Name: conducting hyperscanning experiments with functional near-infrared spectroscopy
Uploaded: 2019-01-19T14:45:00
Description: Watch this Scientific Journal Video about Conducting Hyperscanning Experiments with Functional Near-Infrared Spectroscopy at JoVE.com

This work was funded by the Excellence Initiative of the German federal state and governments (ERS Seed Fund, OPSF449). The Hitachi NIRS system was supported by a funding of the German Research Foundation DFG (INST 948/18-1 FUGG).

Prior to participation, all parents / children provided informed consent / assent. The study was approved by the ethics committee of the Medical Faculty of RWTH Aachen University.
1. Preparation before the Participant Arrives
<ol>
	<li>Prepare NIRS caps.
	<ol>
		<li>Choose the cap sizes the same size or slightly larger than the participant&#8217;s head circumference.</li>
		<li>Cut 15 holes with a diameter of approximately 15 mm each, arranged in a horizontal 3x5 grid, into the forehead area...

<ol>
	<li>Babiloni, F., Astolfi, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Social+neuroscience+and+hyperscanning+techniques:+past,+present+and+future.">Social neuroscience and hyperscanning techniques: past, present and future.</a> Neuroscience &amp; Biobehavioral Reviews. 44, 76-93 (2014).</li><li>Hari, R., Henriksson, L., Malinen, S., Parkkonen, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Centrality+of+social+interaction+in+human+brain+function.">Centrality of social interaction in human brain function.</a> Neuron. 88 (1), 181-193 (2015).</li><li>Funane, T., 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=Synchronous+activity+of+two+people's+prefrontal+cortices+during+a+cooperative+task+measured+by+simultaneous+near-infrared+spectroscopy.">Synchronous activity of two people's prefrontal cortices during a cooperative task measured by simultaneous near-infrared spectroscopy.</a> Journal of Biomedical Optics. 16 (7), 077011 (2011).</li><li>Lindenberger, U., Li, S. -. 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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sensor+space+group+analysis+for+fNIRS+data.">Sensor space group analysis for fNIRS data.</a> Journal of Neuroscience Methods. 264, 103-112 (2016).</li><li>Scholkmann, F., Spichtig, S., Muehlemann, T., Wolf, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+to+detect+and+reduce+movement+artifacts+in+near-infrared+imaging+using+moving+standard+deviation+and+spline+interpolation.">How to detect and reduce movement artifacts in near-infrared imaging using moving standard deviation and spline interpolation.</a> Physiological Measurement. 31 (5), 649-662 (2010).</li><li>van der Kant, A., Biro, S., Levelt, C., Huijbregts, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Negative+affect+is+related+to+reduced+differential+neural+responses+to+social+and+non-social+stimuli+in+5-to-8-month-old+infants:+a+functional+near-infrared+spectroscopy-study.">Negative affect is related to reduced differential neural responses to social and non-social stimuli in 5-to-8-month-old infants: a functional near-infrared spectroscopy-study.</a> Developmental Cognitive Neuroscience. 30, 23-30 (2018).</li><li>Bastos, A. 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In this protocol, we show how to conduct fNIRS hyperscanning experiments and one possible way to analyze brain-to-brain synchrony, measuring concentration changes of oxy-Hb and deoxy-Hb at frontal brain regions of two subjects simultaneously. FNIRS hyperscanning is relatively easy to apply: a single NIRS device is sufficient to measure brain activities of both subjects by splitting the optodes between them. Thus, no synchronization between different devices is necessary1. Moreover, since fNIRS doe...

