Name: electrophysiological measurement of noxious-evoked brain activity in neonates using a flat-tip probe coupled to electroencephalography
Uploaded: 2017-11-29T15:00:00
Description: Watch this Scientific Journal Video about Electrophysiological Measurement of Noxious-evoked Brain Activity in Neonates Using a Flat-tip Probe Coupled to Electroencephalography at JoVE.com

The authors would like to acknowledge Caroline Hartley and Rebeccah Slater (Department of Paediatrics, University of Oxford, UK) for critical reviewing our paper and Walter Magerl (Department of Neurophysiology, Center of Biomedicine and Medical Technology Mannheim (CBTM), University of Heidelberg, Germany) for supporting us with technical equipment and knowledge.

The study was approved by the Competent Ethics Committee of Northwestern Switzerland (EKNZ 2015-079) and informed written parental consent for the participant was obtained before the measurement.
1. Preparation
<ol>
	<li>Make sure the baby is settled. It should be quiet and settled, without sucking motions during the recording because of movement artefacts. The baby can be asleep9.</li>
	<li>Measure the neonate&#39;s head circumference with a measuring tape to define ...

<ol>
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N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterizing+pinprick-evoked+brain+potentials+before+and+after+experimentally+induced+secondary+hyperalgesia.">Characterizing pinprick-evoked brain potentials before and after experimentally induced secondary hyperalgesia.</a> J Neurophysiol. 114 (5), 2672-2681 (2015).</li><li>Verriotis, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cortical+activity+evoked+by+inoculation+needle+prick+in+infants+up+to+one-year+old.">Cortical activity evoked by inoculation needle prick in infants up to one-year old.</a> Pain. 156 (2), 222-230 (2015).</li><li>Rolke, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+sensory+testing+in+the+German+Research+Network+on+Neuropathic+Pain+(DFNS):+standardized+protocol+and+reference+values.">Quantitative sensory testing in the German Research Network on Neuropathic Pain (DFNS): standardized protocol and reference values.</a> Pain. 123 (3), 231-243 (2006).</li><li>Moultrie, F., Slater, R., Hartley, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+the+treatment+of+infant+pain.">Improving the treatment of infant pain.</a> Curr Opin Support Palliat Care. 11 (2), 112-117 (2017).</li><li>Hu, L., Zhang, Z. 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The approach presented here shows how noxious-evoked brain activity in neonates can be measured in an objective way using EEG recording and flat-tip probe stimulators to apply experimental noxious stimuli. This technique can be used in various clinical settings to detect nociception, e.g. in non-verbal persons such as neonates. The complete study can be done within 15 min, including placing the baby, identifying, preparing and mounting the electrodes, and finally applying and recording the 50 noxious stimuli. Th...

Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage1. The inability to communicate verbally does not negate the possibility that an individual is experiencing pain but makes it very challenging to assess pain-relieving treatment, for example in newborn infants2. Several behavioral and physiological indicators are used to assess pain in non-verbal patients. Different scales have been developed over the years, the choice depends on the type of stimulus, gestational age and the environment in which the neonates are embeded3,4,5. These pain assessment tools either rely on the rater&#39;s interpretation or they demand secondary physiological indicators.
In this video, we present a method to assess nociception with electrophysiological recordings optimized for use in newborn infants. Nociception is defined as the neural process of encoding noxious stimuli. Thus, quantitating nociception is an elegant and objective method to determine the neural input in a non-verbal person. Moreover, cortical activity detected by electroencephalography (EEG) is correlated with the intensity of noxious events5,6.
The method presented here combines EEG recording with noxious stimuli produced by a mechanical stimulation with a flat-tip probe, also called a pinprick7, which is not skin-breaking and does not cause behavioral distress6. It has been shown, that nociception following punctuate stimulation is predominantly mediated by A&#948;-fibers, does not need a skin breaking lesion8 and the magnitude of the nociceptive-specific potential is not dependent on sleep state9. The probe is well accepted also by parents when applying this method in a study setting with neonates. The probe is electronically linked to the EEG recording system enabling the EEG recording to be precisely tagged when the probe contacts the skin. This greatly simplifies the process of time locking and is the premise for all subsequent EEG analyses. In order to minimize preparation time of the infant EEG recording we used a modified international 10/20 electrode placement system where we reduced the number of electrodes to the minimum requirement of three electrodes (Figure 1). The central vertex Cz electrode, where the noxious-evoked brain activity is maximal9,10,11, was used together with one reference and one ground electrode.

