Name: using laser doppler imaging and monitoring to analyze spinal cord microcirculation in rat
Uploaded: 2018-05-30T13:00:00
Description: Watch this Scientific Journal Video about Using Laser Doppler Imaging and Monitoring to Analyze Spinal Cord Microcirculation in Rat at JoVE.com

The authors have no acknowledgements.

Animal protocols involving experimental animals followed guidelines established by the National Institutes of Health (NIH) and were approved by the Animal Care and Use Committee of Capital Medical University.
The procedures of introducing SCI and measuring BF of spinal cord using laser Doppler equipment described below were used in a published study1.
1. Preparation for the Surgery
<ol>
	<li>Prepare pentobarbital sodium solution 3% (w/v) in...

<ol>
	<li>Jing, Y. L., Bai, F., Chen, H., Dong, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Meliorating+microcirculatory+with+melatonin+in+rat+model+of+spinal+cord+injury+using+laser+Doppler+flowmetry.">Meliorating microcirculatory with melatonin in rat model of spinal cord injury using laser Doppler flowmetry.</a> Neuroreport. 27 (17), 1248-1255 (2016).</li><li>Jing, Y. 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H., 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=Scanning+laser+Doppler+is+a+useful+technique+to+assess+foot+cutaneous+perfusion+during+femoral+artery+cannulation.">Scanning laser Doppler is a useful technique to assess foot cutaneous perfusion during femoral artery cannulation.</a> Critical Care. 3 (4), 95-100 (1999).</li><li>Emmanuel, A. V., Chung, E. A. L., Kamm, M. A., Middleton, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+between+gut-specific+autonomic+testing+and+bowel+dysfunction+in+spinal+cord+injury+patients.">Relationship between gut-specific autonomic testing and bowel dysfunction in spinal cord injury patients.</a> Spinal Cord. 47 (8), 623-627 (2009).</li><li>Sheu, J. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+circulation+of+the+fetus+in+utero.+Methods+for+studying+distribution+of+blood+flow,+cardiac+output+and+organ+blood+flow.">The circulation of the fetus in utero. Methods for studying distribution of blood flow, cardiac output and organ blood flow.</a> Circ Res. 21 (2), 163-184 (1967).</li><li>Dubory, A., 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=Contrast+Enhanced+Ultrasound+Imaging+for+Assessment+of+Spinal+Cord+Blood+Flow+in+Experimental+Spinal+Cord+Injury.">Contrast Enhanced Ultrasound Imaging for Assessment of Spinal Cord Blood Flow in Experimental Spinal Cord Injury.</a> Jove-Journal of Visualized Experiments. (99), e52536 (2015).</li><li>Kuliga, K. 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A few details should be noticed when performing this protocol. Firstly, the process of anesthesia and surgery should be carried out as quickly and elegantly as possible to minimize the introduced stress to the animal. To reduce disturbance to the results, keep the animal in a relatively peaceful and stable state. Secondly, more attention should be paid to bleeding during the measurement using laser Doppler equipment, since blood could potentially interfere with the reading. Finally, during the data recording, animals sho...

