primary TN treated by microvascular decompression (MVD). A retrospective review of 43 patients who underwent BTEP between January 2016 and June 2016, including 33 patients with TN who underwent MVD and 10 patients without TN. Brainstem trigeminal evoked potentials characteristics of TN and non-TN were summarized, in particular to compare the BTEP changes between pre- and post-MVD, and to discover the relationship between BTEP changes and surgical outcome. Brainstem trigeminal evoked potentials can be recorded in patients without trigeminal neuralgia. Abnormal BTEP could be recorded when different branches were stimulated. After decompression, the original W2, W3 disappeared and then replaced by a large wave in most patients, or original wave poorly differentiated improved in some patients, showed as shorter latency and (or) amplitude increased. Brainstem trigeminal evoked potentials waveform of healthy side in patients with trigeminal neuralgia was similar to the waveform of patients without TN. In 3 patients, after decompression the W2, W3 peaks increased, and the latency, duration, IPLD did not change significantly. Until discharge, 87.9% (29/33) of the patients presented complete absence of pain without medication (BNI I) and 93.9% (31/33) had good pain control without medication (BNI I-II). Brainstem trigeminal evoked potentials can reflect the conduction function of the trigeminal nerve to evaluate the functional level of the trigeminal nerve conduction pathway. The improvement and restoration of BTEP waveforms are closely related to the postoperative curative effect.

Steady-state pattern electroretinogram and short-duration transient visual evoked potentials in glaucomatous and healthy eyes.

PubMed

Amarasekera, Dilru C; Resende, Arthur F; Waisbourd, Michael; Puri, Sanjeev; Moster, Marlene R; Hark, Lisa A; Katz, L Jay; Fudemberg, Scott J; Mantravadi, Anand V

2018-01-01

This study evaluates two rapid electrophysiological glaucoma diagnostic tests that may add a functional perspective to glaucoma diagnosis. This study aimed to determine the ability of two office-based electrophysiological diagnostic tests, steady-state pattern electroretinogram and short-duration transient visual evoked potentials, to discern between glaucomatous and healthy eyes. This is a cross-sectional study in a hospital setting. Forty-one patients with glaucoma and 41 healthy volunteers participated in the study. Steady-state pattern electroretinogram and short-duration transient visual evoked potential testing was conducted in glaucomatous and healthy eyes. A 64-bar-size stimulus with both a low-contrast and high-contrast setting was used to compare steady-state pattern electroretinogram parameters in both groups. A low-contrast and high-contrast checkerboard stimulus was used to measure short-duration transient visual evoked potential parameters in both groups. Steady-state pattern electroretinogram parameters compared were MagnitudeD, MagnitudeD/Magnitude ratio, and the signal-to-noise ratio. Short-duration transient visual evoked potential parameters compared were amplitude and latency. MagnitudeD was significantly lower in glaucoma patients when using a low-contrast (P = 0.001) and high-contrast (P < 0.001) 64-bar-size steady-state pattern electroretinogram stimulus. MagnitudeD/Magnitude ratio and SNR were significantly lower in the glaucoma group when using a high-contrast 64-bar-size stimulus (P < 0.001 and P = 0.010, respectively). Short-duration transient visual evoked potential amplitude and latency were not significantly different between the two groups. Steady-state pattern electroretinogram was effectively able to discern between glaucomatous and healthy eyes. Steady-state pattern electroretinogram may thus have a role as a clinically useful electrophysiological diagnostic tool. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Multifocal Visual Evoked Potential in Eyes With Temporal Hemianopia From Chiasmal Compression: Correlation With Standard Automated Perimetry and OCT Findings.

PubMed

Sousa, Rafael M; Oyamada, Maria K; Cunha, Leonardo P; Monteiro, Mário L R

2017-09-01

To verify whether multifocal visual evoked potential (mfVEP) can differentiate eyes with temporal hemianopia due to chiasmal compression from healthy controls. To assess the relationship between mfVEP, standard automated perimetry (SAP), and Fourier domain-optical coherence tomography (FD-OCT) macular and peripapillary retinal nerve fiber layer (RNFL) thickness measurements. Twenty-seven eyes with permanent temporal visual field (VF) defects from chiasmal compression on SAP and 43 eyes of healthy controls were submitted to mfVEP and FD-OCT scanning. Multifocal visual evoked potential was elicited using a stimulus pattern of 60 sectors and the responses were averaged for the four quadrants and two hemifields. Optical coherence tomography macular measurements were averaged in quadrants and halves, while peripapillary RNFL thickness was averaged in four sectors around the disc. Visual field loss was estimated in four quadrants and each half of the 24-2 strategy test points. Multifocal visual evoked potential measurements in the two groups were compared using generalized estimated equations, and the correlations between mfVEP, VF, and OCT findings were quantified. Multifocal visual evoked potential-measured temporal P1 and N2 amplitudes were significantly smaller in patients than in controls. No significant difference in amplitude was observed for nasal parameters. A significant correlation was found between mfVEP amplitudes and temporal VF loss, and between mfVEP amplitudes and the corresponding OCT-measured macular and RNFL thickness parameters. Multifocal visual evoked potential amplitude parameters were able to differentiate eyes with temporal hemianopia from controls and were significantly correlated with VF and OCT findings, suggesting mfVEP is a useful tool for the detection of visual abnormalities in patients with chiasmal compression.

The impact of red light running camera flashes on younger and older drivers' attention and oculomotor control.

PubMed

Wright, Timothy J; Vitale, Thomas; Boot, Walter R; Charness, Neil

2015-12-01

Recent empirical evidence has suggested that the flashes associated with red light running cameras (RLRCs) distract younger drivers, pulling attention away from the roadway and delaying processing of safety-relevant events. Considering the perceptual and attentional declines that occur with age, older drivers may be especially susceptible to the distracting effects of RLRC flashes, particularly in situations in which the flash is more salient (a bright flash at night compared with the day). The current study examined how age and situational factors potentially influence attention capture by RLRC flashes using covert (cuing effects) and overt (eye movement) indices of capture. We manipulated the salience of the flash by varying its luminance and contrast with respect to the background of the driving scene (either day or night scenes). Results of 2 experiments suggest that simulated RLRC flashes capture observers' attention, but, surprisingly, no age differences in capture were observed. However, an analysis examining early and late eye movements revealed that older adults may have been strategically delaying their eye movements in order to avoid capture. Additionally, older adults took longer to disengage attention following capture, suggesting at least 1 age-related disadvantage in capture situations. Findings have theoretical implications for understanding age differences in attention capture, especially with respect to capture in real-world scenes, and inform future work that should examine how the distracting effects of RLRC flashes influence driver behavior. (c) 2015 APA, all rights reserved).

The Impact of Red Light Running Camera Flashes on Younger and Older Drivers' Attention and Oculomotor Control

PubMed Central

Wright, Timothy J.; Vitale, Thomas; Boot, Walter R; Charness, Neil

2015-01-01

Recent empirical evidence suggests that the flashes associated with red light running cameras (RLRCs) distract younger drivers, pulling attention away from the roadway and delaying processing of safety-relevant events. Considering the perceptual and attentional declines that occur with age, older drivers may be especially susceptible to the distracting effects of RLRC flashes, particularly in situations in which the flash is more salient (a bright flash at night compared to the day). The current study examined how age and situational factors potentially influence attention capture by RLRC flashes using covert (cuing effects) and overt (eye movement) indices of capture. We manipulated the salience of the flash by varying its luminance and contrast with respect to the background of the driving scene (either day or night scenes). Results of two experiments suggest that simulated RLRC flashes capture observers' attention, but, surprisingly, no age differences in capture were observed. However, an analysis examining early and late eye movements revealed that older adults may have been strategically delaying their eye movements in order to avoid capture. Additionally, older adults took longer to disengage attention following capture, suggesting at least one age-related disadvantage in capture situations. Findings have theoretical implications for understanding age differences in attention capture, especially with respect to capture in real-world scenes, and inform future work that should examine how the distracting effects of RLRC flashes influence driver behavior. PMID:26479014

Rhesus macaque model of chronic opiate dependence and neuro-AIDS: longitudinal assessment of auditory brainstem responses and visual evoked potentials

PubMed Central

Riazi, Mariam; Marcario, Joanne K; Samson, Frank K.; Kenjale, Himanshu; Adany, Istvan; Staggs, Vincent; Ledford, Emily; Marquis, Janet; Narayan, Opendra; Cheney, Paul D.

2013-01-01

Our work characterizes the effects of opiate (morphine) dependence on auditory brainstem and visual evoked responses in a rhesus macaque model of neuro-AIDS utilizing a chronic continuous drug delivery paradigm. The goal of this study was to clarify whether morphine is protective, or if it exacerbates simian immunodeficiency virus (SIV) related systemic and neurological disease. Our model employs a macrophage tropic CD4/CCR5 co-receptor virus, SIVmac239 (R71/E17), which crosses the blood brain barrier shortly after inoculation and closely mimics the natural disease course of human immunodeficiency virus (HIV) infection. The cohort was divided into 3 groups: morphine only, SIV only, and SIV + morphine. Evoked potential (EP) abnormalities in sub-clinically infected macaques were evident as early as eight weeks post-inoculation. Prolongations in EP latencies were observed in SIV-infected macaques across all modalities. Animals with the highest CSF viral loads and clinical disease showed more abnormalities than those with sub-clinical disease, confirming our previous work (Raymond et al, 1998, 1999, 2000). Although some differences were observed in auditory and visual evoked potentials in morphine treated compared to untreated SIV-infected animals, the effects were relatively small and not consistent across evoked potential type. However, morphine treated animals with subclinical disease had a clear tendency toward higher virus loads in peripheral and CNS tissues (Marcario et al., 2008) suggesting that if had been possible to follow all animals to end-stage disease, a clearer pattern of evoked potential abnormality might have emerged. PMID:19283490

Investigation of brachial plexus traction lesions by peripheral and spinal somatosensory evoked potentials.

PubMed Central

Jones, S J

1979-01-01

Peripheral, spinal and cortical somatosensory evoked potentials were recorded in 26 patients with unilateral traction injuries of the brachial plexus ganglia. Of 10 cases explored surgically the recordings correctly anticipated the major site of the lesion in eight. PMID:422958

Normalization of auditory evoked potential and visual evoked potential in patients with idiot savant.

PubMed

Chen, X; Zhang, M; Wang, J; Lou, F; Liang, J

1999-03-01

To investigate the variations of auditory evoked potentials (AEP) and visual evoked potentials (VEP) of patients with idiot savant (IS) syndrome. Both AEP and VEP were recorded from 7 patients with IS syndrome, 21 mentally retarded (MR) children without the syndrome and 21 normally age-matched controls, using a Dantec concerto SEEG-16 BEAM instrument. Both AEP and VEP of MR group showed significantly longer latencies (P1 and P2 latencies of AEP, P < 0.01; N1 and N2 latencies of VEP, P < 0.01/0.05), lower P2 amplitudes (P < 0.01) and higher P3 amplitudes (P < 0.01), as compared with normal controls. But none of above-mentioned changes was found with IS group. Almost all MR patients (90.1%) presented P4 component in both AEP and VEP, which was also in sharp contrast with its incidence in other 2 groups (IS: 14.3%; normal controls: 9.5%). Patients with idiot savant syndrome presented normalized AEP and VEP.

[Executive functioning and evoked potentials P300 pre- and post- treatment in attention deficit hyperactivity disorder].

PubMed

Roca, Patricia; Mulas, Fernando; Gandia, Rubén; Ortiz-Sánchez, Pedro; Abad, Luis

2013-02-22

Evoked potentials P300 and the analysis of executive functions have shown their utility in the monitoring of patients with symptoms of attention deficit hyperactivity disorder (ADHD). Neuropsychological profiles and evoked potentials P300 have been analysed for two groups of children with an ADHD treatment with atomoxetine and methylphenidate respectively. Correlations between P300 and the selected neuropsychological parameters are studied, and the differences between basal values and 1 year follow-up are analysed. Two groups were performed: a group of 22 children ADHD in the atomoxetine condition, and a group of 24 children ADHD in the methylphenidate condition. The results show a global improvement of all the parameters, in terms of executive function and P300 values in both, the atomoxetine and the methylphenidate group. Executive functions and evoked potentials P300 reflect an underlying processing and they are very useful in the clinical practice. This exploratory study shows the importance of designing personalized objective variables-based treatments.

Cortico-centric effects of general anesthetics on cerebrocortical evoked potentials.

PubMed

Voss, Logan J; Sleigh, James W

2015-12-01

Despite their ubiquitous use for rendering patients unconscious for surgery, our understanding of how general anesthetics cause hypnosis remains rudimentary at best. Recent years have seen increased interest in "top-down" cortico-centric theories of anesthetic action. The aim of this study was to explore this by investigating direct cortical effects of anesthetics on cerebrocortical evoked potentials in isolated mouse brain slices. Evoked potentials were elicited in cortical layer IV by electrical stimulation of the underlying white matter. The effects of three anesthetics (ketamine, etomidate, and isoflurane) on the amplitude, latency, and slope of short-latency evoked potentials were quantified. The N2/P3/N4 potentials–which represent the early cortical response–were enhanced by etomidate (increased P3-N4 slope, P <0.01), maintained by ketamine, and reduced by isoflurane (lower N2/P3 amplitude, P <0.01). These effects closely resemble those seen in vivo for the same drugs and point to a cortical mechanism independent of effects on subcortical structures such as the thalamus.

An indirect component in the evoked compound action potential of the vagal nerve.

PubMed

Ordelman, Simone C M A; Kornet, Lilian; Cornelussen, Richard; Buschman, Hendrik P J; Veltink, Peter H

2010-12-01

The vagal nerve plays a vital role in the regulation of the cardiovascular system. It not only regulates the heart but also sends sensory information from the heart back to the brain. We hypothesize that the evoked vagal nerve compound action potential contains components that are indirect via the brain stem or coming via the neural network on the heart. In an experimental study of 15 pigs, we identified four components in the evoked compound action potentials. The fourth component was found to be an indirect component, which came from the periphery. The latency of the indirect component increased when heart rate and contractility were decreased by burst stimulation (P = 0.01; n = 7). When heart rate and contractility were increased by dobutamine administration, the latency of the indirect component decreased (P = 0.01; n = 9). This showed that the latency of the indirect component of the evoked compound action potentials may relate to the state of the cardiovascular system.

Lack of habituation of evoked visual potentials in analytic information processing style: evidence in healthy subjects.

PubMed

Buonfiglio, Marzia; Toscano, M; Puledda, F; Avanzini, G; Di Clemente, L; Di Sabato, F; Di Piero, V

2015-03-01

Habituation is considered one of the most basic mechanisms of learning. Habituation deficit to several sensory stimulations has been defined as a trait of migraine brain and also observed in other disorders. On the other hand, analytic information processing style is characterized by the habit of continually evaluating stimuli and it has been associated with migraine. We investigated a possible correlation between lack of habituation of evoked visual potentials and analytic cognitive style in healthy subjects. According to Sternberg-Wagner self-assessment inventory, 15 healthy volunteers (HV) with high analytic score and 15 HV with high global score were recruited. Both groups underwent visual evoked potentials recordings after psychological evaluation. We observed significant lack of habituation in analytical individuals compared to global group. In conclusion, a reduced habituation of visual evoked potentials has been observed in analytic subjects. Our results suggest that further research should be undertaken regarding the relationship between analytic cognitive style and lack of habituation in both physiological and pathophysiological conditions.

The flashing Brownian ratchet and Parrondo’s paradox

PubMed Central

Ethier, S. N.

2018-01-01

A Brownian ratchet is a one-dimensional diffusion process that drifts towards a minimum of a periodic asymmetric sawtooth potential. A flashing Brownian ratchet is a process that alternates between two regimes, a one-dimensional Brownian motion and a Brownian ratchet, producing directed motion. These processes have been of interest to physicists and biologists for nearly 25 years. The flashing Brownian ratchet is the process that motivated Parrondo’s paradox, in which two fair games of chance, when alternated, produce a winning game. Parrondo’s games are relatively simple, being discrete in time and space. The flashing Brownian ratchet is rather more complicated. We show how one can study the latter process numerically using a random walk approximation. PMID:29410868

Activation of Mechanosensitive Transient Receptor Potential/Piezo Channels in Odontoblasts Generates Action Potentials in Cocultured Isolectin B4-negative Medium-sized Trigeminal Ganglion Neurons.

PubMed

Sato, Masaki; Ogura, Kazuhiro; Kimura, Maki; Nishi, Koichi; Ando, Masayuki; Tazaki, Masakazu; Shibukawa, Yoshiyuki

2018-06-01

Various stimuli to the dentin surface elicit dentinal pain by inducing dentinal fluid movement causing cellular deformation in odontoblasts. Although odontoblasts detect deformation by the activation of mechanosensitive ionic channels, it is still unclear whether odontoblasts are capable of establishing neurotransmission with myelinated A delta (Aδ) neurons. Additionally, it is still unclear whether these neurons evoke action potentials by neurotransmitters from odontoblasts to mediate sensory transduction in dentin. Thus, we investigated evoked inward currents and evoked action potentials form trigeminal ganglion (TG) neurons after odontoblast mechanical stimulation. We used patch clamp recordings to identify electrophysiological properties and record evoked responses in TG neurons. We classified TG cells into small-sized and medium-sized neurons. In both types of neurons, we observed voltage-dependent inward currents. The currents from medium-sized neurons showed fast inactivation kinetics. When mechanical stimuli were applied to odontoblasts, evoked inward currents were recorded from medium-sized neurons. Antagonists for the ionotropic adenosine triphosphate receptor (P2X 3 ), transient receptor potential channel subfamilies, and Piezo1 channel significantly inhibited these inward currents. Mechanical stimulation to odontoblasts also generated action potentials in the isolectin B 4 -negative medium-sized neurons. Action potentials in these isolectin B 4 -negative medium-sized neurons showed a short duration. Overall, electrophysiological properties of neurons indicate that the TG neurons with recorded evoked responses after odontoblast mechanical stimulation were myelinated Aδ neurons. Odontoblasts established neurotransmission with myelinated Aδ neurons via P2X 3 receptor activation. The results also indicated that mechanosensitive TRP/Piezo1 channels were functionally expressed in odontoblasts. The activation of P2X 3 receptors induced an action potential in the Aδ neurons, underlying a sensory generation mechanism of dentinal pain. Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Source analysis of short and long latency vestibular-evoked potentials (VsEPs) produced by left vs. right ear air-conducted 500 Hz tone pips.

PubMed

Todd, N P M; Paillard, A C; Kluk, K; Whittle, E; Colebatch, J G

2014-06-01

Todd et al. (2014) have recently demonstrated the presence of vestibular dependent changes both in the morphology and in the intensity dependence of auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs). In this paper we extend this work by comparing left vs. right ear stimulation and by conducting a source analysis of the resulting evoked potentials of short and long latency. Ten healthy, right-handed subjects were recruited and evoked potentials were recorded to both left- and right-ear sound stimulation, above and below vestibular threshold. Below VEMP threshold, typical AEPs were recorded, consisting of mid-latency (MLR) waves Na and Pa followed by long latency AEPs (LAEPs) N1 and P2. In the supra-threshold condition, the expected changes in morphology were observed, consisting of: (1) short-latency vestibular evoked potentials (VsEPs) which have no auditory correlate, i.e. the ocular VEMP (OVEMP) and inion response related potentials; (2) a later deflection, labelled N42/P52, followed by the LAEPs N1 and P2. Statistical analysis of the vestibular dependent responses indicated a contralateral effect for inion related short-latency responses and a left-ear/right-hemisphere advantage for the long-latency responses. Source analysis indicated that the short-latency effects may be mediated by a contralateral projection to left cerebellum, while the long-latency effects were mediated by a contralateral projection to right cingulate cortex. In addition we found evidence of a possible vestibular contribution to the auditory T-complex in radial temporal lobe sources. These last results raise the possibility that acoustic activation of the otolith organs could potentially contribute to auditory processing. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Low-frequency rTMS inhibitory effects in the primary motor cortex: Insights from TMS-evoked potentials.

PubMed

Casula, Elias P; Tarantino, Vincenza; Basso, Demis; Arcara, Giorgio; Marino, Giuliana; Toffolo, Gianna Maria; Rothwell, John C; Bisiacchi, Patrizia S

2014-09-01

The neuromodulatory effects of repetitive transcranial magnetic stimulation (rTMS) have been mostly investigated by peripheral motor-evoked potentials (MEPs). New TMS-compatible EEG systems allow a direct investigation of the stimulation effects through the analysis of TMS-evoked potentials (TEPs). We investigated the effects of 1-Hz rTMS over the primary motor cortex (M1) of 15 healthy volunteers on TEP evoked by single pulse TMS over the same area. A second experiment in which rTMS was delivered over the primary visual cortex (V1) of 15 healthy volunteers was conducted to examine the spatial specificity of the effects. Single-pulse TMS evoked four main components: P30, N45, P60 and N100. M1-rTMS resulted in a significant decrease of MEP amplitude and in a significant increase of P60 and N100 amplitude. There was no effect after V1-rTMS. 1-Hz rTMS appears to increase the amount of inhibition following a TMS pulse, as demonstrated by the higher N100 and P60, which are thought to originate from GABAb-mediated inhibitory post-synaptic potentials. Our results confirm the reliability of the TMS-evoked N100 as a marker of cortical inhibition and provide insight into the neuromodulatory effects of 1-Hz rTMS. The present finding could be of relevance for therapeutic and diagnostic purposes. Copyright © 2014 Elsevier Inc. All rights reserved.

[Evoked potentials extraction based on cross-talk resistant adaptive noise cancellation].

PubMed

Zeng, Qingning; Li, Ling; Liu, Qinghua; Yao, Dezhong

2004-06-01

As Evoked Potentials are much lower in amplitude with respect to the on-going EEC, many trigger-related signals are needed for common averaging technique to enable the extraction of single-trail evoked potentials (EP). How to acquire EP through fewer evocations is an important research project. This paper proposes a cross-talk resistant adaptive noise cancellation method to extract EP. Together with the use of filtering technique and the common averaging technique, the present method needs much less evocations to acquire EP signals. According to the simulating experiment, it needs only several evocations or even only one evocation to get EP signals in good quality.

Effect of mechanical tactile noise on amplitude of visual evoked potentials: multisensory stochastic resonance.

PubMed

Méndez-Balbuena, Ignacio; Huidobro, Nayeli; Silva, Mayte; Flores, Amira; Trenado, Carlos; Quintanar, Luis; Arias-Carrión, Oscar; Kristeva, Rumyana; Manjarrez, Elias

2015-10-01

The present investigation documents the electrophysiological occurrence of multisensory stochastic resonance in the human visual pathway elicited by tactile noise. We define multisensory stochastic resonance of brain evoked potentials as the phenomenon in which an intermediate level of input noise of one sensory modality enhances the brain evoked response of another sensory modality. Here we examined this phenomenon in visual evoked potentials (VEPs) modulated by the addition of tactile noise. Specifically, we examined whether a particular level of mechanical Gaussian noise applied to the index finger can improve the amplitude of the VEP. We compared the amplitude of the positive P100 VEP component between zero noise (ZN), optimal noise (ON), and high mechanical noise (HN). The data disclosed an inverted U-like graph for all the subjects, thus demonstrating the occurrence of a multisensory stochastic resonance in the P100 VEP. Copyright © 2015 the American Physiological Society.

Disturbances of stem circumnutations evoked by wound-induced variation potentials in Helianthus annuus L.

PubMed

Stolarz, Maria; Dziubińska, Halina; Krupa, Maciej; Buda, Agnieszka; Trebacz, Kazimierz; Zawadzki, Tadeusz

2003-01-01

The relationship between evoked electrical activity and stem movements in three-week old sunflowers was demonstrated. Electrical potential changes (recorded by Ag/AgCl extracellular electrodes) and time-lapse images (from a top view camera) were recorded and analyzed. A heat stimulus applied to the tip of one of the second pair of leaves evoked a variation potential, transmitted basipetally along one side of the stem. After stimulation, disturbances of circumnutations occurred. They included: changes in the period, disorders in the elliptical shape, and, in some cases, reversion of direction (of movement). We suggest that asymmetrically propagated variation potential induces asymmetric stem shrinking and bending, which strongly disturbs circumnutations. Our results confirm the involvement of electrical potential changes in the mechanism of stem nutations.

Recovery of TES-MEPs during surgical decompression of the spine: a case series of eight patients.

PubMed

Visser, Jetze; Verra, Wiebe C; Kuijlen, Jos M; Horsting, Philip P; Journée, Henricus L

2014-12-01

This study aimed to illustrate the recovery of transcranial electrical stimulation motor evoked potentials during surgical decompression of the spinal cord in patients with impaired motor function preoperatively. Specific attention was paid to the duration of neurologic symptoms before surgery and the postoperative clinical recovery. A case series of eight patients was selected from a cohort of 74 patients that underwent spine surgery. The selected patients initially had low or absent transcranial electrical stimulation motor evoked potentials followed by a significant increase after surgical decompression of the spinal cord. A significant intraoperative increase in amplitude of motor evoked potentials was detected after decompression of the spinal cord or cauda equina in patients suffering from spinal canal stenosis (n = 2), extradural meningioma (n = 3), or a herniated nucleus polposus (n = 3). This was related to an enhanced neurologic outcome only if patients (n = 6) had a short onset (less than ½ year) of neurologic impairment before surgery. In patients with a short onset of neurologic impairment because of compression of the spinal cord or caudal fibers, an intraoperative recovery of transcranial electrical stimulation motor evoked potentials can indicate an improvement of motor function postoperatively. Therefore, transcranial electrical stimulation motor evoked potentials can be considered as a useful tool to the surgeon to monitor the quality of decompression of the spinal cord.

Normalization of sensorimotor integration by repetitive transcranial magnetic stimulation in cervical dystonia.

PubMed

Zittel, S; Helmich, R C; Demiralay, C; Münchau, A; Bäumer, T

2015-08-01

Previous studies indicated that sensorimotor integration and plasticity of the sensorimotor system are impaired in dystonia patients. We investigated motor evoked potential amplitudes and short latency afferent inhibition to examine corticospinal excitability and cortical sensorimotor integration, before and after inhibitory 1 Hz repetitive transcranial magnetic stimulation over primary sensory and primary motor cortex in patients with cervical dystonia (n = 12). Motor evoked potentials were recorded from the right first dorsal interosseous muscle after application of unconditioned transcranial magnetic test stimuli and after previous conditioning electrical stimulation of the right index finger at short interstimulus intervals of 25, 30 and 40 ms. Results were compared to a group of healthy age-matched controls. At baseline, motor evoked potential amplitudes did not differ between groups. Short latency afferent inhibition was reduced in cervical dystonia patients compared to healthy controls. Inhibitory 1 Hz sensory cortex repetitive transcranial magnetic stimulation but not motor cortex repetitive transcranial magnetic stimulation increased motor evoked potential amplitudes in cervical dystonia patients. Additionally, both 1 Hz repetitive transcranial magnetic stimulation over primary sensory and primary motor cortex normalized short latency afferent inhibition in these patients. In healthy subjects, sensory repetitive transcranial magnetic stimulation had no influence on motor evoked potential amplitudes and short latency afferent inhibition. Plasticity of sensorimotor circuits is altered in cervical dystonia patients.

Analysis of electrically evoked compound action potential of the auditory nerve in children with bilateral cochlear implants.

PubMed

Caldas, Fernanda Ferreira; Cardoso, Carolina Costa; Barreto, Monique Antunes de Souza Chelminski; Teixeira, Marina Santos; Hilgenberg, Anacléia Melo da Silva; Serra, Lucieny Silva Martins; Bahmad Junior, Fayez

2016-01-01

The cochlear implant device has the capacity to measure the electrically evoked compound action potential of the auditory nerve. The neural response telemetry is used in order to measure the electrically evoked compound action potential of the auditory nerve. To analyze the electrically evoked compound action potential, through the neural response telemetry, in children with bilateral cochlear implants. This is an analytical, prospective, longitudinal, historical cohort study. Six children, aged 1-4 years, with bilateral cochlear implant were assessed at five different intervals during their first year of cochlear implant use. There were significant differences in follow-up time (p=0.0082) and electrode position (p=0.0019) in the T-NRT measure. There was a significant difference in the interaction between time of follow-up and electrode position (p=0.0143) when measuring the N1-P1 wave amplitude between the three electrodes at each time of follow-up. The electrically evoked compound action potential measurement using neural response telemetry in children with bilateral cochlear implants during the first year of follow-up was effective in demonstrating the synchronized bilateral development of the peripheral auditory pathways in the studied population. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Oesophageal sensation assessed by electrical stimuli and brain evoked potentials--a new model for visceral nociception.

PubMed Central

Frøbert, O; Arendt-Nielsen, L; Bak, P; Funch-Jensen, P; Bagger, J P

1995-01-01

Sensory thresholds and brain evoked potentials were determined in 12 healthy volunteers using electrical stimulation of the oesophagus 28 and 38 cm from the nares. The peaks of the evoked potentials were designated N for negative deflections and P for positive. Continuous electrical stimulation (40 Hz) at the 38 cm position resembled heartburn (five of 12 subjects) while non-specific ('electrical') sensations were provoked at 28 cm (10 of 12). Thresholds of sensation and of pain were lower at the initial than the second determination, but did not differ with respect to stimulation site. The pain summation threshold to repeated stimuli (2 Hz, 5 stimuli) was determined for the first time in a viscus. This threshold was lower than the pain threshold to single stimuli at 38 cm (p < 0.02). Evoked potential latencies did not change significantly over a six month period while the N1/P2 amplitude was higher at the first measurement (p < 0.05). P1 and N1 latencies were significantly shorter 38 cm (medians 100 and 141 ms) than 28 cm from the nares (102 and 148 ms) (p = 0.04 and p = 0.008). Electrical stimulation of the oesophagus may serve as a human experimental model for visceral pain. Longer evoked potential latencies from the proximal compared with distal stimulations provide new information about the sensory pathways of the oesophagus. PMID:8549932

Effect of caffeine on vestibular evoked myogenic potential: a systematic review with meta-analysis.

PubMed

Souza, Maria Eduarda Di Cavalcanti Alves de; Costa, Klinger Vagner Teixeira da; Menezes, Pedro de Lemos

2017-12-24

Caffeine can be considered the most consumed drug by adults worldwide, and can be found in several foods, such as chocolate, coffee, tea, soda and others. Overall, caffeine in moderate doses, results in increased physical and intellectual productivity, increases the capacity of concentration and reduces the time of reaction to sensory stimuli. On the other hand, high doses can cause noticeable signs of mental confusion and error induction in intellectual tasks, anxiety, restlessness, muscle tremors, tachycardia, labyrinthine changes, and tinnitus. Considering that the vestibular evoked myogenic potential is a clinical test that evaluates the muscular response of high intensity auditory stimulation, the present systematic review aimed to analyze the effects of caffeine on vestibular evoked myogenic potential. This study consisted of the search of the following databases: MEDLINE, CENTRAL, ScienceDirect, Scopus, Web of Science, LILACS, SciELO and ClinicalTrials.gov. Additionally, the gray literature was also searched. The search strategy included terms related to intervention (caffeine or coffee consumption) and the primary outcome (vestibular evoked myogenic potential). Based on the 253 potentially relevant articles identified through the database search, only two full-text publications were retrieved for further evaluation, which were maintained for qualitative analysis. Analyzing the articles found, caffeine has no effect on vestibular evoked myogenic potential in normal individuals. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Waiting for the evidence: VEMP testing and the ability to differentiate utricular versus saccular function.

PubMed

Welgampola, Miriam S; Carey, John P

2010-08-01

The advent of cervical vestibular evoked myogenic potentials (CVEMPs) marked a milestone in clinical vestibular testing because they provided a simple means of assessing human otolith function. The availability of air-conducted (AC) sound and bone-conducted vibration (BCV) to evoke CVEMPs and development of a new technique of recording ocular vestibular-evoked myogenic potentials (OVEMPs) have increased the complexity of this simple test, yet extended its diagnostic capabilities. Here we highlight the evidence-based assumptions that guide interpretation of AC sound- and BCV-evoked VEMPs and the gaps in VEMP research thus far. Copyright (c) 2010 American Academy of Otolaryngology-Head and Neck Surgery Foundation. Published by Mosby, Inc. All rights reserved.

Effect of ischaemia on somatosensory evoked potentials in diabetic patients.

PubMed Central

López-Alburquerque, T; García Miguel, A; Ruiz Ezquerro, J J; de Portugal Alvarez, J

1987-01-01

The nerve action potential at the elbow and somatosensory evoked potentials (SEPs) at the scalp were recorded over 30 minutes of tourniquet-induced limb ischaemia in 10 diabetic patients and 10 controls. According to the SEP changes, an increased resistance to nerve ischaemia in diabetic patients was observed. The pathways involved in SEP conduction are discussed. PMID:3585354

Ghrelin potentiates cardiac reactivity to stress by modulating sympathetic control and beta-adrenergic response.

PubMed

Camargo-Silva, Gabriel; Turones, Larissa Córdova; da Cruz, Kellen Rosa; Gomes, Karina Pereira; Mendonça, Michelle Mendanha; Nunes, Allancer; de Jesus, Itamar Guedes; Colugnati, Diego Basile; Pansani, Aline Priscila; Pobbe, Roger Luis Henschel; Santos, Robson; Fontes, Marco Antônio Peliky; Guatimosim, Silvia; de Castro, Carlos Henrique; Ianzer, Danielle; Ferreira, Reginaldo Nassar; Xavier, Carlos Henrique

2018-03-01

Prior evidence indicates that ghrelin is involved in the integration of cardiovascular functions and behavioral responses. Ghrelin actions are mediated by the growth hormone secretagogue receptor subtype 1a (GHS-R1a), which is expressed in peripheral tissues and central areas involved in the control of cardiovascular responses to stress. In the present study, we assessed the role of ghrelin - GHS-R1a axis in the cardiovascular reactivity to acute emotional stress in rats. Ghrelin potentiated the tachycardia evoked by restraint and air jet stresses, which was reverted by GHS-R1a blockade. Evaluation of the autonomic balance revealed that the sympathetic branch modulates the ghrelin-evoked positive chronotropy. In isolated hearts, the perfusion with ghrelin potentiated the contractile responses caused by stimulation of the beta-adrenergic receptor, without altering the amplitude of the responses evoked by acetylcholine. Experiments in isolated cardiomyocytes revealed that ghrelin amplified the increases in calcium transient changes evoked by isoproterenol. Taken together, our results indicate that the Ghrelin-GHS-R1a axis potentiates the magnitude of stress-evoked tachycardia by modulating the autonomic nervous system and peripheral mechanisms, strongly relying on the activation of cardiac calcium transient and beta-adrenergic receptors. Copyright © 2018 Elsevier Inc. All rights reserved.

TRPM2 activation by cyclic ADP-ribose at body temperature is involved in insulin secretion

PubMed Central

Togashi, Kazuya; Hara, Yuji; Tominaga, Tomoko; Higashi, Tomohiro; Konishi, Yasunobu; Mori, Yasuo; Tominaga, Makoto

2006-01-01

There are eight thermosensitive TRP (transient receptor potential) channels in mammals, and there might be other TRP channels sensitive to temperature stimuli. Here, we demonstrate that TRPM2 can be activated by exposure to warm temperatures (>35°C) apparently via direct heat-evoked channel gating. β-NAD+- or ADP-ribose-evoked TRPM2 activity is robustly potentiated at elevated temperatures. We also show that, even though cyclic ADP-ribose (cADPR) does not activate TRPM2 at 25°C, co-application of heat and intracellular cADPR dramatically potentiates TRPM2 activity. Heat and cADPR evoke similar responses in rat insulinoma RIN-5F cells, which express TRPM2 endogenously. In pancreatic islets, TRPM2 is coexpressed with insulin, and mild heating of these cells evokes increases in both cytosolic Ca2+ and insulin release, which is KATP channel-independent and protein kinase A-mediated. Heat-evoked responses in both RIN-5F cells and pancreatic islets are significantly diminished by treatment with TRPM2-specific siRNA. These results identify TRPM2 as a potential molecular target for cADPR, and suggest that TRPM2 regulates Ca2+ entry into pancreatic β-cells at body temperature depending on the production of cADPR-related molecules, thereby regulating insulin secretion. PMID:16601673

An evaluation of the potential of Sentinel 1 for improving flash flood predictions via soil moisture-data assimilation

NASA Astrophysics Data System (ADS)

Cenci, Luca; Pulvirenti, Luca; Boni, Giorgio; Chini, Marco; Matgen, Patrick; Gabellani, Simone; Squicciarino, Giuseppe; Pierdicca, Nazzareno

2017-11-01

The assimilation of satellite-derived soil moisture estimates (soil moisture-data assimilation, SM-DA) into hydrological models has the potential to reduce the uncertainty of streamflow simulations. The improved capacity to monitor the closeness to saturation of small catchments, such as those characterizing the Mediterranean region, can be exploited to enhance flash flood predictions. When compared to other microwave sensors that have been exploited for SM-DA in recent years (e.g. the Advanced SCATterometer - ASCAT), characterized by low spatial/high temporal resolution, the Sentinel 1 (S1) mission provides an excellent opportunity to monitor systematically soil moisture (SM) at high spatial resolution and moderate temporal resolution. The aim of this research was thus to evaluate the impact of S1-based SM-DA for enhancing flash flood predictions of a hydrological model (Continuum) that is currently exploited for civil protection applications in Italy. The analysis was carried out in a representative Mediterranean catchment prone to flash floods, located in north-western Italy, during the time period October 2014-February 2015. It provided some important findings: (i) revealing the potential provided by S1-based SM-DA for improving discharge predictions, especially for higher flows; (ii) suggesting a more appropriate pre-processing technique to be applied to S1 data before the assimilation; and (iii) highlighting that even though high spatial resolution does provide an important contribution in a SM-DA system, the temporal resolution has the most crucial role. S1-derived SM maps are still a relatively new product and, to our knowledge, this is the first work published in an international journal dealing with their assimilation within a hydrological model to improve continuous streamflow simulations and flash flood predictions. Even though the reported results were obtained by analysing a relatively short time period, and thus should be supported by further research activities, we believe this research is timely in order to enhance our understanding of the potential contribution of the S1 data within the SM-DA framework for flash flood risk mitigation.

Segmental somatosensory-evoked potentials as a diagnostic tool in chronic inflammatory demyelinating polyneuropathies, and other sensory neuropathies.

PubMed

Koutlidis, R M; Ayrignac, X; Pradat, P-F; Le Forestier, N; Léger, J-M; Salachas, F; Maisonobe, T; Fournier, E; Viala, K

2014-09-01

Somatosensory-evoked potentials with segmental recordings were performed with the aim of distinguishing chronic inflammatory demyelinating polyneuropathy from other sensory neuropathies. Four groups of 20 subjects each corresponded to patients with (1) possible sensory chronic inflammatory demyelinating polyneuropathy, (2) patients with sensory polyneuropathy of unknown origin, (3) patients with amyotrophic lateral sclerosis and (4) normal subjects. The patients selected for this study had preserved sensory potentials on electroneuromyogram and all waves were recordable in evoked potentials. Somatosensory-evoked potentials evaluations were carried out by stimulation of the posterior tibial nerve at the ankle, recording peripheral nerve potential in the popliteal fossa, radicular potential and spinal potential at the L4-L5 and T12 levels, and cortical at C'z, with determination of distal conduction time, proximal and radicular conduction time and central conduction time. In the group of chronic inflammatory demyelinating polyneuropathy, 80% of patients had abnormal conduction in the N8-N22 segment and 95% had abnormal N18-N22 conduction time. In the group of neuropathies, distal conduction was abnormal in most cases, whereas 60% of patients had no proximal abnormality. None of the patients in the group of amyotrophic lateral sclerosis had an abnormal N18-N22 conduction time. Somatosensory-evoked potentials with segmental recording can be used to distinguish between atypical sensory chronic inflammatory demyelinating polyneuropathy and other sensory neuropathies, at the early stage of the disease. Graphical representation of segmental conduction times provides a rapid and accurate visualization of the profile of each patient. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Correlation analysis of the long latency auditory evoked potential N2 and cognitive P3 with the level of lead poisoning in children

PubMed Central

Alvarenga, Kátia de Freitas; Alvarez Bernardez-Braga, Gabriela Rosito; Zucki, Fernanda; Duarte, Josilene Luciene; Lopes, Andrea Cintra; Feniman, Mariza Ribeiro

2013-01-01

Summary Introduction: The effects of lead on children's health have been widely studied. Aim: To analyze the correlation between the long latency auditory evoked potential N2 and cognitive P3 with the level of lead poisoning in Brazilian children. Methods: This retrospective study evaluated 20 children ranging in age from 7 to 14 years at the time of audiological and electrophysiological evaluations. We performed periodic surveys of the lead concentration in the blood and basic audiological evaluations. Furthermore, we studied the auditory evoked potential long latency N2 and cognitive P3 by analyzing the absolute latency of the N2 and P3 potentials and the P3 amplitude recorded at Cz. At the time of audiological and electrophysiological evaluations, the average concentration of lead in the blood was less than 10 ug/dL. Results: In conventional audiologic evaluations, all children had hearing thresholds below 20 dBHL for the frequencies tested and normal tympanometry findings; the auditory evoked potential long latency N2 and cognitive P3 were present in 95% of children. No significant correlations were found between the blood lead concentration and latency (p = 0.821) or amplitude (p = 0.411) of the P3 potential. However, the latency of the N2 potential increased with the concentration of lead in the blood, with a significant correlation (p = 0.030). Conclusion: Among Brazilian children with low lead exposure, a significant correlation was found between blood lead levels and the average latency of the auditory evoked potential long latency N2; however, a significant correlation was not observed for the amplitude and latency of the cognitive potential P3. PMID:25991992

Flash floods in the Tatra Mountain streams: frequency and triggers.

PubMed

Ballesteros-Cánovas, J A; Czajka, B; Janecka, K; Lempa, M; Kaczka, R J; Stoffel, M

2015-04-01

Flash floods represent a frequently recurring natural phenomenon in the Tatra Mountains. On the northern slopes of the mountain chain, located in Poland, ongoing and expected future changes in climate are thought to further increase the adverse impacts of flash floods. Despite the repeat occurrence of major floods in the densely populated foothills of the Polish Tatras, the headwaters have been characterized by a surprising lack of data, such that any analysis of process variability or hydrometeorological triggers has been largely hampered so far. In this study, dendrogeomorphic techniques have been employed in four poorly-gauged torrential streams of the northern slope of the Tatra Mountains to reconstruct temporal and spatial patterns of past events. Using more than 1100 increment cores of trees injured by past flash floods, we reconstruct 47 events covering the last 148 years and discuss synoptic situations leading to the triggering of flash floods with the existing meteorological and flow gauge data. Tree-ring analyses have allowed highlighting the seasonality of events, providing new insights about potential hydrometeorological triggers as well as a differentiating flash flood activity between catchments. Results of this study could be useful to design future strategies to deal with flash flood risks at the foothills of the Polish Tatras and in the Vistula River catchment. Copyright © 2014. Published by Elsevier B.V.

Brainstem Auditory Evoked Potential Study in Children with Autistic Disorder.

ERIC Educational Resources Information Center

Wong, Virginia; Wong, Sik Nin

1991-01-01

Brainstem auditory evoked potentials were compared in 109 children with infantile autism, 38 with autistic condition, 19 with mental retardation, and 20 normal children. Children with infantile autism or autistic condition had significantly longer brainstem transmission time than normal children suggesting neurological damage as the basis of…

Intelligence and Complexity of the Averaged Evoked Potential: An Attentional Theory.

ERIC Educational Resources Information Center

Bates, Tim; And Others

1995-01-01

A study measuring average evoked potentials in 21 college students finds that intelligence test scores correlate significantly with the difference between string length in attended and nonattended conditions, a finding that suggests that previous inconsistencies in reporting string length-intelligence correlations may have resulted from confound…

Implementation of a microprocessor-based visual-evoked cortical potential recording and analysis system.

PubMed

Wilson, A; Fram, D; Sistar, J

1981-06-01

An Imsai 8080 microcomputer is being used to simultaneously generate a color graphics stimulus display and to record visual-evoked cortical potentials. A brief description of the hardware and software developed for this system is presented. Data storage and analysis techniques are also discussed.

Neural Dynamics Underlying Event-Related Potentials

NASA Technical Reports Server (NTRS)

Shah, Ankoor S.; Bressler, Steven L.; Knuth, Kevin H.; Ding, Ming-Zhou; Mehta, Ashesh D.; Ulbert, Istvan; Schroeder, Charles E.

2003-01-01

There are two opposing hypotheses about the brain mechanisms underlying sensory event-related potentials (ERPs). One holds that sensory ERPs are generated by phase resetting of ongoing electroencephalographic (EEG) activity, and the other that they result from signal averaging of stimulus-evoked neural responses. We tested several contrasting predictions of these hypotheses by direct intracortical analysis of neural activity in monkeys. Our findings clearly demonstrate evoked response contributions to the sensory ERP in the monkey, and they suggest the likelihood that a mixed (Evoked/Phase Resetting) model may account for the generation of scalp ERPs in humans.

Light transmission and preference of eye patches for occlusion treatment.

PubMed

Heo, Hwan; Park, Jung Won; Park, Sang Woo

2013-01-01

To investigate light transmission and preference for six eye patches for occlusion therapy. Six patches were examined, including; Ortopad Fun Pack, Ortopad Flesh, Kawamoto A-1, Kawamoto A-2, 3M Opticlude, and Everade Eye Guard. The size and the presence of a light blocking pad of patches were investigated. The amount of light transmitted through the patches was evaluated, using a digital light meter and a model eye, in three different environments; indoors with fluorescent light, outdoors on a sunny day, and strong light from illuminator. After patching the normal eye, the flash visual evoked potential (VEP) was measured. Thirty patients with amblyopia or horizontal strabismus, who received occlusion therapy as initial treatment, were included. After using all six patches, patients completed a 7-item questionnaire regarding the patch preference for size, color and shape, adhesive power, pain with removal, skin irritation after removing patch, parent's preference and overall opinion. All patches had a light-blocking pad, except the 3M Nexcare. Ortopad had the strongest light blocking power in the three environments, and the 3M Nexcare had the weakest power. In flash VEP, Ortopad and Kawamoto patches showed flat, but 3M Nexcare and Everade Eye Guard showed normal response. There were significant preferential differences among the patches in all the items of the questionnaire (P<0.05). In comparison between the patches respectively, 3M Nexcare received the lowest satisfaction in pain when removing a patch and skin irritation after removing a patch. Kawamoto A-2 received the lowest score in the overall satisfaction. We found differences in the light-blocking power and in the preference of the various patches for the occlusion treatment. This is a pilot study regarding only characteristics and preferences of patches. Further clinical studies regarding the relationship between characteristics or preferences of patches and outcomes of occlusion treatment are needed.