In recent years, neuroscientists have started to study social interactions by recording the brain activities of two or more persons simultaneously, an approach termed hyperscanning1. This technique opens new opportunities to elucidate the neurobiological mechanisms underlying these interactions. To fully understand social interactions, it may not be sufficient to study single brains in isolation but rather the joint activities of brains of interacting persons2. Using different neuroimaging techniques, hyperscanning studies have shown that brain activities of interacting persons or groups synchronize, e.g., while they coordinate their actions3, make music4, communicate5, engage in classroom activities6 or cooperate7.
The article presents a protocol for conducting simultaneous recordings with functional near-infrared spectroscopy (fNIRS). Similar to functional magnetic resonance imaging (fMRI), fNIRS measures the hemodynamic response to brain activation. Changes in oxygenated and deoxygenated hemoglobin (oxy-Hb and deoxy-Hb) are calculated based on the amount of diffusively transmitted near-infrared light through tissue8. fNIRS is well suited for conducting hyperscanning experiments, especially with children, because it can be applied in less constrained and more natural settings than fMRI. Moreover, it is less prone to movement artifacts than both, fMRI and EEG9. In addition, fNIRS data can be acquired at high sampling frequencies (e.g., 10 Hz), thus it highly oversamples the relatively slow hemodynamic response and thereby potentially provides a more complete temporal picture of the brain hemodynamics10.
This protocol was developed within the study of Reindl et al.11 and has been slightly modified (in particular with respect to the channel placement and bad channel identification) more recently. The aim of the study was to examine synchronized brain activity of parent-child dyads. Using fNIRS hyperscanning, we assessed brain-to-brain synchrony in prefrontal brain areas of children (aged five to nine years) and their parents, mostly mothers, during a cooperative and a competitive computer task. Prefrontal brain regions were targeted as they had been identified as important regions for social interactive processes in previous hyperscanning studies1. The cooperative and competitive task were originally developed by Cui et al.12&#160;and recently employed by several previous studies13,14,15. For the study of Reindl et al.11, the tasks were modified to be suitable for children. Participants were instructed to either respond jointly via button presses in response to a target (cooperation) or to respond faster than the other player (competition). Each child performed each task once with the parent and once with an adult stranger of the same sex as the parent. Within each child-adult dyad, wavelet coherence was calculated for the oxy-Hb signals of corresponding channels as a measure of brain-to-brain synchrony.
This protocol describes the procedures to collect fNIRS hyperscanning data of parent and child during the cooperative and competitive game. The overall procedure, however, is not specific to this research design but is appropriate for different populations (e.g., adult strangers, romantic partners, siblings, etc.) and can be adapted for a number of different experimental tasks. This protocol also outlines one possible analytical procedure, which covers necessary and optional data analysis steps, including fNIRS data preprocessing, bad channel detection, wavelet coherence analysis and validation by random pair analysis.

<table border="0" cellpadding="0" cellspacing="0" style="width:872px;" width="873">
	<tbody>
		<tr height="40">
			<td height="40" style="height:40px;width:222px;">NIRS measurement system with probe sets and probe holder grids</td>
			<td style="width:125px;">Hitachi Medical Corporation, Tokyo, Japan</td>
			<td style="width:355px;">ETG-4000 Optical Topography System&#160;</td>
			<td style="width:171px;">The current study protocol requires an optional second adult probe set for 52 channels of measurement in total as well as two 3x5 probe holder grids.&#160;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">raw EEG caps</td>
			<td>EASYCAP GmbH, Herrsching, Germany</td>
			<td>C-SCMS-56; C-SCMS-58</td>
			<td>Caps must be provided with holes for NIRS probes by the experimenter. Choose cap size the same size or slightly larger than participant&#39;s head circumference.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Technical computing software</td>
			<td>The MathWorks, Inc., Natick, MA</td>
			<td>MATLAB R2014a (or later versions)</td>
			<td>Serves as base for Psychophysics Toolbox extensions (stimulus presentation), SPM for fNIRS toolbox&#160; (fNIRS data analysis), and ASToolbox (WTC computation).</td>
		</tr>
	</tbody>
</table>

conducting hyperscanning experiments with functional near-infrared spectroscopy

Concurrent brain recordings of two or more interacting persons, an approach termed hyperscanning, are gaining increasing importance for our understanding of the neurobiological underpinnings of social interactions, and possibly interpersonal relationships. Functional near-infrared spectroscopy (fNIRS) is well suited for conducting hyperscanning experiments because it measures local hemodynamic effects with a high sampling rate and, importantly, it can be applied in natural settings, not requiring strict motion restrictions. In this article, we present a protocol for conducting fNIRS hyperscanning experiments with parent-child dyads and for analyzing brain-to-brain synchrony. Furthermore, we discuss critical issues and future directions, regarding the experimental design, spatial registration of the fNIRS channels, physiological influences and data analysis methods. The described protocol is not specific to parent-child dyads, but can be applied to a variety of different dyadic constellations, such as adult strangers, romantic partners or siblings. To conclude, fNIRS hyperscanning has the potential to yield new insights into the dynamics of the ongoing social interaction, which possibly go beyond what can be studied by examining the activities of individual brains.