<table>
	<tbody>
		<tr>
			<td>Easycap</td>
			<td>EASYCAP GmbH</td>
			<td>AC-32-C</td>
			<td>EEG caps for infants sizes 34 and 36</td>
		</tr>
		<tr>
			<td>actiCAP</td>
			<td>Brain Products GmbH</td>
			<td>BP-04243-SIG</td>
			<td>active electrodes</td>
		</tr>
		<tr>
			<td>ImpBox</td>
			<td>Brain Products GmbH</td>
			<td></td>
			<td>impedance measurement</td>
		</tr>
		<tr>
			<td>V-Amp</td>
			<td>Brain Products GmbH</td>
			<td></td>
			<td>EEG recording device</td>
		</tr>
		<tr>
			<td>Contact trigger for pinprick stimulation</td>
			<td>MRC Systems GmbH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PinPrick stimulator set</td>
			<td>MRC Systems GmbH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>EEG prepping paste</td>
			<td>USB Pharmacy</td>
			<td></td>
			<td>contains sodium chloride, pumice stone, propylene glycol</td>
		</tr>
		<tr>
			<td>SuperVisc</td>
			<td>EASYCAP GmbH</td>
			<td></td>
			<td>Electrolyte-Gel for active electrodes</td>
		</tr>
		<tr>
			<td>Brain Vision Recorder</td>
			<td>Brain Products GmbH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Brain Vision Analyzer</td>
			<td>Brain Products GmbH</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>MATLAB using EEGLAB
			
			
			
			
			
			</td>
			<td>Swartz Center for Computational Neuroscience, University of California San Diego</td>
			<td></td>
			<td>For EEG processing, including averaging of all EEG epochs
			
			
			
			</td>
		</tr>
	</tbody>
</table>

electrophysiological measurement of noxious-evoked brain activity in neonates using a flat-tip probe coupled to electroencephalography

Pain is an unpleasant sensory and emotional experience. In non-verbal patients, it is very difficult to measure pain, even with pain assessment tools. Those tools are subjective or determine secondary physiological indicators which also have certain limitations particularly when exploring the effectiveness of analgesia. As cortical processing is essential for pain perception, brain activity measures may provide a useful approach to assess pain in infants. Here we present a method to assess nociception with electrophysiological brain activity recordings optimized for the use in newborn infants. To produce highly standardized and reproducible noxious stimuli we applied mechanical stimulation with a flat-tip probe, e.g., PinPrick, which is not skin-breaking and does not cause behavioral distress. The noxious-evoked potential allows the objective measurement of nociception in non-verbal patients. This method can be used in newborn infants as early as 34 weeks of gestational age. Moreover, it could be applied in different situations such as measuring the efficacy of analgesic or anesthetic drugs.

Figure 1 is the diagrammatic representation of the electrode positioning using the modified international 10/20 electrode placement system. Figure 2 shows the EEG activity recorded shortly before and after application of one single noxious stimulus using a flat-tip probe with 32 mN force, stimulation occurred as described in the protocol to the neonate&#39;s right hand (Figure 2A). The noxious-evoked...

Watch this Scientific Journal Video about Electrophysiological Measurement of Noxious-evoked Brain Activity in Neonates Using a Flat-tip Probe Coupled to Electroencephalography at JoVE.com

Electrophysiological Measurement of Noxious-evoked Brain Activity in Neonates Using a Flat-tip Probe Coupled to Electroencephalography

Measuring pain in non-verbal patients is a challenge. In this study we combine EEG recording with stimulation using a flat-tip probe to detect noxious-evoked brain activity in an objective manner.

Pain is an unpleasant sensory and emotional experience. In non-verbal patients, it is very difficult to measure pain, even with pain assessment tools. ...