Automated cortical auditory evoked potentials threshold estimation in neonates.

PubMed

Oliveira, Lilian Sanches; Didoné, Dayane Domeneghini; Durante, Alessandra Spada

2018-02-02

The evaluation of Cortical Auditory Evoked Potential has been the focus of scientific studies in infants. Some authors have reported that automated response detection is effective in exploring these potentials in infants, but few have reported their efficacy in the search for thresholds. To analyze the latency, amplitude and thresholds of Cortical Auditory Evoked Potential using an automatic response detection device in a neonatal population. This is a cross-sectional, observational study. Cortical Auditory Evoked Potentials were recorded in response to pure-tone stimuli of the frequencies 500, 1000, 2000 and 4000Hz presented in an intensity range between 0 and 80dB HL using a single channel recording. P1 was performed in an exclusively automated fashion, using Hotelling's T 2 statistical test. The latency and amplitude were obtained manually by three examiners. The study comprised 39 neonates up to 28 days old of both sexes with presence of otoacoustic emissions and no risk factors for hearing loss. With the protocol used, Cortical Auditory Evoked Potential responses were detected in all subjects at high intensity and thresholds. The mean thresholds were 24.8±10.4dB NA, 25±9.0dB NA, 28±7.8dB NA and 29.4±6.6dB HL for 500, 1000, 2000 and 4000Hz, respectively. Reliable responses were obtained in the assessment of cortical auditory potentials in the neonates assessed with a device for automatic response detection. Copyright © 2018 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Electroencephalogram (EEG) and Magnetoencephalogram (MEG) as Tools for Evaluation of Cognitive Function

NASA Technical Reports Server (NTRS)

Fender, Derek H.; Hestenes, John D.

1985-01-01

We have developed computerized analysis and display techniques to help identify the origins of visually evoked scalped potentials (VESP). The potentials are recorded simultaneously from many electrodes (usually 40 to 48) spaced over the region of the scalp where appreciable evoked potentials are found in response to particular stimulus. Contour mapping algorithms are then used to display the time behavior of equipotential surfaces on the scalp during the VESP. We then use an optimization technique to select the parameters of arrays of current dipole sources within the model until the model equipotential field distribution closely fits the measured data. Computer graphics are then used to display, as a movie, the actual and model scalp potential fields and the parameters of the dipole generators within the model head during the course of VESP activity. We have devised reaction time tests that involve potentially separable stages of cognitive processing and utilize stimuli that produce measurable cognition-related features in the late component of the evoked potential. We have used these techniques to determine the loci in the brain where known cognition-related features in the evoked potential are generated and we have explored the extent to which each of these features can be related to the reaction time tasks. We have also examined the temporal-spatial aspects of their cerebral involvement. Our current work is planned to characterize the age-related changes in the processes performed by such sources. We also use a neuromagnetometer to measure the evoked magnetic fields in similar circumstances; we will discuss the relative merits of the two methodologies.

Attentional load modulates responses of human primary visual cortex to invisible stimuli.

PubMed

Bahrami, Bahador; Lavie, Nilli; Rees, Geraint

2007-03-20

Visual neuroscience has long sought to determine the extent to which stimulus-evoked activity in visual cortex depends on attention and awareness. Some influential theories of consciousness maintain that the allocation of attention is restricted to conscious representations [1, 2]. However, in the load theory of attention [3], competition between task-relevant and task-irrelevant stimuli for limited-capacity attention does not depend on conscious perception of the irrelevant stimuli. The critical test is whether the level of attentional load in a relevant task would determine unconscious neural processing of invisible stimuli. Human participants were scanned with high-field fMRI while they performed a foveal task of low or high attentional load. Irrelevant, invisible monocular stimuli were simultaneously presented peripherally and were continuously suppressed by a flashing mask in the other eye [4]. Attentional load in the foveal task strongly modulated retinotopic activity evoked in primary visual cortex (V1) by the invisible stimuli. Contrary to traditional views [1, 2, 5, 6], we found that availability of attentional capacity determines neural representations related to unconscious processing of continuously suppressed stimuli in human primary visual cortex. Spillover of attention to cortical representations of invisible stimuli (under low load) cannot be a sufficient condition for their awareness.

Unisensory processing and multisensory integration in schizophrenia: A high-density electrical mapping study

PubMed Central

Stone, David B.; Urrea, Laura J.; Aine, Cheryl J.; Bustillo, Juan R.; Clark, Vincent P.; Stephen, Julia M.

2011-01-01

In real-world settings, information from multiple sensory modalities is combined to form a complete, behaviorally salient percept - a process known as multisensory integration. While deficits in auditory and visual processing are often observed in schizophrenia, little is known about how multisensory integration is affected by the disorder. The present study examined auditory, visual, and combined audio-visual processing in schizophrenia patients using high-density electrical mapping. An ecologically relevant task was used to compare unisensory and multisensory evoked potentials from schizophrenia patients to potentials from healthy normal volunteers. Analysis of unisensory responses revealed a large decrease in the N100 component of the auditory-evoked potential, as well as early differences in the visual-evoked components in the schizophrenia group. Differences in early evoked responses to multisensory stimuli were also detected. Multisensory facilitation was assessed by comparing the sum of auditory and visual evoked responses to the audio-visual evoked response. Schizophrenia patients showed a significantly greater absolute magnitude response to audio-visual stimuli than to summed unisensory stimuli when compared to healthy volunteers, indicating significantly greater multisensory facilitation in the patient group. Behavioral responses also indicated increased facilitation from multisensory stimuli. The results represent the first report of increased multisensory facilitation in schizophrenia and suggest that, although unisensory deficits are present, compensatory mechanisms may exist under certain conditions that permit improved multisensory integration in individuals afflicted with the disorder. PMID:21807011

Flash-point prediction for binary partially miscible mixtures of flammable solvents.

PubMed

Liaw, Horng-Jang; Lu, Wen-Hung; Gerbaud, Vincent; Chen, Chan-Cheng

2008-05-30

Flash point is the most important variable used to characterize fire and explosion hazard of liquids. Herein, partially miscible mixtures are presented within the context of liquid-liquid extraction processes. This paper describes development of a model for predicting the flash point of binary partially miscible mixtures of flammable solvents. To confirm the predictive efficacy of the derived flash points, the model was verified by comparing the predicted values with the experimental data for the studied mixtures: methanol+octane; methanol+decane; acetone+decane; methanol+2,2,4-trimethylpentane; and, ethanol+tetradecane. Our results reveal that immiscibility in the two liquid phases should not be ignored in the prediction of flash point. Overall, the predictive results of this proposed model describe the experimental data well. Based on this evidence, therefore, it appears reasonable to suggest potential application for our model in assessment of fire and explosion hazards, and development of inherently safer designs for chemical processes containing binary partially miscible mixtures of flammable solvents.

Electro-optical muzzle flash detection

NASA Astrophysics Data System (ADS)

Krieg, Jürgen; Eisele, Christian; Seiffer, Dirk

2016-10-01

Localizing a shooter in a complex scenario is a difficult task. Acoustic sensors can be used to detect blast waves. Radar technology permits detection of the projectile. A third method is to detect the muzzle flash using electro-optical devices. Detection of muzzle flash events is possible with focal plane arrays, line and single element detectors. In this paper, we will show that the detection of a muzzle flash works well in the shortwave infrared spectral range. Important for the acceptance of an operational warning system in daily use is a very low false alarm rate. Using data from a detector with a high sampling rate the temporal signature of a potential muzzle flash event can be analyzed and the false alarm rate can be reduced. Another important issue is the realization of an omnidirectional view required on an operational level. It will be shown that a combination of single element detectors and simple optics in an appropriate configuration is a capable solution.

The steady-state visual evoked potential in vision research: A review

PubMed Central

Norcia, Anthony M.; Appelbaum, L. Gregory; Ales, Justin M.; Cottereau, Benoit R.; Rossion, Bruno

2015-01-01

Periodic visual stimulation and analysis of the resulting steady-state visual evoked potentials were first introduced over 80 years ago as a means to study visual sensation and perception. From the first single-channel recording of responses to modulated light to the present use of sophisticated digital displays composed of complex visual stimuli and high-density recording arrays, steady-state methods have been applied in a broad range of scientific and applied settings.The purpose of this article is to describe the fundamental stimulation paradigms for steady-state visual evoked potentials and to illustrate these principles through research findings across a range of applications in vision science. PMID:26024451

Binaural Interaction in Specific Language Impairment: An Auditory Evoked Potential Study

ERIC Educational Resources Information Center

Clarke, Elaine M; Adams, Catherine

2007-01-01

The aim of the study was to examine whether auditory binaural interaction, defined as any difference between binaurally evoked responses and the sum of monaurally evoked responses, which is thought to index functions involved in the localization and detection of signals in background noise, is atypical in a group of children with specific language…

On the effects of improved cross-section representation in one dimensional flow routing models applied to ephemeral rivers

USDA-ARS?s Scientific Manuscript database

Flash floods are an important component of the semi-arid hydrological cycle, and provide the potential for groundwater recharge as well as posing a dangerous natural hazard. A number of catchment models have been applied to flash flood prediction; however, in general they perform poorly. This study ...

A Steady State Visually Evoked Potential Investigation of Memory and Ageing

ERIC Educational Resources Information Center

Macpherson, Helen; Pipingas, Andrew; Silberstein, Richard

2009-01-01

Old age is generally accompanied by a decline in memory performance. Specifically, neuroimaging and electrophysiological studies have revealed that there are age-related changes in the neural correlates of episodic and working memory. This study investigated age-associated changes in the steady state visually evoked potential (SSVEP) amplitude and…

Basic Hearing and Echolocation Mechanisms of Marine Mammals: Measured Auditory Evoked Potential and Behavioral Experiments FY 2007

DTIC Science & Technology

2007-01-01

Breese, M. (2007) Evoked-potential recovery during double click stimulation in a whale: A possibility of biosonar automatic gain control. Journal of...Yokohama Japan (published) Supin A.Ya, Nachtigall, P.E., and Breese, M. Source level to sensation level ratio of transmitted biosonar pulses in an

Short-Latency Median-Nerve Somatosensory-Evoked Potentials and Induced Gamma-Oscillations in Humans

ERIC Educational Resources Information Center

Fukuda, Miho; Nishida, Masaaki; Juhasz, Csaba; Muzik, Otto; Sood, Sandeep; Chugani, Harry T.; Asano, Eishi

2008-01-01

Recent studies have suggested that cortical gamma-oscillations are tightly linked with various forms of physiological activity. In the present study, the dynamic changes of intracranially recorded median-nerve somatosensory-evoked potentials (SEPs) and somatosensory-induced gamma-oscillations were animated on a three-dimensional MR image, and the…

Temporal processing and long-latency auditory evoked potential in stutterers.

PubMed

Prestes, Raquel; de Andrade, Adriana Neves; Santos, Renata Beatriz Fernandes; Marangoni, Andrea Tortosa; Schiefer, Ana Maria; Gil, Daniela

Stuttering is a speech fluency disorder, and may be associated with neuroaudiological factors linked to central auditory processing, including changes in auditory processing skills and temporal resolution. To characterize the temporal processing and long-latency auditory evoked potential in stutterers and to compare them with non-stutterers. The study included 41 right-handed subjects, aged 18-46 years, divided into two groups: stutterers (n=20) and non-stutters (n=21), compared according to age, education, and sex. All subjects were submitted to the duration pattern tests, random gap detection test, and long-latency auditory evoked potential. Individuals who stutter showed poorer performance on Duration Pattern and Random Gap Detection tests when compared with fluent individuals. In the long-latency auditory evoked potential, there was a difference in the latency of N2 and P3 components; stutterers had higher latency values. Stutterers have poor performance in temporal processing and higher latency values for N2 and P3 components. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Brainstem auditory evoked potential wave V latency-intensity function in normal Dalmatian and Beagle puppies.

PubMed

Poncelet, L; Coppens, A; Deltenre, P

2000-01-01

This study investigated whether Dalmatian puppies with normal hearing bilaterally had the same click-evoked brainstem auditory potential characteristics as age-matched dogs of another breed. Short-latency brainstem auditory potentials evoked by condensation and rarefaction clicks were recorded in 23 1.5- to 2-month-old Dalmatian puppies with normal hearing bilaterally by a qualitative brainstem auditory evoked potential test and in 16 Beagle dogs of the same age. For each stimulus intensity, from 90 dB normal hearing level down to the wave V threshold, the sum of the potentials evoked by the 2 kinds of stimuli were added, giving an equivalent to the alternate click polarity stimulation. The slope of the L segment of the wave V latency-intensity curve was steeper in Dalmatian (-40 +/- 10 micros/dB) than in Beagles (-28 +/- 5 micros/dB, P < .001) puppies. The hearing threshold was lower in the Beagle puppies (P < .05). These results suggest that interbreed differences may exist at the level of cochlear function in this age class. The wave V latency and wave V-wave I latencies differences at high stimulus intensity were different between the groups of puppies (4.3 +/- 0.2 and 2.5 +/- 0.2 milliseconds, respectively, for Beagles; and 4.1 +/- 0.2 and 2.3 +/- 0.2 milliseconds for Dalmatians, P < .05). A different maturation speed of the neural pathways is one possible explanation of this observation.

Effects of propofol, sevoflurane, remifentanil, and (S)-ketamine in subanesthetic concentrations on visceral and somatosensory pain-evoked potentials.

PubMed

Untergehrer, Gisela; Jordan, Denis; Eyl, Sebastian; Schneider, Gerhard

2013-02-01

Although electroencephalographic parameters and auditory evoked potentials (AEP) reflect the hypnotic component of anesthesia, there is currently no specific and mechanism-based monitoring tool for anesthesia-induced blockade of nociceptive inputs. The aim of this study was to assess visceral pain-evoked potentials (VPEP) and contact heat-evoked potentials (CHEP) as electroencephalographic indicators of drug-induced changes of visceral and somatosensory pain. Additionally, AEP and electroencephalographic permutation entropy were used to evaluate sedative components of the applied drugs. In a study enrolling 60 volunteers, VPEP, CHEP (amplitude N2-P1), and AEP (latency Nb, amplitude Pa-Nb) were recorded without drug application and at two subanesthetic concentration levels of propofol, sevoflurane, remifentanil, or (s)-ketamine. Drug-induced changes of evoked potentials were analyzed. VPEP were generated by electric stimuli using bipolar electrodes positioned in the distal esophagus. For CHEP, heat pulses were given to the medial aspect of the right forearm using a CHEP stimulator. In addition to AEP, electroencephalographic permutation entropy was used to indicate level of sedation. With increasing concentrations of propofol, sevoflurane, remifentanil, and (s)-ketamine, VPEP and CHEP N2-P1 amplitudes decreased. AEP and electroencephalographic permutation entropy showed neither clinically relevant nor statistically significant suppression of cortical activity during drug application. Decreasing VPEP and CHEP amplitudes under subanesthetic concentrations of propofol, sevoflurane, remifentanil, and (s)-ketamine indicate suppressive drug effects. These effects seem to be specific for analgesia.

Visual evoked potentials in patients after methanol poisoning.

PubMed

Urban, Pavel; Zakharov, Sergey; Diblík, Pavel; Pelclová, Daniela; Ridzoň, Petr

2016-01-01

We report the results of the visual evoked potentials (VEP) examination in patients after severe poisoning by methanol. The group of 47 patients (38 males and 9 females) was assembled out of persons who survived an outbreak of poisoning by the methanol adulterated alcohol beverages, which happened in the Czech Republic in 2012-2013. The visual evoked potentials examination was performed using monocular checkerboard pattern-reversal stimulation. Two criteria of abnormality were chosen: missing evoked response, and wave P1 latency > 117 ms. Non-parametric statistical methods (median, range, and the median test) were used to analyze factors influencing the VEP abnormality. The visual evoked potential was abnormal in 20 patients (43%), 5 of them had normal visual acuity on the Snellen chart. The VEP abnormality did not correlate significantly with initial serum concentrations of methanol, formic acid or lactate; however, it showed statistically significant inverse relation to the initial serum pH: the subgroup with the abnormal VEP had significantly lower median pH in comparison with the subgroup with the normal VEP (7.16 vs. 7.34, p = 0.04). The abnormality was not related to chronic alcohol abuse. The visual evoked potentials examination appeared sensitive enough to detected even subclinical impairment of the optic system. Metabolic acidosis is likely to be the key factor related to the development of visual damage induced by methanol. The examination performed with a delay of 1-9 months after the poisoning documented the situation relatively early after the event. It is considered as a baseline for the planned long-term follow-up of the patients, which will make it possible to assess the dynamics of the observed changes, their reversibility, and the occurrence of potential late sequelae. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Use of auditory evoked potentials for intra-operative awareness in anesthesia: a consciousness-based conceptual model.

PubMed

Dong, Xuebao; Suo, Puxia; Yuan, Xin; Yao, Xuefeng

2015-01-01

Auditory evoked potentials (AEPs) have been used as a measure of the depth of anesthesia during the intra-operative process. AEPs are classically divided, on the basis of their latency, into first, fast, middle, slow, and late components. The use of auditory evoked potential has been advocated for the assessment of Intra-operative awareness (IOA), but has not been considered seriously enough to universalize it. It is because we have not explored enough the impact of auditory perception and auditory processing on the IOA phenomena as well as on the subsequent psychological impact of IOA on the patient. More importantly, we have seldom tried to look at the phenomena of IOP from the perspective of consciousness itself. This perspective is especially important because many of IOA phenomena exist in the subconscious domain than they do in the conscious domain of explicit recall. Two important forms of these subconscious manifestations of IOA are the implicit recall phenomena and post-operative dreams related to the operation. Here, we present an integrated auditory consciousness-based model of IOA. We start with a brief description of auditory awareness and the factors affecting it. Further, we proceed to the evaluation of conscious and subconscious information processing by auditory modality and how they interact during and after intra-operative period. Further, we show that both conscious and subconscious auditory processing affect the IOA experience and both have serious psychological implications on the patient subsequently. These effects could be prevented by using auditory evoked potential during monitoring of anesthesia, especially the mid-latency auditory evoked potentials (MLAERs). To conclude our model with present hypothesis, we propose that the use of auditory evoked potential should be universal with general anesthesia use in order to prevent the occurrences of distressing outcomes resulting from both conscious and subconscious auditory processing during anesthesia.

Cultural shaping of neural responses: Feedback-related potentials vary with self-construal and face priming.

PubMed

Hitokoto, Hidefumi; Glazer, James; Kitayama, Shinobu

2016-01-01

Previous work shows that when an image of a face is presented immediately prior to each trial of a speeded cognitive task (face-priming), the error-related negativity (ERN) is upregulated for Asians, but it is downregulated for Caucasians. These findings are consistent with the hypothesis that images of "generalized other" vary cross-culturally such that they evoke anxiety for Asians, whereas they serve as safety cues for Caucasians. Here, we tested whether the cross-cultural variation in the face-priming effect would be observed in a gambling paradigm. Caucasian Americans, Asian Americans, and Asian sojourners were exposed to a brief flash of a schematic face during a gamble. For Asian Americans, face-priming resulted in significant increases of both negative-going deflection of ERP upon negative feedback (feedback-related negativity [FRN]) and positive-going deflection of ERP upon positive feedback (feedback-related positivity [FRP]). For Caucasian Americans, face-priming showed a significant reversal, decreasing both FRN and FRP. The cultural difference in the face-priming effect in FRN and FRP was partially mediated by interdependent self-construal. Curiously, Asian sojourners showed a pattern similar to the one for Caucasian Americans. Our findings suggest that culture shapes neural pathways in both systematic and highly dynamic fashion. © 2015 Society for Psychophysiological Research.

ANXIETY AS A RISK FACTOR FOR MENOPAUSAL HOT FLASHES: EVIDENCE FROM THE PENN OVARIAN AGING COHORT

PubMed Central

Freeman, Ellen W.; Sammel, Mary D.

2016-01-01

Objective The aim of this study was to identify temporal associations of anxiety dimensions with menopausal hot flashes in women progressing through the menopause transition. We hypothesized that associations of both somatic and affective dimensions of anxiety with hot flashes increased in the menopause transition, and that somatic anxiety was an independent risk factor for menopausal hot flashes. Methods Hot flashes, anxiety symptoms, hormone levels and other psychosocial variables were assessed annually for 14 years of follow-up. The 233 women were premenopausal at baseline and continued through one year or more after the final menstrual period. Anxiety dimensions were assessed with the Zung Anxiety Scale (ZAS), a validated measure of affective anxiety and somatic anxiety. Summed item scores were divided by the number of items rated, so that ranges of the two dimensions were comparable. Results Seventy-two percent of the sample reported moderate/severe hot flashes during the 14-year interval. There was no significant interaction between anxiety dimensions and menopausal stages. However, when adjusted for menopausal stage, the magnitude of association between somatic anxiety and hot flashes dramatically increased (OR 3.03, 95% CI: 2.12, 4.32, P<0.001), while the association between affective anxiety and hot flashes increased to a lesser extent (OR 1.27, 95% CI: 1.03, 1.57, P=0.024). Women with high levels of somatic anxiety (top third of the sample) had the greatest risk of hot flashes (P<0.001). When the anxiety dimensions were considered in combination, the additive effect of high affective anxiety symptoms was minimal, with no significant difference between the group with high affective/low somatic symptoms and the low symptom group in incident hot flashes at each menopausal stage (P=0.54). In multivariable analysis, somatic anxiety increased the risk of hot flashes more than 3 times (OR 3.13, 95% CI: 2.16, 4.53, P<0.001), but affective anxiety was not significantly associated with hot flashes after adjustment for other study variables (OR 1.19, 95% CI: 0.96, 1.48, P=0.117). Time-lagged somatic anxiety scores significantly predicted hot flashes, with a 71% increase in risk (OR 1.71, 95% CI: 1.21, 2.41, P=0.002). Time-lagged affective anxiety scores did not predict hot flashes, (OR 1.06, 95% CI: 0.87, 1.31, P=0.58). Conclusions This study showed a strong predictive association of somatic anxiety with the risk of menopausal hot flashes. The temporal associations suggest that somatic anxiety is not simply a redundant measure of hot flashes but predicts the risk of menopausal hot flashes and may be a potential target in clinical management of perimenopausal women. PMID:27433864

Identification of a novel mutation in the PTCH gene in a patient with Gorlin-Goltz syndrome with unusual ocular disorders.

PubMed

Romano, Mary; Iacovello, Daniela; Cascone, Nikhil C; Contestabile, Maria Teresa

2011-01-01

To document the clinical, functional, and in vivo microanatomic characteristics of a patient with Gorlin-Goltz syndrome with a novel nonsense mutation in PTCH (patched). Optical coherence tomography (OCT), fluorescein angiography, electrophysiologic testing, visual field, magnetic resonance imaging, and mutation screening of PTCH gene. Visual acuity was 20/20 in the right eye and 20/25 in the left. Fundus examination revealed myelinated nerve fibers in the left eye and bilateral epiretinal membranes with lamellar macular hole also documented with macular OCT. A reduction of the retinal nerve fiber layers in both eyes was found with fiber nervous OCT. Fluorescein angiography showed bilaterally foveal hyperfluorescence and the visual field revealed inferior hemianopia in the right eye. Pattern visual evoked potentials registered a reduction of amplitude in both eyes and latency was delayed in the left eye. Pattern electroretinogram showed a reduction in P50 and N95 peak time and a delay in P50 peak time in the left eye. Flash electroretinogram was reduced in rod response, maximal response, and oscillatory potentials in both eyes. Cone response was normal and 30-Hz flicker was slightly reduced in both eyes. Mutation screening identified a novel nonsense mutation in PTCH. A novel nonsense mutation in the PTCH gene was found. We report the occurrence of epiretinal membranes and the persistence of myelinated nerve fibers. Electrophysiologic and visual field alterations, supporting a neuroretinal dysfunction, were also documented.

Bisensory stimulation increases gamma-responses over multiple cortical regions.

PubMed

Sakowitz, O W; Quiroga, R Q; Schürmann, M; Başar, E

2001-04-01

In the framework of the discussion about gamma (approx. 40 Hz) oscillations as information carriers in the brain, we investigated the relationship between gamma responses in the EEG and intersensory association. Auditory evoked potentials (AEPs) and visual evoked potentials (VEPs) were compared with bisensory evoked potentials (BEPs; simultaneous auditory and visual stimulation) in 15 subjects. Gamma responses in AEPs, VEPs and BEPs were assessed by means of wavelet decomposition. Overall maximum gamma-components post-stimulus were highest in BEPs (P < 0.01). Bisensory evoked gamma-responses also showed significant central, parietal and occipital amplitude-increases (P < 0.001, P < 0.01, P < 0.05, respectively; prestimulus interval as baseline). These were of greater magnitude when compared with the unisensory responses. As a correlate of the marked gamma responses to bimodal stimulation we suggest a process of 'intersensory association', i.e. one of the steps between sensory transmission and perception. Our data may be interpreted as a further example of function-related gamma responses in the EEG.

Daidzein-rich isoflavone aglycones are potentially effective in reducing hot flashes in menopausal women.

PubMed

Khaodhiar, Lalita; Ricciotti, Hope A; Li, Linglin; Pan, Weijun; Schickel, Mary; Zhou, Jinrong; Blackburn, George L

2008-01-01

The aim of this study was to determine the effect of DRIs on hot flash symptoms in menopausal women. This was a randomized, double-blind, placebo-controlled trial of menopausal women, aged 38 to 60 years, who experienced 4 to 14 hot flashes per day. After a 1-week run-in period, a total of 190 menopausal women were randomized to receive a placebo or 40 or 60 mg/day of a DRI for 12 weeks. The primary outcome was the mean changes from baseline to week 12 in the frequency of hot flashes recorded in the participant diary. The secondary outcomes included changes in quality of life and hormonal profiles. A total of 147 women (77%) completed the study. It was found that 40 and 60 mg of DRI improved hot flash frequency and severity equally. At 8 weeks hot flash frequency was reduced by 43% in the 40-mg DRI group and by 41% in the 60-mg DRI group, compared with 32% in the placebo group (P = not significant vs placebo). The corresponding numbers for 12 weeks were 52%, 51%, and 39%, respectively (P = 0.07 and 0.09 vs placebo). When comparing the two treatment groups with the placebo group, there were significant reductions in mean daily hot flash frequency. The supplement (either 40 or 60 mg) reduced hot flash frequency by 43% at 8 weeks (P = 0.1) and 52% at 12 weeks (P = 0.048) but did not cause any significant changes in endogenous sex hormones or thyroid hormones. Menopausal quality of life improved in all three groups, although there were no statistically significant differences between groups. DRI supplementation may be an effective and acceptable alternative to hormone treatment for menopausal hot flashes.

Influence of detomidine and buprenorphine on motor-evoked potentials in horses.

PubMed

Nollet, H; Van Ham, L; Gasthuys, F; Dewulf, J; Vanderstraeten, G; Deprez, P

2003-04-26

Horses need to be sedated before they are investigated by transcranial magnetic stimulation because of the mild discomfort induced by the evoked muscle contraction and the noise of stimulation. This paper describes the influence of a combination of detomidine (10 microg/kg bodyweight) and a low dose of buprenorphine (2.4 microg/kg) on the onset latency and peak-to-peak amplitude of magnetic motor-evoked potentials in normal horses. There were no significant differences between measurements of these parameters made before the horses were sedated and measurements made 10 and 30 minutes after the drugs were administered.

[Evoked potentials N200/P300 disorders and clinical phenotype in Cuban families with paranoid schizophrenia: a family-based association study].

PubMed

Guerra López, Seidel; Martín Reyes, Migdyrai; Pedroso Rodríguez, María de Los Ángeles; Reyes Berazain, Adnelys; Mendoza Quiñones, Raúl; Bravo Collazo, Tania Martha; Días de Villarvilla, Thais; Machado Cano, María Julia; Bobés León, María Antonieta

2015-04-01

N200 and P300 event-related evoked potentials provide sensitive measurements of sensory and cognitive function and have been used to study information processing in patients with schizophrenia and their unaffected first-degree relatives. Reduced amplitude and increased latency of N200 and P300 potentials have been consistently reported in schizophrenia. Thus, event-related evoked potentials abnormalities are promising possible biological markers for genetic vulnerability to schizophrenia. To assess the association of changes in latency, amplitude and topographic distribution of potentials N200 and P300 of patients with paranoid schizophrenia and their healthy first-degree relatives, in families with schizophrenia multiplex. We measured latency and amplitude of the N200 and P300 component of evoked potentials using an auditory odd-ball paradigm in 25 schizophrenic patients (probands) from 60 families multiply affected with paranoid schizophrenia, 23 of their non-schizophrenic first-degree relatives and 25 unrelated healthy controls, through a study of family association. Schizophrenic patients and their relatives showed significant latency prolongation and amplitude reduction of the N200 and P300 waves compared to controls. Left-temporal as compared to right-temporal N200 and P300 were significantly smaller in schizophrenic patients and their non-schizophrenic first-degree relatives than in controls. Our results suggest that event-related evoked potentials abnormalities may serve as markers of genetic vulnerability in schizophrenia. Confirming results of other researchers, this present study suggests that latency prolongation and amplitude reduction of the N200 and P300 waves and an altered topography at temporal sites may be a trait “marker” of paranoid schizophrenia.

Auditory evoked potentials in children and adolescents with Down syndrome.

PubMed

Gregory, Letícia; Rosa, Rafael F M; Zen, Paulo R G; Sleifer, Pricila

2018-01-01

Down syndrome, or trisomy 21, is the most common genetic alteration in humans. The syndrome presents with several features, including hearing loss and changes in the central nervous system, which may affect language development in children and lead to school difficulties. The present study aimed to investigate group differences in the central auditory system by long-latency auditory evoked potentials and cognitive potential. An assessment of 23 children and adolescents with Down syndrome was performed, and a control group composed of 43 children and adolescents without genetic and/or neurological changes was used for comparison. All children underwent evaluation with pure tone and vocal audiometry, acoustic immitance measures, long-latency auditory evoked potentials, and cognitive potential. Longer latencies of the waves were found in the Down syndrome group than the control group, without significant differences in amplitude, suggesting that individuals with Down syndrome have difficulty in discrimination and auditory memory. It is, therefore, important to stimulate and monitor these children in order to enable adequate development and improve their life quality. We also emphasize the importance of the application of auditory evoked potentials in clinical practice, in order to contribute to the early diagnosis of hearing alterations and the development of more research in this area. © 2017 Wiley Periodicals, Inc.

Laryngeal and tracheal afferent nerve stimulation evokes swallowing in anaesthetized guinea pigs

PubMed Central

Tsujimura, Takanori; Udemgba, Chioma; Inoue, Makoto; Canning, Brendan J

2013-01-01

We describe swallowing reflexes evoked by laryngeal and tracheal vagal afferent nerve stimulation in anaesthetized guinea pigs. The swallowing reflexes evoked by laryngeal citric acid challenges were abolished by recurrent laryngeal nerve (RLN) transection and mimicked by electrical stimulation of the central cut ends of an RLN. By contrast, the number of swallows evoked by upper airway/pharyngeal distensions was not significantly reduced by RLN transection but they were virtually abolished by superior laryngeal nerve transection. Laryngeal citric acid-evoked swallowing was mimicked by laryngeal capsaicin challenges, implicating transient receptor potential vanilloid 1 (TRPV1)-expressing laryngeal afferent nerves arising from the jugular ganglia. The swallowing evoked by citric acid and capsaicin and evoked by electrical stimulation of either the tracheal or the laryngeal mucosa occurred at stimulation intensities that were typically subthreshold for evoking cough in these animals. Swallowing evoked by airway afferent nerve stimulation also desensitized at a much slower rate than cough. We speculate that swallowing is an essential component of airway protection from aspiration associated with laryngeal and tracheal afferent nerve activation. PMID:23858010

Altered Automatic Face Processing in Individuals with High-Functioning Autism Spectrum Disorders: Evidence from Visual Evoked Potentials

ERIC Educational Resources Information Center

Fujita, Takako; Kamio, Yoko; Yamasaki, Takao; Yasumoto, Sawa; Hirose, Shinichi; Tobimatsu, Shozo

2013-01-01

Individuals with autism spectrum disorders (ASDs) have different automatic responses to faces than typically developing (TD) individuals. We recorded visual evoked potentials (VEPs) in 10 individuals with high-functioning ASD (HFASD) and 10 TD individuals. Visual stimuli consisted of upright and inverted faces (fearful and neutral) and objects…

Attentional Modulation of Visual-Evoked Potentials by Threat: Investigating the Effect of Evolutionary Relevance

ERIC Educational Resources Information Center

Brown, Christopher; El-Deredy, Wael; Blanchette, Isabelle

2010-01-01

In dot-probe tasks, threatening cues facilitate attention to targets and enhance the amplitude of the target P1 peak of the visual-evoked potential. While theories have suggested that evolutionarily relevant threats should obtain preferential neural processing, this has not been examined empirically. In this study we examined the effects of…

Effect of combined opioid receptor and α2-adrenoceptor blockade on anxiety and electrically evoked startle responses.

PubMed

Vo, Lechi; Drummond, Peter D

2017-06-01

The R3 component of the electrically evoked blink reflex may form part of a startle reaction. Acoustic startle responses are augmented by yohimbine, an α 2 -adrenoceptor antagonist that blocks α 2 -autoreceptors, and are potentiated by opioid receptor blockade. To investigate these influences on electrically evoked startle responses, 16 mg yohimbine, with (16 participants) or without 50 mg naltrexone (23 participants), was administered in separate double-blind placebo-controlled cross-over experiments. In each experiment, R3 (a probable component of the startle response) was examined before and after high-frequency electrical stimulation of the forearm, a procedure that initiates inhibitory pain controls. Anxiety and somatic symptoms were greater after yohimbine than placebo, and were potentiated by naltrexone. Pain ratings for the electrically evoked startle stimuli decreased after high-frequency electrical stimulation in the placebo session but remained stable after drug administration. Yohimbine with naltrexone, but not yohimbine alone, also blocked an inhibitory effect of high-frequency electrical stimulation on electrically evoked sharp sensations and R3. Together, the findings suggest that adding naltrexone to yohimbine potentiated anxiety and blocked inhibitory influences of high-frequency electrical stimulation on electrically evoked sensations and startle responses. Thus, opioid peptides could reduce activity in nociceptive and startle-reflex pathways, or inhibit crosstalk between these pathways. Failure of this inhibitory opioid influence might be important in chronically painful conditions that are aggravated by startle stimuli.

Unisensory processing and multisensory integration in schizophrenia: a high-density electrical mapping study.

PubMed

Stone, David B; Urrea, Laura J; Aine, Cheryl J; Bustillo, Juan R; Clark, Vincent P; Stephen, Julia M

2011-10-01

In real-world settings, information from multiple sensory modalities is combined to form a complete, behaviorally salient percept - a process known as multisensory integration. While deficits in auditory and visual processing are often observed in schizophrenia, little is known about how multisensory integration is affected by the disorder. The present study examined auditory, visual, and combined audio-visual processing in schizophrenia patients using high-density electrical mapping. An ecologically relevant task was used to compare unisensory and multisensory evoked potentials from schizophrenia patients to potentials from healthy normal volunteers. Analysis of unisensory responses revealed a large decrease in the N100 component of the auditory-evoked potential, as well as early differences in the visual-evoked components in the schizophrenia group. Differences in early evoked responses to multisensory stimuli were also detected. Multisensory facilitation was assessed by comparing the sum of auditory and visual evoked responses to the audio-visual evoked response. Schizophrenia patients showed a significantly greater absolute magnitude response to audio-visual stimuli than to summed unisensory stimuli when compared to healthy volunteers, indicating significantly greater multisensory facilitation in the patient group. Behavioral responses also indicated increased facilitation from multisensory stimuli. The results represent the first report of increased multisensory facilitation in schizophrenia and suggest that, although unisensory deficits are present, compensatory mechanisms may exist under certain conditions that permit improved multisensory integration in individuals afflicted with the disorder. Copyright © 2011 Elsevier Ltd. All rights reserved.

Levetiracetam for the treatment of hot flashes: a phase II study.

PubMed

Thompson, Susan; Bardia, Aditya; Tan, Angelina; Barton, Debra L; Kottschade, Lisa; Sloan, Jeff A; Christensen, Brad; Smith, DeAnne; Loprinzi, Charles L

2008-01-01

The objectives of this pilot trial were to assess the potential efficacy and safety of levetiracetam for the treatment of hot flashes, a major cause of morbidity among breast cancer survivors. Women, aged 18 years or more, with a history of breast cancer or those who wished to avoid estrogen because of a perceived increased risk of breast cancer, who were experiencing bothersome hot flashes (more than or equal to 14 times per week, for more than or equal to 1 month before study entry), were included. During the baseline week, general demographic characteristics, hot flash information, and quality of life data were obtained. At the beginning of week 2, patients were started on levetiracetam for a total of 4 weeks. Information about hot flashes, quality of life, and toxicity were collected during these 4 weeks and compared with the baseline week. After treatment with levetiracetam for 4 weeks (N = 19), mean hot flash scores (frequency times mean severity) were reduced by 57%, and mean hot flash frequencies were reduced by 53%, compared to the baseline week; both these reductions were greater than what would be expected with a placebo (20-25% reduction). There were significant improvements in abnormal sweating (p = 0.004), hot flash distress (p = 0.0002), and satisfaction of hot flash control (p = 0.0001), when comparing data from the fourth week of treatment to the baseline week. Twenty-nine percent of the subjects did not complete the study because of treatment-related adverse events, with the most frequently reported side effects being somnolence, fatigue, and dizziness, usually with mild to moderate intensity. The results of this pilot trial suggest that levetiracetam might be an effective therapy for the treatment of hot flashes. Further data are needed to test this hypothesis, evaluating the efficacy and toxicity of this agent.

Cortical evoked potentials to an auditory illusion: binaural beats.

PubMed

Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

2009-08-01

To define brain activity corresponding to an auditory illusion of 3 and 6Hz binaural beats in 250Hz or 1000Hz base frequencies, and compare it to the sound onset response. Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000Hz to one ear and 3 or 6Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3Hz and 6Hz, in base frequencies of 250Hz and 1000Hz. Tones were 2000ms in duration and presented with approximately 1s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. All stimuli evoked tone-onset P(50), N(100) and P(200) components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P(50) had significantly different sources than the beats-evoked oscillations; and N(100) and P(200) sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp.

Cortical Evoked Potentials to an Auditory Illusion: Binaural Beats

PubMed Central

Pratt, Hillel; Starr, Arnold; Michalewski, Henry J.; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

2009-01-01

Objective: To define brain activity corresponding to an auditory illusion of 3 and 6 Hz binaural beats in 250 Hz or 1,000 Hz base frequencies, and compare it to the sound onset response. Methods: Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000 Hz to one ear and 3 or 6 Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3 Hz and 6 Hz, in base frequencies of 250 Hz and 1000 Hz. Tones were 2,000 ms in duration and presented with approximately 1 s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. Results: All stimuli evoked tone-onset P50, N100 and P200 components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P50 had significantly different sources than the beats-evoked oscillations; and N100 and P200 sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Conclusions: Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Significance: Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp. PMID:19616993

High Risk Flash Flood Rainstorm Mapping Based on Regional L-moments Approach

NASA Astrophysics Data System (ADS)

Ding, Hui; Liao, Yifan; Lin, Bingzhang

2017-04-01

Difficulties and complexities in elaborating flash flood early-warning and forecasting system prompt hydrologists to develop some techniques to substantially reduce the disastrous outcome of a flash flood in advance. An ideal to specify those areas that are subject at high risk to flash flood in terms of rainfall intensity in a relatively large region is proposed in this paper. It is accomplished through design of the High Risk Flash Flood Rainstorm Area (HRFFRA) based on statistical analysis of historical rainfall data, synoptic analysis of prevailing storm rainfalls as well as the field survey of historical flash flood events in the region. A HRFFRA is defined as the area potentially under hitting by higher intense-precipitation for a given duration with certain return period that may cause a flash flood disaster in the area. This paper has presented in detail the development of the HRFFRA through the application of the end-to-end Regional L-moments Approach (RLMA) to precipitation frequency analysis in combination with the technique of spatial interpolation in Jiangxi Province, South China Mainland. Among others, the concept of hydrometeorologically homogenous region, the precision of frequency analysis in terms of parameter estimation, the accuracy of quantiles in terms of uncertainties and the consistency adjustments of quantiles over durations and space, etc., have been addressed. At the end of this paper, the mapping of the HRFFRA and an internet-based visualized user-friendly data-server of the HRFFRA are also introduced. Key words: HRFFRA; Flash Flood; RLMA; rainfall intensity; Hydrometeorological homogenous region.

An investigation of life circumstances associated with the experience of hot flashes in Campeche, Mexico.

PubMed

Huicochea-Gómez, Laura; Sievert, Lynnette Leidy; Cahuich-Campos, Diana; Brown, Daniel E

2017-01-01

The purpose of this study was to better understand the experience of calores (hot flashes) in the state of Campeche, Mexico, and characteristics of women's lives. This study was carried out to understand the sociocultural context of women's lives before conducting a larger semistructured survey in the same communities. Eighty-five women from rural and urban settings participated in open-ended interviews about the menopausal transition, with particular attention to hot flashes. Univariate and logistic regression analyses identified potential determinants of hot flashes. Qualitative responses were analyzed for central themes from the 40 women who experienced "calores" associated with menopause at the time of interview. The word "calores" was used to describe a variety of sensations and experiences related to the hot climate, infections, going in and out of air-conditioning, emotional stress, and physical exertion, as well as the symptom associated with menopause. In quantitative analyses, the likelihood of experiencing hot flashes varied by menopause status and rural/urban residence. In qualitative analyses, themes that characterized the lives of women with hot flashes were as follows: the search for, and the availability of, biomedical care; presence or absence of networks of social support; marital status and quality of the relationship; and occupational stress. Hot flash questionnaires can elicit different symptom frequencies depending on the language used and the sociocultural context of women's lives. Qualitative findings suggest that the themes most likely to influence the perception and experience of hot flashes in Campeche are biomedicine, social support, marriage, and stress.

Thermoreceptive innervation of human glabrous and hairy skin: a contact heat evoked potential analysis.

PubMed

Granovsky, Yelena; Matre, Dagfinn; Sokolik, Alexander; Lorenz, Jürgen; Casey, Kenneth L

2005-06-01

The human palm has a lower heat detection threshold and a higher heat pain threshold than hairy skin. Neurophysiological studies of monkeys suggest that glabrous skin has fewer low threshold heat nociceptors (AMH type 2) than hairy skin. Accordingly, we used a temperature-controlled contact heat evoked potential (CHEP) stimulator to excite selectively heat receptors with C fibers or Adelta-innervated AMH type 2 receptors in humans. On the dorsal hand, 51 degrees C stimulation produced painful pinprick sensations and 41 degrees C stimuli evoked warmth. On the glabrous thenar, 41 degrees C stimulation produced mild warmth and 51 degrees C evoked strong but painless heat sensations. We used CHEP responses to estimate the conduction velocities (CV) of peripheral fibers mediating these sensations. On hairy skin, 41 degrees C stimuli evoked an ultra-late potential (mean, SD; N wave latency: 455 (118) ms) mediated by C fibers (CV by regression analysis: 1.28 m/s, N=15) whereas 51 degrees C stimuli evoked a late potential (N latency: 267 (33) ms) mediated by Adelta afferents (CV by within-subject analysis: 12.9 m/s, N=6). In contrast, thenar responses to 41 and 51 degrees C were mediated by C fibers (average N wave latencies 485 (100) and 433 (73) ms, respectively; CVs 0.95-1.35 m/s by regression analysis, N=15; average CV=1.7 (0.41) m/s calculated from distal glabrous and proximal hairy skin stimulation, N=6). The exploratory range of the human and monkey palm is enhanced by the abundance of low threshold, C-innervated heat receptors and the paucity of low threshold AMH type 2 heat nociceptors.

Comparative investigation of stimulus-evoked rod outer segment movement and retinal electrophysiological activity

NASA Astrophysics Data System (ADS)

Lu, Yiming; Wang, Benquan; Yao, Xincheng

2017-02-01

Transient retinal phototropism (TRP) has been observed in rod photoreceptors activated by oblique visible light flashes. Time-lapse confocal microscopy and optical coherence tomography (OCT) revealed rod outer segment (ROS) movements as the physical source of TRP. However, the physiological source of TRP is still not well understood. In this study, concurrent TRP and electroretinogram (ERG) measurements disclosed a remarkably earlier onset time of the ROS movements (<=10 ms) than that ( 38 ms) of the ERG a-wave. Furthermore, low sodium treatment reversibly blocked the photoreceptor ERG a-wave, which is known to reflect hyperpolarization of retinal photoreceptors, but preserved the TRP associated rod OS movements well. Our experimental results and theoretical analysis suggested that the physiological source of TRP might be attributed to early stages of phototransduction, before the hyperpolarization of retinal photoreceptors.

LOFAR Lightning Imaging: Mapping Lightning With Nanosecond Precision

NASA Astrophysics Data System (ADS)

Hare, B. M.; Scholten, O.; Bonardi, A.; Buitink, S.; Corstanje, A.; Ebert, U.; Falcke, H.; Hörandel, J. R.; Leijnse, H.; Mitra, P.; Mulrey, K.; Nelles, A.; Rachen, J. P.; Rossetto, L.; Rutjes, C.; Schellart, P.; Thoudam, S.; Trinh, T. N. G.; ter Veen, S.; Winchen, T.