The tissue of the spinal cord is highly vascularized and extremely sensitive to hypoxia induced by spinal cord injury (SCI). Our previous studies showed that blood flow of the spinal cord was significantly decreased after concussion injury1,2, which might be related to the deficit of motor function. Recent studies have shown that the integrity of blood vessels following SCI is well-correlated with the improvement of sensory motor function3. It has been reported that improved vascularity might rescue white matter, indirectly leading to improved function4. Therefore, the maintenance of post-injury spinal cord perfusion appeared to be of primary importance for preserving viability and functionality.
The effects of various treatments on perfusion after SCI have been examined by numerous investigators using a variety of techniques in experimental models of SCI5,6,7. Laser Doppler, as a well-established technique, was undoubtedly a useful method for quantifying perfusion in several animal and human studies8,9,10,11. The technique is based on measuring the Doppler shift12 induced by moving red blood cells to the illuminating light. Since the commercialization of the technique in the early 1980s, great progress has been made in laser technology, fiber optics and signal processing for measuring perfusion by laser Doppler instruments13, which made LDF into a reliable technology.
In the current study, both methods of laser Doppler measurement&#160;were applied to evaluate blood flow (BF) in the spinal cords of concussive rats. Due to the noninvasive nature of the technology and its simple setup, our protocol provides a sensitive, rapid and reliable method for BF measurements of the spinal cord. More importantly, this method allows longitudinal study of BF post concussive SCI without animal sacrifice at each time point.
Due to the ability to assess the BF of the tissue and fast changes of perfusion during stimulation, it is possible to apply this protocol to evaluate cerebral BF14,15 as well as measure other tissues such as liver16,17, skin18,19, and bowel20. In a rat model of transient occlusion of the middle cerebral artery, the laser Doppler readings were used to ensure proper reduction of the BF rate to levels that are expected in the ischemic penumbra14. In rats which have undergone critical limb ischemia (CLI) induction, laser Doppler scanning was applied to observe hind limb BF&#160;before and after the CLI procedure and during different periods after treatment21. Additionally, the bioavailability and metabolic clearance of some drugs depended on hepatic BF, which was detected by LDF16. Therefore, LDF could be widely used in experimental model, pharmacodynamic, and pharmacokinetic evaluation.

<table>
	<tbody>
		<tr>
			<td>Laser Doppler Line Scanner</td>
			<td>Moor Instruments</td>
			<td>moorLDLS2</td>
			<td></td>
		</tr>
		<tr>
			<td>Laser Doppler Monitor</td>
			<td>Moor Instruments</td>
			<td>moorVMS-LDF</td>
			<td></td>
		</tr>
		<tr>
			<td>Probe for Monitor</td>
			<td>Moor Instruments</td>
			<td>VP3</td>
			<td>Blunt needle end delivery probe</td>
		</tr>
		<tr>
			<td>Impactor</td>
			<td>Precision Systems and Instrumentation</td>
			<td>IH-0400</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenobarbital sodium</td>
			<td>Sigma-Aldrich</td>
			<td>P3761</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Sigma-Aldrich</td>
			<td>B-908</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe</td>
			<td>Becton Dickinson Medica (s) Pte.Ltd</td>
			<td>300841</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical suture needles with thread</td>
			<td>Shanghai Pudong Jinhuan Medical Products Co., Ltd</td>
			<td></td>
			<td>18T0329 (batch number) /4-0</td>
		</tr>
		<tr>
			<td>Scalpel</td>
			<td>Operation instrument factory of Shanghai Medical Instrument Co., Ltd.</td>
			<td>J11030 4#</td>
			<td></td>
		</tr>
		<tr>
			<td>Scalpel blade</td>
			<td>Operation instrument factory of Shanghai Medical Instrument Co., Ltd.</td>
			<td>J12130 20#</td>
			<td></td>
		</tr>
		<tr>
			<td>Ophthalmic forceps</td>
			<td>Operation instrument factory of Shanghai Medical Instrument Co., Ltd.</td>
			<td>JD1040</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemostatic forceps</td>
			<td>Operation instrument factory of Shanghai Medical Instrument Co., Ltd.</td>
			<td>J31050</td>
			<td></td>
		</tr>
		<tr>
			<td>Benzyl penicillin sodium</td>
			<td>North China Pharmaceutical Co., Ltd</td>
			<td></td>
			<td>F6072116 (batch number)</td>
		</tr>
		<tr>
			<td>75% alcohol</td>
			<td>Dezhou Anjie Gaoke disinfection products Co., Ltd</td>
			<td></td>
			<td>150421R (batch number)</td>
		</tr>
		<tr>
			<td>Iodine</td>
			<td>Shandong Lierkang Medical Technology Co., Ltd</td>
			<td></td>
			<td>20170102 (batch number)</td>
		</tr>
		<tr>
			<td>Rat</td>
			<td>Laboratory Animal Center, The Academy of Millitery Medical Sciences</td>
			<td></td>
			<td>Sprague-Dawly (rat strain)</td>
		</tr>
	</tbody>
</table>

using laser doppler imaging and monitoring to analyze spinal cord microcirculation in rat