The overall goal of this electrophysiological measurement is to objectively asses nociception in newborn infants. This method can help answer key questions in the neonatal field such as how non-verbal patients perceive pain and how it differs in response to different conditions. The main advantage of this technique is that it can be used in neonates born at term or late pre-term starting at 34 weeks of gestational age.The implications of this technique extends toward investigation of pain because it is the first objective measurement of nociception in non-verbal patients. Generally, individuals new to this method will struggle because experience with EEG is required. We first had the idea for this method when we observed after delivery different pain responses in neonates born spontaneously as compared to those born by elective ceasarean section.But also at the neonatal intensive care unit, babies are exposed to so many potentially painful procedures. You don't know how much they perceive even when they are under analgesic drugs. Now we can objectively measure their noxious response.Before starting, ensure the baby is quiet and settled. The baby can be asleep but sucking motion should be absent during the recording because of movement artifacts. Measure the neonate's head circumference with a measuring tape to define the size of the EEG cap.Then identify the active electrode position by marking the middle point between nasion and inion and the middle point between left and right pre-auricular point with a skin marker pencil. A schematic of the electrode positions is shown here. Identify the positions for the ground electrode on the right forehead and for the reference electrode over the left mastoid.Clean the three electrode sites using a cotton swab soaked in skin disinfectant. Then gently scrub the electrode sites with EEG prepping paste to lower the impedance and place the EEG cap with the electrodes attached on the neonate's head. Next, use a syringe with a short plastic needle to inject conductive EEG gel into the electrodes to optimize the contact between the electrodes and the scalp.Then to ensure the impedance is below 50 kilo ohms, connect an impedance meter to the electrodes and set it below 50 kilo ohms. The light will turn green if the impedance is below 50 kilo ohms. After this, connect the electrodes to the amplifier.Position a camera to record the neonate's facial expressions. Then connect the flat-tip probe to the contact trigger device which is fixed to the EEG recording device. Begin by choosing a new work file.Set the sampling rate to 2, 000 Hertz. Set the low cutoff filter to a frequency of one Hertz. Set the high cutoff filter to 70 Hertz and the notch filter to 50 Hertz.Select a study name to store the data. Start the EEG and the video recording. Whilst the neonate's right hand is held in a horizontal position, record background EEG activity.Annotate the EEG recording manually to record periods where no stimuli are applied and the infant is resting. Once the background EEG is stable, administer the required amount of flat-tip probe stimuli to the neonate's right hand. Be careful to use the flat-tip probe perpendicularly to the neonate's hand so the tip does not bend and the correct force is applied.When the flat-tip probe reaches the nominal force on the skin, a trigger signal is generated by the contact trigger device. This signal is sent to the computer tagging the EEG recording with the trigger mark. After the stimuli are administered, stop all the recordings and document the experimental setting details.After taking off the electrodes at the infant's head, clean the scalp with a wet towel to remove any residuals. A flat-tip probe stimulus of 32 millinewtons was applied to the right hand of one patient. The shaded region shows the time window of interest which occurs 200 to 500 milliseconds after the stimulus.After a single stimulus, the noxious-evoked response is visible at approximately 300 milliseconds post stimulus onset. The principle peak at 250 milliseconds is indicated with an arrow. This trace demonstrates the average response of 50 stimuli applied with a force of 32 millinewtons to the same patient.Note that the noxious-evoked potential is clearer if more stimuli are applied. Woody filtering can be used to adjust for slight variability in the response latency. The predefined template shown in red is projected onto the EEG to calculate the magnitude of the noxious-evoked response.Once mastered, this technique can be done in 15 minutes if it is performed properly. While attempting this procedure, it's important to remember to wait to apply the stimuli until the infant is calm. After watching this video, you should have a good understanding of how to objectively measure nociception at bedside.

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Medicine

Segmentation and Measurement of Fat Volumes in Murine Obesity Models Using X-ray Computed Tomography