2018-03-01

Lightning mapping technology has proven instrumental in understanding lightning. In this work we present a pipeline that can use lightning observed by the LOw-Frequency ARray (LOFAR) radio telescope to construct a 3-D map of the flash. We show that LOFAR has unparalleled precision, on the order of meters, even for lightning flashes that are over 20 km outside the area enclosed by LOFAR antennas (˜3,200 km2), and can potentially locate over 10,000 sources per lightning flash. We also show that LOFAR is the first lightning mapping system that is sensitive to the spatial structure of the electrical current during individual lightning leader steps.

Estimating Single-Trial Responses in EEG

NASA Technical Reports Server (NTRS)

Shah, A. S.; Knuth, K. H.; Truccolo, W. A.; Mehta, A. D.; Fu, K. G.; Johnston, T. A.; Ding, M.; Bressler, S. L.; Schroeder, C. E.; Clancy, Daniel (Technical Monitor)

2002-01-01

Accurate characterization of single-trial field potential responses is critical from a number of perspectives. For example, it allows differentiation of an evoked response from ongoing EEG. We previously developed the multiple component Event Related Potential (mcERP) algorithm to improve resolution of the single-trial evoked response. The mcERP model states that multiple components, each specified by a stereotypic waveform varying in latency and amplitude from trial to trial, comprise the evoked response. Application of the mcERP algorithm to simulated data with three independent, synthetic components has shown that the model is capable of separating these components and estimating their variability. Application of the model to single trial, visual evoked potentials recorded simultaneously from all V1 laminae in an awake, fixating macaque yielded local and far-field components. Certain local components estimated by the model were distributed in both granular and supragranular laminae. This suggests a linear coupling between the responses of thalamo-recipient neuronal ensembles and subsequent responses of supragranular neuronal ensembles, as predicted by the feedforward anatomy of V1. Our results indicate that the mcERP algorithm provides a valid estimation of single-trial responses. This will enable analyses that depend on trial-to-trial variations and those that require separation of the evoked response from background EEG rhythms

Auditory fear conditioning modifies steady-state evoked potentials in the rat inferior colliculus.

PubMed

Lockmann, André Luiz Vieira; Mourão, Flávio Afonso Gonçalves; Moraes, Marcio Flávio Dutra

2017-08-01

The rat inferior colliculus (IC) is a major midbrain relay for ascending inputs from the auditory brain stem and has been suggested to play a key role in the processing of aversive sounds. Previous studies have demonstrated that auditory fear conditioning (AFC) potentiates transient responses to brief tones in the IC, but it remains unexplored whether AFC modifies responses to sustained periodic acoustic stimulation-a type of response called the steady-state evoked potential (SSEP). Here we used an amplitude-modulated tone-a 10-kHz tone with a sinusoidal amplitude modulation of 53.7 Hz-as the conditioning stimulus (CS) in an AFC protocol (5 CSs per day in 3 consecutive days) while recording local field potentials (LFPs) from the IC. In the preconditioning session ( day 1 ), the CS elicited prominent 53.7-Hz SSEPs. In the training session ( day 2 ), foot shocks occurred at the end of each CS (paired group) or randomized in the inter-CS interval (unpaired group). In the test session ( day 3 ), SSEPs markedly differed from preconditioning in the paired group: in the first two trials the phase to which the SSEP coupled to the CS amplitude envelope shifted ~90°; in the last two trials the SSEP power and the coherence of SSEP with the CS amplitude envelope increased. LFP power decreased in frequency bands other than 53.7 Hz. In the unpaired group, SSEPs did not change in the test compared with preconditioning. Our results show that AFC causes dissociated changes in the phase and power of SSEP in the IC. NEW & NOTEWORTHY Local field potential oscillations in the inferior colliculus follow the amplitude envelope of an amplitude-modulated tone, originating a neural response called the steady-state evoked potential. We show that auditory fear conditioning of an amplitude-modulated tone modifies two parameters of the steady-state evoked potentials in the inferior colliculus: first the phase to which the evoked oscillation couples to the amplitude-modulated tone shifts; subsequently, the evoked oscillation power increases along with its coherence with the amplitude-modulated tone. Copyright © 2017 the American Physiological Society.

Analysis of wave III of brain stem auditory evoked potential waveforms during microvascular decompression of cranial nerve VII for hemifacial spasm.

PubMed

Thirumala, Parthasarathy D; Krishnaiah, Balaji; Crammond, Donald J; Habeych, Miguel E; Balzer, Jeffrey R

2014-04-01

Intraoperative monitoring of brain stem auditory evoked potential during microvascular decompression (MVD) prevent hearing loss (HL). Previous studies have shown that changes in wave III (wIII) are an early and sensitive sign of auditory nerve injury. To evaluate the changes of amplitude and latency of wIII of brain stem auditory evoked potential during MVD and its association with postoperative HL. Hearing loss was classified by American Academy of Otolaryngology - Head and Neck Surgery (AAO-HNS) criteria, based on changes in pure tone audiometry and speech discrimination score. Retrospective analysis of wIII in patients who underwent intraoperative monitoring with brain stem auditory evoked potential during MVD was performed. A univariate logistic regression analysis was performed on independent variables amplitude of wIII and latency of wIII at change max and On-Skin, or a final recording at the time of skin closure. A further analysis for the same variables was performed adjusting for the loss of wave. The latency of wIII was not found to be significantly different between groups I and II. The amplitude of wIII was significantly decreased in the group with HL. Regression analysis did not find any increased odds of HL with changes in the amplitude of wIII. Changes in wave III did not increase the odds of HL in patients who underwent brain stem auditory evoked potential s during MVD. This information might be valuable to evaluate the value of wIII as an alarm criterion during MVD to prevent HL.

Neurophysiological correlates of abnormal somatosensory temporal discrimination in dystonia.

PubMed

Antelmi, Elena; Erro, Roberto; Rocchi, Lorenzo; Liguori, Rocco; Tinazzi, Michele; Di Stasio, Flavio; Berardelli, Alfredo; Rothwell, John C; Bhatia, Kailash P

2017-01-01

Somatosensory temporal discrimination threshold is often prolonged in patients with dystonia. Previous evidence suggested that this might be caused by impaired somatosensory processing in the time domain. Here, we tested if other markers of reduced inhibition in the somatosensory system might also contribute to abnormal somatosensory temporal discrimination in dystonia. Somatosensory temporal discrimination threshold was measured in 19 patients with isolated cervical dystonia and 19 age-matched healthy controls. We evaluated temporal somatosensory inhibition using paired-pulse somatosensory evoked potentials, spatial somatosensory inhibition by measuring the somatosensory evoked potentials interaction between simultaneous stimulation of the digital nerves in thumb and index finger, and Gamma-aminobutyric acid-ergic (GABAergic) sensory inhibition using the early and late components of high-frequency oscillations in digital nerves somatosensory evoked potentials. When compared with healthy controls, dystonic patients had longer somatosensory temporal discrimination thresholds, reduced suppression of cortical and subcortical paired-pulse somatosensory evoked potentials, less spatial inhibition of simultaneous somatosensory evoked potentials, and a smaller area of the early component of the high-frequency oscillations. A logistic regression analysis found that paired pulse suppression of the N20 component at an interstimulus interval of 5 milliseconds and the late component of the high-frequency oscillations were independently related to somatosensory temporal discrimination thresholds. "Dystonia group" was also a predictor of enhanced somatosensory temporal discrimination threshold, indicating a dystonia-specific effect that independently influences this threshold. Increased somatosensory temporal discrimination threshold in dystonia is related to reduced activity of inhibitory circuits within the primary somatosensory cortex. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

FLASH protects ZEB1 from degradation and supports cancer cells' epithelial-to-mesenchymal transition

PubMed Central

Abshire, C F; Carroll, J L; Dragoi, A-M

2016-01-01

Cancer metastasis remains a significant challenge and the leading cause of cancer-associated deaths. It is postulated that during metastasis cells undergo epithelial-to-mesenchymal transition (EMT), a process characterized by loss of cell–cell contacts and increased migratory and invasive potential. ZEB1 is one the most prominent transcriptional repressors of genes associated with EMT. We identified caspase-8-associated protein 2 (CASP8AP2 or FLASH) as a novel posttranscriptional regulator of ZEB1. Here we demonstrate that FLASH protects ZEB1 from proteasomal degradation brought by the action of the ubiquitin ligases SIAH1 and F-box protein FBXO45. As a result, loss of FLASH rapidly destabilized ZEB1 and reversed EMT cellular characteristics. Importantly, loss of FLASH blocked transforming growth factor-β-induced EMT and enhanced sensitivity to chemotherapy. Thus, we propose that FLASH–ZEB1 interplay may be a protective mechanism against ZEB1 degradation in cells undergoing EMT and may be an efficacious target for therapies aimed to block EMT progression. PMID:27526108

A non-ideal model for predicting the effect of dissolved salt on the flash point of solvent mixtures.

PubMed

Liaw, Horng-Jang; Wang, Tzu-Ai

2007-03-06

Flash point is one of the major quantities used to characterize the fire and explosion hazard of liquids. Herein, a liquid with dissolved salt is presented in a salt-distillation process for separating close-boiling or azeotropic systems. The addition of salts to a liquid may reduce fire and explosion hazard. In this study, we have modified a previously proposed model for predicting the flash point of miscible mixtures to extend its application to solvent/salt mixtures. This modified model was verified by comparison with the experimental data for organic solvent/salt and aqueous-organic solvent/salt mixtures to confirm its efficacy in terms of prediction of the flash points of these mixtures. The experimental results confirm marked increases in liquid flash point increment with addition of inorganic salts relative to supplementation with equivalent quantities of water. Based on this evidence, it appears reasonable to suggest potential application for the model in assessment of the fire and explosion hazard for solvent/salt mixtures and, further, that addition of inorganic salts may prove useful for hazard reduction in flammable liquids.

Flash/crazing effects on simulator pursuit tracking performance

NASA Astrophysics Data System (ADS)

Stamper, D. A.; Lund, D. J.; Levine, R. R.; Molchany, J. W.; Best, P.

1986-03-01

Day sights which are purposefully or inadvertently irradiated with laser radiation may become nonfunctional due to cracking or crazing of the optical glass. The degree of performance degradation may be related to the amount of damage to the glass and possible flash blindness from reradiation. Thirty-two male enlisted men and officers tracked a scale model tank through a constant arc at a simulated distance of 1 km, using a laboratory constructed viscous-damped tracking device. There were four crazing groups (4 men/group) under bright and dim ambient light conditions for a total of eight groups. Each man tracked the target during three flash/crazing and three crazing only trials, which were randomly presented during 30 trials. The simulated countermeasure which included the flash and crazing had dramatic effects on tracking performance, even under daylight conditions. Under the most severe degree of crazing, tracking performance was not possible under either ambient light condition. The relatively small amounts of laser radiation used to craze the BK-7 glass used in this study, which lead to significant performance decrements, demonstrates the potential impact of flash/crazing effects on operators of day sights.

Hot flashes are not predictive for serum concentrations of tamoxifen and its metabolites

PubMed Central

2013-01-01

Background Tamoxifen has dramatically reduced the recurrence and mortality rate of estrogen receptor positive breast cancer. However, the efficacy of tamoxifen varies between individuals and 40% of patients will have a recurrence despite adjuvant tamoxifen treatment. Factors that predict tamoxifen efficacy would be helpful for optimizing treatment. Serum concentrations of the active metabolite, endoxifen, may be positively related to treatment outcome. In addition, hot flashes are suggested to be positively associated with tamoxifen treatment outcome. Methods We investigated in a series of 109 patients whether the frequency and severity of hot flashes were related to concentrations of tamoxifen and its metabolites. A serum sample of all patients was analyzed for the concentration of tamoxifen, N-desmethyltamoxifen, endoxifen and 4-hydroxytamoxifen, as well as for estradiol concentrations and several single nucleotide polymorphisms in CYP2D6. Additionally, these patients completed a questionnaire concerning biometric data and treatment side effects. Results We found no evidence supporting an association between concentrations of tamoxifen or metabolites and either the frequency or severity of hot flashes in the covariate unadjusted analyses. However, including interactions with menopausal status and pre-treatment hot flash (PTHF) history indicated that post-menopausal women with PTHF experienced an increasing frequency of hot flashes with increasing serum concentrations of tamoxifen and its metabolites. This finding was not altered when adjusting for potential confounding factors (duration of tamoxifen treatment, CYP2D6 phenotype, estradiol serum concentration, age and body mass index). In addition we observed a positive association between body mass index and both hot flash frequency (p = 0.04) and severity (p < 0.0001). We also observed that patients with lower estradiol levels reported more severe hot flashes (p = 0.02). Conclusions No univariate associations were observed between concentrations of active tamoxifen metabolites and either the frequency or severity of hot flashes during treatment. However, the frequency of hot flashes may be exacerbated by higher serum concentrations of tamoxifen and its metabolites in post-menopausal women with a history of hot flashes prior to tamoxifen treatment. PMID:24373320

Hearing Screening of High-Risk Newborns with Brainstem Auditory Evoked Potentials: A Follow-Up Study.

ERIC Educational Resources Information Center

Shannon, Dorothy A.; And Others

1984-01-01

The brainstem auditory evoked potential (BAEP) was evaluated as a hearing screening test in 168 high-risk newborns. The BAEP was found to be a sensitive procedure for the early identification of hearing-impaired newborns. However, the yield of significant hearing abnormalities was less than predicted in other studies using BAEP. (Author/CL)

Auditory Evoked Potentials and Hand Preference in 6-Month-Old Infants: Possible Gender-Related Differences in Cerebral Organization.

ERIC Educational Resources Information Center

Shucard, Janet L.; Shucard, David W.

1990-01-01

Verbal and musical stimuli were presented to infants in a study of the relations of evoked potential left-right amplitude asymmetries to gender and hand preference. There was a relation between asymmetry and hand preference, and for girls, between asymmetry and stimulus condition. Results suggest a gender difference in cerebral hemisphere…

The Effectiveness of FES-Evoked EMG Potentials to Assess Muscle Force and Fatigue in Individuals with Spinal Cord Injury

PubMed Central

Ibitoye, Morufu Olusola; Estigoni, Eduardo H.; Hamzaid, Nur Azah; Wahab, Ahmad Khairi Abdul; Davis, Glen M.

2014-01-01

The evoked electromyographic signal (eEMG) potential is the standard index used to monitor both electrical changes within the motor unit during muscular activity and the electrical patterns during evoked contraction. However, technical and physiological limitations often preclude the acquisition and analysis of the signal especially during functional electrical stimulation (FES)-evoked contractions. Hence, an accurate quantification of the relationship between the eEMG potential and FES-evoked muscle response remains elusive and continues to attract the attention of researchers due to its potential application in the fields of biomechanics, muscle physiology, and rehabilitation science. We conducted a systematic review to examine the effectiveness of eEMG potentials to assess muscle force and fatigue, particularly as a biofeedback descriptor of FES-evoked contractions in individuals with spinal cord injury. At the outset, 2867 citations were identified and, finally, fifty-nine trials met the inclusion criteria. Four hypotheses were proposed and evaluated to inform this review. The results showed that eEMG is effective at quantifying muscle force and fatigue during isometric contraction, but may not be effective during dynamic contractions including cycling and stepping. Positive correlation of up to r = 0.90 (p < 0.05) between the decline in the peak-to-peak amplitude of the eEMG and the decline in the force output during fatiguing isometric contractions has been reported. In the available prediction models, the performance index of the eEMG signal to estimate the generated muscle force ranged from 3.8% to 34% for 18 s to 70 s ahead of the actual muscle force generation. The strength and inherent limitations of the eEMG signal to assess muscle force and fatigue were evident from our findings with implications in clinical management of spinal cord injury (SCI) population. PMID:25025551

Flash autoclave settings may influence eradication but not presence of well-established biofilms on orthopaedic implant material.

PubMed

Williams, Dustin L; Taylor, Nicholas B; Epperson, Richard T; Rothberg, David L

2017-10-04

Flash autoclaving is one of the most frequently utilized methods of sterilizing devices, implants or other materials. For a number of decades, it has been common practice for surgeons to remove implantable devices, flash autoclave and then reimplant them in a patient. Data have not yet indicated the potential for biofilms to survive or remain on the surface of orthopaedic-relevant materials following flash autoclave. In this study, monomicrobial and polymicrobial biofilms were grown on the surface of clinically relevant titanium materials and exposed to flash autoclave settings that included varying times and temperatures. Data indicated that when the sterilization and control temperatures of an autoclave were the same, biofilms were able to survive flash autoclaving that was performed for a short duration. Higher temperature and increased duration rendered biofilms non-viable, but none of the autoclave settings had the ability to remove or disperse the presence of biofilms from the titanium surfaces. These findings may be beneficial for facilities, clinics, or hospitals to consider if biofilms are suspected to be present on materials or devices, in particular implants that have had associated infection and are considered for re-implantation. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Large Amplitude Cortical Evoked Potentials in Nonepileptic Patients. Reviving an Old Neurophysiologic Tool to Help Detect CNS Pathology.

PubMed

Martín-Palomeque, Guillermo; Castro-Ortiz, Antonio; Pamplona-Valenzuela, Pilar; Saiz-Sepúlveda, Miguel Á; Cabañes-Martínez, Lidia; López, Jaime R

2017-01-01

Although large amplitude evoked potentials (EPs) are typically associated with progressive myoclonic epilepsy patients, giant EPs imply central nervous system (CNS) hyperexcitability and can be seen in various nonepileptic disorders. We performed a retrospective chart review including history, physical examination, imaging and diagnostic studies of nonepileptic patients with large amplitude somatosensory evoked potentials (SSEPs) and visual evoked potentials (VEPs) during 2007 to 2013. Large amplitude EPs were defined as follows: VEPs (N75-P100) >18 μV; and SSEPs (N20-P25) >6.4 μV. Recording montage for VEPs was Oz-Cz and SSEPs C3'/C4'-Fz. Fifty-two patients (33 females, 19 males; age range, 9-90 years) were identified. No CNS pathology was detected in 7 patients. All remaining patients were diagnosed with new CNS disorders including: vascular (37%); myelopathies (13%); demyelinating (11%); space occupying lesions (8.7%); syringomyelia (8.7%); hydrocephalus (6.5%); Vitamin B-12 deficiency (4.3%); multiple system atrophy (4.3%); and toxins (2.2%). This study supports the notion that large amplitude EP implies CNS hyperexcitability and CNS disease. These results confirm the utility of EP studies in patients with suspected CNS pathology.

Correlation of pattern reversal visual evoked potential parameters with the pattern standard deviation in primary open angle glaucoma.

PubMed

Kothari, Ruchi; Bokariya, Pradeep; Singh, Ramji; Singh, Smita; Narang, Purvasha

2014-01-01

To evaluate whether glaucomatous visual field defect particularly the pattern standard deviation (PSD) of Humphrey visual field could be associated with visual evoked potential (VEP) parameters of patients having primary open angle glaucoma (POAG). Visual field by Humphrey perimetry and simultaneous recordings of pattern reversal visual evoked potential (PRVEP) were assessed in 100 patients with POAG. The stimulus configuration for VEP recordings consisted of the transient pattern reversal method in which a black and white checker board pattern was generated (full field) and displayed on VEP monitor (colour 14″) by an electronic pattern regenerator inbuilt in an evoked potential recorder (RMS EMG EP MARK II). The results of our study indicate that there is a highly significant (P<0.001) negative correlation of P100 amplitude and a statistically significant (P<0.05) positive correlation of N70 latency, P100 latency and N155 latency with the PSD of Humphrey visual field in the subjects of POAG in various age groups as evaluated by Student's t-test. Prolongation of VEP latencies were mirrored by a corresponding increase of PSD values. Conversely, as PSD increases the magnitude of VEP excursions were found to be diminished.

Index finger somatosensory evoked potentials in blind Braille readers.

PubMed

Giriyappa, Dayananda; Subrahmanyam, Roopakala Mysore; Rangashetty, Srinivasa; Sharma, Rajeev

2009-01-01

Traditionally, vision has been considered the dominant modality in our multi-sensory perception of the surrounding world. Sensory input via non-visual tracts becomes of greater behavioural relevance in totally blind individuals to enable effective interaction with the world around them. These include audition and tactile perceptions, leading to an augmentation in these perceptions when compared with normal sighted individuals. The objective of the present work was to study the index finger somatosensory evoked potentials (SEPs) in totally blind and normal sighted individuals. SEPs were recorded in 15 Braille reading totally blind females and compared with 15 age-matched normal sighted females. Latency and amplitudes of somatosensory evoked potential waveforms (N9, N13, and N20) were measured. Amplitude of N20 SEP (a cortical somatosensory evoked potential) was significantly larger in the totally blind than in normal sighted individuals (p < 0.05). The amplitudes of N9 and N13 SEP and the latencies of all recorded SEPs showed no significant differences. Blindness has a profound effect on the Braille reading right index finger. Totally blind Braille readers have larger N20 amplitude, suggestive of greater somatosensory cortical representation of the Braille reading index finger.

RF radiation from lightning

NASA Technical Reports Server (NTRS)

Levine, D. M.

1978-01-01

Radiation from lightning in the RF band from 3-300 MHz were monitored. Radiation in this frequency range is of interest as a potential vehicle for monitoring severe storms and for studying the lightning itself. Simultaneous measurements were made of RF radiation and fast and slow field changes. Continuous analogue recordings with a system having 300 kHz of bandwidth were made together with digital records of selected events (principally return strokes) at greater temporal resolution. The data reveal patterns in the RF radiation for the entire flash which are characteristic of flash type and independent of the frequency of observation. Individual events within the flash also have characteristic RF patterns. Strong radiation occurs during the first return strokes, but delayed about 20 micron sec with respect to the begining of the return stroke; whereas, RF radiation from subsequent return strokes tends to be associated with cloud processes preceding the flash with comparatively little radiation occurring during the return stroke itself.

Relations among Menopausal Symptoms, Sleep Disturbance and Depressive Symptoms in Midlife

PubMed Central

Brown, Jessica P.; Gallicchio, Lisa; Flaws, Jodi F.; Tracy, J. Kathleen

2009-01-01

Objectives To investigate the relations among hot flashes, other menopausal symptoms, sleep quality and depressive symptoms in midlife women Methods A large population-based cross-sectional study of 639 women (ages 45 to 54 years) consisting of a questionnaire including the Center for Epidemiologic Studies-Depression Scale (CES-D), demographics, health behaviors, menstrual history, and menopausal symptoms Results After controlling for menopausal status, physical activity level, smoking status and current self-reported health status elevated CES-D score is associated with frequent nocturnal hot flashes, frequent trouble sleeping, experiencing hot flashes, nausea, headaches, weakness, visual problems, vaginal discharge, irritability, muscle stiffness, and incontinence. Conclusions The present study found significant links between depressive symptoms and several menopausal symptoms including hot flashes, sleep disturbance, irritability, muscle stiffness, and incontinence after controlling for covariates. These findings suggest that a potential mechanism in which bothersome menopausal symptoms may influence depressed mood during the midlife is through sleep disturbance. PMID:19128903

Laser and somatosensory evoked potentials in amyotrophic lateral sclerosis.

PubMed

Isak, Baris; Tankisi, Hatice; Johnsen, Birger; Pugdahl, Kirsten; Finnerup, Nanna Brix; Fuglsang-Frederiksen, Anders

2016-10-01

Mild involvement of sensory nerves has been reported in previous studies in ALS patients. In this study, we assessed sensory pathways in ALS patients using laser evoked potentials (LEPs) and somatosensory evoked potentials (SSEPs). We recruited 18 ALS patients and 31 healthy subjects. Neodymium-doped yttrium aluminium perovskite (Nd:YAP)-laser was used to evoke LEPs in upper (UE) and lower (LE) extremities. N1 and N2P2 potentials were obtained from contralateral insular cortex (T3 or T4) and vertex (Cz), respectively. Median SSEPs were recorded from C3' or C4' and tibial SSEPs from Cz'. Compared to controls, ALS patients had longer N2 and P2 latencies, and smaller N2P2 amplitudes in both UE- and LE-LEPs (p<0.05), and longer latencies for median and tibial SSEPs (p<0.05). LEPs and SSEPs were abnormal in 72.2% and 56.6% patients, respectively. Cortical potentials showed that A-beta or A-delta sensory fibres, or both, were impaired in more than half of the ALS patients. The findings support that ALS is a multi-systemic disorder involving, although to a lesser degree, other systems than the motor. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

On hemispheric differences in evoked potentials to speech stimuli

NASA Technical Reports Server (NTRS)

Galambos, R.; Benson, P.; Smith, T. S.; Schulman-Galambos, C.; Osier, H.

1975-01-01

Confirmation is provided for the belief that evoked potentials may reflect differences in hemispheric functioning that are marginal at best. Subjects were right-handed and audiologically normal men and women, and responses were recorded using standard EEG techniques. Subjects were instructed to listen for the targets while laying in a darkened sound booth. Different stimuli, speech and tone signals, were used. Speech sounds were shown to evoke a response pattern that resembles that to tone or clicks. Analysis of variances on peak amplitude and latency measures showed no significant differences between hemispheres, however, a Wilcoxon test showed significant differences in hemispheres for certain target tasks.

Steady-state visual evoked potential (SSVEP)-based communication: impact of harmonic frequency components

NASA Astrophysics Data System (ADS)

Müller-Putz, Gernot R.; Scherer, Reinhold; Brauneis, Christian; Pfurtscheller, Gert

2005-12-01

Brain-computer interfaces (BCIs) can be realized on the basis of steady-state evoked potentials (SSEPs). These types of brain signals resulting from repetitive stimulation have the same fundamental frequency as the stimulation but also include higher harmonics. This study investigated how the classification accuracy of a 4-class BCI system can be improved by incorporating visually evoked harmonic oscillations. The current study revealed that the use of three SSVEP harmonics yielded a significantly higher classification accuracy than was the case for one or two harmonics. During feedback experiments, the five subjects investigated reached a classification accuracy between 42.5% and 94.4%.

Steady-state visual evoked potential (SSVEP)-based communication: impact of harmonic frequency components.

PubMed

Müller-Putz, Gernot R; Scherer, Reinhold; Brauneis, Christian; Pfurtscheller, Gert

2005-12-01

Brain-computer interfaces (BCIs) can be realized on the basis of steady-state evoked potentials (SSEPs). These types of brain signals resulting from repetitive stimulation have the same fundamental frequency as the stimulation but also include higher harmonics. This study investigated how the classification accuracy of a 4-class BCI system can be improved by incorporating visually evoked harmonic oscillations. The current study revealed that the use of three SSVEP harmonics yielded a significantly higher classification accuracy than was the case for one or two harmonics. During feedback experiments, the five subjects investigated reached a classification accuracy between 42.5% and 94.4%.

A new role for evoked potentials in MS? Repurposing evoked potentials as biomarkers for clinical trials in MS.

PubMed

Hardmeier, Martin; Leocani, Letizia; Fuhr, Peter

2017-09-01

Evoked potentials (EP) characterize signal conduction in selected tracts of the central nervous system in a quantifiable way. Since alteration of signal conduction is the main mechanism of symptoms and signs in multiple sclerosis (MS), multimodal EP may serve as a representative measure of the functional impairment in MS. Moreover, EP have been shown to be predictive for disease course, and thus might help to select patient groups at high risk of progression for clinical trials. EP can detect deterioration, as well as improvement of impulse propagation, independently from the mechanism causing the change. Therefore, they are candidates for biomarkers with application in clinical phase-II trials. Applicability of EP in multicenter trials has been limited by different standards of registration and assessment.

Saturation thresholds of evoked neural and hemodynamic responses in awake and asleep rats

NASA Astrophysics Data System (ADS)

Schei, Jennifer L.; Van Nortwick, Amy S.; Meighan, Peter C.; Rector, David M.

2011-03-01

Neural activation generates a hemodynamic response to the localized region replenishing nutrients to the area. Changes in vigilance state have been shown to alter the vascular response where the vascular response is muted during wake compared to quiet sleep. We tested the saturation thresholds of the neurovascular response in the auditory cortex during wake and sleep by chronically implanting rats with an EEG electrode, a light emitting diode (LED, 600 nm), and photodiode to simultaneously measure evoked response potentials (ERPs) and evoked hemodynamic responses. We stimulated the cortex with a single speaker click delivered at random intervals 2-13 s at varied stimulus intensities ranging from 45-80 dB. To further test the potential for activity related saturation, we sleep deprived animals for 2, 4, or 6 hours and recorded evoked responses during the first hour recovery period. With increasing stimulus intensity, integrated ERPs and evoked hemodynamic responses increased; however the hemodynamic response approached saturation limits at a lower stimulus intensity than the ERP. With longer periods of sleep deprivation, the integrated ERPs did not change but evoked hemodynamic responses decreased. There may be physical limits in cortical blood delivery and vascular compliance, and with extended periods of neural activity during wake, vessels may approach these limits.

Steady-State Somatosensory Evoked Potential for Brain-Computer Interface—Present and Future

PubMed Central

Ahn, Sangtae; Kim, Kiwoong; Jun, Sung Chan

2016-01-01

Brain-computer interface (BCI) performance has achieved continued improvement over recent decades, and sensorimotor rhythm-based BCIs that use motor function have been popular subjects of investigation. However, it remains problematic to introduce them to the public market because of their low reliability. As an alternative resolution to this issue, visual-based BCIs that use P300 or steady-state visually evoked potentials (SSVEPs) seem promising; however, the inherent visual fatigue that occurs with these BCIs may be unavoidable. For these reasons, steady-state somatosensory evoked potential (SSSEP) BCIs, which are based on tactile selective attention, have gained increasing attention recently. These may reduce the fatigue induced by visual attention and overcome the low reliability of motor activity. In this literature survey, recent findings on SSSEP and its methodological uses in BCI are reviewed. Further, existing limitations of SSSEP BCI and potential future directions for the technique are discussed. PMID:26834611

Automatic classification of visual evoked potentials based on wavelet decomposition

NASA Astrophysics Data System (ADS)

Stasiakiewicz, Paweł; Dobrowolski, Andrzej P.; Tomczykiewicz, Kazimierz

2017-04-01

Diagnosis of part of the visual system, that is responsible for conducting compound action potential, is generally based on visual evoked potentials generated as a result of stimulation of the eye by external light source. The condition of patient's visual path is assessed by set of parameters that describe the time domain characteristic extremes called waves. The decision process is compound therefore diagnosis significantly depends on experience of a doctor. The authors developed a procedure - based on wavelet decomposition and linear discriminant analysis - that ensures automatic classification of visual evoked potentials. The algorithm enables to assign individual case to normal or pathological class. The proposed classifier has a 96,4% sensitivity at 10,4% probability of false alarm in a group of 220 cases and area under curve ROC equals to 0,96 which, from the medical point of view, is a very good result.

Median and ulnar muscle and sensory evoked potentials.

PubMed

Felsenthal, G

1978-08-01

The medical literature was reviewed to find suggested clinical applications of the study of the amplitude of evoked muscle action potentials (MAP) and sensory action potentials (SAP). In addition, the literature was reviewed to ascertain the normal amplitude and duration of the evoked MAP and SAP as well as the factors affecting the amplitude: age, sex, temperature, ischemia. The present study determined the normal amplitude and duration of the median and ulnar MAP and SAP in fifty normal subjects. The amplitude of evoked muscle or sensory action potentials depends on multiple factors. Increased skin resistance, capacitance, and impedance at the surface of the recording electrode diminishes the amplitude. Similarly, increased distance from the source of the action potential diminishes its amplitude. Increased interelectrode distance increases the amplitude of the bipolarly recorded sensory action potential until a certain interelectrode distance is exceeded and the diphasic response becomes tri- or tetraphasic. Artifact or poor technique may reduce the potential difference between the recording electrodes or obscure the late positive phase of the action potential and thus diminish the peak to peak amplitude measurement. Intraindividual comparison indicated a marked difference of amplitude in opposite hands. The range of the MAP of the abductor pollicis brevis in one hand was 40.0--100% of the response in the opposite hand. For the abductor digiti minimi, the MAP was 58.5--100% of the response of the opposite hand. The median and ulnar SAP was between 50--100% of the opposite SAP. Consequent to these findings the effect of hand dominance on the amplitude of median and ulnar evoked muscle and sensory action potentials was studied in 41 right handed volunteers. The amplitudes of the median muscle action potential (p less than 0.02) and the median and ulnar sensory action potentials (p less than 0.001) were significantly less in the dominant hand. There was no significant difference between the ulnar muscle action potentials or for the median and ulnar distal motor and sensory latencies in the right and left hands of this group of volunteers.

Kinetic determinations of accurate relative oxidation potentials of amines with reactive radical cations.

PubMed

Gould, Ian R; Wosinska, Zofia M; Farid, Samir

2006-01-01

Accurate oxidation potentials for organic compounds are critical for the evaluation of thermodynamic and kinetic properties of their radical cations. Except when using a specialized apparatus, electrochemical oxidation of molecules with reactive radical cations is usually an irreversible process, providing peak potentials, E(p), rather than thermodynamically meaningful oxidation potentials, E(ox). In a previous study on amines with radical cations that underwent rapid decarboxylation, we estimated E(ox) by correcting the E(p) from cyclic voltammetry with rate constants for decarboxylation obtained using laser flash photolysis. Here we use redox equilibration experiments to determine accurate relative oxidation potentials for the same amines. We also describe an extension of these experiments to show how relative oxidation potentials can be obtained in the absence of equilibrium, from a complete kinetic analysis of the reversible redox kinetics. The results provide support for the previous cyclic voltammetry/laser flash photolysis method for determining oxidation potentials.

Objective quantification of the tinnitus decompensation by synchronization measures of auditory evoked single sweeps.

PubMed

Strauss, Daniel J; Delb, Wolfgang; D'Amelio, Roberto; Low, Yin Fen; Falkai, Peter

2008-02-01

Large-scale neural correlates of the tinnitus decompensation might be used for an objective evaluation of therapies and neurofeedback based therapeutic approaches. In this study, we try to identify large-scale neural correlates of the tinnitus decompensation using wavelet phase stability criteria of single sweep sequences of late auditory evoked potentials as synchronization stability measure. The extracted measure provided an objective quantification of the tinnitus decompensation and allowed for a reliable discrimination between a group of compensated and decompensated tinnitus patients. We provide an interpretation for our results by a neural model of top-down projections based on the Jastreboff tinnitus model combined with the adaptive resonance theory which has not been applied to model tinnitus so far. Using this model, our stability measure of evoked potentials can be linked to the focus of attention on the tinnitus signal. It is concluded that the wavelet phase stability of late auditory evoked potential single sweeps might be used as objective tinnitus decompensation measure and can be interpreted in the framework of the Jastreboff tinnitus model and adaptive resonance theory.

Auditory Evoked Potentials as a Function of Sleep Deprivation and Recovery Sleep

DTIC Science & Technology

1985-09-29

present research: They relate to the effects of: a) 48-hours of sleep deprivation on endogenous event related potentials (ERPs); b) circadian rhythms on...the study were: decreases in amplitude for N2, P3 and N2P3 across the reprivation period; a circadian rhythm was apparent for both ERP recordings and...of cortical evoked response potentials (ERPs)? 2) How do circadian rhythms affect ERPS under conditions of sleep deprivation? 3) How do different

Matched Filtering of Visual Evoked Potentials to Detect Acceleration (+Gz) Induced Blackout

DTIC Science & Technology

1985-01-03

FILTERING OF VISUAL EVOKED POTENTIALS rO DETECT ACCELERATION ( + Gz) INDUCED BLACKOUT John Q. Nelson, Leonid Hrebien and Joseph P. Cammarota Aircraft...8217: , r .,.V -. 1-». .v. IE •> _"->.-"*« A^V :j% _"«;_"V X~«. _~»^"V.i.~» iuTtuTii i."»..-^. .-*._> r /; NOTICES REPORT NUMBERING SYSTEM - The...Potentials to Detect Acceleration (+G2) Induced Blackout 12 PERSONAL AUTHOR(S) John G. Nelson, Leonid Hrebien, Joseph P. Cammarota 13* TYPE OF REPORT

Waveform Similarity Analysis: A Simple Template Comparing Approach for Detecting and Quantifying Noisy Evoked Compound Action Potentials.

PubMed

Potas, Jason Robert; de Castro, Newton Gonçalves; Maddess, Ted; de Souza, Marcio Nogueira

2015-01-01

Experimental electrophysiological assessment of evoked responses from regenerating nerves is challenging due to the typical complex response of events dispersed over various latencies and poor signal-to-noise ratio. Our objective was to automate the detection of compound action potential events and derive their latencies and magnitudes using a simple cross-correlation template comparison approach. For this, we developed an algorithm called Waveform Similarity Analysis. To test the algorithm, challenging signals were generated in vivo by stimulating sural and sciatic nerves, whilst recording evoked potentials at the sciatic nerve and tibialis anterior muscle, respectively, in animals recovering from sciatic nerve transection. Our template for the algorithm was generated based on responses evoked from the intact side. We also simulated noisy signals and examined the output of the Waveform Similarity Analysis algorithm with imperfect templates. Signals were detected and quantified using Waveform Similarity Analysis, which was compared to event detection, latency and magnitude measurements of the same signals performed by a trained observer, a process we called Trained Eye Analysis. The Waveform Similarity Analysis algorithm could successfully detect and quantify simple or complex responses from nerve and muscle compound action potentials of intact or regenerated nerves. Incorrectly specifying the template outperformed Trained Eye Analysis for predicting signal amplitude, but produced consistent latency errors for the simulated signals examined. Compared to the trained eye, Waveform Similarity Analysis is automatic, objective, does not rely on the observer to identify and/or measure peaks, and can detect small clustered events even when signal-to-noise ratio is poor. Waveform Similarity Analysis provides a simple, reliable and convenient approach to quantify latencies and magnitudes of complex waveforms and therefore serves as a useful tool for studying evoked compound action potentials in neural regeneration studies.

[Effects of sevoflurane and propofol on evoked potentials during neurosurgical anesthesia].

PubMed

Nakagawa, Itsuo; Hidaka, Syozo; Okada, Hironori; Kubo, Takashi; Okamura, Kenta; Kato, Takahiro

2006-06-01

The effect of anesthetics on somatosensory evoked potential (SEP) and auditory brain stem response (ABR) has been a subject of intense reseach over the last two decades. In fact, volatile anesthetics have been repeatedly shown to decrease cortical amplitude in a dose-dependent fashion but the information regarding the effect of propofol is incomplete. The purpose of this study was to compare the effects of sevoflurane and propofol on evoked potentials during comparable depth of anesthesia guided by bispectral index (BIS). Forty four patients scheduled for neurosurgery were studied. Anesthesia was maintained with intravenous propofol using target controlled infusion (TCI). We measured the change of amplitude and latency of SEP(N20-P25), ABR (V wave) and visual evoked potential (VEP: P100) at three sets of sevoflurane (0%, 1%, 2%) or propofol concentrations (effect site concentration of 1.5, 2.0, 3.0 microug x ml(-1)). BIS monitor was used to measure relative depth of hypnosis. With increasing concentrations of sevoflurane (0, 1% and 2%), SEP showed dose-related reduction in its amplitude, ABR produced less marked changes and VEP showed a significant reduction at 1%. VEP at the propofol concentration of 3.0 microg x ml(-1) was decreased significantly compared with the amplitude at 1.5 microg x ml(-1) concentration. No significant change was observed with SEP and ABR during the change of propofol dosages. BIS values were almost the same with each anesthetics. VEP was most strongly affected with anesthetics, and ABR showed less marked influence of sevoflurane and propofol. Propofol based TIVA technique would induce less change in evoked potentials than sevoflurane.

Waveform Similarity Analysis: A Simple Template Comparing Approach for Detecting and Quantifying Noisy Evoked Compound Action Potentials

PubMed Central

Potas, Jason Robert; de Castro, Newton Gonçalves; Maddess, Ted; de Souza, Marcio Nogueira

2015-01-01

Experimental electrophysiological assessment of evoked responses from regenerating nerves is challenging due to the typical complex response of events dispersed over various latencies and poor signal-to-noise ratio. Our objective was to automate the detection of compound action potential events and derive their latencies and magnitudes using a simple cross-correlation template comparison approach. For this, we developed an algorithm called Waveform Similarity Analysis. To test the algorithm, challenging signals were generated in vivo by stimulating sural and sciatic nerves, whilst recording evoked potentials at the sciatic nerve and tibialis anterior muscle, respectively, in animals recovering from sciatic nerve transection. Our template for the algorithm was generated based on responses evoked from the intact side. We also simulated noisy signals and examined the output of the Waveform Similarity Analysis algorithm with imperfect templates. Signals were detected and quantified using Waveform Similarity Analysis, which was compared to event detection, latency and magnitude measurements of the same signals performed by a trained observer, a process we called Trained Eye Analysis. The Waveform Similarity Analysis algorithm could successfully detect and quantify simple or complex responses from nerve and muscle compound action potentials of intact or regenerated nerves. Incorrectly specifying the template outperformed Trained Eye Analysis for predicting signal amplitude, but produced consistent latency errors for the simulated signals examined. Compared to the trained eye, Waveform Similarity Analysis is automatic, objective, does not rely on the observer to identify and/or measure peaks, and can detect small clustered events even when signal-to-noise ratio is poor. Waveform Similarity Analysis provides a simple, reliable and convenient approach to quantify latencies and magnitudes of complex waveforms and therefore serves as a useful tool for studying evoked compound action potentials in neural regeneration studies. PMID:26325291

Cortical Auditory Evoked Potentials with Simple (Tone Burst) and Complex (Speech) Stimuli in Children with Cochlear Implant

PubMed Central

Martins, Kelly Vasconcelos Chaves; Gil, Daniela

2017-01-01

Introduction  The registry of the component P1 of the cortical auditory evoked potential has been widely used to analyze the behavior of auditory pathways in response to cochlear implant stimulation. Objective  To determine the influence of aural rehabilitation in the parameters of latency and amplitude of the P1 cortical auditory evoked potential component elicited by simple auditory stimuli (tone burst) and complex stimuli (speech) in children with cochlear implants. Method  The study included six individuals of both genders aged 5 to 10 years old who have been cochlear implant users for at least 12 months, and who attended auditory rehabilitation with an aural rehabilitation therapy approach. Participants were submitted to research of the cortical auditory evoked potential at the beginning of the study and after 3 months of aural rehabilitation. To elicit the responses, simple stimuli (tone burst) and complex stimuli (speech) were used and presented in free field at 70 dB HL. The results were statistically analyzed, and both evaluations were compared. Results  There was no significant difference between the type of eliciting stimulus of the cortical auditory evoked potential for the latency and the amplitude of P1. There was a statistically significant difference in the P1 latency between the evaluations for both stimuli, with reduction of the latency in the second evaluation after 3 months of auditory rehabilitation. There was no statistically significant difference regarding the amplitude of P1 under the two types of stimuli or in the two evaluations. Conclusion  A decrease in latency of the P1 component elicited by both simple and complex stimuli was observed within a three-month interval in children with cochlear implant undergoing aural rehabilitation. PMID:29018498

Suppressive Effects of Resveratrol Treatment on The Intrinsic Evoked Excitability of CA1 Pyramidal Neurons

PubMed Central

Meftahi, Gholamhossein; Ghotbedin, Zohreh; Eslamizade, Mohammad Javad; Hosseinmardi, Narges; Janahmadi, Mahyar

2015-01-01

Objective Resveratrol, a phytoalexin, has a wide range of desirable biological actions. Despite a growing body of evidence indicating that resveratrol induces changes in neu- ronal function, little effort, if any, has been made to investigate the cellular effect of res- veratrol treatment on intrinsic neuronal properties. Materials and Methods This experimental study was performed to examine the acute effects of resveratrol (100 µM) on the intrinsic evoked responses of rat Cornu Ammonis (CA1) pyramidal neurons in brain slices, using whole cell patch clamp re- cording under current clamp conditions. Results Findings showed that resveratrol treatment caused dramatic changes in evoked responses of pyramidal neurons. Its treatment induced a significant (P<0.05) increase in the after hyperpolarization amplitude of the first evoked action potential. Resveratrol-treated cells displayed a significantly broader action potential (AP) when compared with either control or vehicle-treated groups. In addition, the mean instantaneous firing frequency between the first two action potentials was significantly lower in resveratrol-treated neurons. It also caused a significant reduction in the time to maximum decay of AP. The rheobase current and the utilization time were both significantly greater following resveratrol treatment. Neurons exhibited a significantly depolarized voltage threshold when exposed to resveratrol. Conclusion Results provide direct electrophysiological evidence for the inhibitory effects of resveratrol on pyramidal neurons, at least in part, by reducing the evoked neural activity. PMID:26464825

High-temperature ratchets with sawtooth potentials

NASA Astrophysics Data System (ADS)

Rozenbaum, Viktor M.; Shapochkina, Irina V.; Sheu, Sheh-Yi; Yang, Dah-Yen; Lin, Sheng Hsien

2016-11-01

The concept of the effective potential is suggested as an efficient instrument to get a uniform analytical description of stochastic high-temperature on-off flashing and rocking ratchets. The analytical representation for the average particle velocity, obtained within this technique, allows description of ratchets with sharp potentials (and potentials with jumps in particular). For sawtooth potentials, the explicit analytical expressions for the average velocity of on-off flashing and rocking ratchets valid for arbitrary frequencies of potential energy fluctuations are derived; the difference in their high-frequency asymptotics is explored for the smooth and cusped profiles, and profiles with jumps. The origin of the difference as well as the appearance of the jump behavior in ratchet characteristics are interpreted in terms of self-similar universal solutions which give the continuous description of the effect. It is shown how the jump behavior in motor characteristics arises from the competition between the characteristic times of the system.

Vibration-Induced Kinesthetic Illusions and Corticospinal Excitability Changes.