Laser Doppler flowmetry (LDF) is a noninvasive method for blood flow (BF) measurement, which makes it preferable for measuring microcirculatory alterations of the spinal cord. In this article, our goal was to use both Laser Doppler imaging and monitoring to analyze the change of BF after spinal cord injury. Both the laser Doppler image scanner and the probe/monitor were being employed to obtain each readout. The data of LDPI provided a local distribution of BF, which gave an overview of perfusion around the injury site and made it accessible for comparative analysis of BF among different locations. By intensely measuring the probing area over a period of time, a combined probe was used to simultaneously measure the BF and oxygen saturation of the spinal cord, showing overall spinal cord perfusion and oxygen supply. LDF itself has a few limitations, such as relative flux, sensitivity to movement, and biological zero signal. However, the technology has been applied in clinical and experimental study due to its simple setup and rapid measurement of BF.

LDPI was used to measure BF in the spinal cord, which was quantified along the rostral-caudal axis of the spinal cord by extracting linear profiles (Figure 4). Figure 5A and Figure 5B represent the flux imaging of the spinal cord of the sham group and SCI group, respectively. Figure 5C and Figure 5D represent the altering BF along the rostra...

Watch this Scientific Journal Video about Using Laser Doppler Imaging and Monitoring to Analyze Spinal Cord Microcirculation in Rat at JoVE.com

Using Laser Doppler Imaging and Monitoring to Analyze Spinal Cord Microcirculation in Rat

Here we present a combination of laser Doppler perfusion imaging (LDPI) and laser Doppler perfusion monitoring (LDPM) to measure spinal cord local blood flows and oxygen saturation (SO2), as well as a standardized procedure for introducing spinal cord trauma on rat.

Laser Doppler flowmetry (LDF) is a noninvasive method for blood flow (BF) measurement, which makes it preferable for measuring microcirculatory ...