Obesity is associated with increased morbidity and mortality as well as reduced metrics in quality of life.1 Both environmental and genetic factors are associated with obesity, though the precise underlying mechanisms that contribute to the disease are currently being delineated.2,3 Several small animal models of obesity have been developed and are employed in a variety of studies.4 A critical component to these experiments involves the collection of regional and/or total animal fat content data under varied conditions.
Traditional experimental methods available for measuring fat content in small animal models of obesity include invasive (e.g. ex vivo measurement of fat deposits) and non-invasive (e.g. Dual Energy X-ray Absorptiometry (DEXA), or Magnetic Resonance (MR)) protocols, each of which presents relative trade-offs. Current invasive methods for measuring fat content may provide details for organ and region specific fat distribution, but sacrificing the subjects will preclude longitudinal assessments. Conversely, current non-invasive strategies provide limited details for organ and region specific fat distribution, but enable valuable longitudinal assessment. With the advent of dedicated small animal X-ray computed tomography (CT) systems and customized analytical procedures, both organ and region specific analysis of fat distribution and longitudinal profiling may be possible. Recent reports have validated the use of CT for in vivo longitudinal imaging of adiposity in living mice.5,6 Here we provide a modified method that allows for fat/total volume measurement, analysis and visualization utilizing the Carestream Molecular Imaging Albira CT system in conjunction with PMOD and Volview software packages.

Fat content analysis is routinely conducted in studies utilizing murine obesity models. Emerging methods in small animal CT imaging and analysis are providing for longitudinal detail rich fat content analysis. Here we detail step by step procedures for performing small animal CT imaging, analysis, and visualization.

Obesity is associated with increased morbidity and mortality as well as reduced metrics in quality of life.1 Both environmental and genetic factors are ...

Epidural Intracranial Pressure Measurement in Rats Using a Fiber-optic Pressure Transducer

Elevated intracranial pressure (ICP) is a significant problem in several forms of ischemic brain injury including stroke, traumatic brain injury and cardiac arrest. This elevation may result in further neurological injury, in the form of transtentorial herniation1,2,3,4, midbrain compression, neurological deficit or increased cerebral infarct2,4. Current therapies are often inadequate to control elevated ICP in the clinical setting5,6,7 . Thus there is a need for accurate methods of ICP measurement in animal models to further our understanding of the basic mechanisms and to develop new treatments for elevated ICP.
In both the clinical and experimental setting ICP cannot be estimated without direct measurement. Several methods of ICP catheter insertion currently exist. Of these the intraventricular catheter has become the clinical 'gold standard' of ICP measurement in humans8. This method involves the partial removal of skull and the instrumentation of the catheter through brain tissue. Consequently, intraventricular catheters have an infection rate of 6-11%9. For this reason, subdural and epidural cannulations have become the preferred methods in animal models of ischemic injury. 
Various ICP measurement techniques have been adapted for animal models, and of these, fluid-filled telemetry catheters10 and solid state catheters are the most frequently used11,12,13,14,15. The fluid-filled systems are prone to developing air bubbles in the line, resulting in false ICP readings. Solid state probes avoid this problem (Figure 1). An additional problem is fitting catheters under the skull or into the ventricles without causing any brain injury that might alter the experimental outcomes. Therefore, we have developed a method that places an ICP catheter contiguous with the epidural space, but avoids the need to insert it between skull and brain. 
An optic fibre pressure catheter (420LP, SAMBA Sensors, Sweden) was used to measure ICP at the epidural location because the location of the pressure sensor (at the very tip of the catheter) was found to produce a high fidelity ICP signal in this model. There are other manufacturers of similar optic fibre technologies13 that may be used with our methodology. Alternative solid state catheters, which have the pressure sensor located at the side of the catheter tip, would not be appropriate for this model as the signal would be dampened by the presence of the monitoring screw. 
Here, we present a relatively simple and accurate method to measure ICP. This method can be used across a wide range of ICP related animal models.

A novel technique to record the pressures within the skull is described. The minimally invasive method uses a fibre-optic pressure sensing system to accurately measure intracranial pressure (ICP) in anaesthetized rats without causing significant brain trauma. The technique may be used in a wide range of experimental models.

Elevated intracranial pressure (ICP) is a significant problem in several forms of ischemic brain injury including stroke, traumatic brain injury and ...