PubMed

Mancheva, Kapka; Rollnik, Jens D; Wolf, Werner; Dengler, Reinhard; Kossev, Andon

2017-01-01

The authors' aim was to investigate the changes of corticospinal excitability during kinesthetic illusions induced by tendon vibration. Motor-evoked potentials in response to transcranial magnetic stimulation were recorded from the vibrated flexor carpi radialis and its antagonist, extensor carpi radialis. The illusions were evoked under vision conditions without feedback for the position of the wrist (open or closed eyes). In these two conditions motor-evoked potential changes during vibration in the antagonist were not identical. This discrepancy may be a result of 2 simultaneously acting, different and opposite influences and the balance between them depends on visual conditions. Thus, the illusion was accompanied by the facilitation of corticospinal excitability in both vibrated muscle and its antagonist.

Cellular generators of the cortical auditory evoked potential initial component.

PubMed

Steinschneider, M; Tenke, C E; Schroeder, C E; Javitt, D C; Simpson, G V; Arezzo, J C; Vaughan, H G

1992-01-01

Cellular generators of the initial cortical auditory evoked potential (AEP) component were determined by analyzing laminar profiles of click-evoked AEPs, current source density, and multiple unit activity (MUA) in primary auditory cortex of awake monkeys. The initial AEP component is a surface-negative wave, N8, that peaks at 8-9 msec and inverts in polarity below lamina 4. N8 is generated by a lamina 4 current sink and a deeper current source. Simultaneous MUA is present from lower lamina 3 to the subjacent white matter. Findings indicate that thalamocortical afferents are a generator of N8 and support a role for lamina 4 stellate cells. Relationships to the human AEP are discussed.

Adaptive regularization network based neural modeling paradigm for nonlinear adaptive estimation of cerebral evoked potentials.

PubMed

Zhang, Jian-Hua; Böhme, Johann F

2007-11-01

In this paper we report an adaptive regularization network (ARN) approach to realizing fast blind separation of cerebral evoked potentials (EPs) from background electroencephalogram (EEG) activity with no need to make any explicit assumption on the statistical (or deterministic) signal model. The ARNs are proposed to construct nonlinear EEG and EP signal models. A novel adaptive regularization training (ART) algorithm is proposed to improve the generalization performance of the ARN. Two adaptive neural modeling methods based on the ARN are developed and their implementation and performance analysis are also presented. The computer experiments using simulated and measured visual evoked potential (VEP) data have shown that the proposed ARN modeling paradigm yields computationally efficient and more accurate VEP signal estimation owing to its intrinsic model-free and nonlinear processing characteristics.

Auditory and visual P300 evoked potentials do not predict response to valproate treatment of aggression in patients with borderline and antisocial personality disorders.

PubMed

Reeves, Roy R; Struve, Frederick A; Patrick, Gloria

2005-01-01

In this study of patients with borderline personality disorder (BPD) or antisocial personality disorder (ASPD) hospitalized because of aggressive behavior, auditory and visual P300 evoked potentials were obtained prior to treatment with valproate. Eight ASPD patients (8 males, 0 females) and 11 BPD patients (2 males, 9 females) showed improvement, while in 7 patients with ASPD (7 males, 0 females) and 10 patients with BPD (2 males, 8 females), aggression was not improved. Differences in auditory and visual P300 latencies and amplitudes were not significant for either diagnosis, or for both diagnoses combined. These findings suggest that auditory or visual P300 evoked potentials may not be useful for predicting response of aggressive behavior to valproate treatment in patients with BPD or ASPD.

Brain state-dependence of electrically evoked potentials monitored with head-mounted electronics.

PubMed

Richardson, Andrew G; Fetz, Eberhard E

2012-11-01

Inferring changes in brain connectivity is critical to studies of learning-related plasticity and stimulus-induced conditioning of neural circuits. In addition, monitoring spontaneous fluctuations in connectivity can provide insight into information processing during different brain states. Here, we quantified state-dependent connectivity changes throughout the 24-h sleep-wake cycle in freely behaving monkeys. A novel, head-mounted electronic device was used to electrically stimulate at one site and record evoked potentials at other sites. Electrically evoked potentials (EEPs) revealed the connectivity pattern between several cortical sites and the basal forebrain. We quantified state-dependent changes in the EEPs. Cortico-cortical EEP amplitude increased during slow-wave sleep, compared to wakefulness, while basal-cortical EEP amplitude decreased. The results demonstrate the utility of using portable electronics to document state-dependent connectivity changes in freely behaving primates.

Potential Use of a Bayesian Network for Discriminating Flash Type from Future GOES-R Geostationary Lightning Mapper (GLM) data

NASA Technical Reports Server (NTRS)

Solakiewiz, Richard; Koshak, William

2008-01-01

Continuous monitoring of the ratio of cloud flashes to ground flashes may provide a better understanding of thunderstorm dynamics, intensification, and evolution, and it may be useful in severe weather warning. The National Lighting Detection Network TM (NLDN) senses ground flashes with exceptional detection efficiency and accuracy over most of the continental United States. A proposed Geostationary Lightning Mapper (GLM) aboard the Geostationary Operational Environmental Satellite (GOES-R) will look at the western hemisphere, and among the lightning data products to be made available will be the fundamental optical flash parameters for both cloud and ground flashes: radiance, area, duration, number of optical groups, and number of optical events. Previous studies have demonstrated that the optical flash parameter statistics of ground and cloud lightning, which are observable from space, are significantly different. This study investigates a Bayesian network methodology for discriminating lightning flash type (ground or cloud) using the lightning optical data and ancillary GOES-R data. A Directed Acyclic Graph (DAG) is set up with lightning as a "root" and data observed by GLM as the "leaves." This allows for a direct calculation of the joint probability distribution function for the lighting type and radiance, area, etc. Initially, the conditional probabilities that will be required can be estimated from the Lightning Imaging Sensor (LIS) and the Optical Transient Detector (OTD) together with NLDN data. Directly manipulating the joint distribution will yield the conditional probability that a lightning flash is a ground flash given the evidence, which consists of the observed lightning optical data [and possibly cloud data retrieved from the GOES-R Advanced Baseline Imager (ABI) in a more mature Bayesian network configuration]. Later, actual GLM and NLDN data can be used to refine the estimates of the conditional probabilities used in the model; i.e., the Bayesian network is a learning network. Methods for efficient calculation of the conditional probabilities (e.g., an algorithm using junction trees), finding data conflicts, goodness of fit, and dealing with missing data will also be addressed.

Medium range forecasting of Hurricane Harvey flash flooding using ECMWF and social vulnerability data

NASA Astrophysics Data System (ADS)

Pillosu, F. M.; Jurlina, T.; Baugh, C.; Tsonevsky, I.; Hewson, T.; Prates, F.; Pappenberger, F.; Prudhomme, C.

2017-12-01

During hurricane Harvey the greater east Texas area was affected by extensive flash flooding. Their localised nature meant they were too small for conventional large scale flood forecasting systems to capture. We are testing the use of two real time forecast products from the European Centre for Medium-range Weather Forecasts (ECMWF) in combination with local vulnerability information to provide flash flood forecasting tools at the medium range (up to 7 days ahead). Meteorological forecasts are the total precipitation extreme forecast index (EFI), a measure of how the ensemble forecast probability distribution differs from the model-climate distribution for the chosen location, time of year and forecast lead time; and the shift of tails (SOT) which complements the EFI by quantifying how extreme an event could potentially be. Both products give the likelihood of flash flood generating precipitation. For hurricane Harvey, 3-day EFI and SOT products for the period 26th - 29th August 2017 were used, generated from the twice daily, 18 km, 51 ensemble member ECMWF Integrated Forecast System. After regridding to 1 km resolution the forecasts were combined with vulnerable area data to produce a flash flood hazard risk area. The vulnerability data were floodplains (EU Joint Research Centre), road networks (Texas Department of Transport) and urban areas (Census Bureau geographic database), together reflecting the susceptibility to flash floods from the landscape. The flash flood hazard risk area forecasts were verified using a traditional approach against observed National Weather Service flash flood reports, a total of 153 reported flash floods have been detected in that period. Forecasts performed best for SOT = 5 (hit ratio = 65%, false alarm ratio = 44%) and EFI = 0.7 (hit ratio = 74%, false alarm ratio = 45%) at 72 h lead time. By including the vulnerable areas data, our verification results improved by 5-15%, demonstrating the value of vulnerability information within natural hazard forecasts. This research shows that flash flooding from hurricane Harvey was predictable up to 4 days ahead and that filtering the forecasts to vulnerable areas provides a more focused guidance to civil protection agencies planning their emergency response.

Direct detection of a single evoked action potential with MRS in Lumbricus terrestris.

PubMed

Poplawsky, Alexander J; Dingledine, Raymond; Hu, Xiaoping P

2012-01-01

Functional MRI (fMRI) measures neural activity indirectly by detecting the signal change associated with the hemodynamic response following brain activation. In order to alleviate the temporal and spatial specificity problems associated with fMRI, a number of attempts have been made to detect neural magnetic fields (NMFs) with MRI directly, but have thus far provided conflicting results. In this study, we used MR to detect axonal NMFs in the median giant fiber of the earthworm, Lumbricus terrestris, by examining the free induction decay (FID) with a sampling interval of 0.32 ms. The earthworm nerve cords were isolated from the vasculature and stimulated at the threshold of action potential generation. FIDs were acquired shortly after the stimulation, and simultaneous field potential recordings identified the presence or absence of single evoked action potentials. FIDs acquired when the stimulus did not evoke an action potential were summed as background. The phase of the background-subtracted FID exhibited a systematic change, with a peak phase difference of (-1.2 ± 0.3) × 10(-5) radians occurring at a time corresponding to the timing of the action potential. In addition, we calculated the possible changes in the FID magnitude and phase caused by a simulated action potential using a volume conductor model. The measured phase difference matched the theoretical prediction well in both amplitude and temporal characteristics. This study provides the first evidence for the direct detection of a magnetic field from an evoked action potential using MR. Copyright © 2011 John Wiley & Sons, Ltd.

The Direct Detection of a Single Evoked Action Potential with Magnetic Resonance Spectroscopy in Lumbricus Terrestris

PubMed Central

Poplawsky, Alexander J.; Dingledine, Raymond

2011-01-01

Functional MRI (fMRI) indirectly measures neural activity by detecting the signal change associated with the hemodynamic response following brain activation. In order to alleviate the temporal and spatial specificity problems associated with fMRI, a number of attempts have been made to detect neural magnetic fields (NMFs) with MRI directly, but have thus far provided conflicting results. In the present study, we used magnetic resonance to detect axonal NMFs in the median giant fiber of the earthworm, Lumbricus terrestris, by examining the free-induction decay (FID) with a sampling interval of 0.32 ms. The earthworm nerve cords were isolated from the vasculature and stimulated at the threshold of action potential generation. FIDs were acquired shortly after the stimulation and simultaneous field potential recordings identified the presence or absence of single evoked action potentials. FIDs acquired when the stimulus did not evoke an action potential were summed as background. The phase of the background-subtracted FID exhibited a systematic change, with a peak phase difference of [-1.2 ± 0.3] ×10-5 radians occurring at a time corresponding to the timing of the action potential. In addition, we calculated the possible changes in the FID magnitude and phase due to a simulated action potential using a volume conductor model. The measured phase difference matched the theoretical prediction well in both amplitude and temporal characteristics. This study provides the first evidence for the direct detection of a magnetic field from an evoked action potential using magnetic resonance. PMID:21728204

Comparative estimation and assessment of initial soil moisture conditions for Flash Flood warning in Saxony

NASA Astrophysics Data System (ADS)

Luong, Thanh Thi; Kronenberg, Rico; Bernhofer, Christian; Janabi, Firas Al; Schütze, Niels

2017-04-01

Flash Floods are known as highly destructive natural hazards due to their sudden appearance and severe consequences. In Saxony/Germany flash floods occur in small and medium catchments of low mountain ranges which are typically ungauged. Besides rainfall and orography, pre-event moisture is decisive, as it determines the available natural retention in the catchment. The Flash Flood Guidance concept according to WMO and Prof. Marco Borga (University of Padua) will be adapted to incorporate pre-event moisture in real-time flood forecast within the ESF EXTRUSO project (SAB-Nr. 100270097). To arrive at pre-event moisture for the complete area of the low mountain range with flash flood potential, a widely applicable, accurate but yet simple approach is needed. Here, we use radar precipitation as input time series, detailed orographic, land-use and soil information and a lumped parameter model to estimate the overall catchment soil moisture and potential retention. When combined with rainfall forecast and its intrinsic uncertainty, the approach allows to find the point in time when precipitation exceeds the retention potential of the catchment. Then, spatially distributed and complex hydrological modeling and additional measurements can be initiated. Assuming reasonable rainfall forecasts of 24 to 48hrs, this part can start up to two days in advance of the actual event. The lumped-parameter model BROOK90 is used and tested for well observed catchments. First, physical meaningful parameters (like albedo or soil porosity) a set according to standards and second, "free" parameters (like percentage of lateral flow) were calibrated objectively by PEST (Model-Independent Parameter Estimation and Uncertainty Analysis) with the target on evapotranspiration and soil moisture which both have been measured at the study site Anchor Station Tharandt in Saxony/Germany. Finally, first results are presented for the Wernersbach catchment in Tharandt forest for main flood events in the 50-year gauging period since 1968.

I-process Nucleosynthesis and Mass Retention Efficiency in He-shell Flash Evolution of Rapidly Accreting White Dwarfs

NASA Astrophysics Data System (ADS)

Denissenkov, Pavel A.; Herwig, Falk; Battino, Umberto; Ritter, Christian; Pignatari, Marco; Jones, Samuel; Paxton, Bill

2017-01-01

Based on stellar evolution simulations, we demonstrate that rapidly accreting white dwarfs (WDs) in close binary systems are an astrophysical site for the intermediate neutron-capture process. During recurrent and very strong He-shell flashes in the stable H-burning accretion regime H-rich material enters the He-shell flash convection zone. {}12{{C}}(p,γ ){}13{{N}} reactions release enough energy to potentially impact convection, and I process is activated through the {}13{{C}}{(α ,{{n}})}16{{O}} reaction. The H-ingestion flash may not cause a split of the convection zone as it was seen in simulations of He-shell flashes in post-AGB and low-Z asymptotic giant branch (AGB) stars. We estimate that for the production of first-peak heavy elements this site can be of similar importance for galactic chemical evolution as the s-process production by low-mass AGB stars. The He-shell flashes result in the expansion and, ultimately, ejection of the accreted and then I-process enriched material, via super-Eddington-luminosity winds or Roche-lobe overflow. The WD models do not retain any significant amount of the accreted mass, with a He retention efficiency of ≲ 10 % depending on mass and convective boundary mixing assumptions. This makes the evolutionary path of such systems to supernova Ia explosion highly unlikely.

Applying a coupled hydrometeorological simulation system to flash flood forecasting over the Korean Peninsula

NASA Astrophysics Data System (ADS)

Ryu, Young; Lim, Yoon-Jin; Ji, Hee-Sook; Park, Hyun-Hee; Chang, Eun-Chul; Kim, Baek-Jo

2017-11-01

In flash flood forecasting, it is necessary to consider not only traditional meteorological variables such as precipitation, evapotranspiration, and soil moisture, but also hydrological components such as streamflow. To address this challenge, the application of high resolution coupled atmospheric-hydrological models is emerging as a promising alternative. This study demonstrates the feasibility of linking a coupled atmospheric-hydrological model (WRF/WRFHydro) with 150-m horizontal grid spacing for flash flood forecasting in Korea. The study area is the Namgang Dam basin in Southern Korea, a mountainous area located downstream of Jiri Mountain (1915 m in height). Under flash flood conditions, the simulated precipitation over the entire basin is comparable to the domain-averaged precipitation, but discharge data from WRF-Hydro shows some differences in the total available water and the temporal distribution of streamflow (given by the timing of the streamflow peak following precipitation), compared to observations. On the basis of sensitivity tests, the parameters controlling the infiltration of excess precipitation and channel roughness depending on stream order are refined and their influence on temporal distribution of streamflow is addressed with intent to apply WRF-Hydro to flash flood forecasting in the Namgang Dam basin. The simulation results from the WRF-Hydro model with optimized parameters demonstrate the potential utility of a coupled atmospheric-hydrological model for forecasting heavy rain-induced flash flooding over the Korean Peninsula.

[The P300-based brain-computer interface: presentation of the complex "flash + movement" stimuli].

PubMed

Ganin, I P; Kaplan, A Ia

2014-01-01

The P300 based brain-computer interface requires the detection of P300 wave of brain event-related potentials. Most of its users learn the BCI control in several minutes and after the short classifier training they can type a text on the computer screen or assemble an image of separate fragments in simple BCI-based video games. Nevertheless, insufficient attractiveness for users and conservative stimuli organization in this BCI may restrict its integration into real information processes control. At the same time initial movement of object (motion-onset stimuli) may be an independent factor that induces P300 wave. In current work we checked the hypothesis that complex "flash + movement" stimuli together with drastic and compact stimuli organization on the computer screen may be much more attractive for user while operating in P300 BCI. In 20 subjects research we showed the effectiveness of our interface. Both accuracy and P300 amplitude were higher for flashing stimuli and complex "flash + movement" stimuli compared to motion-onset stimuli. N200 amplitude was maximal for flashing stimuli, while for "flash + movement" stimuli and motion-onset stimuli it was only a half of it. Similar BCI with complex stimuli may be embedded into compact control systems requiring high level of user attention under impact of negative external effects obstructing the BCI control.

Does navigated transcranial stimulation increase the accuracy of tractography? A prospective clinical trial based on intraoperative motor evoked potential monitoring during deep brain stimulation.

PubMed

Forster, Marie-Therese; Hoecker, Alexander Claudius; Kang, Jun-Suk; Quick, Johanna; Seifert, Volker; Hattingen, Elke; Hilker, Rüdiger; Weise, Lutz Martin

2015-06-01

Tractography based on diffusion tensor imaging has become a popular tool for delineating white matter tracts for neurosurgical procedures. To explore whether navigated transcranial magnetic stimulation (nTMS) might increase the accuracy of fiber tracking. Tractography was performed according to both anatomic delineation of the motor cortex (n = 14) and nTMS results (n = 9). After implantation of the definitive electrode, stimulation via the electrode was performed, defining a stimulation threshold for eliciting motor evoked potentials recorded during deep brain stimulation surgery. Others have shown that of arm and leg muscles. This threshold was correlated with the shortest distance between the active electrode contact and both fiber tracks. Results were evaluated by correlation to motor evoked potential monitoring during deep brain stimulation, a surgical procedure causing hardly any brain shift. Distances to fiber tracks clearly correlated with motor evoked potential thresholds. Tracks based on nTMS had a higher predictive value than tracks based on anatomic motor cortex definition (P < .001 and P = .005, respectively). However, target site, hemisphere, and active electrode contact did not influence this correlation. The implementation of tractography based on nTMS increases the accuracy of fiber tracking. Moreover, this combination of methods has the potential to become a supplemental tool for guiding electrode implantation.

Origin and Properties of Striatal Local Field Potential Responses to Cortical Stimulation: Temporal Regulation by Fast Inhibitory Connections

PubMed Central

Galiñanes, Gregorio L.; Braz, Barbara Y.; Murer, Mario Gustavo

2011-01-01

Evoked striatal field potentials are seldom used to study corticostriatal communication in vivo because little is known about their origin and significance. Here we show that striatal field responses evoked by stimulating the prelimbic cortex in mice are reduced by more than 90% after infusing the AMPA receptor antagonist CNQX close to the recording electrode. Moreover, the amplitude of local field responses and dPSPs recorded in striatal medium spiny neurons increase in parallel with increasing stimulating current intensity. Finally, the evoked striatal fields show several of the basic known properties of corticostriatal transmission, including paired pulse facilitation and topographical organization. As a case study, we characterized the effect of local GABAA receptor blockade on striatal field and multiunitary action potential responses to prelimbic cortex stimulation. Striatal activity was recorded through a 24 channel silicon probe at about 600 µm from a microdialysis probe. Intrastriatal administration of the GABAA receptor antagonist bicuculline increased by 65±7% the duration of the evoked field responses. Moreover, the associated action potential responses were markedly enhanced during bicuculline infusion. Bicuculline enhancement took place at all the striatal sites that showed a response to cortical stimulation before drug infusion, but sites showing no field response before bicuculline remained unresponsive during GABAA receptor blockade. Thus, the data demonstrate that fast inhibitory connections exert a marked temporal regulation of input-output transformations within spatially delimited striatal networks responding to a cortical input. Overall, we propose that evoked striatal fields may be a useful tool to study corticostriatal synaptic connectivity in relation to behavior. PMID:22163020

Time Perception and Evoked Potentials

DTIC Science & Technology

1988-07-01

ARI Research Note 88-69 0 MitnS.Ktohe U.0 ... Ann-r (. Time Perception and Evoked Potentials Paul FraisseDT ( Lfniversit6 Rene Descartes E LECTE...JOHNSON 00L, [N Technical Dicctojr Cmad Research accomplished under contract for the Department of the Army C. Universite Rene Descartes , Paris )r...ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK Labrato-ire de Psychologie Experimental AREA• WORK UNIT NUMBERS Universite Rene Descartes

Corticomotor excitability during a noxious stimulus before and after exercise in women with fibromyalgia.

PubMed

Hoeger Bement, Marie K; Weyer, Andy D; Yoon, Tejin; Hunter, Sandra K

2014-02-01

The purposes of this study were to assess corticomotor excitability in people with fibromyalgia during a noxious stimulus before and after fatiguing exercise and examine associations with pain perception. Fifteen women with fibromyalgia completed three sessions: one familiarization and two experimental. The experimental sessions were randomized and involved measurement of pain perception and motor evoked potentials before and after (1) quiet rest and (2) isometric contraction of the elbow flexor muscles. Motor evoked potential amplitude of brachioradialis muscle was measured following transcranial magnetic stimulation delivered before, during, and after a noxious mechanical stimulus. After quiet rest, there was no change in pain perception. After the submaximal contraction, there was considerable variability in the pain response. Based on the changes in the experimental pain, subjects were divided into three groups (increase, decrease, and no change in pain). There was an interaction between pain response and the pain-induced change in motor evoked potentials. Those individuals who had an increase in motor evoked potentials during the pain test had an increase in pain after exercise. Thus, women with fibromyalgia were classified based on their pain response to exercise, and this response was associated with the change in corticomotor excitability during the application of a noxious stimulus.

Intraoperative Subcortical Fiber Mapping with Subcortico-Cortical Evoked Potentials.

PubMed

Enatsu, Rei; Kanno, Aya; Ohtaki, Shunya; Akiyama, Yukinori; Ochi, Satoko; Mikuni, Nobuhiro

2016-02-01

During brain surgery, there are difficulties associated with identifying subcortical fibers with no clear landmarks. We evaluated the usefulness of cortical evoked potentials with subcortical stimuli (subcortico-cortical evoked potential [SCEP]) in identifying subcortical fibers intraoperatively. We used SCEP to identify the pyramidal tract in 4 patients, arcuate fasciculus in 1 patient, and both in 2 patients during surgical procedures. After resection, a 1 × 4-electrode plate was placed on the floor of the removal cavity and 1-Hz alternating electrical stimuli were delivered to this electrode. A 4 × 5 recording electrode plate was placed on the central cortical areas to map the pyramidal tract and temporoparietal cortical areas for the arcuate fasciculus. SCEPs were obtained by averaging electrocorticograms time locked to the stimulus onset. The subcortical stimulation within 15 mm of the target fiber induced cortical evoked potentials in the corresponding areas, whereas the stimulation apart from 20 mm did not. Five patients showed transient worsening of neurologic symptoms after surgery. However, all patients recovered. SCEP was useful for identifying subcortical fibers and confirmed the preservation of these fibers. This technique is expected to contribute to the effectiveness and safety of resective surgery in patients with lesions close to eloquent areas. Copyright © 2016 Elsevier Inc. All rights reserved.

High Resolution Flash Flood Forecasting Using a Wireless Sensor Network in the Dallas-Fort Worth Metroplex

NASA Astrophysics Data System (ADS)

Bartos, M. D.; Kerkez, B.; Noh, S.; Seo, D. J.

2017-12-01

In this study, we develop and evaluate a high resolution urban flash flood monitoring system using a wireless sensor network (WSN), a real-time rainfall-runoff model, and spatially-explicit radar rainfall predictions. Flooding is the leading cause of natural disaster fatalities in the US, with flash flooding in particular responsible for a majority of flooding deaths. While many riverine flood models have been operationalized into early warning systems, there is currently no model that is capable of reliably predicting flash floods in urban areas. Urban flash floods are particularly difficult to model due to a lack of rainfall and runoff data at appropriate scales. To address this problem, we develop a wide-area flood-monitoring wireless sensor network for the Dallas-Fort Worth metroplex, and use this network to characterize rainfall-runoff response over multiple heterogeneous catchments. First, we deploy a network of 22 wireless sensor nodes to collect real-time stream stage measurements over catchments ranging from 2-80 km2 in size. Next, we characterize the rainfall-runoff response of each catchment by combining stream stage data with gage and radar-based precipitation measurements. Finally, we demonstrate the potential for real-time flash flood prediction by joining the derived rainfall-runoff models with real-time radar rainfall predictions. We find that runoff response is highly heterogeneous among catchments, with large variabilities in runoff response detected even among nearby gages. However, when spatially-explicit rainfall fields are included, spatial variability in runoff response is largely captured. This result highlights the importance of increased spatial coverage for flash flood prediction.

Debating life after disaster: charity hospital babies and bioscientific futures in post-Katrina New Orleans.

PubMed

Lovell, Anne M

2011-06-01

In Louisiana's unique, populist-derived charity health system, the self-designation Charity Hospital Baby expresses situational identity anchored in the life cycle and the inversion of racist and authoritative connotations. This article draws on theoretical perspectives of stratified reproduction and the politics of time to examine the controversy in which Babies advocate reopening the Katrina-damaged New Orleans Charity Hospital, and administrators and planners support a new state-of-the-art biosciences district, GNOBED. Babies evoke the present, ethical urgency (kairos) of responding to sickness and disability; GNOBED implies prolonging or saving future lives through biotechnologies under development in accelerated time (chronos). As preservationists and residents threatened with displacement join "re-open Charity" proponents, planners symbolically engage in prolepsis, rhetorically precluding opposing arguments with flash forward of supposedly "done deals." At stake is nothing less than social death for a segment of this ethnically diverse city. [public

Roles of N-methyl-d-aspartate receptors during the sensory stimulation-evoked field potential responses in mouse cerebellar cortical molecular layer.

PubMed

Xu, Yin-Hua; Zhang, Guang-Jian; Zhao, Jing-Tong; Chu, Chun-Ping; Li, Yu-Zi; Qiu, De-Lai

2017-11-01

The functions of N-methyl-d-aspartate receptors (NMDARs) in cerebellar cortex have been widely studied under in vitro condition, but their roles during the sensory stimulation-evoked responses in the cerebellar cortical molecular layer in living animals are currently unclear. We here investigated the roles of NMDARs during the air-puff stimulation on ipsilateral whisker pad-evoked field potential responses in cerebellar cortical molecular layer in urethane-anesthetized mice by electrophysiological recording and pharmacological methods. Our results showed that cerebellar surface administration of NMDA induced a dose-dependent decrease in amplitude of the facial stimulation-evoked inhibitory responses (P1) in the molecular layer, accompanied with decreases in decay time, half-width and area under curve (AUC) of P1. The IC 50 of NMDA induced inhibition in amplitude of P1 was 46.5μM. In addition, application of NMDA induced significant increases in the decay time, half-width and AUC values of the facial stimulation-evoked excitatory responses (N1) in the molecular layer. Application of an NMDAR blocker, D-APV (250μM) abolished the facial stimulation-evoked P1 in the molecular layer. These results suggested that NMDARs play a critical role during the sensory information processing in cerebellar cortical molecular layer in vivo in mice. Copyright © 2017 Elsevier B.V. All rights reserved.

Steady-state evoked potentials possibilities for mental-state estimation

NASA Technical Reports Server (NTRS)

Junker, Andrew M.; Schnurer, John H.; Ingle, David F.; Downey, Craig W.

1988-01-01

The use of the human steady-state evoked potential (SSEP) as a possible measure of mental-state estimation is explored. A method for evoking a visual response to a sum-of-ten sine waves is presented. This approach provides simultaneous multiple frequency measurements of the human EEG to the evoking stimulus in terms of describing functions (gain and phase) and remnant spectra. Ways in which these quantities vary with the addition of performance tasks (manual tracking, grammatical reasoning, and decision making) are presented. Models of the describing function measures can be formulated using systems engineering technology. Relationships between model parameters and performance scores during manual tracking are discussed. Problems of unresponsiveness and lack of repeatability of subject responses are addressed in terms of a need for loop closure of the SSEP. A technique to achieve loop closure using a lock-in amplifier approach is presented. Results of a study designed to test the effectiveness of using feedback to consciously connect humans to their evoked response are presented. Findings indicate that conscious control of EEG is possible. Implications of these results in terms of secondary tasks for mental-state estimation and brain actuated control are addressed.

Mecamylamine, dihydro-β-erythroidine, and dextromethorphan block conditioned responding evoked by the conditional stimulus effects of nicotine

PubMed Central

Struthers, Amanda M.; Wilkinson, Jamie L.; Dwoskin, Linda P.; Crooks, Peter A.; Bevins, Rick A.

2009-01-01

Current smokers express the desire to quit. However, the majority find it difficult to remain abstinent. As such, research efforts continually seek to develop more effective treatment. One such area of research involves the interoceptive stimulus effects of nicotine as either a discriminative stimulus in an operant drug discrimination task, or more recently as a conditional stimulus (CS) in a discriminated goal-tracking task. The present work investigated the potential role nicotinic acetylcholine receptors in the CS effects of nicotine (0.4 mg/kg) using antagonists with differential selectivity for β2*, α7*, α6β2*, and α3β4* receptors. Methyllycaconitine (MLA) had no effect on nicotine-evoked conditioned responding. Mecamylamine and dihydro-β-erythroidine (DHβE) dose dependently blocked responding evoked by the nicotine CS. In a time-course assessment of mecamylamine and DHβE, each blocked conditioned responding when given 5 min before testing and still blocked conditioned responding when administered 200 min before testing. Two novel bis-picolinium analogs (N, N’-(3, 3′-(dodecan-1,12-diyl)-bis-picolinium dibromide [bPiDDB], and N, N’-(decan-1,10-diyl)-bis-picolinium diiodide [bPiDI]) did not block nicotine-evoked conditioned responding. Finally, pretreatment with low dose combinations of mecamylamine, dextromethorphan, and/or bupropion were used to target α3β4* receptors. No combination blocked conditioned responding evoked by the training dose of nicotine. However, a combination of mecamylamine and dextromethorphan partially blocked nicotine-evoked conditioned responding to a lower dose of nicotine (0.1 mg/kg). These results indicate that β2* and potentially α3β4* nicotinic acetylcholine receptors play a role in the CS effects of nicotine and are potential targets for the development of nicotine cessation aids. PMID:19778551

Activity in early visual areas predicts interindividual differences in binocular rivalry dynamics

PubMed Central

Yamashiro, Hiroyuki; Mano, Hiroaki; Umeda, Masahiro; Higuchi, Toshihiro; Saiki, Jun

2013-01-01

When dissimilar images are presented to the two eyes, binocular rivalry (BR) occurs, and perception alternates spontaneously between the images. Although neural correlates of the oscillating perception during BR have been found in multiple sites along the visual pathway, the source of BR dynamics is unclear. Psychophysical and modeling studies suggest that both low- and high-level cortical processes underlie BR dynamics. Previous neuroimaging studies have demonstrated the involvement of high-level regions by showing that frontal and parietal cortices responded time locked to spontaneous perceptual alternation in BR. However, a potential contribution of early visual areas to BR dynamics has been overlooked, because these areas also responded to the physical stimulus alternation mimicking BR. In the present study, instead of focusing on activity during perceptual switches, we highlighted brain activity during suppression periods to investigate a potential link between activity in human early visual areas and BR dynamics. We used a strong interocular suppression paradigm called continuous flash suppression to suppress and fluctuate the visibility of a probe stimulus and measured retinotopic responses to the onset of the invisible probe using functional MRI. There were ∼130-fold differences in the median suppression durations across 12 subjects. The individual differences in suppression durations could be predicted by the amplitudes of the retinotopic activity in extrastriate visual areas (V3 and V4v) evoked by the invisible probe. Weaker responses were associated with longer suppression durations. These results demonstrate that retinotopic representations in early visual areas play a role in the dynamics of perceptual alternations during BR. PMID:24353304

Experience-dependent increase in spine calcium evoked by backpropagating action potentials in layer 2/3 pyramidal neurons in rat somatosensory cortex.

PubMed

Krieger, Patrik

2009-11-01

In spines on basal dendrites of layer 2/3 pyramidal neurons in somatosensory barrel cortex, calcium transients evoked by back-propagating action potentials (bAPs) were investigated (i) along the length of the basal dendrite, (ii) with postnatal development and (iii) with sensory deprivation during postnatal development. Layer 2/3 pyramidal neurons were investigated at three different ages. At all ages [postnatal day (P)8, P14, P21] the bAP-evoked calcium transient amplitude increased with distance from the soma with a peak at around 50 microm, followed by a gradual decline in amplitude. The effect of sensory deprivation on the bAP-evoked calcium was investigated using two different protocols. When all whiskers on one side of the rat snout were trimmed daily from P8 to P20-24 there was no difference in the bAP-evoked calcium transient between cells in the contralateral hemisphere, lacking sensory input from the whisker, and cells in the ipsilateral barrel cortex, with intact whisker activation. When, however, only the D-row whiskers on one side were trimmed the distribution of bAP-evoked calcium transients in spines was shifted towards larger amplitudes in cells located in the deprived D-column. In conclusion, (i) the bAP-evoked calcium transient gradient along the dendrite length is established at P8, (ii) the calcium transient increases in amplitude with age and (iii) this increase is enhanced in layer 2/3 pyramidal neurons located in a sensory-deprived barrel column that is bordered by non-deprived barrel columns.

Complexin Mutants Reveal Partial Segregation between Recycling Pathways That Drive Evoked and Spontaneous Neurotransmission

PubMed Central

Sabeva, Nadezhda; Cho, Richard W.; Vasin, Alexander; Gonzalez, Agustin; Littleton, J. Troy

2017-01-01

Synaptic vesicles fuse at morphological specializations in the presynaptic terminal termed active zones (AZs). Vesicle fusion can occur spontaneously or in response to an action potential. Following fusion, vesicles are retrieved and recycled within nerve terminals. It is still unclear whether vesicles that fuse spontaneously or following evoked release share similar recycling mechanisms. Genetic deletion of the SNARE-binding protein complexin dramatically increases spontaneous fusion, with the protein serving as the synaptic vesicle fusion clamp at Drosophila synapses. We examined synaptic vesicle recycling pathways at complexin null neuromuscular junctions, where spontaneous release is dramatically enhanced. We combined loading of the lipophilic dye FM1–43 with photoconversion, electron microscopy, and electrophysiology to monitor evoked and spontaneous recycling vesicle pools. We found that the total number of recycling vesicles was equal to those retrieved through spontaneous and evoked pools, suggesting that retrieval following fusion is partially segregated for spontaneous and evoked release. In addition, the kinetics of FM1–43 destaining and synaptic depression measured in the presence of the vesicle-refilling blocker bafilomycin indicated that spontaneous and evoked recycling pools partially intermix during the release process. Finally, FM1–43 photoconversion combined with electron microscopy analysis indicated that spontaneous recycling preferentially involves synaptic vesicles in the vicinity of AZs, whereas vesicles recycled following evoked release involve a larger intraterminal pool. Together, these results suggest that spontaneous and evoked vesicles use separable recycling pathways and then partially intermix during subsequent rounds of fusion. SIGNIFICANCE STATEMENT Neurotransmitter release involves fusion of synaptic vesicles with the plasma membrane in response to an action potential, or spontaneously in the absence of stimulation. Upon fusion, vesicles are retrieved and recycled, and it is unclear whether recycling pathways for evoked and spontaneous vesicles are segregated after fusion. We addressed this question by taking advantage of preparations lacking the synaptic protein complexin, which have elevated spontaneous release that enables reliable tracking of the spontaneous recycling pool. Our results suggest that spontaneous and evoked recycling pathways are segregated during the retrieval process but can partially intermix during stimulation. PMID:28077717

The question of simultaneity in multisensory integration

NASA Astrophysics Data System (ADS)

Leone, Lynnette; McCourt, Mark E.

2012-03-01

Early reports of audiovisual (AV) multisensory integration (MI) indicated that unisensory stimuli must evoke simultaneous physiological responses to produce decreases in reaction time (RT) such that for unisensory stimuli with unequal RTs the stimulus eliciting the faster RT had to be delayed relative to the stimulus eliciting the slower RT. The "temporal rule" states that MI depends on the temporal proximity of unisensory stimuli, the neural responses to which must fall within a window of integration. Ecological validity demands that MI should occur only for simultaneous events (which may give rise to non-simultaneous neural activations). However, spurious neural response simultaneities which are unrelated to singular environmental multisensory occurrences must somehow be rejected. Using an RT/race model paradigm we measured AV MI as a function of stimulus onset asynchrony (SOA: +/-200 ms, 50 ms intervals) under fully dark adapted conditions for visual (V) stimuli that were either weak (scotopic 525 nm flashes; 511 ms mean RT) or strong (photopic 630 nm flashes; 356 ms mean RT). Auditory (A) stimulus (1000 Hz pure tone) intensity was constant. Despite the 155 ms slower mean RT to the scotopic versus photopic stimulus, facilitative AV MI in both conditions nevertheless occurred exclusively at an SOA of 0 ms. Thus, facilitative MI demands both physical and physiological simultaneity. We consider the mechanisms by which the nervous system may take account of variations in response latency arising from changes in stimulus intensity in order to selectively integrate only those physiological simultaneities that arise from physical simultaneities.

Stimulus-dependent modulation of spontaneous low-frequency oscillations in the rat visual cortex.

PubMed

Huang, Liangming; Liu, Yadong; Gui, Jianjun; Li, Ming; Hu, Dewen

2014-08-06

Research on spontaneous low-frequency oscillations is important to reveal underlying regulatory mechanisms in the brain. The mechanism for the stimulus modulation of low-frequency oscillations is not known. Here, we used the intrinsic optical imaging technique to examine stimulus-modulated low-frequency oscillation signals in the rat visual cortex. The stimulation was presented monocularly as a flashing light with different frequencies and intensities. The phases of low-frequency oscillations in different regions tended to be synchronized and the rhythms typically accelerated within a 30-s period after stimulation. These phenomena were confined to visual stimuli with specific flashing frequencies (12.5-17.5 Hz) and intensities (5-10 mA). The acceleration and synchronization induced by the flashing frequency were more marked than those induced by the intensity. These results show that spontaneous low-frequency oscillations can be modulated by parameter-dependent flashing lights and indicate the potential utility of the visual stimulus paradigm in exploring the origin and function of low-frequency oscillations.

Effect of head circumference on parameters of pattern reversal visual evoked potential in healthy adults of central India.

PubMed

Kothari, R; Singh, R; Singh, S; Bokariya, P

2012-06-01

Visual evoked response testing has been one of the most exciting clinical tools to be developed from neurophysiologic research in recent years and has provided us with an objective method of identifying abnormalities of the afferent visual pathways. Investigation were carried out to see whether the head circumference influence the pattern reversal visual evoked potential (PRVEP) parameters. The study comprised of pattern reversal visual evoked potential (PRVEP) recordings in 400 eyes of 200 normal subjects. Two hundred fourty eight eyes were males and 152 eyes were from 76 female subjects recruited from the Central Indian population in the age range of 40-79 years. Visual evoked potential (VEP) recordings were performed in accordance to the standardized methodology of International Federation of Clinical Neurophysiology (IFCN) Committee Recommendations and International Society for Clinical Electrophysiology of Vision (ISCEV) Guidelines and montages were kept as per 10-20 International System of EEG Electrode placements. The stimulus configuration in this study consisted of the transient pattern reversal method in which a black and white checker board was generated (full field) and displayed on a VEP Monitor by an electronic pattern regenerator inbuilt in an Evoked Potential Recorder (RMS EMG EP MARK II). VEP latencies, duration and amplitude were measured in all subjects and the data were analyzed. The correlation of all the electrophysiological parameters with head circumference was evaluated by Pearson's correlation co-efficient (r) and its statistical significance was evaluated. The prediction equations for all the VEP parameters with respect to head circumference were derived. We found a positive correlation of P 100 latency and N 155 latency with mean head circumference, while a highly significant negative correlation were noted of P 100 amplitude with head circumference. N 70 latency was significantly correlated with head circumference. P 100 duration showed in negative correlation with head circumference. These findings suggest that VEP latencies, duration and amplitude are influenced by the head circumference of the individual in a sample of healthy subjects and head circumference can be a useful predictor of VEP peak latencies, amplitude and duration.

The effects of click and tone-burst stimulus parameters on the vestibular evoked myogenic potential (VEMP).

PubMed

Akin, Faith Wurm; Murnane, Owen D; Proffitt, Tina M

2003-11-01

Vestibular evoked myogenic potentials (VEMP) are short latency electromyograms (EMG) evoked by high-level acoustic stimuli and recorded from surface electrodes over the tonically contracted sternocleidomastoid (SCM) muscle and are presumed to originate in the saccule. The present experiments examined the effects of click and tone-burst level and stimulus frequency on the latency, amplitude, and threshold of the VEMP in subjects with normal hearing sensitivity and no history of vestibular disease. VEMPs were recorded in all subjects using 100 dB nHL click stimuli. Most subjects had VEMPs present at 500, 750, and 1000 Hz, and few subjects had VEMPs present at 2000 Hz. The response amplitude of the VEMP increased with click and tone-burst level, whereas VEMP latency was not influenced by the stimulus level. The largest tone-burst-evoked VEMPs and lowest thresholds were obtained at 500 and 750 Hz. VEMP latency was independent of stimulus frequency when tone-burst duration was held constant.

Evoked potential application to study of echolocation in cetaceans

NASA Astrophysics Data System (ADS)

Supin, Alexander Ya.; Nactigall, Paul E.; Pawloski, Jeffrey; Au, Whitlow W. L.

2002-05-01

The evoked-potential (EP) method is effective in studies of hearing capabilities of cetaceans. However, until now EP studies in cetaceans were performed only in conditions of passive hearing by recording EP to external stimuli. Can this method be applied to study active echolocation in odontocetes? To answer this question, auditory brainstem evoked responses (ABR) were recorded in a false killer whale while the animal echolocated a target within an experiment in which the animal reported the target present or absent. The ABR collection was triggered by echolocation clicks. In these conditions, the recorded ABR pattern contained a duplicate set of waves. A comparison of ABR wave delays recorded during echolocation with those recorded during regular external stimulation has shown that the first set of waves is a response to the emitted click whereas the second one is a response to the echo. Both responses, to the emitted click and to the echo, were of comparable amplitude in spite of the intensity difference of these two sounds of more than 40 dB near the animal's head. This finding indicates some mechanisms releasing responses to echoes from masking by loud emitted clicks. The evoked-potential method may be productive to investigate these mechanisms.

Brainstem auditory-evoked potentials as an objective tool for evaluating hearing dysfunction in traumatic brain injury.

PubMed

Lew, Henry L; Lee, Eun Ha; Miyoshi, Yasushi; Chang, Douglas G; Date, Elaine S; Jerger, James F

2004-03-01

Because of the violent nature of traumatic brain injury, traumatic brain injury patients are susceptible to various types of trauma involving the auditory system. We report a case of a 55-yr-old man who presented with communication problems after traumatic brain injury. Initial results from behavioral audiometry and Weber/Rinne tests were not reliable because of poor cooperation. He was transferred to our service for inpatient rehabilitation, where review of the initial head computed tomographic scan showed only left temporal bone fracture. Brainstem auditory-evoked potential was then performed to evaluate his hearing function. The results showed bilateral absence of auditory-evoked responses, which strongly suggested bilateral deafness. This finding led to a follow-up computed tomographic scan, with focus on bilateral temporal bones. A subtle transverse fracture of the right temporal bone was then detected, in addition to the left temporal bone fracture previously identified. Like children with hearing impairment, traumatic brain injury patients may not be able to verbalize their auditory deficits in a timely manner. If hearing loss is suspected in a patient who is unable to participate in traditional behavioral audiometric testing, brainstem auditory-evoked potential may be an option for evaluating hearing dysfunction.

Early-Stage Visual Processing and Cortical Amplification Deficits in Schizophrenia

PubMed Central

Butler, Pamela D.; Zemon, Vance; Schechter, Isaac; Saperstein, Alice M.; Hoptman, Matthew J.; Lim, Kelvin O.; Revheim, Nadine; Silipo, Gail; Javitt, Daniel C.

2005-01-01

Background Patients with schizophrenia show deficits in early-stage visual processing, potentially reflecting dysfunction of the magnocellular visual pathway. The magnocellular system operates normally in a nonlinear amplification mode mediated by glutamatergic (N-methyl-d-aspartate) receptors. Investigating magnocellular dysfunction in schizophrenia therefore permits evaluation of underlying etiologic hypotheses. Objectives To evaluate magnocellular dysfunction in schizophrenia, relative to known neurochemical and neuroanatomical substrates, and to examine relationships between electrophysiological and behavioral measures of visual pathway dysfunction and relationships with higher cognitive deficits. Design, Setting, and Participants Between-group study at an inpatient state psychiatric hospital and out-patient county psychiatric facilities. Thirty-three patients met DSM-IV criteria for schizophrenia or schizoaffective disorder, and 21 nonpsychiatric volunteers of similar ages composed the control group. Main Outcome Measures (1) Magnocellular and parvocellular evoked potentials, analyzed using nonlinear (Michaelis-Menten) and linear contrast gain approaches; (2) behavioral contrast sensitivity measures; (3) white matter integrity; (4) visual and nonvisual neuropsychological measures, and (5) clinical symptom and community functioning measures. Results Patients generated evoked potentials that were significantly reduced in response to magnocellular-biased, but not parvocellular-biased, stimuli (P=.001). Michaelis-Menten analyses demonstrated reduced contrast gain of the magnocellular system (P=.001). Patients showed decreased contrast sensitivity to magnocellular-biased stimuli (P<.001). Evoked potential deficits were significantly related to decreased white matter integrity in the optic radiations (P<.03). Evoked potential deficits predicted impaired contrast sensitivity (P=.002), which was in turn related to deficits in complex visual processing (P≤.04). Both evoked potential (P≤.04) and contrast sensitivity (P=.01) measures significantly predicted community functioning. Conclusions These findings confirm the existence of early-stage visual processing dysfunction in schizophrenia and provide the first evidence that such deficits are due to decreased nonlinear signal amplification, consistent with glutamatergic theories. Neuroimaging studies support the hypothesis of dysfunction within low-level visual pathways involving thalamocortical radiations. Deficits in early-stage visual processing significantly predict higher cognitive deficits. PMID:15867102

The action of ether and methoxyflurane on synaptic transmission in isolated preparations of the mammalian cortex.