The overall goal of this procedure is to present a combination of laser doppler imaging and monitoring to measure spinal cord local blood flows and oxygen saturation, as well as a standardized procedure for introducing spinal cord trauma on a rat. This method can help answer key questions in the field of micro circulation such as how blood flow redistributed over time and its impact on the surrounding area after spinal cord injury. The main advantage of this technique is by using both laser doppler imaging and monitoring device we could rapidly derive data of the local distribution of the blood flow as well as the blood flow variation over a period of time, which allows more sophisticated analysis of the blood flow in the problem area.Begin by checking the anesthetized rat for a surgical plane of anesthesia by the absence of a reaction to a toe pinch. Shave the dorsal area of the rat from the lower back to the neck. Then place the rat dorsal side up on a 40-degrees Celsius heating pad to maintain a constant body temperature.Sterilize the shaved area by wiping with cotton balls soaked in iodine followed by 75%alcohol. After making a skin incision over the laminectomy site covering thoracic vertebrae T7 to T11, cut the attached muscles on both sides from T8 to T10 to expose the spinous processes, the laminae, and the facet joints. Use the scalpel to make incisions that disconnect the junction between T10 and T11.Further expose the junction by carefully dissecting the muscle layer away to expose the bone. Use the scissors to further clear muscle away from the lamina and around the pedicle with small snips. This will open a small space between the vertebrae at T10 and T11.Slowly and delicately insert hemostatic forceps into this gap and break the pedicle. Repeat on the other side. Expose the spinal cord and carefully lift and break off the lamina without leaving free or jagged bone fragments behind.Repeat the process to further remove T9 and T8 laminae. An impactor may now be used to induce concussion injury in experimental groups. To scan the exposed spinal cord, place the rat dorsal side up on a black, non-reflective background, then set up the scanning parameters in the software by clicking Measure to enter the measurement graphical user interface and then the Scanner Setup button to open the Scanner Setup interface.To scan small areas such as in this experiment, click Scan Size and Display options and select High Resolution for a fine scanning mode with higher resolution. Click on the Image Scan option to check the scanning parameters. Check the live video image by clicking on the Video and Distance option.Position the scanner 10 to 13 centimeters above the surgical window and move the background with the animal to center the exposed spinal cord on the scanning window. Select the Auto Distance function to fine adjust the scanning height, which should be kept consistent across all measurements in the experiment. Use a non-reflective cover with a window to expose only the surgical area to further minimize background and mark the animal's direction.Click on Repeat Scan to set the number of scans, then click Okay to open the Repeat Scan interface. Click the Start button to start scanning. The whole process will take approximately three to four minutes.A scanner monitor with a VP3 blunt needle and delivery probe is used here to monitor blood flow and oxygen saturation over time. Begin by attaching the probe perpendicular to a stereotaxic instrument to set up the monitoring equipment. Put the rat on the stereotaxic apparatus, dorsal side up, and underlay the animal with a small piece of Styrofoam to level the exposed spinal cord.Examine the incision and remove any excessive liquid or blood using a cotton pad. Use the apparatus's x-and y-axes to locate the probe to two millimeters rostral to the center point of the exposed spinal cord or lesion point and devoid the central vein. Use the z-axis to slowly lower the probe to the level just touching the surface of the spinal cord.The probe should just touch the surface of the spinal cord but not be so loose as to allow bright light to escape from the side of the contact point. Proper positioning is critical for adapting and implementing the monitoring protocol. The probe should be perpendicular to the measured surface and excessive pressure should be avoided.To record data, click on the New Experiment button in the software to open the setup interface. Under the General option, check the system configuration, then click Next. In the Display setup, select the channel for blood flow and oxygen saturation and click Next.Input file information and click Next to enter the data recording interface. Click on the green triangle button to start recording data from the probe. Once the signal is stable, record data for eight consecutive minutes, then lift the probe and remove the animal from the stereotaxic apparatus.After suturing the muscle and the skin, place the rat on its side in a clean cage on a heating pad, avoiding contact between the surgery site and the cage bottom. Monitor the animal until it wakes up from anesthesia to ensure no post-surgery bleeding and that the sutures remain closed. These images represent the flux imaging of the spinal cord of the sham group on the left and the spinal cord injury group on the right.Flux imaging demonstrated that spinal cord injury induced reduction of blood flow and blood flow of the epicenter was lower than rostral cord and caudal cord. These images show the alternating blood flow along the rostral-caudal axis of the spinal cord of the sham group on the left and the SCI group on the right. As shown here, spinal cord blood flow of the spinal cord injury group significantly decreased compared to the sham group.Simultaneously, the oxygen saturation of the spinal cord was remarkably lower after spinal cord concussion, which was consistent with the change in blood flow after injury. After watching this video, you should have a good understanding of how to measure blood flow of the spinal cord using both laser doppler perfusion imaging and the laser doppler perfusion monitoring. Once mastered, the surgery of introducing spinal cord injury can be done in 20 minutes and the measurements, including use both laser doppler instruments, will take roughly 20 minutes if it is performed properly.While attempting this procedure, it's important to remember to use a non-reflective cover with a window to expose only the surgical area to further minimize background and mark the animal's direction. This technique paved the way for researchers in the field of microcirculation to explore the changes of blood flow for its pharamacodynamics and pharmacokinetics evaluation.