The Measurement and Treatment of Suppression in Amblyopia

Amblyopia, a developmental disorder of the visual cortex, is one of the leading causes of visual dysfunction in the working age population. Current estimates put the prevalence of amblyopia at approximately 1-3%1-3, the majority of cases being monocular2. Amblyopia is most frequently caused by ocular misalignment (strabismus), blur induced by unequal refractive error (anisometropia), and in some cases by form deprivation.
Although amblyopia is initially caused by abnormal visual input in infancy, once established, the visual deficit often remains when normal visual input has been restored using surgery and/or refractive correction. This is because amblyopia is the result of abnormal visual cortex development rather than a problem with the amblyopic eye itself4,5 . Amblyopia is characterized by both monocular and binocular deficits6,7 which include impaired visual acuity and poor or absent stereopsis respectively. The visual dysfunction in amblyopia is often associated with a strong suppression of the inputs from the amblyopic eye under binocular viewing conditions8. Recent work has indicated that suppression may play a central role in both the monocular and binocular deficits associated with amblyopia9,10 .
Current clinical tests for suppression tend to verify the presence or absence of suppression rather than giving a quantitative measurement of the degree of suppression. Here we describe a technique for measuring amblyopic suppression with a compact, portable device11,12 . The device consists of a laptop computer connected to a pair of virtual reality goggles. The novelty of the technique lies in the way we present visual stimuli to measure suppression. Stimuli are shown to the amblyopic eye at high contrast while the contrast of the stimuli shown to the non-amblyopic eye are varied. Patients perform a simple signal/noise task that allows for a precise measurement of the strength of excitatory binocular interactions. The contrast offset at which neither eye has a performance advantage is a measure of the "balance point" and is a direct measure of suppression. This technique has been validated psychophysically both in control13,14 and patient6,9,11 populations.
In addition to measuring suppression this technique also forms the basis of a novel form of treatment to decrease suppression over time and improve binocular and often monocular function in adult patients with amblyopia12,15,16 . This new treatment approach can be deployed either on the goggle system described above or on a specially modified iPod touch device15.

Amblyopia is a developmental disorder of the visual cortex that is often accompanied by strong suppression of one eye. We present a new technique for measuring and treating interocular suppression in patients with amblyopia that can be deployed using virtual reality goggles or a portable iPod Touch device.

Amblyopia, a developmental disorder of the visual cortex, is one of the leading causes of visual dysfunction in the working age population. Current ...

State of the Art Cranial Ultrasound Imaging in Neonates

Cranial ultrasound (CUS) is a reputable tool for brain imaging in critically ill neonates. It is safe, relatively cheap and easy to use, even when a patient is unstable. In addition it is radiation-free and allows serial imaging. CUS possibilities have steadily expanded. However, in many neonatal intensive care units, these possibilities are not optimally used. We present a comprehensive approach for neonatal CUS, focusing on optimal settings, different probes, multiple acoustic windows and Doppler techniques. This approach is suited for both routine clinical practice and research purposes. In a live demonstration, we show how this technique is performed in the neonatal intensive care unit. Using optimal settings and probes allows for better imaging quality and improves the diagnostic value of CUS in experienced hands. Traditionally, images are obtained through the anterior fontanel. Use of supplemental acoustic windows (lambdoid, mastoid, and lateral fontanels) improves detection of brain injury. Adding Doppler studies allows screening of patency of large intracranial arteries and veins. Flow velocities and indices can be obtained. Doppler CUS offers the possibility of detecting cerebral sinovenous thrombosis at an early stage, creating a window for therapeutic intervention prior to thrombosis-induced tissue damage. Equipment, data storage and safety aspects are also addressed.

Cranial ultrasound (CUS) is a valuable tool for brain imaging in critically ill neonates. This video shows a comprehensive approach for neonatal (Doppler) CUS for both clinical and research purposes, including a bedside demonstration of the technique.

Cranial ultrasound (CUS) is a reputable tool for brain imaging in critically ill neonates. It is safe, relatively cheap and easy to use, even when a ...