PubMed Central

Richards, C D; Russell, W J; Smaje, J C

1975-01-01

1. The actions of ether and methoxyflurane on the evoked potentials of in vitro preparations of the guinea-pig olfactory cortex were studied. Following stimulation of the lateral olfactory tract (l.o.t.) evoked potentials could be recorded from the cortical surface; these potentials consisted of an initial wave (the compound action potential of the l.o.t.) followed by a negative field potential which was associated with the synchronous excitation of many superficial excitatory synapses (population e.p.s.p.). Superimposed on the population e.p.s.p. was a number of positive peaks. These positive peaks reflect the synchronous discharge of many neurones and so have been called population spikes. 2. When ether or methoxyflurane was added to the gas stream that superfused the surface of the preparations, the population e.p.s.p.s. and population spikes were depressed at lower concentrations than those required to depress the compound action potential of the afferent fibres. 3. The evoked activity of individual cells in the cortex was depressed by ether and methoxyflurane. However, five of the twelve cells tested in ether showed an increase in their evoked activity at concentrations below 4-5%, but at higher concentrations these cells also became depressed. 4. Both ether and methoxyflurane depressed the sensitivity of cortical neurones to iontophoretically applied L-glutamate and may similarly depress the sensitivity of the post-synaptic membrane to the released transmitter substance. 5. Neither anaesthetic appeared to increase the threshold depolarization required for nerve impulse generation. Thus, the decrease of the discharge of the post-synaptic cells was primarily caused by a depression of chemical transmission. 6. Ether caused some cells in the cortex to alter their normal pattern of synaptically evoked discharge and both anaesthetics induced similar changes during excitation by glutamate. PMID:168356

Hydrogen-rich saline promotes survival of retinal ganglion cells in a rat model of optic nerve crush.

PubMed

Sun, Jing-chuan; Xu, Tao; Zuo, Qiao; Wang, Ruo-bing; Qi, Ai-qing; Cao, Wen-luo; Sun, Ai-jun; Sun, Xue-jun; Xu, Jiajun

2014-01-01

To investigate the effect of molecular hydrogen (H2) in a rat model subjected to optic nerve crush (ONC). We tested the hypothesis that after optic nerve crush (ONC), retinal ganglion cell (RGC) could be protected by H₂. Rats in different groups received saline or hydrogen-rich saline every day for 14 days after ONC. Retinas from animals in each group underwent measurements of hematoxylin and eosin (H&E) staining, cholera toxin beta (CTB) tracing, gamma synuclein staining, and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining 2 weeks post operation. Flash visual evoked potentials (FVEP) and pupillary light reflex (PLR) were then tested to evaluate the function of optic nerve. The malondialdehyde (MDA) level in retina was evaluated. H&E, gamma synuclein staining and CTB tracing showed that the survival rate of RGCs in hydrogen saline-treated group was significantly higher than that in saline-treated group. Apoptosis of RGCs assessed by TUNEL staining were less observed in hydrogen saline-treated group. The MDA level in retina of H₂ group was much lower than that in placebo group. Furthermore, animals treated with hydrogen saline showed better function of optic nerve in assessments of FVEP and PLR. These results demonstrated that H₂ protects RGCs and helps preserve the visual function after ONC and had a neuroprotective effect in a rat model subjected to ONC.

Sustained visual-spatial attention produces costs and benefits in response time and evoked neural activity.

PubMed

Mangun, G R; Buck, L A

1998-03-01

This study investigated the simple reaction time (RT) and event-related potential (ERP) correlates of biasing attention towards a location in the visual field. RTs and ERPs were recorded to stimuli flashed randomly and with equal probability to the left and right visual hemifields in the three blocked, covert attention conditions: (i) attention divided equally to left and right hemifield locations; (ii) attention biased towards the left location; or (iii) attention biased towards the right location. Attention was biased towards left or right by instructions to the subjects, and responses were required to all stimuli. Relative to the divided attention condition, RTs were significantly faster for targets occurring where more attention was allocated (benefits), and slower to targets where less attention was allocated (costs). The early P1 (100-140 msec) component over the lateral occipital scalp regions showed attentional benefits. There were no amplitude modulations of the occipital N1 (125-180 msec) component with attention. Between 200 and 500 msec latency, a late positive deflection (LPD) showed both attentional costs and benefits. The behavioral findings show that when sufficiently induced to bias attention, human observers demonstrate RT benefits as well as costs. The corresponding P1 benefits suggest that the RT benefits of spatial attention may arise as the result of modulations of visual information processing in the extrastriate visual cortex.

Interoceptive signals impact visual processing: Cardiac modulation of visual body perception.

PubMed

Ronchi, Roberta; Bernasconi, Fosco; Pfeiffer, Christian; Bello-Ruiz, Javier; Kaliuzhna, Mariia; Blanke, Olaf

2017-09-01

Multisensory perception research has largely focused on exteroceptive signals, but recent evidence has revealed the integration of interoceptive signals with exteroceptive information. Such research revealed that heartbeat signals affect sensory (e.g., visual) processing: however, it is unknown how they impact the perception of body images. Here we linked our participants' heartbeat to visual stimuli and investigated the spatio-temporal brain dynamics of cardio-visual stimulation on the processing of human body images. We recorded visual evoked potentials with 64-channel electroencephalography while showing a body or a scrambled-body (control) that appeared at the frequency of the on-line recorded participants' heartbeat or not (not-synchronous, control). Extending earlier studies, we found a body-independent effect, with cardiac signals enhancing visual processing during two time periods (77-130 ms and 145-246 ms). Within the second (later) time-window we detected a second effect characterised by enhanced activity in parietal, temporo-occipital, inferior frontal, and right basal ganglia-insula regions, but only when non-scrambled body images were flashed synchronously with the heartbeat (208-224 ms). In conclusion, our results highlight the role of interoceptive information for the visual processing of human body pictures within a network integrating cardio-visual signals of relevance for perceptual and cognitive aspects of visual body processing. Copyright © 2017 Elsevier Inc. All rights reserved.

Cortical Auditory Evoked Potentials to Evaluate Cochlear Implant Candidacy in an Ear With Long-standing Hearing Loss: A Case Report.

PubMed

Patel, Tirth R; Shahin, Antoine J; Bhat, Jyoti; Welling, D Bradley; Moberly, Aaron C

2016-10-01

We describe a novel use of cortical auditory evoked potentials in the preoperative workup to determine ear candidacy for cochlear implantation. A 71-year-old male was evaluated who had a long-deafened right ear, had never worn a hearing aid in that ear, and relied heavily on use of a left-sided hearing aid. Electroencephalographic testing was performed using free field auditory stimulation of each ear independently with pure tones at 1000 and 2000 Hz at approximately 10 dB above pure-tone thresholds for each frequency and for each ear. Mature cortical potentials were identified through auditory stimulation of the long-deafened ear. The patient underwent successful implantation of that ear. He experienced progressively improving aided pure-tone thresholds and binaural speech recognition benefit (AzBio score of 74%). Findings suggest that use of cortical auditory evoked potentials may serve a preoperative role in ear selection prior to cochlear implantation. © The Author(s) 2016.

Stability of Evoked Potentials during Auditory Attention

DTIC Science & Technology

1988-12-01

attention ef- (S2), to which the subject made a behavioral response and fects upon NI components of the evoked potential received food reinforcement for a... food dipper mounted in the floor, and a driver, with a sound tube attached, mounted in the top of the box. Histology Four weeks after surgery, the cats...response paradigm dose of intravenous sodium pentobarbital. Electrolytic lesions were using food reinforcement. They were gradually deprived of food

Intraoperative Neurophysiological Monitoring for Endoscopic Endonasal Approaches to the Skull Base: A Technical Guide

PubMed Central

Lober, Robert M.; Doan, Adam T.; Matsumoto, Craig I.; Kenning, Tyler J.; Evans, James J.

2016-01-01

Intraoperative neurophysiological monitoring during endoscopic, endonasal approaches to the skull base is both feasible and safe. Numerous reports have recently emerged from the literature evaluating the efficacy of different neuromonitoring tests during endonasal procedures, making them relatively well-studied. The authors report on a comprehensive, multimodality approach to monitoring the functional integrity of at risk nervous system structures, including the cerebral cortex, brainstem, cranial nerves, corticospinal tract, corticobulbar tract, and the thalamocortical somatosensory system during endonasal surgery of the skull base. The modalities employed include electroencephalography, somatosensory evoked potentials, free-running and electrically triggered electromyography, transcranial electric motor evoked potentials, and auditory evoked potentials. Methodological considerations as well as benefits and limitations are discussed. The authors argue that, while individual modalities have their limitations, multimodality neuromonitoring provides a real-time, comprehensive assessment of nervous system function and allows for safer, more aggressive management of skull base tumors via the endonasal route. PMID:27293965

Applications of pain-related evoked potentials and short-latency somatosensory evoked potentials in acupuncture research: a narrative review.

PubMed

Lin, Chi; Ma, Liangxiao; Zhu, Shipeng; Hu, Nijuan; Wang, Pei; Zhang, Peng; Qi, Dandan; Hao, Jie; Li, Jing; Xin, Siyuan; Zhu, Jiang

2015-10-01

To review and discuss the Chinese and English literature on the use of pain-related evoked potentials (PREP) and short-latency somatosensory EP (SLSEP) in acupuncture research. China National Knowledge Infrastructure Database and MEDLINE were searched for the following key words: acupuncture and PREP or SLSEP. Thirty-seven articles were included in the review. Researchers usually use PREPs to study the analgesic effect of acupuncture, observe influential factors, or for mechanistic exploration. In the SLSEP studies, researchers focused on response characteristics of acupuncture, acupoint specificity, and influential factors of the treatment. There were some problems with the study design and conclusions. Researchers could use PREP and SLSEP to objectively validate the effects of acupuncture and explore its mechanisms using nerve electrophysiology. Further studies can benefit from observing more acupoints' effects using PREPs or SLSEPs and investigating the placebo effect of acupuncture.

Multifocal visual evoked potentials for early glaucoma detection.

PubMed

Weizer, Jennifer S; Musch, David C; Niziol, Leslie M; Khan, Naheed W

2012-07-01

To compare multifocal visual evoked potentials (mfVEP) with other detection methods in early open-angle glaucoma. Ten patients with suspected glaucoma and 5 with early open-angle glaucoma underwent mfVEP, standard automated perimetry (SAP), short-wave automated perimetry, frequency-doubling technology perimetry, and nerve fiber layer optical coherence tomography. Nineteen healthy control subjects underwent mfVEP and SAP for comparison. Comparisons between groups involving continuous variables were made using independent t tests; for categorical variables, Fisher's exact test was used. Monocular mfVEP cluster defects were associated with an increased SAP pattern standard deviation (P = .0195). Visual fields that showed interocular mfVEP cluster defects were more likely to also show superior quadrant nerve fiber layer thinning by OCT (P = .0152). Multifocal visual evoked potential cluster defects are associated with a functional and an anatomic measure that both relate to glaucomatous optic neuropathy. Copyright 2012, SLACK Incorporated.

Substance P analogues potentiate the pressor response to microinjection of L-glutamate into laminas I and II of the cat dorsal horn.

PubMed

Beyaert, C A; Hill, J M; Kaufman, M P

1997-06-06

Microinjection of a substance P analogue (1 mM; 7 or 10 nl) into laminae I and II of the L7 dorsal horn of decerebrate cats significantly potentiated (P < 0.05) the increase in arterial pressure evoked by microinjection of L-glutamate (109 mM; 7 or 10 nl) into these spinal sites. Microinjection of the substance P analogues (i.e., GR73638 and [Sar9,Met(O2)11]-substance P) which were selective NK-1 receptor agonists, had no impact on the cardioacceleration evoked by microinjection of L-glutamate (P > 0.05). In addition, microinjection of these analogues had no effect on the modest and non-significant increase in phrenic nerve discharge evoked by L-glutamate. We conclude that stimulation of NK-1 receptors in the superficial laminae of the dorsal horn potentiates the pressor responses to microinjection of L-glutamate.

Cholesterol-dependent balance between evoked and spontaneous synaptic vesicle recycling

PubMed Central

Wasser, Catherine R; Ertunc, Mert; Liu, Xinran; Kavalali, Ege T

2007-01-01

Cholesterol is a prominent component of nerve terminals. To examine cholesterol's role in central neurotransmission, we treated hippocampal cultures with methyl-β-cyclodextrin, which reversibly binds cholesterol, or mevastatin, an inhibitor of cholesterol biosynthesis, to deplete cholesterol. We also used hippocampal cultures from Niemann-Pick type C1-deficient mice defective in intracellular cholesterol trafficking. These conditions revealed an augmentation in spontaneous neurotransmission detected electrically and an increase in spontaneous vesicle endocytosis judged by horseradish peroxidase uptake after cholesterol depletion by methyl-β-cyclodextrin. In contrast, responses evoked by action potentials and hypertonicity were severely impaired after the same treatments. The increase in spontaneous vesicle recycling and the decrease in evoked neurotransmission were reversible upon cholesterol addition. Cholesterol removal did not impact on the low level of evoked neurotransmission seen in the absence of synaptic vesicle SNARE protein synaptobrevin-2 whereas the increase in spontaneous fusion remained. These results suggest that synaptic cholesterol balances evoked and spontaneous neurotransmission by hindering spontaneous synaptic vesicle turnover and sustaining evoked exo-endocytosis. PMID:17170046

Total Lightning Characteristics with Respect to Radar-Derived Mesocyclone Strength

NASA Technical Reports Server (NTRS)

Stough, Sarah M.; Carey, Lawrence D.; Schultz, Christopher J.

2015-01-01

Recent work investigating the microphysical and kinematic relationship between a storm's updraft, its total lightning production, and manifestations of severe weather has resulted in development of tools for improved nowcasting of storm intensity. The total lightning jump algorithm, which identifies rapid increases in total lightning flash rate that often precede severe events, has shown particular potential to benefit warning operations. Maximizing this capability of total lightning and its operational implementation via the lightning jump may best be done through its fusion with radar and radar-derived intensity metrics. Identification of a mesocyclone, or quasi-steady rotating updraft, in Doppler velocity is the predominant radar-inferred early indicator of severe potential in a convective storm. Fused lightning-radar tools that capitalize on the most robust intensity indicators would allow enhanced situational awareness for increased warning confidence. A foundational step toward such tools comes from a better understanding of the updraft-centric relationship between intensification of total lightning production and mesocyclone development and strength. The work presented here utilizes a sample of supercell case studies representing a spectrum of severity. These storms are analyzed with respect to total lightning flash rate and the lightning jump alongside mesocyclone strength derived objectively from the National Severe Storms Laboratory (NSSL) Mesocyclone Detection Algorithm (MDA) and maximum azimuthal shear through a layer. Early results indicate that temporal similarities exist in the trends between total lightning flash rate and low- to mid-level rotation in supercells. Other characteristics such as polarimetric signatures of rotation, flash size, and cloud-to-ground flash ratio are explored for added insight into the significance of these trends with respect to the updraft and related processes of severe weather production.

Interhemispheric Asymmetries in Visual Evoked Potential Amplitude

DTIC Science & Technology

1980-06-12

Layne, 1965) and of patients with Korsakoff’s syndrome (Malerstein and Callaway, 1969) . In the schizophrenics, the high variability is related to poor...communication. Malerstein, A. J., Callaway, E. Two-tone average evoked response in Korsakoff patients. J. Psychiatr. Res. 6: 253-260, 1969. Marsh, G

Small-scale (flash) flood early warning in the light of operational requirements: opportunities and limits with regard to user demands, driving data, and hydrologic modeling techniques

NASA Astrophysics Data System (ADS)

Philipp, Andy; Kerl, Florian; Büttner, Uwe; Metzkes, Christine; Singer, Thomas; Wagner, Michael; Schütze, Niels

2016-05-01

In recent years, the Free State of Saxony (Eastern Germany) was repeatedly hit by both extensive riverine flooding, as well as flash flood events, emerging foremost from convective heavy rainfall. Especially after a couple of small-scale, yet disastrous events in 2010, preconditions, drivers, and methods for deriving flash flood related early warning products are investigated. This is to clarify the feasibility and the limits of envisaged early warning procedures for small catchments, hit by flashy heavy rain events. Early warning about potentially flash flood prone situations (i.e., with a suitable lead time with regard to required reaction-time needs of the stakeholders involved in flood risk management) needs to take into account not only hydrological, but also meteorological, as well as communication issues. Therefore, we propose a threefold methodology to identify potential benefits and limitations in a real-world warning/reaction context. First, the user demands (with respect to desired/required warning products, preparation times, etc.) are investigated. Second, focusing on small catchments of some hundred square kilometers, two quantitative precipitation forecasts are verified. Third, considering the user needs, as well as the input parameter uncertainty (i.e., foremost emerging from an uncertain QPF), a feasible, yet robust hydrological modeling approach is proposed on the basis of pilot studies, employing deterministic, data-driven, and simple scoring methods.

Augmenting responses evoked in area 17 of the cat by intracortical axon collaterals of cortico-geniculate cells.

PubMed Central

Ferster, D; Lindström, S

1985-01-01

Evoked potentials were recorded in the visual cortex of the cat after electrical stimulation of the lateral geniculate nucleus (l.g.n.). The primary response, mediated by geniculo-cortical fibres, was depressed at stimulation frequencies above 7 Hz and replaced by a late potential, the incremental response, which gradually increased in amplitude with successive stimuli. The incremental response was a negative-positive potential in the depth of the cortex with the negative component having maximal amplitude in layer 4. The response reversed polarity in layer 1 to become a positive-negative potential at the surface. The latency of the negative component of the incremental response was about 3.5-4 ms in layer 4, compared to about 1.5 and 2.5 ms for the mono- and disynaptic components of the primary response. The incremental response could only be evoked from the l.g.n. and the optic radiation, not from the optic tract, superior colliculus or other surrounding structures. Within the l.g.n., the effect was only evoked from stimulation sites in approximate retinotopic register with the recording site in the cortex. Low threshold points were found in the A laminae, completely overlapping with the low threshold points for the primary response. Thresholds increased steeply when the stimulation electrode was lowered into the C laminae. The incremental response could still be evoked ten days after the destruction of all cells in the l.g.n. complex by kainic acid. It is concluded that the described incremental response is identical to the augmenting response of Dempsey & Morison (1943) and is mediated by intracortical axon collaterals of antidromically activated cortico-geniculate neurones. Images Plate 1 PMID:4057097

A Temporal Locality-Aware Page-Mapped Flash Translation Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Youngjae; Gupta, Aayush; Urgaonkar, Bhuvan

2013-01-01

The poor performance of random writes has been a cause of major concern which needs to be addressed to better utilize the potential of flash in enterprise-scale environments. We examine one of the important causes of this poor performance: the design of the flash translation layer (FTL) which performs the virtual-to-physical address translations and hides the erase-before-write characteristics of flash. We propose a complete paradigm shift in the design of the core FTL engine from the existing techniques with our Demand-Based Flash Translation Layer (DFTL) which selectively caches page- level address mappings. Our experimental evaluation using FlashSim with realistic enterprise-scalemore » workloads endorses the utility of DFTL in enterprise-scale storage systems by demonstrating: 1) improved performance, 2) reduced garbage collection overhead and 3) better overload behavior compared with hybrid FTL schemes which are the most popular implementation methods. For example, a predominantly random-write dominant I/O trace from an OLTP application running at a large financial institution shows a 78% improvement in average response time (due to a 3-fold reduction in operations of the garbage collector), compared with the hybrid FTL scheme. Even for the well-known read-dominant TPC-H benchmark, for which DFTL introduces additional overheads, we improve system response time by 56%. Moreover, interestingly, when write-back cache on DFTL-based SSD is enabled, DFTL even outperforms the page-based FTL scheme, improving their response time by 72% in Financial trace.« less

Total Lightning and Radar Storm Characteristics Associated with Severe Storms in Central Florida

NASA Technical Reports Server (NTRS)

Goodman, Steven J; Raghavan, R.; Buechler, Dennis; Hodanish, S.; Sharp, D.; Williams, E.; Boldi, B.; Matlin, A.; Weber, M.

1998-01-01

This paper examines the three dimensional characteristics of lightning flashes and severe storms observed in Central Florida during 1997-1998. The lightning time history of severe and tornadic storms were captured during the on-going ground validation campaign supporting the Lightning Imaging Sensor (LIS) experiment on the Tropical Rainfall Measuring Mission (TRMM). The ground validation campaign is a collaborative experiment that began in 1997 and involves scientists at the Global Hydrology and Climate Center, MIT/Lincoln Laboratories, and the NWS Forecast Office at Melbourne, FL. Lightning signatures that may provide potential early warning of severe storms are being evaluated by the forecasters at the NWS/MLB office. Severe storms with extreme flash rates sometimes exceeding 300 per minute and accompanying rapid increases in flash rate prior to the onset of the severe weather (hall, damaging winds, tornadoes) have been reported by Hodanish et al. and Williams et al. (1998-this conference). We examine the co-evolving changes in storm structure (mass, echo top, shear, latent heat release) and kinematics associated with these extreme and rapid flash rate changes over time. The flash frequency and density are compared with the three dimensional radar reflectivity structure of the storm to help interpret the possible mechanisms producing the extreme and rapidly increasing flash rates. For two tornadic storms examined thus far, we find the burst of lightning is associated with the development of upper level rotation in the storm. In one case, the lightning burst follows the formation of a bounded weak echo region (BWER). The flash rates diminish with time as the rotation develops to the ground in conjunction with the decent of the reflectivity core. Our initial findings suggest the dramatic increase of flash rates is associated with a sudden and dramatic increase in storm updraft intensity which we hypothesize is stretching vertical vorticity as well as enhancing the development of the mixed phase region of the storm. We discuss the importance of these factors in producing both the observed extreme flash rates and the severe weather that follows in these storms and others to be presented.

Single-trial extraction of cognitive evoked potentials by combination of third-order correlation and wavelet denoising.

PubMed

Zhang, Z; Tian, X

2005-01-01

The application of a recently proposed denoising implementation for obtaining cognitive evoked potentials (CEPs) at the single-trial level is shown. The aim of this investigation is to develop the technique of extracting CEPs by combining both the third-order correlation and the wavelet denoising methods. First, the noisy CEPs was passed through a finite impulse response filter whose impulse response is matched with the shape of the noise-free signal. It was shown that it is possible to estimate the filter impulse response on basis of a select third-order correlation slice (TOCS) of the input noisy CEPs. Second, the output from the third-order correlation filter is decomposed with bi-orthogonal splines at 5 levels. The CEPs is reconstructed by wavelet final approximation a5. We study its performance in simulated data as well as in cognitive evoked potentials of normal rat and Alzheimer's disease (AD) model rat. For the simulated data, the method gives a significantly better reconstruction of the single-trial cognitive evoked potentials responses in comparison with the simulated data. Moreover, with this approach we obtain a significantly better estimation of the amplitudes and latencies of the simulated CEPs. For the real data, the method clearly improves the visualization of single-trial CEPs. This allows the calculation of better averages as well as the study of systematic or unsystematic variations between trials.

Sensitivity of visual evoked potentials and spectral domain optical coherence tomography in early relapsing remitting multiple sclerosis.

PubMed

Behbehani, Raed; Ahmed, Samar; Al-Hashel, Jasem; Rousseff, Rossen T; Alroughani, Raed

2017-02-01

Visual evoked potentials and spectral-domain optical coherence tomography are common ancillary studies that assess the visual pathways from a functional and structural aspect, respectively. To compare prevalence of abnormalities of Visual evoked potentials (VEP) and spectral-domain optical coherence tomography (SDOCT) in patients with relapsing remitting multiple sclerosis (RRMS). A cross-sectional study of 100 eyes with disease duration of less than 5 years since the diagnosis. Correlation between retinal nerve fiber layer and ganglion-cell/inner plexiform layer with pattern-reversal visual evoked potentials amplitude and latency and contrast sensitivity was performed. The prevalence of abnormalities in pattern-reversal visual VEP was 56% while that of SOCT was 48% in all eyes. There was significant negative correlations between the average RNFL (r=-0.34, p=0.001) and GCIPL (r=-0.39, p<0.001) with VEP latency. In eyes with prior optic neuritis, a significant negative correlation was seen between average RNFL (r=-0.33, p=0.037) and GCIPL (r=-0.40, p=0.010) with VEP latency. We have found higher prevalence of VEP abnormalities than SCOCT in early relapsing-remitting multiple sclerosis. This suggests that VEP has a higher sensitivity for detecting lesions of the visual pathway in patients with early RRMS. Copyright © 2016 Elsevier B.V. All rights reserved.

Objective Assessment of Spectral Ripple Discrimination in Cochlear Implant Listeners Using Cortical Evoked Responses to an Oddball Paradigm

PubMed Central

Lopez Valdes, Alejandro; Mc Laughlin, Myles; Viani, Laura; Walshe, Peter; Smith, Jaclyn; Zeng, Fan-Gang; Reilly, Richard B.

2014-01-01

Cochlear implants (CIs) can partially restore functional hearing in deaf individuals. However, multiple factors affect CI listener's speech perception, resulting in large performance differences. Non-speech based tests, such as spectral ripple discrimination, measure acoustic processing capabilities that are highly correlated with speech perception. Currently spectral ripple discrimination is measured using standard psychoacoustic methods, which require attentive listening and active response that can be difficult or even impossible in special patient populations. Here, a completely objective cortical evoked potential based method is developed and validated to assess spectral ripple discrimination in CI listeners. In 19 CI listeners, using an oddball paradigm, cortical evoked potential responses to standard and inverted spectrally rippled stimuli were measured. In the same subjects, psychoacoustic spectral ripple discrimination thresholds were also measured. A neural discrimination threshold was determined by systematically increasing the number of ripples per octave and determining the point at which there was no longer a significant difference between the evoked potential response to the standard and inverted stimuli. A correlation was found between the neural and the psychoacoustic discrimination thresholds (R2 = 0.60, p<0.01). This method can objectively assess CI spectral resolution performance, providing a potential tool for the evaluation and follow-up of CI listeners who have difficulty performing psychoacoustic tests, such as pediatric or new users. PMID:24599314

Use of NK1 receptor antagonists in the exploration of physiological functions of substance P and neurokinin A.

PubMed

Otsuka, M; Yoshioka, K; Yanagisawa, M; Suzuki, H; Zhao, F Y; Guo, J Z; Hosoki, R; Kurihara, T

1995-07-01

Tachykinin NK1 receptor antagonists were used to explore the physiological functions of substance P (SP) and neurokinin A (NKA). Pharmacological profiles of three NK1 receptor antagonists, GR71251, GR82334, and RP 67580, were examined in the isolated spinal cord preparation of the neonatal rat. These tachykinin receptor antagonists exhibited considerable specificities and antagonized the actions of both SP and NKA to induce the depolarization of ventral roots. Electrical stimulation of the saphenous nerve with C-fiber strength evoked a depolarization lasting about 30 s of the ipsilateral L3 ventral root. This response, which is referred to as saphenous-nerve-evoked slow ventral root potential (VRP), was depressed by these NK1 receptor antagonists. In contrast, the saphenous-nerve-evoked slow VRP was potentiated by application of a mixture of peptidase inhibitors, including thiorphan, actinonin, and captopril in the presence of naloxone, but not after further addition of GR71251. Likewise, in the isolated coeliac ganglion of the guinea pig, electrical stimulation of the mesenteric nerves evoked in some ganglionic cells slow excitatory postsynaptic potentials (EPSPs), which were depressed by GR71251 and potentiated by peptidase inhibitors. These results further support the notion that SP and NKA serve as neurotransmitters producing slow EPSPs in the neonatal rat spinal cord and guinea pig prevertebral ganglia.

Objective assessment of spectral ripple discrimination in cochlear implant listeners using cortical evoked responses to an oddball paradigm.

PubMed

Lopez Valdes, Alejandro; Mc Laughlin, Myles; Viani, Laura; Walshe, Peter; Smith, Jaclyn; Zeng, Fan-Gang; Reilly, Richard B

2014-01-01

Cochlear implants (CIs) can partially restore functional hearing in deaf individuals. However, multiple factors affect CI listener's speech perception, resulting in large performance differences. Non-speech based tests, such as spectral ripple discrimination, measure acoustic processing capabilities that are highly correlated with speech perception. Currently spectral ripple discrimination is measured using standard psychoacoustic methods, which require attentive listening and active response that can be difficult or even impossible in special patient populations. Here, a completely objective cortical evoked potential based method is developed and validated to assess spectral ripple discrimination in CI listeners. In 19 CI listeners, using an oddball paradigm, cortical evoked potential responses to standard and inverted spectrally rippled stimuli were measured. In the same subjects, psychoacoustic spectral ripple discrimination thresholds were also measured. A neural discrimination threshold was determined by systematically increasing the number of ripples per octave and determining the point at which there was no longer a significant difference between the evoked potential response to the standard and inverted stimuli. A correlation was found between the neural and the psychoacoustic discrimination thresholds (R2=0.60, p<0.01). This method can objectively assess CI spectral resolution performance, providing a potential tool for the evaluation and follow-up of CI listeners who have difficulty performing psychoacoustic tests, such as pediatric or new users.

Passive attenuation of cortical pattern evoked potentials with increasing body weight in young male rhesus macaques.

PubMed

Komaromy, Andras M; Brooks, Dennis E; Kallberg, Maria E; Dawson, William W; Sapp, Harold L; Sherwood, Mark B; Lambrou, George N; Percicot, Christine L

2003-05-01

The purpose of our study was to determine changes in amplitudes and implicit times of retinal and cortical pattern evoked potentials with increasing body weight in young, growing rhesus macaques (Macaca mulatta). Retinal and cortical pattern evoked potentials were recorded from 29 male rhesus macaques between 3 and 7 years of age. Thirteen animals were reexamined after 11 months. Computed tomography (CT) was performed on two animals to measure the distance between the location of the skin electrode and the surface of the striate cortex. Spearman correlation coefficients were calculated to describe the relationship between body weights and either root mean square (rms) amplitudes or implicit times. For 13 animals rms amplitudes and implicit times were compared with the Wilcoxon matched pairs signed rank test for recordings taken 11 months apart. Highly significant correlations between increases in body weights and decreases in cortical rms amplitudes were noted in 29 monkeys (p < 0.0005). No significant changes were found in the cortical rms amplitudes in thirteen monkeys over 11 months. Computed tomography showed a large increase of soft tissue thickness over the skull and striate cortex with increased body weight. The decreased amplitude in cortical evoked potentials with weight gain associated with aging can be explained by the increased distance between skin electrode and striate cortex due to soft tissue thickening (passive attenuation).

The Theoretical Distribution of Evoked Brainstem Activity in Preterm, High-Risk, and Healthy Infants.

ERIC Educational Resources Information Center

Salamy, A.

1981-01-01

Determines the frequency distribution of Brainstem Auditory Evoked Potential variables (BAEP) for premature babies at different stages of development--normal newborns, infants, young children, and adults. The author concludes that the assumption of normality underlying most "standard" statistical analyses can be met for many BAEP…

The Middle Latency Response (MLR) and Steady State Evoked Potential (SSEP) in Neonates.

DTIC Science & Technology

1985-05-01

diagnostic audiologic information will enhance habilitation efforts in prescribing hearing aids and designing appropriate language intervention strategies...auditory evoked brain stem response. A study of patients with sensory hearing loss. SCANDINAVIAN AUDIOLOGY 8: 67-70, 1979. Page 165 "- FILMED 10-85 DTIC * 4 N . . -. N

Functional ligand-gated purinergic receptors (P2X) in rat vestibular ganglion neurons.

PubMed

Ito, Ken; Chihara, Yasuhiro; Iwasaki, Shinichi; Komuta, Yukari; Sugasawa, Masashi; Sahara, Yoshinori

2010-08-01

The expression of purinergic receptors (P2X) on rat vestibular ganglion neurons (VGNs) was examined using whole-cell patch-clamp recordings. An application of adenosine 5'-triphosphate (ATP; 100microM) evoked inward currents in VGNs at a holding potential of -60mV. The decay time constant of the ATP-evoked currents was 2-4s, which is in between the values for rapidly desensitizing subgroups (P2X1 and P2X3) and slowly desensitizing subgroups (P2X2, P2X4, etc.), suggesting the heterogeneous expression of P2X receptors. A dose-response experiment showed an EC(50) of 11.0microM and a Hill's coefficient of 0.82. Suramin (100microM) reversibly inhibited the ATP-evoked inward currents. Alpha, beta-methylene ATP (100microM), a P2X-specific agonist, also evoked inward currents but less extensively than ATP. An application of adenosine 5'-dihosphate (ADP; 100microM) evoked similar, but much smaller, currents. The current-voltage relationship of the ATP-evoked conductance showed pronounced inward rectification with a reversal potential more positive than 0mV, suggesting non-selective cation conductance. However, the channel was not permeable to a large cation (N-methyl-d-glucamine) and acidification (pH 6.3) had little effect on the ATP-evoked conductance. RT-PCR confirmed the expression of five subtypes (P2X2-P2X6) in VGNs. The physiological role of P2X receptors includes the modulation of excitability at the synapses between hair cells and dendrites and/or trophic support (or also neuromodulation) from supporting cells surrounding the VGNs. Copyright 2010 Elsevier B.V. All rights reserved.

Development of a mobile app for flash flood alerting and data cataloging

NASA Astrophysics Data System (ADS)

Gourley, J. J.; Flamig, Z.; Nguyen, M.

2016-12-01

No matter how accurate and specific a forecast of flash flooding is made, there are local nuances with the communities related to the built environment that often dictate the locations and magnitudes of impacts. These are difficult, if not impossible, to identify, classify, and measure using remote sensing methods. This presentation presents a Thriving Earth Exchange project that is developing a mobile app that serves two purposes. First, it will provide detailed forecasts of flash flooding down to the 1-km pixel scale with 10-min updates using the state-of-the-science hydrologic forecasting system called FLASH. The display of model outputs on an app will greatly facilitate their use and can potentially increase first responders' reactions to the specific locations of impending disasters. Then, the first responders will have the capability of reporting the geotagged impacts they are witnessing, including those local "trouble spots". Over time, we will catalog the trouble spots for the community so that they can be flagged in future events. If proven effective, the app will then be advertised in other flood-prone communities and the database will be expanded accordingly. In summary, we are engaging local communities to provide information that can inform and improve future forecasts of flash flood, ultimately reducing their impacts and saving lives.

Spectrum pattern resolution after noise exposure in a beluga whale, Delphinapterus leucas: Evoked potential study.

PubMed

Popov, Vladimir V; Nechaev, Dmitry I; Sysueva, Evgenia V; Rozhnov, Viatcheslav V; Supin, Alexander Ya

2015-07-01

Temporary threshold shift (TTS) and the discrimination of spectrum patterns after fatiguing noise exposure (170 dB re 1 μPa, 10 min duration) was investigated in a beluga whale, Delphinapterus leucas, using the evoked potential technique. Thresholds were measured using rhythmic (1000/s) pip trains of varying levels and recording the rhythmic evoked responses. Discrimination of spectrum patterns was investigated using rippled-spectrum test stimuli of various levels and ripple densities, recording the rhythmic evoked responses to ripple phase reversals. Before noise exposure, the greatest responses to rippled-spectrum probes were evoked by stimuli with a low ripple density with a decrease in the response magnitude occurring with an increasing ripple density. After noise exposure, both a TTS and a reduction of the responses to rippled-spectrum probes appeared and recovered in parallel. The reduction of the responses to rippled-spectrum probes was maximal for high-magnitude responses at low ripple densities and was negligible for low-magnitude responses at high ripple densities. It is hypothesized that the impacts of fatiguing sounds are not limited by increased thresholds and decreased sensitivity results in reduced ability to discriminate fine spectral content with the greatest impact on the discrimination of spectrum content that may carry the most obvious information about stimulus properties.

Why Flash Type Matters: A Statistical Analysis

NASA Astrophysics Data System (ADS)

Mecikalski, Retha M.; Bitzer, Phillip M.; Carey, Lawrence D.

2017-09-01

While the majority of research only differentiates between intracloud (IC) and cloud-to-ground (CG) flashes, there exists a third flash type, known as hybrid flashes. These flashes have extensive IC components as well as return strokes to ground but are misclassified as CG flashes in current flash type analyses due to the presence of a return stroke. In an effort to show that IC, CG, and hybrid flashes should be separately classified, the two-sample Kolmogorov-Smirnov (KS) test was applied to the flash sizes, flash initiation, and flash propagation altitudes for each of the three flash types. The KS test statistically showed that IC, CG, and hybrid flashes do not have the same parent distributions and thus should be separately classified. Separate classification of hybrid flashes will lead to improved lightning-related research, because unambiguously classified hybrid flashes occur on the same order of magnitude as CG flashes for multicellular storms.

A low power flash-FPGA based brain implant micro-system of PID control.

PubMed

Lijuan Xia; Fattah, Nabeel; Soltan, Ahmed; Jackson, Andrew; Chester, Graeme; Degenaar, Patrick

2017-07-01

In this paper, we demonstrate that a low power flash FPGA based micro-system can provide a low power programmable interface for closed-loop brain implant inter- faces. The proposed micro-system receives recording local field potential (LFP) signals from an implanted probe, performs closed-loop control using a first order control system, then converts the signal into an optogenetic control stimulus pattern. Stimulus can be implemented through optoelectronic probes. The long term target is for both fundamental neuroscience applications and for clinical use in treating epilepsy. Utilizing our device, closed-loop processing consumes only 14nJ of power per PID cycle compared to 1.52μJ per cycle for a micro-controller implementation. Compared to an application specific digital integrated circuit, flash FPGA's are inherently programmable.

Transcranial electrical stimulation over visual cortex evokes phosphenes with a retinal origin.

PubMed

Kar, Kohitij; Krekelberg, Bart

2012-10-01

Transcranial electrical stimulation (tES) is a promising therapeutic tool for a range of neurological diseases. Understanding how the small currents used in tES spread across the scalp and penetrate the brain will be important for the rational design of tES therapies. Alternating currents applied transcranially above visual cortex induce the perception of flashes of light (phosphenes). This makes the visual system a useful model to study tES. One hypothesis is that tES generates phosphenes by direct stimulation of the cortex underneath the transcranial electrode. Here, we provide evidence for the alternative hypothesis that phosphenes are generated in the retina by current spread from the occipital electrode. Building on the existing literature, we first confirm that phosphenes are induced at lower currents when electrodes are placed farther away from visual cortex and closer to the eye. Second, we explain the temporal frequency tuning of phosphenes based on the well-known response properties of primate retinal ganglion cells. Third, we show that there is no difference in the time it takes to evoke phosphenes in the retina or by stimulation above visual cortex. Together, these findings suggest that phosphenes induced by tES over visual cortex originate in the retina. From this, we infer that tES currents spread well beyond the area of stimulation and are unlikely to lead to focal neural activation. Novel stimulation protocols that optimize current distributions are needed to overcome these limitations of tES.

Body Doping Profile of Select Device to Minimize Program Disturbance in Three-Dimensional Stack NAND Flash Memory

NASA Astrophysics Data System (ADS)

Choe, Byeong-In; Park, Byung-Gook; Lee, Jong-Ho

2013-06-01

The program disturbance characteristic in the three-dimensional (3D) stack NAND flash was analyzed for the first time in terms of string select line (SSL) threshold voltage (Vth) and p-type body doping profile. From the edge word line (W/L) program disturbance, we can observe the boosted channel potential loss as a function of SSL Vth and body doping profile for SSL device. According to simulation work, a high Vth of the SSL device is required to suppress channel leakage during programming. When the body doping of the SSL device is high in the channel, there is a large band bending near the gate edge of the SSL adjacent to the edge W/L cell of boosted cell strings, which generates significantly electron-hole pairs. The generated electrons decreases the boosted channel potential, resulting in increase of program disturbance of the inhibit strings. Through optimization of the body doping profile of the SSL device, both channel leakage and the program disturbance are successfully suppressed for a highly reliable 3D stack NAND flash memory cell operation.

The Design, Synthesis and Screening of Potential Pyridinium Oxime Prodrugs

DTIC Science & Technology

1985-09-30

210 ml stainless steel bombs were each filled with 100 ml of 28% aqueous NH4OH, 2.8 g (11 imol) of copper sulfate pentahydrate , and 15 g (87 mol) of...ethyl acetate. The organic extracts were washed twice with brine, dried over sodium sulfate , filtered and flashed to a black oil. A vacuum distillation...extracts were washed with brine, dried with sodium sulfate , filtered and flashed. The residue was then purified by column chromatography (silica gel

Gender differences in binaural speech-evoked auditory brainstem response: are they clinically significant?

PubMed

Jalaei, Bahram; Azmi, Mohd Hafiz Afifi Mohd; Zakaria, Mohd Normani

2018-05-17

Binaurally evoked auditory evoked potentials have good diagnostic values when testing subjects with central auditory deficits. The literature on speech-evoked auditory brainstem response evoked by binaural stimulation is in fact limited. Gender disparities in speech-evoked auditory brainstem response results have been consistently noted but the magnitude of gender difference has not been reported. The present study aimed to compare the magnitude of gender difference in speech-evoked auditory brainstem response results between monaural and binaural stimulations. A total of 34 healthy Asian adults aged 19-30 years participated in this comparative study. Eighteen of them were females (mean age=23.6±2.3 years) and the remaining sixteen were males (mean age=22.0±2.3 years). For each subject, speech-evoked auditory brainstem response was recorded with the synthesized syllable /da/ presented monaurally and binaurally. While latencies were not affected (p>0.05), the binaural stimulation produced statistically higher speech-evoked auditory brainstem response amplitudes than the monaural stimulation (p<0.05). As revealed by large effect sizes (d>0.80), substantive gender differences were noted in most of speech-evoked auditory brainstem response peaks for both stimulation modes. The magnitude of gender difference between the two stimulation modes revealed some distinct patterns. Based on these clinically significant results, gender-specific normative data are highly recommended when using speech-evoked auditory brainstem response for clinical and future applications. The preliminary normative data provided in the present study can serve as the reference for future studies on this test among Asian adults. Copyright © 2018 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Evoked potential correlates of selective attention with multi-channel auditory inputs

NASA Technical Reports Server (NTRS)

Schwent, V. L.; Hillyard, S. A.

1975-01-01

Ten subjects were presented with random, rapid sequences of four auditory tones which were separated in pitch and apparent spatial position. The N1 component of the auditory vertex evoked potential (EP) measured relative to a baseline was observed to increase with attention. It was concluded that the N1 enhancement reflects a finely tuned selective attention to one stimulus channel among several concurrent, competing channels. This EP enhancement probably increases with increased information load on the subject.

Auditory Evoked Potentials for the Evaluation of Hearing Sensitivity in Navy Dolphins. Assessment of Hearing Sensitivity in Adult Male Elephant Seals

DTIC Science & Technology

2006-12-01

Biology of Marine Mammals, San Diego, California, 12 - 16 December. Finneran, J. J. and Houser, D. S. 2004. Objective measures of steady-state...Gervais’ beaked whale auditory evoked potential hearing measurements. 16th Biennial Conference on the Biology of Marine Mammals, San Diego, California...Biennial Conference on the Biology of Marine Mammals, San Diego, California, 12 - 16 December. 16 FTR N00014-04-1-0455 BIOMIMETICA Invited Lectures

Human lateral geniculate nucleus and visual cortex respond to screen flicker.

PubMed

Krolak-Salmon, Pierre; Hénaff, Marie-Anne; Tallon-Baudry, Catherine; Yvert, Blaise; Guénot, Marc; Vighetto, Alain; Mauguière, François; Bertrand, Olivier

2003-01-01

The first electrophysiological study of the human lateral geniculate nucleus (LGN), optic radiation, striate, and extrastriate visual areas is presented in the context of presurgical evaluation of three epileptic patients (Patients 1, 2, and 3). Visual-evoked potentials to pattern reversal and face presentation were recorded with depth intracranial electrodes implanted stereotactically. For Patient 1, electrode anatomical registration, structural magnetic resonance imaging, and electrophysiological responses confirmed the location of two contacts in the geniculate body and one in the optic radiation. The first responses peaked approximately 40 milliseconds in the LGN in Patient 1 and 60 milliseconds in the V1/V2 complex in Patients 2 and 3. Moreover, steady state visual-evoked potentials evoked by the unperceived but commonly experienced video-screen flicker were recorded in the LGN, optic radiation, and V1/V2 visual areas. This study provides topographic and temporal propagation characteristics of steady state visual-evoked potentials along human visual pathways. We discuss the possible relationship between the oscillating signal recorded in subcortical and cortical areas and the electroencephalogram abnormalities observed in patients suffering from photosensitive epilepsy, particularly video-game epilepsy. The consequences of high temporal frequency visual stimuli delivered by ubiquitous video screens on epilepsy, headaches, and eyestrain must be considered.

Direct sensorimotor corticospinal modulation of dorsal horn neuronal C-fiber responses in the rat.