Representative data of one parent-child dyad during the cooperative condition are shown in Figure 1. The cooperative task consists of three 30 s rest blocks and two task blocks, with 20 trials each, presented in alternating order. In each trial, participants have to react as simultaneously as possible to a signal to earn a point11.
<img alt="Figure 1" class="xfigimg" src="/fi...

Watch this Scientific Journal Video about Conducting Hyperscanning Experiments with Functional Near-Infrared Spectroscopy at JoVE.com

Conducting Hyperscanning Experiments with Functional Near-Infrared Spectroscopy

The present protocol describes how to conduct fNIRS hyperscanning experiments and analyze brain-to-brain synchrony. Further, we discuss challenges and possible solutions.

Concurrent brain recordings of two or more interacting persons, an approach termed hyperscanning, are gaining increasing importance for our understanding ...

By measuring brain activities of two or more people simultaneously, this method can shed light on the neurobiological mechanisms underlying social interactions. Functional near-infrared spectroscopy, or fNIRS, is well suited for conducting such hyperscanning experiments because it measures brain hemodynamic response with a high sampling rate and can be applied in relatively natural settings. While this protocol shows how to conduct simultaneous fNIRS recordings of adult-child dyads, it can be adapted to different dyadic constellations such as romantic partners and to different experimental tasks.Begin by choosing a cap size that is the same size or slightly larger than the participant's head circumference. Cut 15 holes with a diameter of approximately 15 millimeters each, arranged in a horizontal three-by-five grid into the forehead area of each of two raw EEG caps. Ensure that the holes are spaced 30 millimeters from each other in any direction, that the middle column of holes is located in the center of the forehead.In order to make the caps more comfortable and minimize pressure marks, attach soft foam material at the inner side of the holder grid between the probe sockets and at the edges. Next, mount an empty three-by-five probe holder grid to each of the modified EEG caps such that the holder grid itself is placed on the inside of the cap and the holder sockets stick in the holes. Then, gently insert the probes into the appropriate holder sockets on the grid such that only the first ridge of each probe is mounted in the socket which results in one clicking sound.Open the probe set monitor window at the nearest measurement system and select two probe sets arranged in a three-by-five grid each, one for the participating child and one for the adult. Ensure that the probe arrangements of the two caps corresponds to the arrangements in the probe set window. Next, switch on the laser diodes of the nearest measurement system 30 minutes before measuring so that the system reaches a stable operating temperature.Set all the necessary options at the nearest measurement system. Make sure that the device is set to event-related measurement and that the RS232 serial input necessary for receiving triggers from the experimental paradigm is active. Then, prepare the experimental paradigm by starting the technical computing software that serves as base for the Psychophysics Toolbox extensions and setting the current directory to the folder that the paradigm is saved in.Finally, place two chin rests in front of the computer screen to prevent head movements during the experiment. Begin by escorting the two participants into the testing room and explaining the experimental set-up. Then, seat the participants next to each other in front of the computer screen.Adjust the height of the chin rests such that both participants sit comfortably. Provide instructions and administer practice trials of both the cooperative and the competitive game. Next, measure and mark the Fpz point according to the 10-20 system, which is 10%of the distance between nasion and inion on each participant's head.Then turn off the laser, and place the caps with the probes carefully on the participants'heads. Ensure that the middle probe of the bottom row is placed on Fpz and the middle probe column is aligned along the sagittal reference curve. Place the fiber strings on the holder arm attached to the nearest measurement system so that they hang loosely without contact with the participant or chair and that they do not pull on the caps.Next, push each probe further into its socket until the small white nose in the center of the top of the probe casing is visible. Then, turn the laser on again, and test the signal quality by clicking on the Auto Gain button in the probe set monitor window of the nearest measurement system. If a channel is marked in yellow, meaning insufficient signal, gently put the hair underneath the surrounding probe tip aside.Make probe adjustments, and click the Auto Gain button again to see if signal quality has improved or is marked in green. Once the signal quality is satisfactory, place a towel over the participants'hands so that they cannot see the hand movements of their respective game partner. Then, start the experiment.Then, after the experiment is complete, save the data and export the raw light intensity data as a text file by clicking on the Text File Out button. Finally, clean the probes, probe holders, and chin rests with ethnol, and wash the caps with mild detergent. As a measure of brain-to-brain synchrony, the wavelet coherence is calculated between the fNIRS signals of interacting subjects.Wavelet coherence coefficients are visualized using a color map ranging from blue, little or no coherence, to red, meaning strong or maximum coherence. Results show a strong coherence throughout the experiment in a high-frequency band until a period length of about one second, which likely results from the cardiac rhythms of the subjects. Additionally, a strong coherence appears in a lower frequency band between the two-and eight-second period length.Coherence in this low frequency range likely reflects a synchronization of brain activities of both subjects during the task. While attempting this procedure, it's important to double-check that the caps are placed correctly on the participants'heads and to ensure a good signal quality. After its development, this technique paved the way for researchers in the field of social neuroscience to explore brain-to-brain synchrony in a variety of different tasks, examining behavior correlates and associations to characteristics of the individuals and their relationship.