using-laser-doppler-imaging-monitoring-to-analyze-spinal-cord

Research

JoVE Journal

Behavior

How to Detect Amygdala Activity with Magnetoencephalography using Source Imaging

In trace fear conditioning a conditional stimulus (CS) predicts the occurrence of the unconditional stimulus (UCS), which is presented after a brief stimulus free period (trace interval)1. Because the CS and UCS do not co-occur temporally, the subject must maintain a representation of that CS during the trace interval. In humans, this type of learning requires awareness of the stimulus contingencies in order to bridge the trace interval2-4. However when a face is used as a CS, subjects can implicitly learn to fear the face even in the absence of explicit awareness*. This suggests that there may be additional neural mechanisms capable of maintaining certain types of "biologically-relevant" stimuli during a brief trace interval. Given that the amygdala is involved in trace conditioning, and is sensitive to faces, it is possible that this structure can maintain a representation of a face CS during a brief trace interval.
It is challenging to understand how the brain can associate an unperceived face with an aversive outcome, even though the two stimuli are separated in time. Furthermore investigations of this phenomenon are made difficult by two specific challenges. First, it is difficult to manipulate the subject's awareness of the visual stimuli. One common way to manipulate visual awareness is to use backward masking. In backward masking, a target stimulus is briefly presented (&lt; 30 msec) and immediately followed by a presentation of an overlapping masking stimulus5. The presentation of the mask renders the target invisible6-8. Second, masking requires very rapid and precise timing making it difficult to investigate neural responses evoked by masked stimuli using many common approaches. Blood-oxygenation level dependent (BOLD) responses resolve at a timescale too slow for this type of methodology, and real time recording techniques like electroencephalography (EEG) and magnetoencephalography (MEG) have difficulties recovering signal from deep sources.
However, there have been recent advances in the methods used to localize the neural sources of the MEG signal9-11. By collecting high-resolution MRI images of the subject's brain, it is possible to create a source model based on individual neural anatomy. Using this model to "image" the sources of the MEG signal, it is possible to recover signal from deep subcortical structures, like the amygdala and the hippocampus*.

This article describes how to record amygdala activity with magnetoencephalography (MEG). In addition this article will describe how to conduct trace fear conditioning without awareness, a task that activates the amygdala. It will cover 3 topics: 1) Designing a trace conditioning paradigm using backward masking to manipulate awareness. 2) Recording brain activity during the task using magnetoencephalography. 3) Using source imaging to recover signal from subcortical structures.

In trace fear conditioning a conditional  stimulus (CS) predicts the occurrence of the unconditional stimulus (UCS),  which is presented after a brief ...

Measurement of Fronto-limbic Activity Using an Emotional Oddball Task in Children with Familial High Risk for Schizophrenia

Adolescence is a critical developmental period where the early symptoms of schizophrenia frequently emerge. First-degree relatives of people with schizophrenia who are at familial high risk (FHR) may show similar cognitive and emotional changes. However, the neurological changes underlying the emergence of these symptoms remain unclear. This study sought to identify differences in frontal, striatal, and limbic regions in children and adolescents with FHR using functional magnetic resonance imaging. Groups of 21 children and adolescents at FHR and 21 healthy controls completed an emotional oddball task that relied on selective attention and the suppression of task-irrelevant emotional information. The standard oddball task was modified to include aversive and neutral distractors in order to examine potential group differences in both emotional and executive processing. This task was designed specifically to allow for children and adolescents to complete by keeping the difficulty and emotional image content age-appropriate. Furthermore, we demonstrate a technique for suitable fMRI registration for children and adolescent participants. This paradigm may also be applied in future studies to measure changes in neural activity in other populations with hypothesized developmental changes in executive and emotional processing.

This paper describes how to use the emotional oddball task and fMRI to measure brain activation in children and adolescents at familial high risk for schizophrenia (FHR).&#160;FMRI was used to measure differences in fronto-striato-limbic regions during an emotional oddball task. Children with FHR exhibited abnormal functional activation during adolescence.

Adolescence is a critical developmental period where the early symptoms of schizophrenia frequently emerge. First-degree relatives of people with ...

Uncovering Beat Deafness: Detecting Rhythm Disorders with Synchronized Finger Tapping and Perceptual Timing Tasks

A set of behavioral tasks for assessing perceptual and sensorimotor timing abilities in the general population (i.e., non-musicians) is presented here with the goal of uncovering rhythm disorders, such as beat deafness. Beat deafness is characterized by poor performance in perceiving durations in auditory rhythmic patterns or poor synchronization of movement with auditory rhythms (e.g., with musical beats). These tasks include the synchronization of finger tapping to the beat of simple and complex auditory stimuli and the detection of rhythmic irregularities (anisochrony detection task) embedded in the same stimuli. These tests, which are easy to administer, include an assessment of both perceptual and sensorimotor timing abilities under different conditions (e.g., beat rates and types of auditory material) and are based on the same auditory stimuli, ranging from a simple metronome to a complex musical excerpt. The analysis of synchronized tapping data is performed with circular statistics, which provide reliable measures of synchronization accuracy (e.g., the difference between the timing of the taps and the timing of the pacing stimuli) and consistency. Circular statistics on tapping data are particularly well-suited for detecting individual differences in the general population. Synchronized tapping and anisochrony detection are sensitive measures for identifying profiles of rhythm disorders and have been used with success to uncover cases of poor synchronization with spared perceptual timing. This systematic assessment of perceptual and sensorimotor timing can be extended to populations of patients with brain damage, neurodegenerative diseases (e.g., Parkinson&#8217;s disease), and developmental disorders (e.g., Attention Deficit Hyperactivity Disorder).