PubMed

Rojas-Piloni, Gerardo; Martínez-Lorenzana, Guadalupe; Condés-Lara, Miguel; Rodríguez-Jiménez, Javier

2010-09-10

Clinically, the stimulation of motor cortical areas has been used to alleviate certain pain conditions. However, the attempts to understand the mechanisms of cortical nociceptive modulation at the spinal cord level have yielded controversial results. The objectives of the present work were to: 1) determine the effects of activating and suppressing the activity of sensorimotor cortical neurons on the nociceptive electrophysiological responses of the segmental C-fibers, and 2) evaluate the contribution of direct and indirect corticospinal projections in segmental nociceptive modulation. By means of a bipolar matrix of stimulation electrodes we mapped the stimulation of cortical areas that modulate C-fiber evoked field potentials in the dorsal horn. In addition, suppressing the cortical activity by means of cortical spreading depression, we observed that the C-fiber evoked field potentials in the dorsal horn are facilitated when cortical activity is suppressed specifically in sensorimotor cortex. Moreover, the C-fiber evoked field potentials were inhibited during spontaneous activation of cortical projecting neurons. Furthermore, after a lesion of the pyramidal tract contralateral to the spinal cord recording sites, the cortical action was suppressed. Our results show that corticospinal tract fibers arising from the sensorimotor cortex modulate directly the nociceptive C-fiber evoked responses of the dorsal horn. 2010. Published by Elsevier B.V.

Oxaloacetate decreases the infarct size and attenuates the reduction in evoked responses after photothrombotic focal ischemia in the rat cortex.

PubMed

Nagy, David; Marosi, Mate; Kis, Zsolt; Farkas, Tamas; Rakos, Gabriella; Vecsei, Laszlo; Teichberg, Vivian I; Toldi, Jozsef

2009-09-01

A traumatic brain injury or a focal brain lesion is followed by acute excitotoxicity caused by the presence of abnormally high glutamate (Glu) levels in the cerebrospinal and interstitial fluids. It has recently been demonstrated that this excess Glu in the brain can be eliminated into the blood following the intravenous administration of oxaloacetate (OxAc), which, by scavenging the blood Glu, induces an enhanced and neuroprotective brain-to-blood Glu efflux. In this study, we subjected rats to a photothrombotic lesion and treated them after the illumination with a single 30-min-long administration of OxAc (1.2 mg/100 g, i.v.). Following induction of the lesion, we measured the infarct size and the amplitudes of the somatosensory evoked potentials (SEPs) as recorded from the skull surface. The photothrombotic lesion resulted in appreciably decreased amplitudes of the evoked potentials, but OxAc administration significantly attenuated this reduction, and also the infarct size assessed histologically. We suggest that the neuroprotective effects of OxAc are due to its blood Glu-scavenging activity, which, by increasing the brain-to-blood Glu efflux, reduces the excess Glu responsible for the anatomical and functional correlates of the ischemia, as evaluated by electrophysiological evoked potential (EP) measurements.

Trends in flash flood events versus convective precipitation in the Mediterranean region: The case of Catalonia

NASA Astrophysics Data System (ADS)

Llasat, Maria Carmen; Marcos, Raul; Turco, Marco; Gilabert, Joan; Llasat-Botija, Montserrat

2016-10-01

The aim of this paper is to analyse the potential relationship between flash flood events and convective precipitation in Catalonia, as well as any related trends. The paper starts with an overview of flash floods and their trends in the Mediterranean region, along with their associated factors, followed by the definition of, identification of, and trends in convective precipitation. After this introduction the paper focuses on the north-eastern Iberian Peninsula, for which there is a long-term precipitation series (since 1928) of 1-min precipitation from the Fabra Observatory, as well as a shorter (1996-2011) but more extensive precipitation series (43 rain gauges) of 5-min precipitation. Both series have been used to characterise the degree of convective contribution to rainfall, introducing the β parameter as the ratio between convective precipitation versus total precipitation in any period. Information about flood events was obtained from the INUNGAMA database (a flood database created by the GAMA team), with the aim of finding any potential links to convective precipitation. These flood data were gathered using information on damage where flood is treated as a multifactorial risk, and where any trend or anomaly might have been caused by one or more factors affecting hazard, vulnerability or exposure. Trend analysis has shown an increase in flash flood events. The fact that no trends were detected in terms of extreme values of precipitation on a daily scale, nor on the associated ETCCDI (Expert Team on Climate Change Detection and Indices) extreme index, could point to an increase in vulnerability, an increase in exposure, or changes in land use. However, the summer increase in convective precipitation was concentrated in less torrential events, which could partially explain this positive trend in flash flood events. The β parameter has been also used to characterise the type of flood event according to the features of the precipitation. The highest values correspond to short and local events, usually with daily β values above 0.5, while the minimum threshold of daily β for catastrophic flash floods is 0.31.

A Brief 30-Year Review: Research Highlights from Lightning Mapping Systems 1970-2000

NASA Astrophysics Data System (ADS)

MacGorman, D. R.

2016-12-01

Modern lightning mapping began in the 1970s, the decade in which VHF mapping systems, acoustic mapping systems, and ground strike locating systems were introduced. Adding GPS synchronization of VHF systems in the late 1990s enabled real-time VHF mapping systems to be deployed more extensively. Data these systems provided by 2000 revolutionized our understanding of how storms produce lightning. Among key results: Electrostatics, not electrodynamics, governs where lightning is initiated and where it propagates, contrary to early expectations. Lightning is initiated in a region of large electric field magnitude, typically between a positive charge region and a negative charge region. The geometry of a storm's charge regions governs the spatial extent of each end of the flash. The flash initially propagates bidirectionally toward the two charge regions that initiated it, and once it reaches the charge regions and maximizes the ambient potential difference spanned by the flash structure, it extends through each charge region's ambient electric potential well until the total electric field magnitude at the ends of the flash drops below the threshold for continued propagation. The typical charge distribution producing a cloud-to-ground flash is a region of charge of the polarity being lowered to ground, above a lesser amount of charge of the opposite polarity; the lower region has too little charge to capture the downward propagating channel. Contrary to previous understanding, naturally occurring cloud-to-ground lightning often lowers positive charge to ground, instead of the usual negative charge, in several situations, including winter storms, stratiform precipitation regions, some severe storms, and storms on the High Plains of the United States. The reason cloud-to-ground activity in some storms is dominated by flashes that lower positive charge to ground is that the polarity of the main charge regions in those storms is inverted from the usual polarity, with the main mid-level charge being positive and the main upper-level charge being negative. This strongly implies that the dominant non-inductive electrification mechanism is inverted in those storms, probably because the liquid water content in the mixed phase region is larger than in most storms.

Investigation of Abnormal Left Temporal Functioning in Dyslexia through rCBF, Auditory Evoked Potentials, and Positron Emission Tomography.

ERIC Educational Resources Information Center

Wood, Frank; And Others

1991-01-01

Investigates the proposed left hemisphere dysfunction in dyslexia by reviewing four studies using regional cerebral blood flow (RCBF) and combined auditory evoked responses with positron emission tomography. Emphasizes methodological issues. Finds that dyslexics showed a positive correlation between Heschl's gyrus activation and phonemic…

Non-provocative diagnostics of photosensitivity using visual evoked potentials.

PubMed

Vermeulen, Joost; Kalitzin, Stiliyan; Parra, Jaime; Dekker, Erwin; Vossepoel, Albert; da Silva, Fernando Lopes

2008-04-01

Photosensitive epilepsy (PSE) is the most common form of reflex epilepsy. Usually, to find out whether a patient is sensitive, he/she is stimulated visually with, e.g. a stroboscopic light stimulus at variable frequency and intensity until a photo paroxysmal response (PPR) occurs. The research described in this work aims to find whether photosensitivity can be detected without provoking a PPR. Twenty-two subjects, 15 with known photosensitivity, were stimulated with visual stimuli that did not provoke a PPR. Using an "evoked response representation", 18 features were analytically derived from EEG signals. Single- and multi-feature classification paradigms were applied to extract those features that separate best subjects with PSE from controls. Two variables in the "evoked response representation", a frequency term and a goodness of fit term to a particular template, appeared to be best suited to make a prediction about the photosensitivity of a subject. Evoked responses appear to carry information about potential PSE. This result can be useful for screening patients for photosensitivity and it may also help to assess in a quantitative way the effectiveness of medical therapy.

The hybrid BCI system for movement control by combining motor imagery and moving onset visual evoked potential.

PubMed

Ma, Teng; Li, Hui; Deng, Lili; Yang, Hao; Lv, Xulin; Li, Peiyang; Li, Fali; Zhang, Rui; Liu, Tiejun; Yao, Dezhong; Xu, Peng

2017-04-01

Movement control is an important application for EEG-BCI (EEG-based brain-computer interface) systems. A single-modality BCI cannot provide an efficient and natural control strategy, but a hybrid BCI system that combines two or more different tasks can effectively overcome the drawbacks encountered in single-modality BCI control. In the current paper, we developed a new hybrid BCI system by combining MI (motor imagery) and mVEP (motion-onset visual evoked potential), aiming to realize the more efficient 2D movement control of a cursor. The offline analysis demonstrates that the hybrid BCI system proposed in this paper could evoke the desired MI and mVEP signal features simultaneously, and both are very close to those evoked in the single-modality BCI task. Furthermore, the online 2D movement control experiment reveals that the proposed hybrid BCI system could provide more efficient and natural control commands. The proposed hybrid BCI system is compensative to realize efficient 2D movement control for a practical online system, especially for those situations in which P300 stimuli are not suitable to be applied.

Design and optimization of geothermal power generation, heating, and cooling

NASA Astrophysics Data System (ADS)

Kanoglu, Mehmet

Most of the world's geothermal power plants have been built in 1970s and 1980s following 1973 oil crisis. Urgency to generate electricity from alternative energy sources and the fact that geothermal energy was essentially free adversely affected careful designs of plants which would maximize their performance for a given geothermal resource. There are, however, tremendous potentials to improve performance of many existing geothermal power plants by retrofitting, optimizing the operating conditions, re-selecting the most appropriate binary fluid in binary plants, and considering cogeneration such as a district heating and/or cooling system or a system to preheat water entering boilers in industrial facilities. In this dissertation, some representative geothermal resources and existing geothermal power plants in Nevada are investigated to show these potentials. Economic analysis of a typical geothermal resource shows that geothermal heating and cooling may generate up to 3 times as much revenue as power generation alone. A district heating/cooling system is designed for its incorporation into an existing 27 MW air-cooled binary geothermal power plant. The system as designed has the capability to meet the entire heating needs of an industrial park as well as 40% of its cooling needs, generating potential revenues of $14,040,000 per year. A study of the power plant shows that evaporative cooling can increase the power output by up to 29% in summer by decreasing the condenser temperature. The power output of the plant can be increased by 2.8 percent by optimizing the maximum pressure in the cycle. Also, replacing the existing working fluid isobutane by butane, R-114, isopentane, and pentane can increase the power output by up to 2.5 percent. Investigation of some well-known geothermal power generation technologies as alternatives to an existing 12.8 MW single-flash geothermal power plant shows that double-flash, binary, and combined flash/binary designs can increase the net power output by up to 31 percent, 35 percent, and 54 percent, respectively, at optimum operating conditions. An economic comparison of these designs appears to favor the combined flash/binary design, followed by the double-flash design.

[Effect of the novel dipeptide nootropic agent noopept and its metabolite cyclo-L-prolylglycine on the transcallosal evoked potential in the rat brain].

PubMed

Molodavkin, G M; Borlikova, G G; Voronina, T A; Gudasheva, T A; Ostrovskaia, R U; Tushmalova, N A; Seredenin, S B

2002-01-01

The effect of new nootropic dipeptides--noopept (N-phenylacetyl-L-prolylglycine, GVS-111) and its metabolite (cyclo-L-prolylglycine)--and a standard nootrope piracetam on the transcallosal evoked potential (TEP) in rat brain was studied. In the dose range from 150 to 300 mg/kg, piracetam increased the TEP amplitude, which exhibited a maximum after 1.5-2 h and then gradually decreased. Both noopept and cyclo-L-prolylglycine also increased the TEP amplitude, which attained a plateau and retained this level over the entire observation time (above 3.5 h). All the nootropes studied increased both components of the evoked potential. Piracetam and cyclo-L-prolylglycine led to an approximately equal increase in both waves, while noopept induced a somewhat greater increase in the negative TEP wave amplitude. It is suggested that the positive effect of noopept and cyclo-L-prolylglycine upon the interhemispheric signal transfer (indicated by the improved transcallosal response) can be considered as a potential neurophysiological basis for a positive drug influence on the behavioral level.

Auditory effects of aircraft noise on people living near an airport.

PubMed

Chen, T J; Chen, S S; Hsieh, P Y; Chiang, H C

1997-01-01

Two groups of randomly chosen individuals who lived in two communities located different distances from the airport were studied. We monitored audiometry and brainstem auditory-evoked potentials to evaluate cochlear and retrocochlear functions in the individuals studied. The results of audiometry measurements indicated that hearing ability was reduced significantly in individuals who lived near the airport and who were exposed frequently to aircraft noise. Values of pure-tone average, high pure-tone average, and threshold at 4 kHz were all higher in individuals who lived near the airport, compared with those who lived farther away. With respect to brainstem auditory-evoked potentials, latencies between the two groups were not consistently different; however, the abnormality rate of such potentials was significantly higher in volunteers who lived near the airport, compared with less-exposed counterparts. In addition, a positive correlation was found between brainstem auditory-evoked potential latency and behavioral hearing threshold of high-frequency tone in exposed volunteers. We not only confirmed that damage to the peripheral cochlear organs occurred in individuals exposed frequently to aircraft noise, but we demonstrated involvement of the central auditory pathway.

Mapping the vestibular evoked myogenic potential (VEMP).

PubMed

Colebatch, James G

2012-01-01

Effects of different electrode placements and indifferent electrodes were investigated for the vestibular evoked myogenic potential (VEMP) recorded from the sternocleidomastoid muscle (SCM). In 5 normal volunteers, the motor point of the left SCM was identified and an electrode placed there. A grid of 7 additional electrodes was laid out, along and across the SCM, based upon the location of the motor point. One reference electrode was placed over the sternoclavicular joint and another over C7. There were clear morphological changes with differing recording sites and for the two reference electrodes, but the earliest and largest responses were recorded from the motor point. The C7 reference affected the level of rectified EMG and was associated with an initial negativity in some electrodes. The latencies of the p13 potentials increased with distance from the motor point but the n23 latencies did not. Thus the p13 potential behaved as a travelling wave whereas the n23 behaved as a standing wave. The C7 reference may be contaminated by other evoked myogenic activity. Ideally recordings should be made with an active electrode over the motor point.

Effects of musical training on the auditory cortex in children.

PubMed

Trainor, Laurel J; Shahin, Antoine; Roberts, Larry E

2003-11-01

Several studies of the effects of musical experience on sound representations in the auditory cortex are reviewed. Auditory evoked potentials are compared in response to pure tones, violin tones, and piano tones in adult musicians versus nonmusicians as well as in 4- to 5-year-old children who have either had or not had extensive musical experience. In addition, the effects of auditory frequency discrimination training in adult nonmusicians on auditory evoked potentials are examined. It was found that the P2-evoked response is larger in both adult and child musicians than in nonmusicians and that auditory training enhances this component in nonmusician adults. The results suggest that the P2 is particularly neuroplastic and that the effects of musical experience can be seen early in development. They also suggest that although the effects of musical training on cortical representations may be greater if training begins in childhood, the adult brain is also open to change. These results are discussed with respect to potential benefits of early musical training as well as potential benefits of musical experience in aging.

Flash-flood potential assessment and mapping by integrating the weights-of-evidence and frequency ratio statistical methods in GIS environment - case study: Bâsca Chiojdului River catchment (Romania)

NASA Astrophysics Data System (ADS)

Costache, Romulus; Zaharia, Liliana

2017-06-01

Given the significant worldwide human and economic losses caused due to floods annually, reducing the negative consequences of these hazards is a major concern in development strategies at different spatial scales. A basic step in flood risk management is identifying areas susceptible to flood occurrences. This paper proposes a methodology allowing the identification of areas with high potential of accelerated surface run-off and consequently, of flash-flood occurrences. The methodology involves assessment and mapping in GIS environment of flash flood potential index (FFPI), by integrating two statistical methods: frequency ratio and weights-of-evidence. The methodology was applied for Bâsca Chiojdului River catchment (340 km2), located in the Carpathians Curvature region (Romania). Firstly, the areas with torrential phenomena were identified and the main factors controlling the surface run-off were selected (in this study nine geographical factors were considered). Based on the features of the considered factors, many classes were set for each of them. In the next step, the weights of each class/category of the considered factors were determined, by identifying their spatial relationships with the presence or absence of torrential phenomena. Finally, the weights for each class/category of geographical factors were summarized in GIS, resulting the FFPI values for each of the two statistical methods. These values were divided into five classes of intensity and were mapped. The final results were used to estimate the flash-flood potential and also to identify the most susceptible areas to this phenomenon. Thus, the high and very high values of FFPI characterize more than one-third of the study catchment. The result validation was performed by (i) quantifying the rate of the number of pixels corresponding to the torrential phenomena considered for the study (training area) and for the results' testing (validating area) and (ii) plotting the ROC (receiver operating characteristics) curve.

Active Flash: Performance-Energy Tradeoffs for Out-of-Core Processing on Non-Volatile Memory Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boboila, Simona; Kim, Youngjae; Vazhkudai, Sudharshan S

2012-01-01

In this abstract, we study the performance and energy tradeoffs involved in migrating data analysis into the flash device, a process we refer to as Active Flash. The Active Flash paradigm is similar to 'active disks', which has received considerable attention. Active Flash allows us to move processing closer to data, thereby minimizing data movement costs and reducing power consumption. It enables true out-of-core computation. The conventional definition of out-of-core solvers refers to an approach to process data that is too large to fit in the main memory and, consequently, requires access to disk. However, in Active Flash, processing outsidemore » the host CPU literally frees the core and achieves real 'out-of-core' analysis. Moving analysis to data has long been desirable, not just at this level, but at all levels of the system hierarchy. However, this requires a detailed study on the tradeoffs involved in achieving analysis turnaround under an acceptable energy envelope. To this end, we first need to evaluate if there is enough computing power on the flash device to warrant such an exploration. Flash processors require decent computing power to run the internal logic pertaining to the Flash Translation Layer (FTL), which is responsible for operations such as address translation, garbage collection (GC) and wear-leveling. Modern SSDs are composed of multiple packages and several flash chips within a package. The packages are connected using multiple I/O channels to offer high I/O bandwidth. SSD computing power is also expected to be high enough to exploit such inherent internal parallelism within the drive to increase the bandwidth and to handle fast I/O requests. More recently, SSD devices are being equipped with powerful processing units and are even embedded with multicore CPUs (e.g. ARM Cortex-A9 embedded processor is advertised to reach 2GHz frequency and deliver 5000 DMIPS; OCZ RevoDrive X2 SSD has 4 SandForce controllers, each with 780MHz max frequency Tensilica core). Efforts that take advantage of the available computing cycles on the processors on SSDs to run auxiliary tasks other than actual I/O requests are beginning to emerge. Kim et al. investigate database scan operations in the context of processing on the SSDs, and propose dedicated hardware logic to speed up scans. Also, cluster architectures have been explored, which consist of low-power embedded CPUs coupled with small local flash to achieve fast, parallel access to data. Processor utilization on SSD is highly dependent on workloads and, therefore, they can be idle during periods with no I/O accesses. We propose to use the available processing capability on the SSD to run tasks that can be offloaded from the host. This paper makes the following contributions: (1) We have investigated Active Flash and its potential to optimize the total energy cost, including power consumption on the host and the flash device; (2) We have developed analytical models to analyze the performance-energy tradeoffs for Active Flash, by treating the SSD as a blackbox, this is particularly valuable due to the proprietary nature of the SSD internal hardware; and (3) We have enhanced a well-known SSD simulator (from MSR) to implement 'on-the-fly' data compression using Active Flash. Our results provide a window into striking a balance between energy consumption and application performance.« less

MobRISK: a model for assessing the exposure of road users to flash flood events

NASA Astrophysics Data System (ADS)

Shabou, Saif; Ruin, Isabelle; Lutoff, Céline; Debionne, Samuel; Anquetin, Sandrine; Creutin, Jean-Dominique; Beaufils, Xavier

2017-09-01

Recent flash flood impact studies highlight that road networks are often disrupted due to adverse weather and flash flood events. Road users are thus particularly exposed to road flooding during their daily mobility. Previous exposure studies, however, do not take into consideration population mobility. Recent advances in transportation research provide an appropriate framework for simulating individual travel-activity patterns using an activity-based approach. These activity-based mobility models enable the prediction of the sequence of activities performed by individuals and locating them with a high spatial-temporal resolution. This paper describes the development of the MobRISK microsimulation system: a model for assessing the exposure of road users to extreme hydrometeorological events. MobRISK aims at providing an accurate spatiotemporal exposure assessment by integrating travel-activity behaviors and mobility adaptation with respect to weather disruptions. The model is applied in a flash-flood-prone area in southern France to assess motorists' exposure to the September 2002 flash flood event. The results show that risk of flooding mainly occurs in principal road links with considerable traffic load. However, a lag time between the timing of the road submersion and persons crossing these roads contributes to reducing the potential vehicle-related fatal accidents. It is also found that sociodemographic variables have a significant effect on individual exposure. Thus, the proposed model demonstrates the benefits of considering spatiotemporal dynamics of population exposure to flash floods and presents an important improvement in exposure assessment methods. Such improved characterization of road user exposures can present valuable information for flood risk management services.

Detection of asymptomatic cranial neuropathies in patients with systemic lupus erythematosus and their relation to antiribosomal P antibody levels and disease activity.

PubMed

Gaber, Wafaa; Ezzat, Yasser; El Fayoumy, Neveen M; Helmy, Hanan; Mohey, Abeer M

2014-01-01

The objectives of this study are to assess the risk of asymptomatic cranial neuropathy among patients with systemic lupus erythematosus (SLE) and find any association with disease activity and antiribosomal P antibodies. This study is a case-control study including 60 female patients and 30 healthy female controls. Disease activity was measured with the SLE disease activity index (SLEDAI). All patients were evaluated using evoked potentials, blink reflex, and levels of antiribosomal P antibodies. Patients with abnormal electrophysiological parameters had significantly higher levels of antiribosomal P antibodies (P = 0.034) and secondary antiphospholipid syndrome (P = 0.044). Antiribosomal P antibodies (odds ratio 5.4, 95 % confidence interval 1.002-1.03, P = 0.002) and presence of anti-DNA antibodies (odds ratio 1.01, 95 % confidence interval 1.2-24.8, P = 0.032) were independent risk factors for the presence of the abnormal electrophysiological parameters. Disease duration was positively correlated with wave 1 of the auditory brain reflex (P < 0.001) and a latency of the evoked blink reflex (component R1, P = 0.013). SLEDAI scores were positively correlated with latencies of the visually evoked potential (P100, P = 0.02), wave 1 of the auditory brain reflex (P < 0.001), and a latency of the evoked blink reflex (R2c, P = 0.005). Steroid dosage was negatively correlated with P100 latencies (P = 0.042) and components of the evoked blink reflex (R1, P = 0.042; R2i, P = 0.041; R2c, P < 0.001). Because abnormalities in the visually evoked potential and blink reflex were associated with antiribosomal P antibodies, they can be useful for detecting asymptomatic cranial neuropathy. Further studies on large number of patients should be done to determine any association.

Long latency auditory evoked potentials in children with cochlear implants: systematic review.

PubMed

Silva, Liliane Aparecida Fagundes; Couto, Maria Inês Vieira; Matas, Carla Gentile; Carvalho, Ana Claudia Martinho de

2013-11-25

The aim of this study was to analyze the findings on Cortical Auditory Evoked Potentials in children with cochlear implant through a systematic literature review. After formulation of research question and search of studies in four data bases with the following descriptors: electrophysiology (eletrofisiologia), cochlear implantation (implante coclear), child (criança), neuronal plasticity (plasticidade neuronal) and audiology (audiologia), were selected articles (original and complete) published between 2002 and 2013 in Brazilian Portuguese or English. A total of 208 studies were found; however, only 13 contemplated the established criteria and were further analyzed; was made data extraction for analysis of methodology and content of the studies. The results described suggest rapid changes in P1 component of Cortical Auditory Evoked Potentials in children with cochlear implants. Although there are few studies on the theme, cochlear implant has been shown to produce effective changes in central auditory path ways especially in children implanted before 3 years and 6 months of age.

Artifacts produced during electrical stimulation of the vestibular nerve in cats. [autonomic nervous system components of motion sickness

NASA Technical Reports Server (NTRS)

Tang, P. C.

1973-01-01

Evidence is presented to indicate that evoked potentials in the recurrent laryngeal, the cervical sympathetic, and the phrenic nerve, commonly reported as being elicited by vestibular nerve stimulation, may be due to stimulation of structures other than the vestibular nerve. Experiments carried out in decerebrated cats indicated that stimulation of the petrous bone and not that of the vestibular nerve is responsible for the genesis of evoked potentials in the recurrent laryngeal and the cervical sympathetic nerves. The phrenic response to electrical stimulation applied through bipolar straight electrodes appears to be the result of stimulation of the facial nerve in the facial canal by current spread along the petrous bone, since stimulation of the suspended facial nerve evoked potentials only in the phrenic nerve and not in the recurrent laryngeal nerve. These findings indicate that autonomic components of motion sickness represent the secondary reactions and not the primary responses to vestibular stimulation.

[Recommendations for the clinical use of motor evoked potentials in multiple sclerosis].

PubMed

Fernández, V; Valls-Sole, J; Relova, J L; Raguer, N; Miralles, F; Dinca, L; Taramundi, S; Costa-Frossard, L; Ferrandiz, M; Ramió-Torrentà, Ll; Villoslada, P; Saiz, A; Calles, C; Antigüedad, A; Alvarez-Cermeño, J C; Prieto, J M; Izquierdo, G; Montalbán, X; Fernández, O

2013-09-01

To establish clinical guidelines for the clinical use and interpretation of motor evoked potentials (MEP) in diagnosing and monitoring patients with multiple sclerosis (MS). Recommendations for MEP use and interpretation will help us rationalise and optimise resources used in MS patient diagnosis and follow up. We completed an extensive literature review and pooled our own data to produce a consensus statement with recommendations for the clinical use of MEPs in the study of MS. MEPs, in addition to spinal and cranial magnetic resonance imaging (MRI), help us diagnose and assess MS patients whose disease initially presents as spinal cord syndrome and those with non-specific brain MRI findings, or a normal brain MRI and clinical signs of MS. Whenever possible, a multimodal evoked potential study should be performed on patients with suspected MS in order to demonstrate involvement of the motor pathway which supports a diagnosis of dissemination in space. Copyright © 2012 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

A computer-controlled, closed-loop infusion system for infusing muscle relaxants: its use during motor-evoked potential monitoring.

PubMed

Stinson, L W; Murray, M J; Jones, K A; Assef, S J; Burke, M J; Behrens, T L; Lennon, R L

1994-02-01

A microcomputer-controlled closed-loop infusion system (MCCLIS) has been developed that provides stable intraoperative levels of partial neuromuscular blockade. Complete neuromuscular blockade interferes with intraoperative motor-evoked potential (MEP) monitoring used for patients undergoing surgical procedures that place them at risk for spinal cord ischemia. Nine patients were studied during which the MCCLIS maintained stable levels of partial neuromuscular blockade and allowed transcranial magnetic motor-evoked potential (TcM-MEP) monitoring during thoracoabdominal aortic aneurysmectomy. The use of TcM-MEP for monitoring intraoperative spinal cord function was balanced against surgical considerations for muscle relaxation with 80% to 90% neuromuscular blockade fulfilling each requirement. Intraoperative adjustment of partial neuromuscular blockade to facilitate TcM-MEP monitoring was also possible with the MCCLIS. The MCCLIS should allow for further investigation into the sensitivity, specificity, and predictability of TcM-MEP monitoring for any patient at risk for intraoperative spinal cord ischemia including those undergoing thoracoabdominal aortic aneurysmectomy.

Oscillatory frontal theta responses are increased upon bisensory stimulation.

PubMed

Sakowitz, O W; Schürmann, M; Başar, E

2000-05-01

To investigate the functional correlation of oscillatory EEG components with the interaction of sensory modalities following simultaneous audio-visual stimulation. In an experimental study (15 subjects) we compared auditory evoked potentials (AEPs) and visual evoked potentials (VEPs) to bimodal evoked potentials (BEPs; simultaneous auditory and visual stimulation). BEPs were assumed to be brain responses to complex stimuli as a marker for intermodal associative functioning. Frequency domain analysis of these EPs showed marked theta-range components in response to bimodal stimulation. These theta components could not be explained by linear addition of the unimodal responses in the time domain. Considering topography the increased theta-response showed a remarkable frontality in proximity to multimodal association cortices. Referring to methodology we try to demonstrate that, even if various behavioral correlates of brain oscillations exist, common patterns can be extracted by means of a systems-theoretical approach. Serving as an example of functionally relevant brain oscillations, theta responses could be interpreted as an indicator of associative information processing.

Brain function monitoring during off-pump cardiac surgery: a case report

PubMed Central

Zanatta, Paolo; Bosco, Enrico; Di Pasquale, Piero; Nivedita, Agarwal; Valfrè, Carlo; Sorbara, Carlo

2008-01-01

Background Early postoperative stroke is an adverse syndrome after coronary bypass surgery. This report focuses on overcoming of cerebral ischemia as a result of haemodynamic instability during heart enucleation in off-pump procedure. Case presentation A 67 year old male patient, Caucasian race, with a body mass index of 28, had a recent non-Q posterolateral myocardial infarction one month before and recurrent instable angina. His past history includes an uncontrolled hypertension, dyslipidemia, insulin dependent diabetes mellitus, epiaortic vessel stenosis. The patient was scheduled for an off-pump procedure and monitored with bilateral somatosensory evoked potentials, whose alteration signalled the decrement of the cardiac index during operation. The somatosensory evoked potentials appeared when the blood pressure was increased with a pharmacological treatment. Conclusion During the off-pump coronary bypass surgery, a lower cardiac index, predisposes patients, with multiple stroke risk factors, to a reduction of the cerebral blood flow. Intraoperative somatosensory evoked potentials monitoring provides informations about the functional status of somatosensory cortex to reverse effects of brain ischemia. PMID:18706094

Changes in visual-evoked potential habituation induced by hyperventilation in migraine.

PubMed

Coppola, Gianluca; Currà, Antonio; Sava, Simona Liliana; Alibardi, Alessia; Parisi, Vincenzo; Pierelli, Francesco; Schoenen, Jean

2010-12-01

Hyperventilation is often associated with stress, an established trigger factor for migraine. Between attacks, migraine is associated with a deficit in habituation to visual-evoked potentials (VEP) that worsens just before the attack. Hyperventilation slows electroencephalographic (EEG) activity and decreases the functional response in the occipital cortex during visual stimulation. The neural mechanisms underlying deficient-evoked potential habituation in migraineurs remain unclear. To find out whether hyperventilation alters VEP habituation, we recorded VEPs before and after experimentally induced hyperventilation lasting 3 min in 18 healthy subjects and 18 migraine patients between attacks. We measured VEP P100 amplitudes in six sequential blocks of 100 sweeps and habituation as the change in amplitude over the six blocks. In healthy subjects, hyperventilation decreased VEP amplitude in block 1 and abolished the normal VEP habituation. In migraine patients, hyperventilation further decreased the already low block 1 amplitude and worsened the interictal habituation deficit. Hyperventilation worsens the habituation deficit in migraineurs possibly by increasing dysrhythmia in the brainstem-thalamo-cortical network.

Simulation of the Universal-Time Diurnal Variation of the Global Electric Circuit Charging Rate

NASA Technical Reports Server (NTRS)

Mackerras, D.; Darvenzia, M.; Orville, R. E.; Williams, E. R.; Goodman, S. J.

1999-01-01

A global lightning model that includes diurnal and annual lightning variation, and total flash density versus latitude for each major land and ocean, has been used as the basis for simulating the global electric circuit charging rate. A particular objective has been to reconcile the difference in amplitude ratios [AR=(max-min)/mean] between global lightning diurnal variation (AR approx. = 0.8) and the diurnal variation of typical atmospheric potential gradient curves (AR approx. = 0.35). A constraint on the simulation is that the annual mean charging current should be about 1000 A. The global lightning model shows that negative ground flashes can contribute, at most, about 10-15% of the required current. For the purpose of the charging rate simulation, it was assumed that each ground flash contributes 5 C to the charging process. It was necessary to assume that all electrified clouds contribute to charging by means other than lightning, that the total flash rate can serve as an indirect indicator of the rate of charge transfer, and that oceanic electrified clouds contribute to charging even though they are relatively inefficient in producing lightning. It was also found necessary to add a diurnally invariant charging current component. By trial and error it was found that charging rate diurnal variation curves in Universal time (UT) could be produced with amplitude ratios and general shapes similar to those of the potential gradient diurnal variation curves measured over ocean and arctic regions during voyages of the Carnegie Institute research vessels.

The development of a flash flood severity index

NASA Astrophysics Data System (ADS)

Schroeder, Amanda J.; Gourley, Jonathan J.; Hardy, Jill; Henderson, Jen J.; Parhi, Pradipta; Rahmani, Vahid; Reed, Kimberly A.; Schumacher, Russ S.; Smith, Brianne K.; Taraldsen, Matthew J.

2016-10-01

Flash flooding is a high impact weather event that requires clear communication regarding severity and potential hazards among forecasters, researchers, emergency managers, and the general public. Current standards used to communicate these characteristics include return periods and the United States (U.S.) National Weather Service (NWS) 4-tiered river flooding severity scale. Return periods are largely misunderstood, and the NWS scale is limited to flooding on gauged streams and rivers, often leaving out heavily populated urban corridors. To address these shortcomings, a student-led group of interdisciplinary researchers came together in a collaborative effort to develop an impact-based Flash Flood Severity Index (FFSI). The index was proposed as a damage-based, post-event assessment tool, and preliminary work toward the creation of this index has been completed and presented here. Numerous case studies were analyzed to develop the preliminary outline for the FFSI, and three examples of such cases are included in this paper. The scale includes five impact-based categories ranging from Category 1 very minor flooding to Category 5 catastrophic flooding. Along with the numerous case studies used to develop the initial outline of the scale, empirical data in the form of semi-structured interviews were conducted with multiple NWS forecasters across the country and their responses were analyzed to gain more perspective on the complicated nature of flash flood definitions and which tools were found to be most useful. The feedback from these interviews suggests the potential for acceptance of such an index if it can account for specific challenges.

Auditory evoked potential could reflect emotional sensitivity and impulsivity

PubMed Central

Kim, Ji Sun; Kim, Sungkean; Jung, Wookyoung; Im, Chang-Hwan; Lee, Seung-Hwan

2016-01-01

Emotional sensitivity and impulsivity could cause interpersonal conflicts and neuropsychiatric problems. Serotonin is correlated with behavioral inhibition and impulsivity. This study evaluated whether the loudness dependence of auditory evoked potential (LDAEP), a potential biological marker of central serotonergic activity, could reflect emotional sensitivity and impulsivity. A total of 157 healthy individuals were recruited, who performed LDAEP and Go/Nogo paradigms during electroencephalogram measurement. Barratt impulsivity scale (BIS), Conners’ Adult ADHD rating scale (CAARS), and affective lability scale (ALS) were evaluated. Comparison between low and high LDAEP groups was conducted for behavioural, psychological, and event-related potential (ERP) measures. The high LDAEP group showed significantly increased BIS, a subscale of the CAARS, ALS, and false alarm rate of Nogo stimuli compared to the low LDAEP group. LDAEP showed significant positive correlations with the depression scale, ALS scores, subscale of the CAARS and Nogo-P3 amplitude. In the source activity of Nogo-P3, the cuneus, lingual gyrus, and precentral gyrus activities were significantly increased in the high LDAEP group. Our study revealed that LDAEP could reflect emotional sensitivity and impulsivity. LDAEP, an auditory evoked potential could be a useful tool to evaluate emotional regulation. PMID:27910865

Ion diffusion may introduce spurious current sources in current-source density (CSD) analysis.

PubMed

Halnes, Geir; Mäki-Marttunen, Tuomo; Pettersen, Klas H; Andreassen, Ole A; Einevoll, Gaute T

2017-07-01

Current-source density (CSD) analysis is a well-established method for analyzing recorded local field potentials (LFPs), that is, the low-frequency part of extracellular potentials. Standard CSD theory is based on the assumption that all extracellular currents are purely ohmic, and thus neglects the possible impact from ionic diffusion on recorded potentials. However, it has previously been shown that in physiological conditions with large ion-concentration gradients, diffusive currents can evoke slow shifts in extracellular potentials. Using computer simulations, we here show that diffusion-evoked potential shifts can introduce errors in standard CSD analysis, and can lead to prediction of spurious current sources. Further, we here show that the diffusion-evoked prediction errors can be removed by using an improved CSD estimator which accounts for concentration-dependent effects. NEW & NOTEWORTHY Standard CSD analysis does not account for ionic diffusion. Using biophysically realistic computer simulations, we show that unaccounted-for diffusive currents can lead to the prediction of spurious current sources. This finding may be of strong interest for in vivo electrophysiologists doing extracellular recordings in general, and CSD analysis in particular. Copyright © 2017 the American Physiological Society.

Can Vestibular-Evoked Myogenic Potentials Help Differentiate Ménière Disease from Vestibular Migraine?

PubMed Central

Zuniga, M. Geraldine; Janky, Kristen L.; Schubert, Michael C.; Carey, John P.

2013-01-01

Objectives To characterize both cervical and ocular vestibular-evoked myogenic potential (cVEMP, oVEMP) responses to air-conducted sound (ACS) and midline taps in Ménière disease (MD), vestibular migraine (VM), and controls, as well as to determine if cVEMP or oVEMP responses can differentiate MD from VM. Study Design Prospective cohort study. Setting Tertiary referral center. Subjects and Methods Unilateral definite MD patients (n = 20), VM patients (n = 21) by modified Neuhauser criteria, and age-matched controls (n = 28). cVEMP testing used ACS (clicks), and oVEMP testing used ACS (clicks and 500-Hz tone bursts) and midline tap stimuli (reflex hammer and Mini-Shaker). Outcome parameters were cVEMP peak-to-peak amplitudes and oVEMP n10 amplitudes. Results Relative to controls, MD and VM groups both showed reduced click-evoked cVEMP (P < .001) and oVEMP (P < .001) amplitudes. Only the MD group showed reduction in tone-evoked amplitudes for oVEMP. Tone-evoked oVEMPs differentiated MD from controls (P = .001) and from VM (P = .007). The oVEMPs in response to the reflex hammer and Mini-Shaker midline taps showed no differences between groups (P > .210). Conclusions Using these techniques, VM and MD behaved similarly on most of the VEMP test battery. A link in their pathophysiology may be responsible for these responses. The data suggest a difference in 500-Hz tone burst–evoked oVEMP responses between MD and MV as a group. However, no VEMP test that was investigated segregated individuals with MD from those with VM. PMID:22267492

The ventricular intracardiac unipolar paced-evoked potential in an isolated animal heart.

PubMed

Economides, A P; Walton, C; Gergely, S

1988-02-01

The endocardial unipolar paced evoked response has excited a great deal of interest due to its possible use in the measurement of the metabolic state of the body and other pacer-related areas. Although rate-responsive pacing utilizing this signal has been clinically evaluated, little is known regarding the behavior of the components of this waveform under normal physiological conditions. We have developed an electronic circuit which allows the recording of the evoked response within a few milliseconds of a pacing stimulus of 5 V and 0.5 ms duration being applied using a single unipolar, smooth platinum electrode of 14 mm2 surface area. The paced evoked response was measured using a total of 20 isolated rabbit heart preparations. Five were run for 8 hours and the remaining fifteen were run for 5 hours. Our results indicate that the waveform components of the evoked response remain stable while the preparation is viable, but that two of the time-related measurements change with loss of viability. A significant lengthening of the stimulus-R interval was seen together with a dramatic shortening of the R-T period. The net result of these changes was an overall reduction of 17% in the complex duration. In addition, we found the R-T shortening to be a sensitive measure of myocardial integrity. We conclude that the combination of our interface charge elimination circuit and the isolated heart preparation has proved a useful system for the investigation of the paced evoked potential. Furthermore, the loss of myocardial viability has a complex action on this response.

A short latency vestibular evoked potential (VsEP) produced by bone-conducted acoustic stimulation

NASA Astrophysics Data System (ADS)

McAngus Todd, Neil P.; Rosengren, Sally M.; Colebatch, James G.

2003-12-01

In this paper data are presented from an experiment which provides evidence for the existence of a short latency, acoustically evoked potential of probable vestibular origin. The experiment was conducted in two phases using bone-conducted acoustic stimulation. In the first phase subjects were stimulated with 6-ms, 500-Hz tone bursts in order to obtain the threshold VT for vestibular evoked myogenic potentials (VEMP). It was confirmed that the difference between bone-conducted auditory and acoustic vestibular thresholds was slightly over 30 dB. The estimated threshold was then used as a reference value in the second part of the experiment to stimulate subjects over a range of intensities from -6 to +18 dB (re:VT). Averaged EEG recordings were made with eight Ag/AgCl electrodes placed on the scalp at Fpz, F3, F4, F7, F8, Cz, T3, and T4 according to the 10-20 system. Below VT auditory midlatency responses (MLRs) were observed. Above VT two additional potentials appeared: a positivity at about 10 ms (P10) which was maximal at Cz, and a negativity at about 15 ms (N15) which was maximal at Fpz. Extrapolation of the growth functions for the P10 and N15 indicated a threshold close to VT, consistent with a vestibular origin of these potentials. Given the low threshold of vestibular acoustic sensitivity it is possible that this mode may make a contribution to the detection of and affective responses to loud low frequency sounds. The evoked potentials may also have application as a noninvasive and nontraumatic test of vestibular projections to the cortex.

Effects of phloretin and phloridzin on Ca2+ handling, the action potential, and ion currents in rat ventricular myocytes.

PubMed

Olson, Marnie L; Kargacin, Margaret E; Ward, Christopher A; Kargacin, Gary J

2007-06-01

The effects of the phytoestrogens phloretin and phloridzin on Ca(2+) handling, cell shortening, the action potential, and Ca(2+) and K(+) currents in freshly isolated cardiac myocytes from rat ventricle were examined. Phloretin increased the amplitude and area and decreased the rate of decline of electrically evoked Ca(2+) transients in the myocytes. These effects were accompanied by an increase in the Ca(2+) load of the sarcoplasmic reticulum, as determined by the area of caffeine-evoked Ca(2+) transients. An increase in the extent of shortening of the myocytes in response to electrically evoked action potentials was also observed in the presence of phloretin. To further examine possible mechanisms contributing to the observed changes in Ca(2+) handling and contractility, the effects of phloretin on the cardiac action potential and plasma membrane Ca(2+) and K(+) currents were examined. Phloretin markedly increased the action potential duration in the myocytes, and it inhibited the Ca(2+)-independent transient outward K(+) current (I(to)). The inwardly rectifying K(+) current, the sustained outward delayed rectifier K(+) current, and L-type Ca(2+) currents were not significantly different in the presence and absence of phloretin, nor was there any evidence that the Na(+)/Ca(2+) exchanger was affected. The effects of phloretin on Ca(2+) handling in the myocytes are consistent with its effects on I(to). Phloridzin did not significantly alter the amplitude or area of electrically evoked Ca(2+) transients in the myocytes, nor did it have detectable effects on the sarcoplasmic reticulum Ca(2+) load, cell shortening, or the action potential.

Cerebellar interaction with the acoustic reflex.

PubMed

Jastreboff, P J

1981-01-01

The involvement of the cerebellar vermis in the acoustic reflex was analyzed in 12 cats, decerebrated or in pentobarbital anesthesia. Anatomical data suggested the existence of a connection of lobules VIII with the ventral cochlear nucleus. Single cell recording and evoked potential techniques demonstrated the existence of the acoustic projection to lobulus VIII. Electrical stimulation of this area changed the tension of the middle ear muscle and caused evoked potential responses in the caudal part of the ventral cochlear nucleus. Electrical stimulation of the motor nucleus of the facial nerve evoked a slow wave in the recording taken from the surrounding of the cochlear round window. A hypothesis is proposed which postulates the involvement of the acoustic reflex in space localization of acoustic stimuli and the action of cerebellar vermis in order to assure the stability and plasticity of the acoustic reflex arc.

Diagnostic value of conventional visual evoked potentials applied to patients with multiple sclerosis.

PubMed

Balnytė, Renata; Ulozienė, Ingrida; Rastenytė, Daiva; Vaitkus, Antanas; Malcienė, Lina; Laučkaitė, Kristina

2011-01-01

The aim of this study was to determine the sensitivity and specificity of this classical technique employed at the Hospital of Lithuanian University of Health Sciences for the patients with multiple sclerosis and to assess its possible correlations with affected neurological systems. Pattern shift visual evoked potentials were recorded in 63 patients with multiple sclerosis, 17 (27%) of whom had a history of optic neuritis, and in 63 control patients with other neurological diseases. The latencies and amplitudes of P100 were measured. In total, 126 patients were referred to the inpatient department of neurology for differential diagnosis of demyelinating disorders between January and December of 2007. Abnormalities of visual evoked potentials were observed by 73% more frequently in patients with multiple sclerosis than in control patients (α=0.05, β<0.01). The combined monocular/interocular test showed a specificity of 90.5% and a sensitivity of 82.5%. The probability of an affection of the pyramidal system was 5 times greater (95% CI, 2.2-11.0; P<0.01) and the probability of the optic pathways involvement was 4.8 times greater (95% CI, 1.9-11.9; P<0.01) in patients with multiple sclerosis than in controls. Conventional visual evoked potentials must be reappraised in light of their diagnostic value in multiple sclerosis given their high diagnostic efficiency, relatively easy, short, and cheap implementation, and easy availability in everyday clinical practice.

Generation of useful energy from process fluids using the biphase turbine

NASA Astrophysics Data System (ADS)

Helgeson, N. L.

1981-01-01

The six largest energy consuming industries in the United States were surveyed to determine the energy savings that could result from applying the Biphase turbine to industrial process streams. A national potential energy savings of 58 million barrels of oil per year (technical market) was identified. This energy is recoverable from flashing gas liquid process streams and is separate and distinct from exhaust gas waste heat recovery. The industries surveyed in this program were the petroleum chemical, primary metals, paper and pulp, stone-clay-glass, and food. It was required to determine the applicability of the Biphase turbine to flashing operations connected with process streams, to determine the energy changes associated with these flashes if carried out in a Biphase turbine, and to determine the suitability (technical and economical feasibility) of applying the Biphase turbine to these processes.