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Neuroscience

Functional Mapping with Simultaneous MEG and EEG

We use magnetoencephalography (MEG) and electroencephalography (EEG) to locate and determine the temporal evolution in brain areas involved in the processing of simple sensory stimuli. We will use somatosensory stimuli to locate the hand somatosensory areas, auditory stimuli to locate the auditory cortices, visual stimuli in four quadrants of the visual field to locate the early visual areas. These type of experiments are used for functional mapping in epileptic and brain tumor patients to locate eloquent cortices. In basic neuroscience similar experimental protocols are used to study the orchestration of cortical activity. The acquisition protocol includes quality assurance procedures, subject preparation for the combined MEG/EEG study, and acquisition of evoked-response data with somatosensory, auditory, and visual stimuli. We also demonstrate analysis of the data using the equivalent current dipole model and cortically-constrained minimum-norm estimates. Anatomical MRI data are employed in the analysis for visualization and for deriving boundaries of tissue boundaries for forward modeling and cortical location and orientation constraints for the minimum-norm estimates.

We use magnetoencephalography (MEG) and electroencephalography (EEG) to map brain areas involved in the processing of simple sensory stimuli.

We use magnetoencephalography (MEG) and electroencephalography (EEG) to locate and determine the temporal evolution in brain areas involved in the ...

Combining Computer Game-Based Behavioural Experiments With High-Density EEG and Infrared Gaze Tracking

Experimental paradigms are valuable insofar as the timing and other parameters of their stimuli are well specified and controlled, and insofar as they yield data relevant to the cognitive processing that occurs under ecologically valid conditions. These two goals often are at odds, since well controlled stimuli often are too repetitive to sustain subjects' motivation. Studies employing electroencephalography (EEG) are often especially sensitive to this dilemma between ecological validity and experimental control: attaining sufficient signal-to-noise in physiological averages demands large numbers of repeated trials within lengthy recording sessions, limiting the subject pool to individuals with the ability and patience to perform a set task over and over again. This constraint severely limits researchers' ability to investigate younger populations as well as clinical populations associated with heightened anxiety or attentional abnormalities. Even adult, non-clinical subjects may not be able to achieve their typical levels of performance or cognitive engagement: an unmotivated subject for whom an experimental task is little more than a chore is not the same, behaviourally, cognitively, or neurally, as a subject who is intrinsically motivated and engaged with the task. A growing body of literature demonstrates that embedding experiments within video games may provide a way between the horns of this dilemma between experimental control and ecological validity. The narrative of a game provides a more realistic context in which tasks occur, enhancing their ecological validity (Chaytor &amp; Schmitter-Edgecombe, 2003). Moreover, this context provides motivation to complete tasks. In our game, subjects perform various missions to collect resources, fend off pirates, intercept communications or facilitate diplomatic relations. In so doing, they also perform an array of cognitive tasks, including a Posner attention-shifting paradigm (Posner, 1980), a go/no-go test of motor inhibition, a psychophysical motion coherence threshold task, the Embedded Figures Test (Witkin, 1950, 1954) and a theory-of-mind (Wimmer &amp; Perner, 1983) task. The game software automatically registers game stimuli and subjects' actions and responses in a log file, and sends event codes to synchronise with physiological data recorders. Thus the game can be combined with physiological measures such as EEG or fMRI, and with moment-to-moment tracking of gaze. Gaze tracking can verify subjects' compliance with behavioural tasks (e.g. fixation) and overt attention to experimental stimuli, and also physiological arousal as reflected in pupil dilation (Bradley et al., 2008). At great enough sampling frequencies, gaze tracking may also help assess covert attention as reflected in microsaccades - eye movements that are too small to foveate a new object, but are as rapid in onset and have the same relationship between angular distance and peak velocity as do saccades that traverse greater distances. The distribution of directions of microsaccades correlates with the (otherwise) covert direction of attention (Hafed &amp; Clark, 2002).