Behavioral tasks that allow for the assessment of perceptual and sensorimotor timing abilities in the general population (i.e., non-musicians) are presented. Synchronization of finger tapping to the beat of an auditory stimuli and detecting rhythmic irregularities provides a means of uncovering rhythm disorders.

A set of behavioral tasks for assessing perceptual and sensorimotor timing abilities in the general population (i.e., non-musicians) is presented here ...

Behavioral and Locomotor Measurements Using an Open Field Activity Monitoring System for Skeletal Muscle Diseases

The open field activity monitoring system comprehensively assesses locomotor and behavioral activity levels of mice. It is a useful tool for assessing locomotive impairment in animal models of neuromuscular disease and efficacy of therapeutic drugs that may improve locomotion and/or muscle function. The open field activity measurement provides a different measure than muscle strength, which is commonly assessed by grip strength measurements. It can also show how drugs may affect other body systems as well when used with additional outcome measures. In addition, measures such as total distance traveled mirror the 6 min walk test, a clinical trial outcome measure. However, open field activity monitoring is also associated with significant challenges: Open field activity measurements vary according to animal strain, age, sex, and circadian rhythm. In addition, room temperature, humidity, lighting, noise, and even odor can affect assessment outcomes. Overall, this manuscript provides a well-tested and standardized open field activity SOP for preclinical trials in animal models of neuromuscular diseases. We provide a discussion of important considerations, typical results, data analysis, and detail the strengths and weaknesses of open field testing. In addition, we provide recommendations for optimal study design when using open field activity in a preclinical trial.

Open field activity levels are used to assess locomotive and behavioral activity levels. This protocol provides a well-designed, standardized protocol to use in preclinical trials for neuromuscular disorders.

The open field activity monitoring system comprehensively assesses locomotor and behavioral activity levels of mice. It is a useful tool for assessing ...

Using Fiberless, Wearable fNIRS to Monitor Brain Activity in Real-world Cognitive Tasks

Functional Near Infrared Spectroscopy (fNIRS) is a neuroimaging technique that uses near-infrared light to monitor brain activity. Based on neurovascular coupling, fNIRS is able to measure the haemoglobin concentration changes secondary to neuronal activity. Compared to other neuroimaging techniques, fNIRS represents a good compromise in terms of spatial and temporal resolution. Moreover, it is portable, lightweight, less sensitive to motion artifacts and does not impose significant physical restraints. It is therefore appropriate to monitor a wide range of cognitive tasks (e.g., auditory, gait analysis, social interaction) and different age populations (e.g., new-borns, adults, elderly people). The recent development of fiberless fNIRS devices has opened the way to new applications in neuroscience research. This represents a unique opportunity to study functional activity during real-world tests, which can be more sensitive and accurate in assessing cognitive function and dysfunction than lab-based tests. This study explored the use of fiberless fNIRS to monitor brain activity during a real-world prospective memory task. This protocol is performed outside the lab and brain haemoglobin concentration changes are continuously measured over the prefrontal cortex while the subject walks around in order to accomplish several different tasks.

Monitoring brain activity outside the lab without physical constraints presents methodological challenges. A fiberless, wearable functional Near Infrared Spectroscopy (fNIRS) system was used to measure brain activity during an ecological prospective memory task. It was demonstrated that this system could be used to monitor brain activity during non-lab based experiments.

Functional Near Infrared Spectroscopy (fNIRS) is a neuroimaging technique that uses near-infrared light to monitor brain activity. Based on neurovascular ...