Heavy Rain, Flash Flooding Possible Across Parts of Lower Mississippi Valley, Southeast

NASA Image and Video Library

2017-12-08

The system that brought heavy rainfall and flash flooding to parts of the southern Plains and western Gulf Coast over the past several days continues to push eastward, with the greatest potential for heavy rain and flash flooding on Monday across parts of the lower Mississippi Valley and Southeast. This image was taken by GOES East at 1515Z on October 26, 2015. Credit: NOAA/NASA GOES Project Credit: NASA/NOAA via NOAA Environmental Visualization Laboratory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Measuring hot flash phenomenonology using ambulatory prospective digital diaries

PubMed Central

Fisher, William I.; Thurston, Rebecca C.

2016-01-01

Objective This study provides the description, protocol, and results from a novel prospective ambulatory digital hot flash phenomenon diary. Methods This study included 152 midlife women with daily hot flashes who completed an ambulatory electronic hot flash diary continuously for the waking hours of 3 consecutive days. In this diary, women recorded their hot flashes and accompanying characteristics and associations as the hot flashes occurred. Results Self-reported hot flash severity on the digital diaries indicated that the majority of hot flashes were rated as mild (41.3%) or moderate (43.7%). Severe (13.1%) and very severe (1.8%) hot flashes were less common. Hot flash bother ratings were rated as mild (43%), or moderate (33.5%), with fewer hot flashes reported bothersome (17.5%) or very bothersome (6%). The majority of hot flashes were reported as occurring on the on the face (78.9%), neck (74.7%), and chest (61.3%). Prickly skin was reported concurrently with 32% of hot flashes, 7% with anxiety and 5% with nausea. A novel finding, 38% of hot flashes were accompanied by a premonitory aura. Conclusion A prospective electronic digital hot flash diary allows for a more precise quantitation of hot flashes while overcoming many of the limitations of commonly employed retrospective questionnaires and paper diaries. Unique insights into the phenomenology, loci and associated characteristics of hot flashes were obtained using this device. The digital hot flash phenomenology diary is recommended for future ambulatory studies of hot flashes as a prospective measure of the hot flash experience. PMID:27404030

Measuring hot flash phenomenonology using ambulatory prospective digital diaries.

PubMed

Fisher, William I; Thurston, Rebecca C

2016-11-01

This study provides the description, protocol, and results from a novel prospective ambulatory digital hot flash phenomenon diary. This study included 152 midlife women with daily hot flashes who completed an ambulatory electronic hot flash diary continuously for the waking hours of three consecutive days. In this diary, women recorded their hot flashes and accompanying characteristics and associations as the hot flashes occurred. Self-reported hot flash severity on the digital diaries indicated that the majority of hot flashes were rated as mild (41.3%) or moderate (43.7%). Severe (13.1%) and very severe (1.8%) hot flashes were less common. Hot flash bother ratings were rated as mild (43%), or moderate (33.5%), with fewer hot flashes reported bothersome (17.5%) or very bothersome (6%). The majority of hot flashes were reported as occurring on the face (78.9%), neck (74.7%), and chest (61.3%). Of all reported hot flashes, 32% occurred concurrently with prickly skin, 7% with anxiety, and 5% with nausea. A novel finding from the study was that 38% of hot flashes were accompanied by a premonitory aura. A prospective electronic digital hot flash diary allows for a more precise quantitation of hot flashes while overcoming many of the limitations of commonly used retrospective questionnaires and paper diaries. Unique insights into the phenomenology, loci, and associated characteristics of hot flashes were obtained using this device. The digital hot flash phenomenology diary is recommended for future ambulatory studies of hot flashes as a prospective measure of the hot flash experience.

Parvalbumin interneuron mediated feedforward inhibition controls signal output in the deep layers of the perirhinal‐entorhinal cortex

PubMed Central

Willems, Janske G. P.; Wadman, Wytse J.

2018-01-01

Abstract The perirhinal (PER) and lateral entorhinal (LEC) cortex form an anatomical link between the neocortex and the hippocampus. However, neocortical activity is transmitted through the PER and LEC to the hippocampus with a low probability, suggesting the involvement of the inhibitory network. This study explored the role of interneuron mediated inhibition, activated by electrical stimulation in the agranular insular cortex (AiP), in the deep layers of the PER and LEC. Activated synaptic input by AiP stimulation rarely evoked action potentials in the PER‐LEC deep layer excitatory principal neurons, most probably because the evoked synaptic response consisted of a small excitatory and large inhibitory conductance. Furthermore, parvalbumin positive (PV) interneurons—a subset of interneurons projecting onto the axo‐somatic region of principal neurons—received synaptic input earlier than principal neurons, suggesting recruitment of feedforward inhibition. This synaptic input in PV interneurons evoked varying trains of action potentials, explaining the fast rising, long lasting synaptic inhibition received by deep layer principal neurons. Altogether, the excitatory input from the AiP onto deep layer principal neurons is overruled by strong feedforward inhibition. PV interneurons, with their fast, extensive stimulus‐evoked firing, are able to deliver this fast evoked inhibition in principal neurons. This indicates an essential role for PV interneurons in the gating mechanism of the PER‐LEC network. PMID:29341361

Flash x-ray radiography of argon jets in ambient air

NASA Astrophysics Data System (ADS)

Geiswiller, J.; Robert, E.; Huré, L.; Cachoncinlle, C.; Viladrosa, R.; Pouvesle, J. M.

1998-09-01

This paper describes the development and application of a soft x-ray flash radiography technique. A very compact soft x-ray flash source has been specially designed for these studies. The table-top x-ray source developed in this work emits strong doses, up to one roentgen at the output window, of x-ray photons, with most of them in the characteristic lines of the anode material (photon energy in the energy range 5-10 keV), in pulse of 20 ns FWHM with an x-ray emission zone smaller than 0957-0233/9/9/024/img1. All these characteristics make this source attractive for the x-ray radiography of high-speed phenomena, down to ten nanoseconds duration and/or for the media presenting weak absorption for the harder x-ray photons emitted by more conventional flash x-ray systems. Argon streams in ambient air were chosen as a typical case to enlighten the potentialities of this method. Single-shot radiographs of such an argon jet through rectangular nozzles were obtained. No attempt of quantitative measurement of local density in the argon stream has yet been performed, only the qualitative structure of the jet has been investigated. Nevertheless, these preliminary results enable us to state that the diagnostics of gaseous or plasma media, even at rather low pressures, can proceed using soft x-ray flash radiography.

Structural, microstructural and magnetic evolution in cryo milled carbon doped MnAl.

PubMed

Fang, Hailiang; Cedervall, Johan; Hedlund, Daniel; Shafeie, Samrand; Deledda, Stefano; Olsson, Fredrik; von Fieandt, Linus; Bednarcik, Jozef; Svedlindh, Peter; Gunnarsson, Klas; Sahlberg, Martin

2018-02-06

The low cost, rare earth free τ-phase of MnAl has high potential to partially replace bonded Nd 2 Fe 14 B rare earth permanent magnets. However, the τ-phase is metastable and it is experimentally difficult to obtain powders suitable for the permanent magnet alignment process, which requires the fine powders to have an appropriate microstructure and high τ-phase purity. In this work, a new method to make high purity τ-phase fine powders is presented. A high purity τ-phase Mn 0.55 Al 0.45 C 0.02 alloy was synthesized by the drop synthesis method. The drop synthesized material was subjected to cryo milling and  followed by a flash heating process. The crystal structure and microstructure of the drop synthesized, cryo milled and flash heated samples were studied by X-ray in situ powder diffraction, scanning electron microscopy, X-ray energy dispersive spectroscopy and electron backscatter diffraction. Magnetic properties and magnetic structure of the drop synthesized, cryo milled, flash heated  samples were characterized by magnetometry and neutron powder diffraction, respectively. The results reveal that the 2 and 4 hours cryo milled and flash heated samples both exhibit high τ-phase purity and micron-sized round particle shapes. Moreover, the flash heated samples display high saturation magnetization as well as increased coercivity.

Postconditioning with inhaled hydrogen promotes survival of retinal ganglion cells in a rat model of retinal ischemia/reperfusion injury.

PubMed

Wang, Ruobing; Wu, Jiangchun; Chen, Zeli; Xia, Fangzhou; Sun, Qinglei; Liu, Lin

2016-02-01

Retinal ischemia/reperfusion (I/R) injury plays a crucial role in the pathophysiology of various ocular diseases. Intraperitoneal injection or ocular instillation with hydrogen (H2)-rich saline was recently shown to be neuroprotective in the retina due to its anti-oxidative and anti-inflammatory effects. Our study aims to explore whether postconditioning with inhaled H2 can protect retinal ganglion cells (RGCs) in a rat model of retinal I/R injury. Retinal I/R injury was performed on the right eyes of rats and was followed by inhalation of 67% H2 mixed with 33% oxygen immediately after ischemia for 1h daily for one week. RGC density was counted using haematoxylin and eosin (HE) staining and retrograde labeling with cholera toxin beta (CTB). Visual function was assessed using flash visual evoked potentials (FVEP) and pupillary light reflex (PLR). Potential biomarkers of retinal oxidative stress and inflammatory responses were measured, including the expression of 4-Hydroxynonenalv (4-HNE), interleukin-1 beta (IL1-β) and tumor necrosis factor alpha (TNF-α). HE and CTB tracing showed that the survival rate of RGCs in the H2-treated group was significantly higher than the rate in the I/R group. Rats with H2 inhalation showed better visual function in assessments of FVEP and PLR. Moreover, H2 treatment significantly decreased the number of 4-HNE-stained cells in the ganglion cell layer and inhibited the retinal overexpression of IL1-β and TNF-α that was induced by retinal I/R injury. Our results demonstrate that postconditioning with inhaled high-dose H2 appears to confer neuroprotection against retinal I/R injury via anti-oxidative, anti-inflammatory and anti-apoptosis pathways. Copyright © 2015 Elsevier B.V. All rights reserved.

Auditory Evoked Potentials from the Frog Eighth Nerve

DTIC Science & Technology

1989-09-01

superior olivary nucleus 6, 10-100 ms in torus semicircularis’ 2,4’ 14, 1618, 30-120 ms in thalamus 7’ 1,13,14, and greater than 30 ms in telencephalon 12...899. 12 Mudry, K.M. and Capranica, R.R., Evoked auditory activity within the telencephalon of the bullfrog (Rana catesbeiana), Brain Res., 182 (1980

Damage assessment in Braunsbach 2016: data collection and analysis for an improved understanding of damaging processes during flash floods

NASA Astrophysics Data System (ADS)

Laudan, Jonas; Rözer, Viktor; Sieg, Tobias; Vogel, Kristin; Thieken, Annegret H.

2017-12-01

Flash floods are caused by intense rainfall events and represent an insufficiently understood phenomenon in Germany. As a result of higher precipitation intensities, flash floods might occur more frequently in future. In combination with changing land use patterns and urbanisation, damage mitigation, insurance and risk management in flash-flood-prone regions are becoming increasingly important. However, a better understanding of damage caused by flash floods requires ex post collection of relevant but yet sparsely available information for research. At the end of May 2016, very high and concentrated rainfall intensities led to severe flash floods in several southern German municipalities. The small town of Braunsbach stood as a prime example of the devastating potential of such events. Eight to ten days after the flash flood event, damage assessment and data collection were conducted in Braunsbach by investigating all affected buildings and their surroundings. To record and store the data on site, the open-source software bundle KoBoCollect was used as an efficient and easy way to gather information. Since the damage driving factors of flash floods are expected to differ from those of riverine flooding, a post-hoc data analysis was performed, aiming to identify the influence of flood processes and building attributes on damage grades, which reflect the extent of structural damage. Data analyses include the application of random forest, a random general linear model and multinomial logistic regression as well as the construction of a local impact map to reveal influences on the damage grades. Further, a Spearman's Rho correlation matrix was calculated. The results reveal that the damage driving factors of flash floods differ from those of riverine floods to a certain extent. The exposition of a building in flow direction shows an especially strong correlation with the damage grade and has a high predictive power within the constructed damage models. Additionally, the results suggest that building materials as well as various building aspects, such as the existence of a shop window and the surroundings, might have an effect on the resulting damage. To verify and confirm the outcomes as well as to support future mitigation strategies, risk management and planning, more comprehensive and systematic data collection is necessary.

Evoking prescribed spike times in stochastic neurons

NASA Astrophysics Data System (ADS)

Doose, Jens; Lindner, Benjamin

2017-09-01

Single cell stimulation in vivo is a powerful tool to investigate the properties of single neurons and their functionality in neural networks. We present a method to determine a cell-specific stimulus that reliably evokes a prescribed spike train with high temporal precision of action potentials. We test the performance of this stimulus in simulations for two different stochastic neuron models. For a broad range of parameters and a neuron firing with intermediate firing rates (20-40 Hz) the reliability in evoking the prescribed spike train is close to its theoretical maximum that is mainly determined by the level of intrinsic noise.

Human auditory evoked potentials. I - Evaluation of components

NASA Technical Reports Server (NTRS)

Picton, T. W.; Hillyard, S. A.; Krausz, H. I.; Galambos, R.

1974-01-01

Fifteen distinct components can be identified in the scalp recorded average evoked potential to an abrupt auditory stimulus. The early components occurring in the first 8 msec after a stimulus represent the activation of the cochlea and the auditory nuclei of the brainstem. The middle latency components occurring between 8 and 50 msec after the stimulus probably represent activation of both auditory thalamus and cortex but can be seriously contaminated by concurrent scalp muscle reflex potentials. The longer latency components occurring between 50 and 300 msec after the stimulus are maximally recorded over fronto-central scalp regions and seem to represent widespread activation of frontal cortex.

Vestibular evoked myogenic potential (VEMP) in patients with acoustic neuromas.

PubMed

Takeichi, N; Sakamoto, T; Fukuda, S; Inuyama, Y

2001-05-01

To study the utility of VEMP (vestibular-evoked myogenic potential) in the diagnosis of acoustic neuromas. Eighteen patients with unilateral acoustic neuromas were subjected to this study. Myogenic potential responding to loud click stimuli was recorded at ipsilateral sternocleidomastoid muscle. A normal range of VEMP was obtained from 20 controls. VEMP responses were compared with both, clinical symptoms and results of caloric tests. Thirteen out of 18 patients showed decreased responses of VEMP at the affected side. VEMP responses seemed to have little relation with dysequilibrium, spontaneous nystagmus, canal paresis and pure-tone hearing. VEMP is useful for detecting dysfunction of inferior vestibular nerve in patients with acoustic neuromas.

The N-methyl-D-aspartate-evoked cytoplasmic calcium increase in adult rat dorsal root ganglion neuronal somata was potentiated by substance P pretreatment in a protein kinase C-dependent manner.

PubMed

Castillo, C; Norcini, M; Baquero-Buitrago, J; Levacic, D; Medina, R; Montoya-Gacharna, J V; Blanck, T J J; Dubois, M; Recio-Pinto, E

2011-03-17

The involvement of substance P (SP) in neuronal sensitization through the activation of the neurokinin-1-receptor (NK1r) in postsynaptic dorsal horn neurons has been well established. In contrast, the role of SP and NK1r in primary sensory dorsal root ganglion (DRG) neurons, in particular in the soma, is not well understood. In this study, we evaluated whether SP modulated the NMDA-evoked transient increase in cytoplasmic Ca2+ ([Ca2+]cyt) in the soma of dissociated adult DRG neurons. Cultures were treated with nerve growth factor (NGF), prostaglandin E2 (PGE2) or both NGF+PGE2. Treatment with NGF+PGE2 increased the percentage of N-methyl-D-aspartate (NMDA) responsive neurons. There was no correlation between the percentage of NMDA responsive neurons and the level of expression of the NR1 and NR2B subunits of the NMDA receptor or of the NK1r. Pretreatment with SP did not alter the percentage of NMDA responsive neurons; while it potentiated the NMDA-evoked [Ca2+]cyt transient by increasing its magnitude and by prolonging the period during which small- and some medium-sized neurons remained NMDA responsive. The SP-mediated potentiation was blocked by the SP-antagonist ([D-Pro4, D-Trp7,9]-SP (4-11)) and by the protein kinase C (PKC) blocker bisindolylmaleimide I (BIM); and correlated with the phosphorylation of PKCε. The Nk1r agonist [Sar9, Met(O2)11]-SP (SarMet-SP) also potentiated the NMDA-evoked [Ca2+]cyt transient. Exposure to SP or SarMet-SP produced a rapid increase in the labeling of phosphorylated-PKCε. In none of the conditions we detected phosphorylation of the NR2B subunit at Ser-1303. Phosphorylation of the NR2B subunit at Tyr1472 was enhanced to a similar extent in cells exposed to NMDA, SP or NMDA+SP, and that enhancement was blocked by BIM. Our findings suggest that NGF and PGE2 may contribute to the injury-evoked sensitization of DRG neurons in part by enhancing their NMDA-evoked [Ca2+]cyt transient in all sized DRG neurons; and that SP may further contribute to the DRG sensitization by enhancing and prolonging the NMDA-evoked increase in [Ca2+]cyt in small- and medium-sized DRG neurons. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

The Emergence of Contrast-Invariant Orientation Tuning in Simple Cells of Cat Visual Cortex

PubMed Central

Finn, Ian M.; Priebe, Nicholas J.; Ferster, David

2007-01-01

Simple cells in primary visual cortex exhibit contrast-invariant orientation tuning, in seeming contradiction to feed-forward models relying on lateral geniculate nucleus (LGN) input alone. Contrast invariance has therefore been thought to depend on the presence of intracortical lateral inhibition. In vivo intracellular recordings instead suggest that contrast invariance can be explained by three properties of the excitatory pathway. 1) Depolarizations evoked by orthogonal stimuli are determined by the amount of excitation a cell receives from the LGN, relative to the excitation it receives from other cortical cells. 2) Depolarizations evoked by preferred stimuli saturate at lower contrasts than the spike output of LGN relay cells. 3) Visual stimuli evoke contrast-dependent changes in trial-to-trial variability, which lead to contrast-dependent changes in the relationship between membrane potential and spike rate. Thus, high-contrast, orthogonally-oriented stimuli that evoke significant depolarizations evoke few spikes. Together these mechanisms, without lateral inhibition, can account for contrast-invariant stimulus selectivity. PMID:17408583

Adaptive P300 based control system

PubMed Central

Jin, Jing; Allison, Brendan Z.; Sellers, Eric W.; Brunner, Clemens; Horki, Petar; Wang, Xingyu; Neuper, Christa

2015-01-01

An adaptive P300 brain-computer interface (BCI) using a 12 × 7 matrix explored new paradigms to improve bit rate and accuracy. During online use, the system adaptively selects the number of flashes to average. Five different flash patterns were tested. The 19-flash paradigm represents the typical row/column presentation (i.e., 12 columns and 7 rows). The 9- and 14-flash A & B paradigms present all items of the 12 × 7 matrix three times using either nine or 14 flashes (instead of 19), decreasing the amount of time to present stimuli. Compared to 9-flash A, 9-flash B decreased the likelihood that neighboring items would flash when the target was not flashing, thereby reducing interference from items adjacent to targets. 14-flash A also reduced adjacent item interference and 14-flash B additionally eliminated successive (double) flashes of the same item. Results showed that accuracy and bit rate of the adaptive system were higher than the non-adaptive system. In addition, 9- and 14-flash B produced significantly higher performance than their respective A conditions. The results also show the trend that the 14-flash B paradigm was better than the 19-flash pattern for naïve users. PMID:21474877

Overview of emerging nonvolatile memory technologies

PubMed Central

2014-01-01

Nonvolatile memory technologies in Si-based electronics date back to the 1990s. Ferroelectric field-effect transistor (FeFET) was one of the most promising devices replacing the conventional Flash memory facing physical scaling limitations at those times. A variant of charge storage memory referred to as Flash memory is widely used in consumer electronic products such as cell phones and music players while NAND Flash-based solid-state disks (SSDs) are increasingly displacing hard disk drives as the primary storage device in laptops, desktops, and even data centers. The integration limit of Flash memories is approaching, and many new types of memory to replace conventional Flash memories have been proposed. Emerging memory technologies promise new memories to store more data at less cost than the expensive-to-build silicon chips used by popular consumer gadgets including digital cameras, cell phones and portable music players. They are being investigated and lead to the future as potential alternatives to existing memories in future computing systems. Emerging nonvolatile memory technologies such as magnetic random-access memory (MRAM), spin-transfer torque random-access memory (STT-RAM), ferroelectric random-access memory (FeRAM), phase-change memory (PCM), and resistive random-access memory (RRAM) combine the speed of static random-access memory (SRAM), the density of dynamic random-access memory (DRAM), and the nonvolatility of Flash memory and so become very attractive as another possibility for future memory hierarchies. Many other new classes of emerging memory technologies such as transparent and plastic, three-dimensional (3-D), and quantum dot memory technologies have also gained tremendous popularity in recent years. Subsequently, not an exaggeration to say that computer memory could soon earn the ultimate commercial validation for commercial scale-up and production the cheap plastic knockoff. Therefore, this review is devoted to the rapidly developing new class of memory technologies and scaling of scientific procedures based on an investigation of recent progress in advanced Flash memory devices. PMID:25278820

Overview of emerging nonvolatile memory technologies.

PubMed

Meena, Jagan Singh; Sze, Simon Min; Chand, Umesh; Tseng, Tseung-Yuen

2014-01-01

Nonvolatile memory technologies in Si-based electronics date back to the 1990s. Ferroelectric field-effect transistor (FeFET) was one of the most promising devices replacing the conventional Flash memory facing physical scaling limitations at those times. A variant of charge storage memory referred to as Flash memory is widely used in consumer electronic products such as cell phones and music players while NAND Flash-based solid-state disks (SSDs) are increasingly displacing hard disk drives as the primary storage device in laptops, desktops, and even data centers. The integration limit of Flash memories is approaching, and many new types of memory to replace conventional Flash memories have been proposed. Emerging memory technologies promise new memories to store more data at less cost than the expensive-to-build silicon chips used by popular consumer gadgets including digital cameras, cell phones and portable music players. They are being investigated and lead to the future as potential alternatives to existing memories in future computing systems. Emerging nonvolatile memory technologies such as magnetic random-access memory (MRAM), spin-transfer torque random-access memory (STT-RAM), ferroelectric random-access memory (FeRAM), phase-change memory (PCM), and resistive random-access memory (RRAM) combine the speed of static random-access memory (SRAM), the density of dynamic random-access memory (DRAM), and the nonvolatility of Flash memory and so become very attractive as another possibility for future memory hierarchies. Many other new classes of emerging memory technologies such as transparent and plastic, three-dimensional (3-D), and quantum dot memory technologies have also gained tremendous popularity in recent years. Subsequently, not an exaggeration to say that computer memory could soon earn the ultimate commercial validation for commercial scale-up and production the cheap plastic knockoff. Therefore, this review is devoted to the rapidly developing new class of memory technologies and scaling of scientific procedures based on an investigation of recent progress in advanced Flash memory devices.

The changing face of P300 BCIs: a comparison of stimulus changes in a P300 BCI involving faces, emotion, and movement.

PubMed

Jin, Jing; Allison, Brendan Z; Kaufmann, Tobias; Kübler, Andrea; Zhang, Yu; Wang, Xingyu; Cichocki, Andrzej

2012-01-01

One of the most common types of brain-computer interfaces (BCIs) is called a P300 BCI, since it relies on the P300 and other event-related potentials (ERPs). In the canonical P300 BCI approach, items on a monitor flash briefly to elicit the necessary ERPs. Very recent work has shown that this approach may yield lower performance than alternate paradigms in which the items do not flash but instead change in other ways, such as moving, changing colour or changing to characters overlaid with faces. The present study sought to extend this research direction by parametrically comparing different ways to change items in a P300 BCI. Healthy subjects used a P300 BCI across six different conditions. Three conditions were similar to our prior work, providing the first direct comparison of characters flashing, moving, and changing to faces. Three new conditions also explored facial motion and emotional expression. The six conditions were compared across objective measures such as classification accuracy and bit rate as well as subjective measures such as perceived difficulty. In line with recent studies, our results indicated that the character flash condition resulted in the lowest accuracy and bit rate. All four face conditions (mean accuracy >91%) yielded significantly better performance than the flash condition (mean accuracy = 75%). Objective results reaffirmed that the face paradigm is superior to the canonical flash approach that has dominated P300 BCIs for over 20 years. The subjective reports indicated that the conditions that yielded better performance were not considered especially burdensome. Therefore, although further work is needed to identify which face paradigm is best, it is clear that the canonical flash approach should be replaced with a face paradigm when aiming at increasing bit rate. However, the face paradigm has to be further explored with practical applications particularly with locked-in patients.

Delta and gamma oscillations in operculo-insular cortex underlie innocuous cold thermosensation

PubMed Central

Vinding, Mikkel C.; Allen, Micah; Jensen, Troels Staehelin; Finnerup, Nanna Brix

2017-01-01

Cold-sensitive and nociceptive neural pathways interact to shape the quality and intensity of thermal and pain perception. Yet the central processing of cold thermosensation in the human brain has not been extensively studied. Here, we used magnetoencephalography and EEG in healthy volunteers to investigate the time course (evoked fields and potentials) and oscillatory activity associated with the perception of cold temperature changes. Nonnoxious cold stimuli consisting of Δ3°C and Δ5°C decrements from an adapting temperature of 35°C were delivered on the dorsum of the left hand via a contact thermode. Cold-evoked fields peaked at around 240 and 500 ms, at peak latencies similar to the N1 and P2 cold-evoked potentials. Importantly, cold-related changes in oscillatory power indicated that innocuous thermosensation is mediated by oscillatory activity in the range of delta (1–4 Hz) and gamma (55–90 Hz) rhythms, originating in operculo-insular cortical regions. We suggest that delta rhythms coordinate functional integration between operculo-insular and frontoparietal regions, while gamma rhythms reflect local sensory processing in operculo-insular areas. NEW & NOTEWORTHY Using magnetoencephalography, we identified spatiotemporal features of central cold processing, with respect to the time course, oscillatory profile, and neural generators of cold-evoked responses in healthy human volunteers. Cold thermosensation was associated with low- and high-frequency oscillatory rhythms, both originating in operculo-insular regions. These results support further investigations of central cold processing using magnetoencephalography or EEG and the clinical utility of cold-evoked potentials for neurophysiological assessment of cold-related small-fiber function and damage. PMID:28250150

Somatosensory evoked potentials in patients with hypocalcaemia after parathyroidectomy.

PubMed

Kanda, F; Jinnai, J; Fujita, T

1988-01-01

The effects of hypocalcaemia on somatosensory evoked potentials (SEPs) were studied in five patients after parathyroidectomy. Despite normal latencies the mean value of amplitudes of the SEPs in hypocalcaemic patients was greater than that in normocalcaemic subjects. Recovery functions of the SEPs showed a significant decrease in hypocalcaemic patients at interstimulus intervals of about 10 ms compared with those in normocalcaemic patients and in normal volunteers. Recovery functions appear to be a valid indicator of synaptic efficacy, especially for evaluation of the reduction in conduction efficacy of the central nervous system in hypocalcaemia.

The division of attention and the human auditory evoked potential

NASA Technical Reports Server (NTRS)

Hink, R. F.; Van Voorhis, S. T.; Hillyard, S. A.; Smith, T. S.

1977-01-01

The sensitivity of the scalp-recorded, auditory evoked potential to selective attention was examined while subjects responded to stimuli presented to one ear (focused attention) and to both ears (divided attention). The amplitude of the N1 component was found to be largest to stimuli in the ear upon which attention was to be focused, smallest to stimuli in the ear to be ignored, and intermediate to stimuli in both ears when attention was divided. The results are interpreted as supporting a capacity model of attention.

Intraoperative monitoring of somatosensory-evoked potential in the spinal cord rectification operation by means of wavelet analysis

NASA Astrophysics Data System (ADS)

Liu, W.; Du, M. H.; Chan, Francis H. Y.; Lam, F. K.; Luk, D. K.; Hu, Y.; Fung, Kan S. M.; Qiu, W.

1998-09-01

Recently there has been a considerable interest in the use of a somatosensory evoked potential (SEP) for monitoring the functional integrity of the spinal cord during surgery such as spinal scoliosis. This paper describes a monitoring system and signal processing algorithms, which consists of 50 Hz mains filtering and a wavelet signal analyzer. Our system allows fast detection of changes in SEP peak latency, amplitude and signal waveform, which are the main parameters of interest during intra-operative procedures.

The Role of Auditory Evoked Potentials in the Context of Cochlear Implant Provision.

PubMed

Hoth, Sebastian; Dziemba, Oliver Christian

2017-12-01

: Auditory evoked potentials (AEP) are highly demanded during the whole process of equipping patients with cochlear implants (CI). They play an essential role in preoperative diagnostics, intraoperative testing, and postoperative monitoring of auditory performance and success. The versatility of AEP's is essentially enhanced by their property to be evokable by acoustic as well as electric stimuli. Thus, the electric responses of the auditory system following acoustic stimulation and recorded by the conventional surface technique as well as by transtympanic derivation from the promontory (Electrocochleography [ECochG]) are used for the quantitative determination of hearing loss and, additionally, electrically evoked compound actions potentials (ECAP) can be recorded with the intracochlear electrodes of the implant just adjacent to the stimulation electrode to check the functional integrity of the device and its coupling to the auditory system. The profile of ECAP thresholds is used as basis for speech processor fitting, the spread of excitation (SOE) allows the identification of electrode mislocations such as array foldover, and recovery functions may serve to optimize stimulus pulse rate. These techniques as well as those relying on scalp surface activity originating in the brainstem or the auditory cortex accompany the CI recipient during its whole life span and they offer valuable insights into functioning and possible adverse effects of the CI for clinical and scientific purposes.

Normative data for Aδ contact heat evoked potentials in adult population: a multicenter study.

PubMed

Granovsky, Yelena; Anand, Praveen; Nakae, Aya; Nascimento, Osvaldo; Smith, Benn; Sprecher, Elliot; Valls-Solé, Josep

2016-05-01

There has been a significant increase over recent years in the use of contact heat evoked potentials (CHEPs) for the evaluation of small nerve fiber function. Measuring CHEP amplitude and latency has clinical utility for the diagnosis and assessment of conditions with neuropathic pain. This international multicenter study aimed to provide reference values for CHEPs to stimuli at 5 commonly examined body sites. Contact heat evoked potentials were recorded from 226 subjects (114 females), distributed per age decade between 20 and 79 years. Temperature stimuli were delivered by a thermode (32°C-51°C at a rate of 70°C/s). In phase I of the study, we investigated side-to-side differences and reported the maximum normal side-to-side difference in Aδ CHEP peak latency and amplitude for leg, forearm, and face. In phase II, we obtained normative data for 3 CHEP parameters (N2P2 amplitude, N2 latency, and P2 latency), stratified for gender and age decades from face, upper and lower limbs, and overlying cervical and lumbar spine. In general, larger CHEP amplitudes were associated with higher evoked pain scores. Females had CHEPs of larger amplitude and shorter latency than males. This substantive data set of normative values will facilitate the clinical use of CHEPs as a rapid, noninvasive, and objective technique for the assessment of patients presenting with neuropathic pain.

Synaptic potentials in respiratory neurones during evoked phase switching after NMDA receptor blockade in the cat

PubMed Central

Pierrefiche, O; Haji, A; Foutz, A S; Takeda, R; Champagnat, J; Denavit-Saubié, M

1998-01-01

Blockade of NMDA receptors by dizocilpine impairs the inspiratory off-switch (IOS) of central origin but not the IOS evoked by stimulation of sensory afferents. To investigate whether this difference was due to the effects of different patterns of synaptic interactions on respiratory neurones, we stimulated electrically the superior laryngeal nerve (SLN) or vagus nerve in decerebrate cats before and after i.v. administration of dizocilpine, whilst recording intracellularly. Phrenic nerve responses to ipsilateral SLN or vagal stimulation were: at mid-inspiration, a transient inhibition often followed by a brief burst of activity; at late inspiration, an IOS; and at mid-expiration, a late burst of activity. In all neurones (n = 16), SLN stimulation at mid-inspiration evoked an early EPSP during phase 1 (latency to the arrest of phrenic nerve activity), followed by an IPSP in inspiratory (I) neurones (n = 8) and by a wave of EPSPs in post-inspiratory (PI) neurones (n = 8) during phase 2 (inhibition of phrenic activity). An EPSP in I neurones and an IPSP in PI neurones occurred during phase 3 (brief phrenic burst) following phase 2. Evoked IOS was associated with a fast (phase 1) activation of PI neurones, whereas during spontaneous IOS, a progressive (30-50 ms) depolarization of PI neurones preceded the arrest of phrenic activity. Phase 3 PSPs were similar to those occurring during the burst of activity seen at the start of spontaneous inspiration. Dizocilpine did not suppress the evoked phrenic inhibition and the late burst of activity. The shapes and timing of the evoked PSPs and the changes in membrane potential in I and PI neurones during the phase transition were not altered. We hypothesize that afferent sensory pathways not requiring NMDA receptors (1) terminate inspiration through a premature activation of PI neurones, and (2) evoke a late burst of phrenic activity which might be the first stage of the inspiratory on-switch. PMID:9508816

Adverse Effects of Induced Hot Flashes on Objectively Recorded and Subjectively Reported Sleep: Results of a Gonadotropin-Releasing Hormone Agonist Experimental Protocol

PubMed Central

Joffe, Hadine; White, David P.; Crawford, Sybil L.; McCurnin, Kristin E.; Economou, Nicole; Connors, Stephanie; Hall, Janet E.

2013-01-01

Objectives The impact of hot flashes on sleep is of great clinical interest, but results are inconsistent, especially when both hot flashes and sleep are measured objectively. Using objective and subjective measurements, we examined the impact of hot flashes on sleep by inducing hot flashes with a gonadotropin-releasing hormone agonist (GnRHa). Methods The GnRHa leuprolide was administered to 20 healthy premenopausal volunteers without hot flashes or sleep disturbances. Induced hot flashes were assessed objectively (skin-conductance monitor) and subjectively (daily diary) during one-month follow-up. Changes from baseline in objective (actigraphy) and subjective sleep quality (Pittsburgh Sleep Quality Index [PSQI]) were compared between women who did and did not develop objective hot flashes, and, in parallel analyses, subjective hot flashes. Results New-onset hot flashes were recorded in 14 (70%) and reported by 14 (70%) women (80% concordance). Estradiol was universally suppressed. Objective sleep efficiency worsened in women with objective hot flashes and improved in women without objective hot flashes (median decrease 2.6%, increase 4.2%, p=0.005). Subjective sleep quality worsened more in those with than without subjective hot flashes (median increase PSQI 2.5 vs. 1.0, p=0.03). Objective hot flashes were not associated with subjective sleep quality, nor were subjective symptoms linked to objective sleep measures. Conclusions This experimental model of induced hot flashes demonstrates a causal relationship between hot flashes and poor sleep quality. Objective hot flashes result in worse objective sleep efficiency, while subjective hot flashes worsen perceived sleep quality. PMID:23481119

Recruitment of Occipital Cortex during Sensory Substitution Training Linked to Subjective Experience of Seeing in People with Blindness

PubMed Central

Ortiz, Tomás; Poch, Joaquín; Santos, Juan M.; Requena, Carmen; Martínez, Ana M.; Ortiz-Terán, Laura; Turrero, Agustín; Barcia, Juan; Nogales, Ramón; Calvo, Agustín; Martínez, José M.; Córdoba, José L.; Pascual-Leone, Alvaro

2011-01-01

Over three months of intensive training with a tactile stimulation device, 18 blind and 10 blindfolded seeing subjects improved in their ability to identify geometric figures by touch. Seven blind subjects spontaneously reported ‘visual qualia’, the subjective sensation of seeing flashes of light congruent with tactile stimuli. In the latter subjects tactile stimulation evoked activation of occipital cortex on electroencephalography (EEG). None of the blind subjects who failed to experience visual qualia, despite identical tactile stimulation training, showed EEG recruitment of occipital cortex. None of the blindfolded seeing humans reported visual-like sensations during tactile stimulation. These findings support the notion that the conscious experience of seeing is linked to the activation of occipital brain regions in people with blindness. Moreover, the findings indicate that provision of visual information can be achieved through non-visual sensory modalities which may help to minimize the disability of blind individuals, affording them some degree of object recognition and navigation aid. PMID:21853098

Altered Negative Unconscious Processing in Major Depressive Disorder: An Exploratory Neuropsychological Study

PubMed Central

Yang, Zhi; Zhao, Jinping; Jiang, Yi; Li, Chunbo; Wang, Jijun; Weng, Xuchu; Northoff, Georg

2011-01-01

Objective Major depressive disorder (MDD) has been characterized by abnormalities in emotional processing. However, what remains unclear is whether MDD also shows deficits in the unconscious processing of either positive or negative emotions. We conducted a psychological study in healthy and MDD subjects to investigate unconscious emotion processing and its valence-specific alterations in MDD patients. Methods We combined a well established paradigm for unconscious visual processing, the continuous flash suppression, with positive and negative emotional valences to detect the attentional preference evoked by the invisible emotional facial expressions. Results Healthy subjects showed an attentional bias for negative emotions in the unconscious condition while this valence bias remained absent in MDD patients. In contrast, this attentional bias diminished in the conscious condition for both healthy subjects and MDD. Conclusion Our findings demonstrate for the first time valence-specific deficits specifically in the unconscious processing of emotions in MDD; this may have major implications for subsequent neurobiological investigations as well as for clinical diagnosis and therapy. PMID:21755006

Altered negative unconscious processing in major depressive disorder: an exploratory neuropsychological study.

PubMed

Yang, Zhi; Zhao, Jinping; Jiang, Yi; Li, Chunbo; Wang, Jijun; Weng, Xuchu; Northoff, Georg

2011-01-01

Major depressive disorder (MDD) has been characterized by abnormalities in emotional processing. However, what remains unclear is whether MDD also shows deficits in the unconscious processing of either positive or negative emotions. We conducted a psychological study in healthy and MDD subjects to investigate unconscious emotion processing and its valence-specific alterations in MDD patients. We combined a well established paradigm for unconscious visual processing, the continuous flash suppression, with positive and negative emotional valences to detect the attentional preference evoked by the invisible emotional facial expressions. Healthy subjects showed an attentional bias for negative emotions in the unconscious condition while this valence bias remained absent in MDD patients. In contrast, this attentional bias diminished in the conscious condition for both healthy subjects and MDD. Our findings demonstrate for the first time valence-specific deficits specifically in the unconscious processing of emotions in MDD; this may have major implications for subsequent neurobiological investigations as well as for clinical diagnosis and therapy.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luketa, Anay; Rudeen, David Keith

The objective of this work is to assess dispersion distances of a vapor mixture of species released from a railcar containing a tight crude oil. Tight crude oils can have higher levels of light ends as compared to conventional crude oils [1], which if released and dispersed could pose a potential hazard with regards to a flash fire, explosion, and/or asphyxiation. A historical accident involving rail transport in Viareggio, Italy illustrates how the spillage of LPG can lead to severe damage as a result of a propagating vapor cloud [2]. One of 14 railcars was punctured after derailment, releasing aboutmore » 110 m 3 of LPG into a densely populated area (2000 persons/km 2 ). The resulting vapor cloud propagated and infiltrated nearby buildings and houses which were an average of 10 m in height. Ignition of the cloud occurred approximately 100 to 300 seconds after the start of the spill. A flash fire and explosions resulted, killing 31 people. Evidence suggests that most deaths occurred due to the asphyxiation and thermal hazards from the flash fire. Thus, the motivation for this work is to assess if significant vapors can develop from a railcar carrying a tight crude oil and if this cloud could disperse potentially to nearby populations.« less

The effects of altered intrathoracic pressure on resting cerebral blood flow and its response to visual stimulation

PubMed Central

Hayen, Anja; Herigstad, Mari; Kelly, Michael; Okell, Thomas W.; Murphy, Kevin; Wise, Richard G.; Pattinson, Kyle T.S.

2013-01-01

Investigating how intrathoracic pressure changes affect cerebral blood flow (CBF) is important for a clear interpretation of neuroimaging data in patients with abnormal respiratory physiology, intensive care patients receiving mechanical ventilation and in research paradigms that manipulate intrathoracic pressure. Here, we investigated the effect of experimentally increased and decreased intrathoracic pressures upon CBF and the stimulus-evoked CBF response to visual stimulation. Twenty healthy volunteers received intermittent inspiratory and expiratory loads (plus or minus 9 cmH2O for 270 s) and viewed an intermittent 2 Hz flashing checkerboard, while maintaining stable end-tidal CO2. CBF was recorded with transcranial Doppler sonography (TCD) and whole-brain pseudo-continuous arterial spin labeling magnetic resonance imaging (PCASL MRI). Application of inspiratory loading (negative intrathoracic pressure) showed an increase in TCD-measured CBF of 4% and a PCASL-measured increase in grey matter CBF of 5%, but did not alter mean arterial pressure (MAP). Expiratory loading (positive intrathoracic pressure) did not alter CBF, while MAP increased by 3%. Neither loading condition altered the perfusion response to visual stimulation in the primary visual cortex. In both loading conditions localized CBF increases were observed in the somatosensory and motor cortices, and in the cerebellum. Altered intrathoracic pressures, whether induced experimentally, therapeutically or through a disease process, have possible significant effects on CBF and should be considered as a potential systematic confound in the interpretation of perfusion-based neuroimaging data. PMID:23108273

Calcium released by photolysis of DM-nitrophen stimulates transmitter release at squid giant synapse.

PubMed

Delaney, K R; Zucker, R S

1990-07-01

1. Transmitter release at the squid giant synapse was stimulated by photolytic release of Ca2+ from the 'caged' Ca2+ compound DM-nitrophen (Kaplan & Ellis-Davies, 1988) inserted into presynaptic terminals. 2. Competing binding reactions cause the amount of Ca2+ released by DM-nitrophen photolysis to depend on the concentrations of DM-nitrophen, total Ca2+, Mg+, ATP and native cytoplasmic Ca2+ buffer. Measurements of presynaptic [Ca2+] changes by co-injection of the fluorescent indicator dye Fura-2 show that DM-nitrophen photolysis causes a transient rise in Ca2+ followed by decay within about 150 ms to an increased steady-state level. 3. Rapid photolysis of Ca2(+)-loaded nitrophen within the presynaptic terminal was followed in less than a millisecond by depolarization of the postsynaptic membrane. As with action potential-evoked excitatory postsynaptic potentials (EPSPs), the light-evoked response was partially and reversibly blocked by 1-3 mM-kainic acid which desensitizes postsynaptic glutamate receptors. 4. Release was similar in magnitude and rate to normal action potential-mediated EPSPs. 5. The release of transmitter by photolysis of Ca2(+)-loaded DM-nitrophen was not affected by removal of Ca2+ from the saline or addition of tetrodotoxin. Photolysis of DM-nitrophen injected into presynaptic terminals without added Ca2+ did not stimulate release of transmitter nor did it interfere with normal action potential-mediated release. 6. Stimulation of presynaptic action potentials in Ca2(+)-free saline during the light-evoked response did not elicit increased release of transmitter if the ganglion was bathed in Ca2(+)-free saline, i.e. in the absence of Ca2+ influx. Increasing the intensity of the light or stimulating presynaptic action potentials in Ca2(+)-containing saline increased the release of transmitter. Therefore the failure of presynaptic voltage change to increase transmitter release resulting from release of caged Ca2+ was not due to saturation or inhibition of the release mechanism by light-released Ca2+. 7. Decreasing the temperature of the preparation increased the delay to onset of the light-evoked response and reduced its amplitude and rate of rise to an extent similar to that observed for action potential-evoked EPSPs.

Reduction hybrid artifacts of EMG-EOG in electroencephalography evoked by prefrontal transcranial magnetic stimulation

NASA Astrophysics Data System (ADS)

Bai, Yang; Wan, Xiaohong; Zeng, Ke; Ni, Yinmei; Qiu, Lirong; Li, Xiaoli

2016-12-01

Objective. When prefrontal-transcranial magnetic stimulation (p-TMS) performed, it may evoke hybrid artifact mixed with muscle activity and blink activity in EEG recordings. Reducing this kind of hybrid artifact challenges the traditional preprocessing methods. We aim to explore method for the p-TMS evoked hybrid artifact removal. Approach. We propose a novel method used as independent component analysis (ICA) post processing to reduce the p-TMS evoked hybrid artifact. Ensemble empirical mode decomposition (EEMD) was used to decompose signal into multi-components, then the components were separated with artifact reduced by blind source separation (BSS) method. Three standard BSS methods, ICA, independent vector analysis, and canonical correlation analysis (CCA) were tested. Main results. Synthetic results showed that EEMD-CCA outperformed others as ICA post processing step in hybrid artifacts reduction. Its superiority was clearer when signal to noise ratio (SNR) was lower. In application to real experiment, SNR can be significantly increased and the p-TMS evoked potential could be recovered from hybrid artifact contaminated signal. Our proposed method can effectively reduce the p-TMS evoked hybrid artifacts. Significance. Our proposed method may facilitate future prefrontal TMS-EEG researches.

Functional connectivity between right and left mesial temporal structures.

PubMed

Lacuey, Nuria; Zonjy, Bilal; Kahriman, Emine S; Kaffashi, Farhad; Miller, Jonathan; Lüders, Hans O

2015-09-01

The aim of this study is to investigate functional connectivity between right and left mesial temporal structures using cerebrocerebral evoked potentials. We studied seven patients with drug-resistant focal epilepsy who were explored with stereotactically implanted depth electrodes in bilateral hippocampi. In all patients cerebrocerebral evoked potentials evoked by stimulation of the fornix were evaluated as part of a research project assessing fornix stimulation for control of hippocampal seizures. Stimulation of the fornix elicited responses in the ipsilateral hippocampus in all patients with a mean latency of 4.6 ms (range 2-7 ms). Two patients (29 %) also had contralateral hippocampus responses with a mean latency of 7.5 ms (range 5-12 ms) and without involvement of the contralateral temporal neocortex or amygdala. This study confirms the existence of connections between bilateral mesial temporal structures in some patients and explains seizure discharge spreading between homotopic mesial temporal structures without neocortical involvement.