Procedures for recording high-density EEG and gaze data during computer game-based cognitive tasks are described. Using a video game to present cognitive tasks enhances ecological validity without sacrificing experimental control.

Experimental paradigms are valuable insofar as the timing and other parameters of their stimuli are well specified and controlled, and insofar as they ...

Using MazeSuite and Functional Near Infrared Spectroscopy to Study Learning in Spatial Navigation

MazeSuite is a complete toolset to prepare, present and analyze navigational and spatial experiments1. MazeSuite can be used to design and edit adapted virtual 3D environments, track a participants' behavioral performance within the virtual environment and synchronize with external devices for physiological and neuroimaging measures, including electroencephalogram and eye tracking.
Functional near-infrared spectroscopy (fNIR) is an optical brain imaging technique that enables continuous, noninvasive, and portable monitoring of changes in cerebral blood oxygenation related to human brain functions2-7. Over the last decade fNIR is used to effectively monitor cognitive tasks such as attention, working memory and problem solving7-11. fNIR can be implemented in the form of a wearable and minimally intrusive device; it has the capacity to monitor brain activity in ecologically valid environments. 
Cognitive functions assessed through task performance involve patterns of brain activation of the prefrontal cortex (PFC) that vary from the initial novel task performance, after practice and during retention12. Using positron emission tomography (PET), Van Horn and colleagues found that regional cerebral blood flow was activated in the right frontal lobe during the encoding (i.e., initial na&iuml;ve performance) of spatial navigation of virtual mazes while there was little to no activation of the frontal regions after practice and during retention tests. Furthermore, the effects of contextual interference, a learning phenomenon related to organization of practice, are evident when individuals acquire multiple tasks under different practice schedules13,14. High contextual interference (random practice schedule) is created when the tasks to be learned are presented in a non-sequential, unpredictable order. Low contextual interference (blocked practice schedule) is created when the tasks to be learned are presented in a predictable order.
Our goal here is twofold: first to illustrate the experimental protocol design process and the use of MazeSuite, and second, to demonstrate the setup and deployment of the fNIR brain activity monitoring system using Cognitive Optical Brain Imaging (COBI) Studio software15. To illustrate our goals, a subsample from a study is reported to show the use of both MazeSuite and COBI Studio in a single experiment. The study involves the assessment of cognitive activity of the PFC during the acquisition and learning of computer maze tasks for blocked and random orders. Two right-handed adults (one male, one female) performed 315 acquisition, 30 retention and 20 transfer trials across four days. Design, implementation, data acquisition and analysis phases of the study were explained with the intention to provide a guideline for future studies.

MazeSuite is a complete toolset to prepare, present and analyze navigational and spatial experiments. Functional near-infrared spectroscopy (fNIR) is an optical brain imaging technique that enables noninvasive and portable monitoring of cerebral blood oxygenation changes. This paper summarizes collective use of MazeSuite and fNIR within a cognitive processing learning paradigm.

MazeSuite is a complete toolset to prepare, present and analyze navigational and spatial experiments1. MazeSuite can be used to design and edit adapted ...