Molecular Probe Optimization to Determine Cell Mortality in a Photosynthetic Organism (Microcystis aeruginosa) Using Flow Cytometry

Microbial subpopulations in field and laboratory studies have been shown to display high heterogeneity in morphological and physiological parameters. Determining the real time state of a microbial cell goes beyond live or dead categories, as microbes can exist in a dormant state, whereby cell division and metabolic activities are reduced. Given the need for detection and quantification of microbes, flow cytometry (FCM) with molecular probes provides a rapid and accurate method to help determine overall population viability. By using SYTOX Green and SYTOX Orange in the model cyanobacteria Microcystis aeruginosa to detect membrane integrity, we develop a transferable method for rapid indication of single cell mortality. The molecular probes used within this journal will be referred to as green or orange nucleic acid probes respectively (although there are other products with similar excitation and emission wavelengths that have a comparable modes of action, we specifically refer to the fore mentioned probes). Protocols using molecular probes vary between species, differing principally in concentration and incubation times. Following this protocol set out on M.aeruginosa the green nucleic acid probe was optimized at concentrations of 0.5 &#181;M after 30 min of incubation and the orange nucleic acid probe at 1 &#181;M after 10 min. In both probes concentrations less than the stated optimal led to an under reporting of cells with membrane damage. Conversely, 5 &#181;M concentrations and higher in both probes exhibited a type of non-specific staining, whereby &#39;live&#39; cells produced a target fluorescence, leading to an over representation of &#39;non-viable&#39; cell numbers. The positive controls (heat-killed) provided testable dead biomass, although the appropriateness of control generation remains subject to debate. By demonstrating a logical sequence of steps for optimizing the green and orange nucleic acid probes we demonstrate how to create a protocol that can be used to analyse cyanobacterial physiological state effectively.

Molecular Probe Optimization to Determine Cell Mortality in a Photosynthetic Organism Microcystis aeruginosa Using Flow Cytometry

Microbial populations contain substantial cell heterogeneity, which can dictate overall behavior. Molecular probe analysis through flow cytometry can determine physiological states of cells, however its application varies between species. This study provides a protocol to accurately determine cell mortality within a cyanobacterium population, without underestimating or recording false positive results.

Microbial subpopulations in field and laboratory studies have been shown to display high heterogeneity in morphological and physiological parameters. ...

Transcutaneous Microcirculatory Imaging in Preterm Neonates

Microcirculatory imaging (MI) is a relatively new research tool mainly used in the intensive care setting. MI provides a clear view of the smallest capillaries, arterioles and venules. The magnifying effect visualizes the flow pattern of erythrocytes through these vessels.
It's non-invasive character makes it suitable to apply in (preterm) neonates, even in cardiorespiratory unstable patients. In adults and children, MI is mainly performed sublingually, but this is not possible in preterm infants as these cannot cooperate and the size of the probe is problematic. In preterm infants, MI is therefore performed transcutaneously. Their thin skin makes it possible to obtain high quality images of peripheral microcirculation. 
In this manuscript we will demonstrate the method of transcutaneous MI in preterm infants. We will focus on the different techniques and provide tips to optimize image quality. The highlights of software settings, safety and offline analysis are also addressed.

Microcirculatory imaging (MI) is used to monitor peripheral perfusion in critically ill or preterm neonates. This manuscript and video demonstrates the optimal approach for obtaining high-quality images.

Microcirculatory imaging (MI) is a relatively new research tool mainly used in the intensive care setting. MI provides a clear view of the smallest ...

Using Saccadometry with Deep Brain Stimulation to Study Normal and Pathological Brain Function

The oculomotor system involves a large number of brain areas including parts of the basal ganglia, and various neurodegenerative diseases including Parkinson's and Huntington's can disrupt it. People with Parkinson's disease, for example, tend to have increased saccadic latencies. Consequently, the quantitative measurement of saccadic eye movements has received considerable attention as a potential biomarker for neurodegenerative conditions. A lot more can be learned about the brain in both health and disease by observing what happens to eye movements when the function of specific brain areas is perturbed. Deep brain stimulation is a surgical intervention used for the management of a range of neurological conditions including Parkinson's disease, in which stimulating electrodes are placed in specific brain areas including several sites in the basal ganglia. Eye movement measurements can then be made with the stimulator systems both off and on and the results compared. With suitable experimental design, this approach can be used to study the pathophysiology of the disease being treated, the mechanism by which DBS exerts it beneficial effects, and even aspects of normal neurophysiology.

This paper describes the use of quantitative measurement of eye movements in conjunction with stimulation of focal areas of the deep brain in order to study physiology, pathophysiology, and the mechanisms of deep brain stimulation.

The oculomotor system involves a large number of brain areas including parts of the basal ganglia, and various neurodegenerative diseases including ...