Treating Low Back Pain in Failed Back Surgery Patients with Multicolumn-lead Spinal Cord Stimulation

Failed back surgery syndrome (FBSS) refers to persistent, chronic pain following spinal surgery. Spinal cord stimulation with dorsal epidural leads can be used to treat back and leg pain in FBSS patients. This paper presents a detailed protocol for using spinal cord stimulation with surgical leads in FBSS patients. In our department, with the patient under general anesthesia, we place the lead in the epidural space by means of a small laminectomy at the 10th thoracic level. Placement of the lead is followed by a 1 month trial period with an externalized lead. If pain relief is greater than 50% at the end of this 1 month stimulation trial (required by Belgian reimbursement criteria), an internal pulse generator is then placed under the skin and connected to the lead in a second surgical procedure. We have demonstrated that using this technique in rigorously selected FBSS patients can significantly improve back pain, leg pain, patient activity, and quality of life for a sustained period of time.

This paper presents a method that uses spinal cord stimulation with a multicolumn lead to treat neuropathic low back pain in failed back surgery patients.

Failed back surgery syndrome (FBSS) refers to persistent, chronic pain following spinal surgery. Spinal cord stimulation with dorsal epidural leads can be ...

Paradigms of Lower Extremity Electrical Stimulation Training After Spinal Cord Injury

Skeletal muscle atrophy, increased adiposity and reduced physical activity are key changes observed after spinal cord injury (SCI) and are associated with numerous cardiometabolic health consequences. These changes are likely to increase the risk of developing chronic secondary conditions and impact the quality of life in persons with SCI. Surface neuromuscular electrical stimulation evoked resistance training (NMES-RT) was developed as a strategy to attenuate the process of skeletal muscle atrophy, decrease ectopic adiposity, improve insulin sensitivity and enhance mitochondrial capacity. However, NMES-RT is limited to only a single muscle group. Involving multiple muscle groups of the lower extremities may maximize the health benefits of training. Functional electrical stimulation-lower extremity cycling (FES-LEC) allows for the activation of 6 muscle groups, which is likely to evoke greater metabolic and cardiovascular adaptation. Appropriate knowledge of the stimulation parameters is key to maximizing the outcomes of electrical stimulation training in persons with SCI. Adopting strategies for long-term use of NMES-RT and FES-LEC during rehabilitation may maintain the integrity of the musculoskeletal system, a pre-requisite for clinical trials aiming to restore walking after injury. The current manuscript presents a combined protocol using NMES-RT prior to FES-LEC. We hypothesize that muscles conditioned for 12 weeks prior to cycling will be capable of generating greater power, cycle against higher resistance and result in greater adaptation in persons with SCI.

Spinal cord injury is a traumatic medical condition that may result in elevated risks of chronic secondary metabolic disorders. Here, we presented a protocol using surface neuromuscular electrical stimulation-resistance training in conjunction with functional electrical stimulation-lower extremities cycling as a strategy to ameliorate several of these medical problems.

Skeletal muscle atrophy, increased adiposity and reduced physical activity are key changes observed after spinal cord injury (SCI) and are associated with ...

Simultaneous Recordings of Cortical Local Field Potentials and Electrocorticograms in Response to Nociceptive Laser Stimuli from Freely Moving Rats