Accumulation and detoxication responses of the gastropod Lymnaea stagnalis to single and combined exposures to natural (cyanobacteria) and anthropogenic (the herbicide RoundUp(®) Flash) stressors.

PubMed

Lance, Emilie; Desprat, Julia; Holbech, Bente Frost; Gérard, Claudia; Bormans, Myriam; Lawton, Linda A; Edwards, Christine; Wiegand, Claudia

2016-08-01

Freshwater gastropods are increasingly exposed to multiple stressors in the field such as the herbicide glyphosate in Roundup formulations and cyanobacterial blooms either producing or not producing microcystins (MCs), potentially leading to interacting effects. Here, the responses of Lymnaea stagnalis to a 21-day exposure to non-MC or MC-producing (33μgL(-1)) Planktothrix agardhii alone or in combination with the commercial formulation RoundUp(®) Flash at a concentration of 1μgL(-1) glyphosate, followed by 14days of depuration, were studied via i) accumulation of free and bound MCs in tissues, and ii) activities of anti-oxidant (catalase CAT) and biotransformation (glutathione-S-transferase GST) enzymes. During the intoxication, the cyanobacterial exposure induced an early increase of CAT activity, independently of the MC content, probably related to the production of secondary cyanobacterial metabolites. The GST activity was induced by RoundUp(®) Flash alone or in combination with non MC-producing cyanobacteria, but was inhibited by MC-producing cyanobacteria with or without RoundUp(®) Flash. Moreover, MC accumulation in L. stagnalis was 3.2 times increased when snails were concomitantly exposed to MC-producing cyanobacteria with RoundUp(®), suggesting interacting effects of MCs on biotransformation processes. The potent inhibition of detoxication systems by MCs and RoundUp(®) Flash was reversible during the depuration, during which CAT and GST activities were significantly higher in snails previously exposed to MC-producing cyanobacteria with or without RoundUp(®) Flash than in other conditions, probably related to the oxidative stress caused by accumulated MCs remaining in tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrahigh-field imaging of the biliary tract at 7 T: initial results of gadoxetic acid-enhanced magnetic resonance cholangiography.

PubMed

Fischer, Anja; Kraff, Oliver; Orzada, Stephan; Nensa, Felix; Schäfer, Lena C; Ladd, Mark E; Umutlu, Lale; Lauenstein, Thomas C

2014-05-01

The objectives of this study were to assess the feasibility of magnetic resonance cholangiography (MRC) using biliary-secreted gadoxetic acid at 7 T and to compare it with T2-weighted (w) MRC at 3 T. Ten healthy volunteers were examined on a 7-T whole-body magnetic resonance system. T2-weighted turbo-spin-echo sequence, T1-w volume-interpolated breath-hold examination (VIBE), and fast low-angle shot (FLASH) with inversion recovery (IR) were acquired in coronal orientation. For dynamic imaging, gadoxetic acid was administrated and data were collected for a period of 5 to 40 minutes after injection. The volunteers underwent subsequent T2-w respiratory-gated MRC at 3 T. For qualitative analysis, a 5-point scale was used. Contrast ratios (CRs) were calculated for quantitative assessment. Contrast-enhanced T1-w MRC at 7 T showed a homogeneous depiction of the intrahepatic and extrahepatic biliary tract with a maximum enhancement of 20 minutes after contrast. Volume-interpolated breath-hold examination and FLASH IR provided a good image quality for the intrahepatic (VIBE, 3.60; FLASH IR, 3.67) and extrahepatic bile ducts (VIBE, 3.50; FLASH IR, 3.72). The quantitative analysis revealed high CR values for FLASH IR (intrahepatic CR, 0.41; extrahepatic CR, 0.45) because of an effective suppression of hepatic tissue and vessels. The T2-w TSE at 7 T showed only a poor image quality without diagnostic potential (intrahepatic, 2.22; extrahepatic, 1.93). Seven-tesla VIBE and FLASH revealed superiority in the depiction of the intrahepatic bile ducts, whereas 3-T MRC was superior in the delineation of the extrahepatic biliary tract. Our results demonstrate the feasibility of contrast-enhanced imaging of the biliary ducts at 7 T.

Bright flash response recovery of mammalian rods in vivo is rate limited by RGS9

PubMed Central

Peinado Allina, Gabriel; Fortenbach, Christopher; Gross, Owen P.; Pugh, Edward N.

2017-01-01

The temporal resolution of scotopic vision is thought to be constrained by the signaling kinetics of retinal rods, which use a highly amplified G-protein cascade to transduce absorbed photons into changes in membrane potential. Much is known about the biochemical mechanisms that determine the kinetics of rod responses ex vivo, but the rate-limiting mechanisms in vivo are unknown. Using paired flash electroretinograms with improved signal-to-noise, we have recorded the amplitude and kinetics of rod responses to a wide range of flash strengths from living mice. Bright rod responses in vivo recovered nearly twice as fast as all previous recordings, although the kinetic consequences of genetic perturbations previously studied ex vivo were qualitatively similar. In vivo, the dominant time constant of recovery from bright flashes was dramatically reduced by overexpression of the RGS9 complex, revealing G-protein deactivation to be rate limiting for recovery. However, unlike previous ex vivo recordings, dim flash responses in vivo were relatively unaffected by RGS9 overexpression, suggesting that other mechanisms, such as calcium feedback dynamics that are strongly regulated by the restricted subretinal microenvironment, act to determine rod dim flash kinetics. To assess the consequences for scotopic vision, we used a nocturnal wheel-running assay to measure the ability of wild-type and RGS9-overexpressing mice to detect dim flickering stimuli and found no improvement when rod recovery was speeded by RGS9 overexpression. These results are important for understanding retinal circuitry, in particular as modeled in the large literature that addresses the relationship between the kinetics and sensitivity of retinal responses and visual perception. PMID:28302678

Activation of serotonin 2A receptors underlies the psilocybin-induced effects on α oscillations, N170 visual-evoked potentials, and visual hallucinations.

PubMed

Kometer, Michael; Schmidt, André; Jäncke, Lutz; Vollenweider, Franz X

2013-06-19

Visual illusions and hallucinations are hallmarks of serotonergic hallucinogen-induced altered states of consciousness. Although the serotonergic hallucinogen psilocybin activates multiple serotonin (5-HT) receptors, recent evidence suggests that activation of 5-HT2A receptors may lead to the formation of visual hallucinations by increasing cortical excitability and altering visual-evoked cortical responses. To address this hypothesis, we assessed the effects of psilocybin (215 μg/kg vs placebo) on both α oscillations that regulate cortical excitability and early visual-evoked P1 and N170 potentials in healthy human subjects. To further disentangle the specific contributions of 5-HT2A receptors, subjects were additionally pretreated with the preferential 5-HT2A receptor antagonist ketanserin (50 mg vs placebo). We found that psilocybin strongly decreased prestimulus parieto-occipital α power values, thus precluding a subsequent stimulus-induced α power decrease. Furthermore, psilocybin strongly decreased N170 potentials associated with the appearance of visual perceptual alterations, including visual hallucinations. All of these effects were blocked by pretreatment with the 5-HT2A antagonist ketanserin, indicating that activation of 5-HT2A receptors by psilocybin profoundly modulates the neurophysiological and phenomenological indices of visual processing. Specifically, activation of 5-HT2A receptors may induce a processing mode in which stimulus-driven cortical excitation is overwhelmed by spontaneous neuronal excitation through the modulation of α oscillations. Furthermore, the observed reduction of N170 visual-evoked potentials may be a key mechanism underlying 5-HT2A receptor-mediated visual hallucinations. This change in N170 potentials may be important not only for psilocybin-induced states but also for understanding acute hallucinatory states seen in psychiatric disorders, such as schizophrenia and Parkinson's disease.

Epileptiform activity induced by lowering extracellular [Mg2+] in combined hippocampal-entorhinal cortex slices: modulation by receptors for norepinephrine and N-methyl-D-aspartate.

PubMed

Stanton, P K; Jones, R S; Mody, I; Heinemann, U

1987-01-01

Reduction of extracellular Mg2+ concentration induced spontaneous and evoked epileptiform activity in the entorhinal cortex (EC) and dentate gyrus (DG) of combined hippocampus (HC)-EC slices. Extracellular field potentials, as well as changes in extracellular Ca2+ and K+ concentrations, were measured in EC and DG with ion-selective/reference electrodes during both repetitive and single stimuli. In the EC, lowering extracellular [Mg2+] induces both spontaneous and single stimulus evoked ictal events consisting of extracellular negative potential shifts (up to 5 mV, 30 sec), decreases in [Ca2+]0 and increases in [K+]0. In the DG, spontaneous events were much shorter, but similar changes in [Ca2+]0, [K+]0 and field potentials (FPs) could be evoked by brief high-frequency stimulation. In both areas, the N-methyl-D-aspartate (NMDA) receptor antagonist 2-aminophosphonovalerate (2-APV) completely blocked spontaneous as well as stimulus evoked epileptiform events. The neurotransmitter norepinephrine (NE), which has previously been shown to modulate long-term potentiation in the DG, was found to exhibit differential modulation of epileptiform activity in the EC and DG. In the EC, NE, acting via alpha 1-receptors, completely blocked low Mg2+-induced epileptiform activity. In contrast, in the DG, NE exhibited a beta-receptor mediated prolongation of the low Mg2+-induced ictal events, and enhanced the stimulus-induced ionic and field potential changes. From these results, we conclude that lowering extracellular [Mg2+], acting in large part through the removal of the Mg2+ voltage-dependent blockade of NMDA receptors, leads to induction of epileptiform activity in both the EC and DG.(ABSTRACT TRUNCATED AT 250 WORDS)

The developmental effects of extremely low frequency electric fields on visual and somatosensory evoked potentials in adult rats.

PubMed

Gok, Deniz Kantar; Akpinar, Deniz; Hidisoglu, Enis; Ozen, Sukru; Agar, Aysel; Yargicoglu, Piraye

2016-01-01

The purpose of our study was to investigate the developmental effects of extremely low frequency electric fields (ELF-EFs) on visual evoked potentials (VEPs) and somatosensory-evoked potentials (SEPs) and to examine the relationship between lipid peroxidation and changes of these potentials. In this context, thiobarbituric acid reactive substances (TBARS) levels were determined as an indicator of lipid peroxidation. Wistar albino female rats were divided into four groups; Control (C), gestational (prenatal) exposure (Pr), gestational+ postnatal exposure (PP) and postnatal exposure (Po) groups. Pregnant rats of Pr and PP groups were exposed to 50 Hz electric field (EF) (12 kV/m; 1 h/day), while those of C and Po groups were placed in an inactive system during pregnancy. Following parturition, rats of PP and Po groups were exposed to ELF-EFs whereas rats of C and Pr groups were kept under the same experimental conditions without being exposed to any EF during 68 days. On postnatal day 90, rats were prepared for VEP and SEP recordings. The latencies of VEP components in all experimental groups were significantly prolonged versus C group. For SEPs, all components of PP group, P2, N2 components of Pr group and P1, P2, N2 components of Po group were delayed versus C group. As brain TBARS levels were significantly increased in Pr and Po groups, retina TBARS levels were significantly elevated in all experimental groups versus C group. In conclusion, alterations seen in evoked potentials, at least partly, could be explained by lipid peroxidation in the retina and brain.

Multimodal evoked potentials in patients with multiple sclerosis in assessment of the course of the disease.

PubMed

Łabuz-Roszak, Beata; Torbus, Magdalena; Kubicka-Bączyk, Katarzyna; Machowska-Majchrzak, Agnieszka; Kierber, Agata; Borucka, Katarzyna; Zellner, Małgorzata; Starostak-Tatar, Anna; Pierzchała, Krystyna

Multiple sclerosis (MS) is a chronic inflammatory, demyelinating disease of the central nervous system with a multifocal damage. The assessment of the MS course by multimodal evoked potentials (EP). We evaluated 95 patients (63 female, 32 male) with relapsing-remitting MS in the average age of 36.4±10.4. The average disease duration was 4.6±7.4 year. Among them, 48 patients (50.5%) were treated with immunomodulatory drugs. All patients underwent neurological examination and EP testing: VEP (visual evoked potentials), SEP (somatosensory evoked potentials), endogenous potential P300. The latencies of following waves were evaluated: P100 (VEP), N4 , N9 , N13, N20, P22 (SEP) and P300, with the reference values of the Neurophysiological Research Laboratory of the Department of Neurology in Zabrze. Abnormal VEP(I) was found in 80 patients (84.2%), SEP(I) in 9 patients (9.5%), P300(I) in 15 patients (15.8%). Abnormal result of the control research VEP (II) was found in 23 patients (82.1%), SEP(II) in 1 patient (3.6%), P300(II) in 4 patients (14.3%). The average values of the waves latencies in the control study were higher, however the statistical significance was not found. The correlation was observed between EDSS, and N20 and P22. No relationship was found between EP and age, disease duration, number of relapses and treatment. In the era of neuroimaging, usage of EP in the diagnosis and assessment of MS is limited. Electrophysiological studies may be used in addition to the clinical examination to confirm the multifocal damage.

A novel component of cannabis extract potentiates excitatory synaptic transmission in rat olfactory cortex in vitro.

PubMed

Whalley, Benjamin J; Wilkinson, Jonathan D; Williamson, Elizabeth M; Constanti, Andrew

2004-07-15

Cannabis is a potential treatment for epilepsy, although the few human studies supporting this use have proved inconclusive. Previously, we showed that a standardized cannabis extract (SCE), isolated Delta9-tetrahydrocannabinol (Delta9-THC), and even Delta9-THC-free SCE inhibited muscarinic agonist-induced epileptiform bursting in rat olfactory cortical brain slices, acting via CB1 receptors. The present work demonstrates that although Delta9-THC (1 microM) significantly depressed evoked depolarizing postsynaptic potentials (PSPs) in rat olfactory cortex neurones, both SCE and Delta9-THC-free SCE significantly potentiated evoked PSPs (all results were fully reversed by the CB1 receptor antagonist SR141716A, 1 microM); interestingly, the potentiation by Delta9-THC-free SCE was greater than that produced by SCE. On comparing the effects of Delta9-THC-free SCE upon evoked PSPs and artificial PSPs (aPSPs; evoked electrotonically following brief intracellular current injection), PSPs were enhanced, whereas aPSPs were unaffected, suggesting that the effect was not due to changes in background input resistance. Similar recordings made using CB1 receptor-deficient knockout mice (CB1-/-) and wild-type littermate controls revealed cannabinoid or extract-induced changes in membrane resistance, cell excitability and synaptic transmission in wild-type mice that were similar to those seen in rat neurones, but no effect on these properties were seen in CB1-/- cells. It appears that the unknown extract constituent(s) effects over-rode the suppressive effects of Delta9-THC on excitatory neurotransmitter release, which may explain some patients' preference for herbal cannabis rather than isolated Delta9-THC (due to attenuation of some of the central Delta9-THC side effects) and possibly account for the rare incidence of seizures in some individuals taking cannabis recreationally.

Contralateral Inhibition of Click- and Chirp-Evoked Human Compound Action Potentials

PubMed Central

Smith, Spencer B.; Lichtenhan, Jeffery T.; Cone, Barbara K.

2017-01-01

Cochlear outer hair cells (OHC) receive direct efferent feedback from the caudal auditory brainstem via the medial olivocochlear (MOC) bundle. This circuit provides the neural substrate for the MOC reflex, which inhibits cochlear amplifier gain and is believed to play a role in listening in noise and protection from acoustic overexposure. The human MOC reflex has been studied extensively using otoacoustic emissions (OAE) paradigms; however, these measurements are insensitive to subsequent “downstream” efferent effects on the neural ensembles that mediate hearing. In this experiment, click- and chirp-evoked auditory nerve compound action potential (CAP) amplitudes were measured electrocochleographically from the human eardrum without and with MOC reflex activation elicited by contralateral broadband noise. We hypothesized that the chirp would be a more optimal stimulus for measuring neural MOC effects because it synchronizes excitation along the entire length of the basilar membrane and thus evokes a more robust CAP than a click at low to moderate stimulus levels. Chirps produced larger CAPs than clicks at all stimulus intensities (50–80 dB ppeSPL). MOC reflex inhibition of CAPs was larger for chirps than clicks at low stimulus levels when quantified both in terms of amplitude reduction and effective attenuation. Effective attenuation was larger for chirp- and click-evoked CAPs than for click-evoked OAEs measured from the same subjects. Our results suggest that the chirp is an optimal stimulus for evoking CAPs at low stimulus intensities and for assessing MOC reflex effects on the auditory nerve. Further, our work supports previous findings that MOC reflex effects at the level of the auditory nerve are underestimated by measures of OAE inhibition. PMID:28420960

Vestibular Evoked Myogenic Potential Produced by Bone-Conducted Stimuli: A Study on its Basics and Clinical Applications in Patients with Conductive and Sensorineural Hearing Loss and a Group with Vestibular Schawannoma.

PubMed

Mahdi, Parvane; Amali, Amin; Pourbakht, Akram; Karimi Yazdi, Alireza; Bassam, Ali

2013-06-01

Vestibular evoked myogenic potential (VEMP) has recently been broadly studied in vestibular disorders. As it is evoked by loud sound stimulation, even mild conductive hearing loss may affect VEMP results. Bone-conducted (BC) stimulus is an alternative stimulation for evoking this response. This study aims to assess the characteristics of BC-VEMP in different groups of patients. We performed a cross sectional analysis on 20 healthy volunteers with normal pure-tone audiometry as a control group; and on a group of patients consisted of 20 participants with conductive hearing loss, five with bilateral sensorineural hearing loss and four with vestibular schawannoma. AC and BC-VEMP were performed in all participants. In control group the VEMP responses to both kinds of stimuli had an acceptable morphology and consisted of p13 and n23 waves. Latency value of these main components in each type of stimulus was not significantly different (P>0.05). However, the mean amplitude was larger in BC modality than AC stimulation (P=0.025). In the group with conductive hearing loss, the VEMP response was absent in fifteen (46.87%) of the 32 ears using the AC method, whereas all (100%) displayed positive elicitability of VEMP by BC method. Normal VEMP responses in both stimuli were evoked in all patients with sensorineural hearing loss. In patients with unilateral vestibular schwannomas (VS), 2 (50.00%) had neither AC-VEMP nor BC-VEMP. Auditory stimuli delivered by bone conduction can evoke VEMP response. These responses are of vestibular origin and can be used in vestibular evaluation of patients with conductive hearing loss.

Vestibular Evoked Myogenic Potential Produced by Bone-Conducted Stimuli: A Study on its Basics and Clinical Applications in Patients with Conductive and Sensorineural Hearing Loss and a Group with Vestibular Schawannoma

PubMed Central

Mahdi, Parvane; Amali, Amin; Pourbakht, Akram; Karimi Yazdi, Alireza; Bassam, Ali

2013-01-01

Introduction: Vestibular evoked myogenic potential (VEMP) has recently been broadly studied in vestibular disorders. As it is evoked by loud sound stimulation, even mild conductive hearing loss may affect VEMP results. Bone-conducted (BC) stimulus is an alternative stimulation for evoking this response. This study aims to assess the characteristics of BC-VEMP in different groups of patients. Materials and Methods: We performed a cross sectional analysis on 20 healthy volunteers with normal pure-tone audiometry as a control group; and on a group of patients consisted of 20 participants with conductive hearing loss, five with bilateral sensorineural hearing loss and four with vestibular schawannoma. AC and BC-VEMP were performed in all participants. Results: In control group the VEMP responses to both kinds of stimuli had an acceptable morphology and consisted of p13 and n23 waves. Latency value of these main components in each type of stimulus was not significantly different (P>0.05). However, the mean amplitude was larger in BC modality than AC stimulation (P=0.025). In the group with conductive hearing loss, the VEMP response was absent in fifteen (46.87%) of the 32 ears using the AC method, whereas all (100%) displayed positive elicitability of VEMP by BC method. Normal VEMP responses in both stimuli were evoked in all patients with sensorineural hearing loss. In patients with unilateral vestibular schwannomas (VS), 2 (50.00%) had neither AC-VEMP nor BC-VEMP. Conclusion: Auditory stimuli delivered by bone conduction can evoke VEMP response. These responses are of vestibular origin and can be used in vestibular evaluation of patients with conductive hearing loss. PMID:24303434

Menopausal hot flashes: Randomness or rhythmicity

NASA Astrophysics Data System (ADS)

Kronenberg, Fredi

1991-10-01

Menopausal hot flashes are episodes of flushing, increased heart rate, skin blood flow and skin temperature, and a sensation of heat. The thermoregulatory and cardiovascular concomitants of hot flashes are associated with peaks in the levels of various hormones and neurotransmitters in the peripheral circulation. Although hot flashes affect about 75% of women, and are the primary reason that women at menopause seek medical attention, the mechanism of hot flashes is still not understood. Hot flashes vary in frequency and intensity both within and between individuals, and have been thought of as occurring randomly. Yet, some women report that their hot flashes are worse at a particular time of day or year. Initial examination of subjects' recordings of their hot flashes showed diurnal patterns of hot flash occurrence. There also seems to be a diurnal rhythm of hot flash intensity. Continuous physiological monitoring of hot flashes is facilitating the analysis of these patterns, which is revealing circadian and ultradian periodicities. The occurrence of hot flashes can be modulated by external and internal factors, including ambient temperature and fever. Rhythms of thermoregulatory and endocrine functions also may influence hot flash patterns. Examination of the interrelationships between the various systems of the body involved in hot flashes, and a multidisciplinary approach to the analysis of hot flash patterns, will aid our understanding of this complex phenomenon.

Mismatch negativity to the patient's own name in chronic disorders of consciousness.

PubMed

Qin, Pengmin; Di, Haibo; Yan, Xiaodan; Yu, Senming; Yu, Dan; Laureys, Steven; Weng, Xuchu

2008-12-19

Previous studies implicated potential value of mismatch negativity (MMN) in predicting recovery of consciousness in patients with disorders of consciousness (DOC). We have adopted a novel MMN evoked by subject's own name (SON), a self-referential stimulus thought to be powerful in evoking residual brain activity, and examined the correlation between the MMN and recovery of consciousness in patients with chronic (>1 month) DOC. Twelve patients and 12 age-matched healthy controls were investigated. The patients were diagnosed as coma (n=4), vegetative state (VS, n=6), and minimally conscious state (MCS, n=2), mainly based on the JFK Coma Recovery Scale-Revised. The SON-evoked MMN (SON-MMN) was present in seven patients. Critically, the presence of SON-MMN was significantly correlated with recovery of consciousness. While four of the five patients (three VS and two coma) showing SON-MMN changed to MCS 3 months later, the rest of the patients (three VS and two coma) without SON-MMN failed to show any clinical improvement. Our study thus illustrates that the subject's own name is effective in evoking MMN in patients with DOC, and that SON-MMN has potential prognostic values in predicting recovery of consciousness.

The hybrid BCI system for movement control by combining motor imagery and moving onset visual evoked potential

NASA Astrophysics Data System (ADS)

Ma, Teng; Li, Hui; Deng, Lili; Yang, Hao; Lv, Xulin; Li, Peiyang; Li, Fali; Zhang, Rui; Liu, Tiejun; Yao, Dezhong; Xu, Peng

2017-04-01

Objective. Movement control is an important application for EEG-BCI (EEG-based brain-computer interface) systems. A single-modality BCI cannot provide an efficient and natural control strategy, but a hybrid BCI system that combines two or more different tasks can effectively overcome the drawbacks encountered in single-modality BCI control. Approach. In the current paper, we developed a new hybrid BCI system by combining MI (motor imagery) and mVEP (motion-onset visual evoked potential), aiming to realize the more efficient 2D movement control of a cursor. Main result. The offline analysis demonstrates that the hybrid BCI system proposed in this paper could evoke the desired MI and mVEP signal features simultaneously, and both are very close to those evoked in the single-modality BCI task. Furthermore, the online 2D movement control experiment reveals that the proposed hybrid BCI system could provide more efficient and natural control commands. Significance. The proposed hybrid BCI system is compensative to realize efficient 2D movement control for a practical online system, especially for those situations in which P300 stimuli are not suitable to be applied.

Flashing characters with famous faces improves ERP-based brain-computer interface performance

NASA Astrophysics Data System (ADS)

Kaufmann, T.; Schulz, S. M.; Grünzinger, C.; Kübler, A.

2011-10-01

Currently, the event-related potential (ERP)-based spelling device, often referred to as P300-Speller, is the most commonly used brain-computer interface (BCI) for enhancing communication of patients with impaired speech or motor function. Among numerous improvements, a most central feature has received little attention, namely optimizing the stimulus used for eliciting ERPs. Therefore we compared P300-Speller performance with the standard stimulus (flashing characters) against performance with stimuli known for eliciting particularly strong ERPs due to their psychological salience, i.e. flashing familiar faces transparently superimposed on characters. Our results not only indicate remarkably increased ERPs in response to familiar faces but also improved P300-Speller performance due to a significant reduction of stimulus sequences needed for correct character classification. These findings demonstrate a promising new approach for improving the speed and thus fluency of BCI-enhanced communication with the widely used P300-Speller.

Multimodal intraoperative neuromonitoring in corrective surgery for adolescent idiopathic scoliosis: Evaluation of 354 consecutive cases

PubMed Central

Kundnani, Vishal K; Zhu, Lisa; Tak, HH; Wong, HK

2010-01-01

Background: Multimodal intraoperative neuromonitoring is recommended during corrective spinal surgery, and has been widely used in surgery for spinal deformity with successful outcomes. Despite successful outcomes of corrective surgery due to increased safety of the patients with the usage of spinal cord monitoring in many large spine centers, this modality has not yet achieved widespread popularity. We report the analysis of prospectively collected intraoperative neurophysiological monitoring data of 354 consecutive patients undergoing corrective surgery for adolescent idiopathic scoliosis (AIS) to establish the efficacy of multimodal neuromonitoring and to evaluate comparative sensitivity and specificity. Materials and Methods: The study group consisted of 354 (female = 309; male = 45) patients undergoing spinal deformity corrective surgery between 2004 and 2008. Patients were monitored using electrophysiological methods including somatosensory-evoked potentials and motor-evoked potentials simultaneously. Results: Mean age of patients was 13.6 years (±2.3 years). The operative procedures involved were instrumented fusion of the thoracic/lumbar/both curves, Baseline somatosensory-evoked potentials (SSEP) and neurogenic motor-evoked potentials (NMEP) were recorded successfully in all cases. Thirteen cases expressed significant alert to prompt reversal of intervention. All these 13 cases with significant alert had detectable NMEP alerts, whereas significant SSEP alert was detected in 8 cases. Two patients awoke with new neurological deficit (0.56%) and had significant intraoperative SSEP + NMEP alerts. There were no false positives with SSEP (high specificity) but 5 patients with false negatives with SSEP (38%) reduced its sensitivity. There was no false negative with NMEP but 2 of 13 cases were false positive with NMEP (15%). The specificity of SSEP (100%) is higher than NMEP (96%); however, the sensitivity of NMEP (100%) is far better than SSEP (51%). Due to these results, the overall sensitivity, specificity and positive predictive value of combined multimodality neuromonitoring in this adult deformity series was 100, 98.5 and 85%, respectively. Conclusion: Neurogenic motor-evoked potential (NMEP) monitoring appears to be superior to conventional SSEP monitoring for identifying evolving spinal cord injury. Used in conjunction, the sensitivity and specificity of combined neuromonitoring may reach up to 100%. Multimodality monitoring with SSEP + NMEP should be the standard of care. PMID:20165679

Network activity influences the subthreshold and spiking visual responses of pyramidal neurons in the three-layer turtle cortex.

PubMed

Wright, Nathaniel C; Wessel, Ralf

2017-10-01

A primary goal of systems neuroscience is to understand cortical function, typically by studying spontaneous and stimulus-modulated cortical activity. Mounting evidence suggests a strong and complex relationship exists between the ongoing and stimulus-modulated cortical state. To date, most work in this area has been based on spiking in populations of neurons. While advantageous in many respects, this approach is limited in scope: it records the activity of a minority of neurons and gives no direct indication of the underlying subthreshold dynamics. Membrane potential recordings can fill these gaps in our understanding, but stable recordings are difficult to obtain in vivo. Here, we recorded subthreshold cortical visual responses in the ex vivo turtle eye-attached whole brain preparation, which is ideally suited for such a study. We found that, in the absence of visual stimulation, the network was "synchronous"; neurons displayed network-mediated transitions between hyperpolarized (Down) and depolarized (Up) membrane potential states. The prevalence of these slow-wave transitions varied across turtles and recording sessions. Visual stimulation evoked similar Up states, which were on average larger and less reliable when the ongoing state was more synchronous. Responses were muted when immediately preceded by large, spontaneous Up states. Evoked spiking was sparse, highly variable across trials, and mediated by concerted synaptic inputs that were, in general, only very weakly correlated with inputs to nearby neurons. Together, these results highlight the multiplexed influence of the cortical network on the spontaneous and sensory-evoked activity of individual cortical neurons. NEW & NOTEWORTHY Most studies of cortical activity focus on spikes. Subthreshold membrane potential recordings can provide complementary insight, but stable recordings are difficult to obtain in vivo. Here, we recorded the membrane potentials of cortical neurons during ongoing and visually evoked activity. We observed a strong relationship between network and single-neuron evoked activity spanning multiple temporal scales. The membrane potential perspective of cortical dynamics thus highlights the influence of intrinsic network properties on visual processing. Copyright © 2017 the American Physiological Society.

Electrocortical amplification for emotionally arousing natural scenes: The contribution of luminance and chromatic visual channels

PubMed Central

Miskovic, Vladimir; Martinovic, Jasna; Wieser, Matthias M.; Petro, Nathan M.; Bradley, Margaret M.; Keil, Andreas

2015-01-01

Emotionally arousing scenes readily capture visual attention, prompting amplified neural activity in sensory regions of the brain. The physical stimulus features and related information channels in the human visual system that contribute to this modulation, however, are not known. Here, we manipulated low-level physical parameters of complex scenes varying in hedonic valence and emotional arousal in order to target the relative contributions of luminance based versus chromatic visual channels to emotional perception. Stimulus-evoked brain electrical activity was measured during picture viewing and used to quantify neural responses sensitive to lower-tier visual cortical involvement (steady-state visual evoked potentials) as well as the late positive potential, reflecting a more distributed cortical event. Results showed that the enhancement for emotional content was stimulus-selective when examining the steady-state segments of the evoked visual potentials. Response amplification was present only for low spatial frequency, grayscale stimuli, and not for high spatial frequency, red/green stimuli. In contrast, the late positive potential was modulated by emotion regardless of the scene’s physical properties. Our findings are discussed in relation to neurophysiologically plausible constraints operating at distinct stages of the cortical processing stream. PMID:25640949

Electrocortical amplification for emotionally arousing natural scenes: the contribution of luminance and chromatic visual channels.

PubMed

Miskovic, Vladimir; Martinovic, Jasna; Wieser, Matthias J; Petro, Nathan M; Bradley, Margaret M; Keil, Andreas

2015-03-01

Emotionally arousing scenes readily capture visual attention, prompting amplified neural activity in sensory regions of the brain. The physical stimulus features and related information channels in the human visual system that contribute to this modulation, however, are not known. Here, we manipulated low-level physical parameters of complex scenes varying in hedonic valence and emotional arousal in order to target the relative contributions of luminance based versus chromatic visual channels to emotional perception. Stimulus-evoked brain electrical activity was measured during picture viewing and used to quantify neural responses sensitive to lower-tier visual cortical involvement (steady-state visual evoked potentials) as well as the late positive potential, reflecting a more distributed cortical event. Results showed that the enhancement for emotional content was stimulus-selective when examining the steady-state segments of the evoked visual potentials. Response amplification was present only for low spatial frequency, grayscale stimuli, and not for high spatial frequency, red/green stimuli. In contrast, the late positive potential was modulated by emotion regardless of the scene's physical properties. Our findings are discussed in relation to neurophysiologically plausible constraints operating at distinct stages of the cortical processing stream. Copyright © 2015 Elsevier B.V. All rights reserved.

Controlling a stream of paranoia evoking events in a virtual reality environment.

PubMed

Isnanda, Reza Giga; Brinkman, Willem-Paul; Veling, Wim; van der Gaag, Mark; Neerincx, Mark

2014-01-01

Although virtual reality exposure has been reported as a method to induce paranoid thought, little is known about mechanisms to control specific virtual stressors. This paper reports on a study that examines the effect of controlling the stream of potential paranoia evoking events in a virtual restaurant world. A 2-by-2 experiment with a non-clinical group (n = 24) was conducted with as two within-subject factors: (1) the cycle time (short/long) for when the computer considers activation of a paranoia evoking event and (2) the probability that a paranoia-evoking event (low/high) would be triggered at the completion of a cycle. The results showed a significant main effect for the probability factor and two-way interaction effect with the cycle time factor on the number of paranoid comments participants made and their self-reported anxiety.

floodX: urban flash flood experiments monitored with conventional and alternative sensors

NASA Astrophysics Data System (ADS)

Moy de Vitry, Matthew; Dicht, Simon; Leitão, João P.

2017-09-01

The data sets described in this paper provide a basis for developing and testing new methods for monitoring and modelling urban pluvial flash floods. Pluvial flash floods are a growing hazard to property and inhabitants' well-being in urban areas. However, the lack of appropriate data collection methods is often cited as an impediment for reliable flood modelling, thereby hindering the improvement of flood risk mapping and early warning systems. The potential of surveillance infrastructure and social media is starting to draw attention for this purpose. In the floodX project, 22 controlled urban flash floods were generated in a flood response training facility and monitored with state-of-the-art sensors as well as standard surveillance cameras. With these data, it is possible to explore the use of video data and computer vision for urban flood monitoring and modelling. The floodX project stands out as the largest documented flood experiment of its kind, providing both conventional measurements and video data in parallel and at high temporal resolution. The data set used in this paper is available at https://doi.org/10.5281/zenodo.830513.

Monitoring auditory cortical plasticity in hearing aid users with long latency auditory evoked potentials: a longitudinal study.

PubMed

Leite, Renata Aparecida; Magliaro, Fernanda Cristina Leite; Raimundo, Jeziela Cristina; Bento, Ricardo Ferreira; Matas, Carla Gentile

2018-02-19

The objective of this study was to compare long-latency auditory evoked potentials before and after hearing aid fittings in children with sensorineural hearing loss compared with age-matched children with normal hearing. Thirty-two subjects of both genders aged 7 to 12 years participated in this study and were divided into two groups as follows: 14 children with normal hearing were assigned to the control group (mean age 9 years and 8 months), and 18 children with mild to moderate symmetrical bilateral sensorineural hearing loss were assigned to the study group (mean age 9 years and 2 months). The children underwent tympanometry, pure tone and speech audiometry and long-latency auditory evoked potential testing with speech and tone burst stimuli. The groups were assessed at three time points. The study group had a lower percentage of positive responses, lower P1-N1 and P2-N2 amplitudes (speech and tone burst), and increased latencies for the P1 and P300 components following the tone burst stimuli. They also showed improvements in long-latency auditory evoked potentials (with regard to both the amplitude and presence of responses) after hearing aid use. Alterations in the central auditory pathways can be identified using P1-N1 and P2-N2 amplitude components, and the presence of these components increases after a short period of auditory stimulation (hearing aid use). These findings emphasize the importance of using these amplitude components to monitor the neuroplasticity of the central auditory nervous system in hearing aid users.

Monitoring auditory cortical plasticity in hearing aid users with long latency auditory evoked potentials: a longitudinal study

PubMed Central

Leite, Renata Aparecida; Magliaro, Fernanda Cristina Leite; Raimundo, Jeziela Cristina; Bento, Ricardo Ferreira; Matas, Carla Gentile

2018-01-01

OBJECTIVE: The objective of this study was to compare long-latency auditory evoked potentials before and after hearing aid fittings in children with sensorineural hearing loss compared with age-matched children with normal hearing. METHODS: Thirty-two subjects of both genders aged 7 to 12 years participated in this study and were divided into two groups as follows: 14 children with normal hearing were assigned to the control group (mean age 9 years and 8 months), and 18 children with mild to moderate symmetrical bilateral sensorineural hearing loss were assigned to the study group (mean age 9 years and 2 months). The children underwent tympanometry, pure tone and speech audiometry and long-latency auditory evoked potential testing with speech and tone burst stimuli. The groups were assessed at three time points. RESULTS: The study group had a lower percentage of positive responses, lower P1-N1 and P2-N2 amplitudes (speech and tone burst), and increased latencies for the P1 and P300 components following the tone burst stimuli. They also showed improvements in long-latency auditory evoked potentials (with regard to both the amplitude and presence of responses) after hearing aid use. CONCLUSIONS: Alterations in the central auditory pathways can be identified using P1-N1 and P2-N2 amplitude components, and the presence of these components increases after a short period of auditory stimulation (hearing aid use). These findings emphasize the importance of using these amplitude components to monitor the neuroplasticity of the central auditory nervous system in hearing aid users. PMID:29466495

Short latency vestibular evoked potentials in the chicken embryo

NASA Technical Reports Server (NTRS)

Jones, S. M.; Jones, T. A.

1996-01-01

Electrophysiological responses to pulsed linear acceleration stimuli were recorded in chicken embryos incubated for 19 or 20 days (E19/E20). Responses occurred within the first 16 ms following the stimulus onset. The evoked potentials disappeared following bilateral labyrinthectomy, but persisted following cochlear destruction alone, thus demonstrating that the responses were vestibular. Approximately 8 to 10 response peaks could be identified. The first 4 positive and corresponding negative components (early peaks with latencies < 6.0 ms) were scored and latencies and amplitudes quantified. Vestibular response latencies were significantly longer (P < 0.01) and amplitudes significantly smaller (P < 0.001) than those observed in 2-week-old birds. Mean response threshold for anesthetized embryos was -15.9dBre 1.0 g/ms, which was significantly higher (P < 0.03) than those observed in 2-week-old birds (-23.0dBre 1.0 g/ms). Latency/intensity functions (that is, slopes) were not significantly different between embryos and 2-week-old animals, but amplitude/intensity functions for embryos were significantly shallower than those for 2-week-old birds (P < 0.001). We presume that these differences reflect the refinement of sensory function that occurs following 19 to 20 days of incubation. The recording of vestibular evoked potentials provides an objective, direct and noninvasive measure of peripheral vestibular function in the embryo and, as such, the method shows promise as an investigative tool. The results of the present study form the definitive basis for using vestibular evoked potentials in the detailed study of avian vestibular ontogeny and factors that may influence it.

Dynamic Ca2+ signalling in rat arterial smooth muscle cells under the control of local renin–angiotensin system

PubMed Central

Asada, Yukinori; Yamazawa, Toshiko; Hirose, Kenzo; Takasaka, Tomonori; Iino, Masamitsu

1999-01-01

We visualized the changes in intracellular Ca2+ concentration ([Ca2+]i), using fluo-3 as an indicator, in individual smooth muscle cells within intact rat tail artery preparations. On average in about 45 % of the vascular smooth muscle cells we found spontaneous Ca2+ waves and oscillations (≈0.13 Hz), which we refer to here as Ca2+ ripples because the peak amplitude of [Ca2+]i was about one-seventh of that of Ca2+ oscillations evoked by noradrenaline. We also found another pattern of spontaneous Ca2+ transients often in groups of two to three cells. They were rarely observed and are referred to as Ca2+ flashes because their peak amplitude was nearly twice as large as that in noradrenaline-evoked responses. Sympathetic nerve activity was not considered responsible for the Ca2+ ripples, and they were abolished by inhibitors of either the Ca2+ pump in the sarcoplasmic reticulum (cyclopiazonic acid) or phospholipase C (U-73122). Both angiotensin antagonists ([Sar1,Ile8]-angiotensin II and losartan) and an angiotensin converting enzyme inhibitor (captopril) inhibited the Ca2+ ripples. The extracellular Ca2+-dependent tension borne by unstimulated arterial rings was reduced by the angiotensin antagonist by ≈50 %. These results indicate that the Ca2+ ripples are generated via inositol 1,4,5-trisphosphate-induced Ca2+ release from the intracellular Ca2+ stores in response to locally produced angiotensin II, which contributes to the maintenance of vascular tone. PMID:10581318

Cervical intraspinal microstimulation evokes robust forelimb movements before and after injury

NASA Astrophysics Data System (ADS)

Sunshine, Michael D.; Cho, Frances S.; Lockwood, Danielle R.; Fechko, Amber S.; Kasten, Michael R.; Moritz, Chet T.

2013-06-01

Objective. Intraspinal microstimulation (ISMS) is a promising method for reanimating paralyzed limbs following neurological injury. ISMS within the cervical and lumbar spinal cord is capable of evoking a variety of highly-functional movements prior to injury, but the ability of ISMS to evoke forelimb movements after cervical spinal cord injury is unknown. Here we examine the forelimb movements and muscles activated by cervical ISMS both before and after contusion injury. Approach. We documented the forelimb muscles activated and movements evoked via systematic stimulation of the rodent cervical spinal cord both before injury and three, six and nine weeks following a moderate C4/C5 lateralized contusion injury. Animals were anesthetized with isoflurane to permit construction of somatotopic maps of evoked movements and quantify evoked muscle synergies between cervical segments C3 and T1. Main results. When ISMS was delivered to the cervical spinal cord, a variety of responses were observed at 68% of locations tested, with a spatial distribution that generally corresponded to the location of motor neuron pools. Stimulus currents required to achieve movement and the number of sites where movements could be evoked were unchanged by spinal cord injury. A transient shift toward extension-dominated movements and restricted muscle synergies were observed at three and six weeks following injury, respectively. By nine weeks after injury, however, ISMS-evoked patterns were similar to spinally-intact animals. Significance. The results demonstrate the potential for cervical ISMS to reanimate hand and arm function following spinal cord injury. Robust forelimb movements can be evoked both before and during the chronic stages of recovery from a clinically relevant and sustained cervical contusion injury.

Anti-Aversive Effects of Cannabidiol on Innate Fear-Induced Behaviors Evoked by an Ethological Model of Panic Attacks Based on a Prey vs the Wild Snake Epicrates cenchria crassus Confrontation Paradigm

PubMed Central

Uribe-Mariño, Andrés; Francisco, Audrey; Castiblanco-Urbina, Maria Angélica; Twardowschy, André; Salgado-Rohner, Carlos José; Crippa, José Alexandre S; Hallak, Jaime Eduardo Cecílio; Zuardi, Antônio Waldo; Coimbra, Norberto Cysne

2012-01-01

Several pharmacological targets have been proposed as modulators of panic-like reactions. However, interest should be given to other potential therapeutic neurochemical agents. Recent attention has been given to the potential anxiolytic properties of cannabidiol, because of its complex actions on the endocannabinoid system together with its effects on other neurotransmitter systems. The aim of this study was to investigate the effects of cannabidiol on innate fear-related behaviors evoked by a prey vs predator paradigm. Male Swiss mice were submitted to habituation in an arena containing a burrow and subsequently pre-treated with intraperitoneal administrations of vehicle or cannabidiol. A constrictor snake was placed inside the arena, and defensive and non-defensive behaviors were recorded. Cannabidiol caused a clear anti-aversive effect, decreasing explosive escape and defensive immobility behaviors outside and inside the burrow. These results show that cannabidiol modulates defensive behaviors evoked by the presence of threatening stimuli, even in a potentially safe environment following a fear response, suggesting a panicolytic effect. PMID:21918503

Effects of Mental Load and Fatigue on Steady-State Evoked Potential Based Brain Computer Interface Tasks: A Comparison of Periodic Flickering and Motion-Reversal Based Visual Attention.

PubMed

Xie, Jun; Xu, Guanghua; Wang, Jing; Li, Min; Han, Chengcheng; Jia, Yaguang

Steady-state visual evoked potentials (SSVEP) based paradigm is a conventional BCI method with the advantages of high information transfer rate, high tolerance to artifacts and the robust performance across users. But the occurrence of mental load and fatigue when users stare at flickering stimuli is a critical problem in implementation of SSVEP-based BCIs. Based on electroencephalography (EEG) power indices α, θ, θ + α, ratio index θ/α and response properties of amplitude and SNR, this study quantitatively evaluated the mental load and fatigue in both of conventional flickering and the novel motion-reversal visual attention tasks. Results over nine subjects revealed significant mental load alleviation in motion-reversal task rather than flickering task. The interaction between factors of "stimulation type" and "fatigue level" also illustrated the motion-reversal stimulation as a superior anti-fatigue solution for long-term BCI operation. Taken together, our work provided an objective method favorable for the design of more practically applicable steady-state evoked potential based BCIs.

Auditory brain stem response and cortical evoked potentials in children with type 1 diabetes mellitus.

PubMed

Radwan, Heba Mohammed; El-Gharib, Amani Mohamed; Erfan, Adel Ali; Emara, Afaf Ahmad

2017-05-01

Delay in ABR and CAEPs wave latencies in children with type 1DM indicates that there is abnormality in the neural conduction in DM patients. The duration of DM has greater effect on auditory function than the control of DM. Diabetes mellitus (DM) is a common endocrine and metabolic disorder. Evoked potentials offer the possibility to perform a functional evaluation of neural pathways in the central nervous system. To investigate the effect of type 1 diabetes mellitus (T1DM) on auditory brain stem response (ABR) and cortical evoked potentials (CAEPs). This study included two groups: a control group (GI), which consisted of 20 healthy children with normal peripheral hearing, and a study group (GII), which consisted of 30 children with type I DM. Basic audiological evaluation, ABR, and CAEPs were done in both groups. Delayed absolute latencies of ABR and CAEPs waves were found. Amplitudes showed no significant difference between both groups. Positive correlation was found between ABR wave latencies and duration of DM. No correlation was found between ABR, CAEPs, and glycated hemoglobin.