Imaging Metals in Brain Tissue by Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry (LA-ICP-MS)

Metals are found ubiquitously throughout an organism, with their biological role dictated by both their chemical reactivity and abundance within a specific anatomical region. Within the brain, metals have a highly compartmentalized distribution, depending on the primary function they play within the central nervous system. Imaging the spatial distribution of metals has provided unique insight into the biochemical architecture of the brain, allowing direct correlation between neuroanatomical regions and their known function with regard to metal-dependent processes. In addition, several age-related neurological disorders feature disrupted metal homeostasis, which is often confined to small regions of the brain that are otherwise difficult to analyze. Here, we describe a comprehensive method for quantitatively imaging metals in the mouse brain, using laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS) and specially designed image processing software. Focusing on iron, copper and zinc, which are three of the most abundant and disease-relevant metals within the brain, we describe the essential steps in sample preparation, analysis, quantitative measurements and image processing to produce maps of metal distribution within the low micrometer resolution range. This technique, applicable to any cut tissue section, is capable of demonstrating the highly variable distribution of metals within an organ or system, and can be used to identify changes in metal homeostasis and absolute levels within fine anatomical structures.

Imaging Metals in Brain Tissue by Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry LA-ICP-MS

Quantitatively mapping metals in tissue by laser ablation - inductively coupled plasma - mass spectrometry (LA-ICP-MS) is a sensitive analytical technique that can provide new insight into how metals participate in normal function and disease processes. Here, we describe a protocol for quantitatively imaging metals in thin sections of mouse neurological tissue.

Metals are found ubiquitously throughout an organism, with their biological role dictated by both their chemical reactivity and abundance within a ...

Repeated Measurement of Respiratory Muscle Activity and Ventilation in Mouse Models of Neuromuscular Disease

Accessory respiratory muscles help to maintain ventilation when diaphragm function is impaired. The following protocol describes a method for repeated measurements over weeks or months of accessory respiratory muscle activity while simultaneously measuring ventilation in a non-anesthetized, freely behaving mouse. The technique includes the surgical implantation of a radio transmitter and the insertion of electrode leads into the scalene and trapezius muscles to measure the electromyogram activity of these inspiratory muscles. Ventilation is measured by whole-body plethysmography, and animal movement is assessed by video and is synchronized with electromyogram activity. Measurements of muscle activity and ventilation in a mouse model of amyotrophic lateral sclerosis are presented to show how this tool can be used to investigate how respiratory muscle activity changes over time and to assess the impact of muscle activity on ventilation. The described methods can easily be adapted to measure the activity of other muscles or to assess accessory respiratory muscle activity in additional mouse models of disease or injury.

This paper introduces a method for repeated measurements of ventilation and respiratory muscle activity in a freely behaving amyotrophic lateral sclerosis (ALS) mouse model throughout disease progression with whole-body plethysmography and electromyography via an implanted telemetry device.

Accessory respiratory muscles help to maintain ventilation when diaphragm function is impaired. The following protocol describes a method for repeated ...

Application of an Amplitude-integrated EEG Monitor (Cerebral Function Monitor) to Neonates

Amplitude-integrated EEG (aEEG) is an easily accessible technique to monitor the electrocortical activity in preterm and term infants in neonatal intensive care units (NICUs). This method was first used to monitor newborns after asphyxia, providing information about future neurological outcomes. The aEEG is also helpful to select newborns who benefit from cooling. The aEEG monitoring of preterm infants is becoming more widespread, as various studies have shown that neurodevelopmental outcome is related to early aEEG tracings. Here, we demonstrate the application of the aEEG monitoring system and present typical patterns that depend upon gestational age and pathophysiological conditions. Furthermore, we mention pitfalls in the interpretation of the aEEG, as this method requires accurate fixation and localization of the electrodes. Additionally, the raw EEG can be used to detect neonatal seizures or to identify aEEG application problems. In conclusion, aEEG is a safe and generally well-tolerated method for the bedside monitoring of neonatal cerebral function; it can even provide information about long-term outcome.

Application of an Amplitude-integrated EEG Monitor Cerebral Function Monitor to Neonates

Here, we show how to apply amplitude-integrated electroencephalography to monitor cerebral function in neonates.