Electrocortical responses, elicited by laser heat pulses that selectively activate nociceptive free nerve endings, are widely used in many animal and human studies to investigate the cortical processing of nociceptive information. These laser-evoked brain potentials (LEPs) consist of several transient responses that are time-locked to the onset of laser stimuli. However, the functional properties of the LEP responses are still largely unknown, due to the lack of a sampling technique that can simultaneously record neural activities at the surface of the cortex (i.e., electrocorticogram [ECoG] and scalp electroencephalogram [scalp EEG]) and inside the brain (i.e., local field potential [LFP]). To address this issue, we present here an animal protocol using freely moving rats. This protocol is composed of three main procedures: (1) animal preparation and surgical procedures, (2) a simultaneous recording of ECoG and LFP in response to nociceptive laser stimuli, and (3) data analysis and feature extraction. Specifically, with the help of a 3D-printed protective shell, both ECoG and LFP electrodes implanted on the rat&#39;s skull were securely held together. During data collection, laser pulses were delivered on the rat&#39;s forepaws through gaps in the bottom of the chamber when the animal was in spontaneous stillness. Ongoing white noise was played to avoid the activation of the auditory system by the laser-generated ultrasounds. As a consequence, only nociceptive responses were selectively recorded. Using the standard analytical procedures (e.g., band-pass filtering, epoch extraction, and baseline correction) to extract stimulus-related brain responses, we obtained results showing that LEPs with a high signal-to-noise ratio were simultaneously recorded from ECoG and LFP electrodes. This methodology makes the simultaneous recording of ECoG and LFP activities possible, which provides a bridge of electrocortical signals at the mesoscopic and macroscopic levels, thereby facilitating the investigation of nociceptive information processing in the brain.

We developed a technique that simultaneously records both electrocorticography and local field potentials in response to nociceptive laser stimuli from freely moving rats. This technique helps establish a direct relationship of electrocortical signals at the mesoscopic and macroscopic levels, which facilitates the investigation of nociceptive information processing in the brain.

Electrocortical responses, elicited by laser heat pulses that selectively activate nociceptive free nerve endings, are widely used in many animal and ...

Using Facial Electromyography to Assess Facial Muscle Reactions to Experienced and Observed Affective Touch in Humans

"Affective" touch is believed to be processed in a manner distinct from discriminatory touch and to involve activation of C-tactile (CT) afferent fibers. Touch that optimally activates CT fibers is consistently rated as hedonically pleasant. Patient groups with impaired social-emotional functioning also show disordered affective touch ratings. However, relying on self-reported ratings of touch has many limitations, including recall bias and communication barriers. Here, we describe a methodological approach to study affective responses to touch via facial electromyography (EMG) that circumvents the reliance on self-report ratings. Facial EMG is an objective, quantitative, and non-invasive method to measure facial muscle activity indicative of affective responses. Responses can be assessed across healthy and patient populations without the need for verbal communication. Here, we provide two separate datasets demonstrating that CT-optimal and non-optimal touch elicit distinct facial muscle reactions. Moreover, facial EMG responses are consistent across stimulus modalities, e.g. tactile (experienced touch) and visual (observed touch). Finally, the temporal resolution of facial EMG can detect responses on timescales that supersede that of verbal reporting. Together, our data suggest that facial EMG is a suitable methodology for use in affective tactile research that can be used to supplement, or in some cases, supplant, existing measures.

We describe a protocol to assess facial muscle activity in response to experienced and observed tactile stimulation using facial electromyography.

"Affective" touch is believed to be processed in a manner distinct from discriminatory touch and to involve activation of C-tactile (CT) afferent fibers. ...

Using Practice Testing, Public Speaking, and Source Monitoring to Examine the Influences of Learning Strategies and Stress on Episodic Memory

Prior research demonstrated that learning information via retrieval practice, which entails studying and taking practice tests, resulted in less memory impairment under stress than learning information via repeated studying. The present experiment combined three experimental procedures to further examine the memory mechanisms underlying the efficacy of retrieval practice in the context of stress. A list-discrimination task was implemented, in which participants learned two distinct wordlists. This was combined with a retrieval-practice manipulation, as half of the participants engaged in practice testing and half engaged in conventional studying during learning. A week later, participants underwent stress induction, using the Trier Social Stress Test. Before and after stress induction, participants completed tests of item and source memory (i.e., list discrimination). The combination of these three procedures yielded informative results: retrieval practice, in the context of stress, improved item memory but not source memory relative to conventional studying. Limitations and future directions for the use of this methodology are discussed.

The present experiment combined three experimental procedures &#8212; a retrieval-practice learning manipulation, a list-discrimination task, and a stress-induction technique &#8212; to examine the influences of different learning strategies and acute stress on multiple measures of episodic memory.

Prior research demonstrated that learning information via retrieval practice, which entails studying and taking practice tests, resulted in less memory ...