Micron-scale Resolution Optical Tomography of Entire Mouse Brains with Confocal Light Sheet Microscopy

Understanding the architecture of mammalian brain at single-cell resolution is one of the key issues of neuroscience. However, mapping neuronal soma and projections throughout the whole brain is still challenging for imaging and data management technologies. Indeed, macroscopic volumes need to be reconstructed with high resolution and contrast in a reasonable time, producing datasets in the TeraByte range. We recently demonstrated an optical method (confocal light sheet microscopy, CLSM) capable of obtaining micron-scale reconstruction of entire mouse brains labeled with enhanced green fluorescent protein (EGFP). Combining light sheet illumination and confocal detection, CLSM allows deep imaging inside macroscopic cleared specimens with high contrast and speed. Here we describe the complete experimental pipeline to obtain comprehensive and human-readable images of entire mouse brains labeled with fluorescent proteins. The clearing and the mounting procedures are described, together with the steps to perform an optical tomography on its whole volume by acquiring many parallel adjacent stacks. We showed the usage of open-source custom-made software tools enabling stitching of the multiple stacks and multi-resolution data navigation. Finally, we illustrated some example of brain maps: the cerebellum from an L7-GFP transgenic mouse, in which all Purkinje cells are selectively labeled, and the whole brain from a thy1-GFP-M mouse, characterized by a random sparse neuronal labeling.

In this article we describe the full experimental procedure to reconstruct, with high resolution, the fine brain anatomy of fluorescently labeled mouse brains. The described protocol includes sample preparation and clearing, specimen mounting for imaging, data post-processing and multi-scale visualization.

Understanding the architecture of mammalian  brain at single-cell resolution is one of the key issues of neuroscience.  However, mapping neuronal soma and ...

Neuroimaging Field Methods Using Functional Near Infrared Spectroscopy (NIRS) Neuroimaging to Study Global Child Development: Rural Sub-Saharan Africa

Portable neuroimaging approaches provide new advances to the study of brain function and brain development with previously inaccessible populations and in remote locations. This paper shows the development of field functional Near Infrared Spectroscopy (fNIRS) imaging to the study of child language, reading, and cognitive development in a rural village setting of C&#244;te d&#39;Ivoire. Innovation in methods and the development of culturally appropriate neuroimaging protocols allow&#160;a first-time look into the brain&#39;s development and children&#39;s learning outcomes in understudied environments. This paper demonstrates protocols for transporting and setting up a mobile laboratory, discusses considerations for field versus laboratory neuroimaging, and presents a guide for developing neuroimaging consent procedures and building meaningful long-term collaborations with local government and science partners. Portable neuroimaging methods can be used to study complex child development contexts, including the impact of significant poverty and adversity on brain development. The protocol presented here has been developed for use in C&#244;te d&#39;Ivoire, the world&#39;s primary source of cocoa, and where reports of child labor in the cocoa sector are common. Yet, little is known about the impact of child labor on brain development and learning. Field neuroimaging methods have the potential to yield new insights into such urgent issues, and the development of children globally.

Neuroimaging Field Methods Using Functional Near Infrared Spectroscopy NIRS Neuroimaging to Study Global Child Development: Rural Sub-Saharan Africa

Portable neuroimaging approaches (functional Near Infrared Spectroscopy) provide advances to the study of the brain in previously inaccessible regions; here, rural C&#244;te d&#39;Ivoire. Innovation in methods and development of culturally-appropriate neuroimaging protocols permits novel study of the brain&#39;s development and children&#39;s learning outcomes in environments with significant poverty and adversity.

Portable neuroimaging approaches provide new advances to the study of brain function and brain development with previously inaccessible populations and in ...

Lipid Bilayer Experiments with Contact Bubble Bilayers for Patch-Clampers

Lipid bilayers provide a unique experimental platform for functional studies of ion channels, allowing the examination of channel-membrane interactions under various membrane lipid compositions. Among them, the droplet interface bilayer has gained popularity; however, the large membrane size hinders the recording of low electrical background noise. We have established a contact bubble bilayer (CBB) method that combines the benefits of planar lipid bilayer and patch-clamp methods, such as the ability to vary the lipid composition and to manipulate the bilayer mechanics, respectively. Using the setup for conventional patch-clamp experiments, CBB-based experiments can be readily performed. In brief, an electrolyte solution in a glass pipette is blown into an organic solvent phase (hexadecane), and the pipette pressure is maintained to obtain a stable bubble size. The bubble is spontaneously lined with a lipid monolayer (pure lipids or mixed lipids), which is provided from liposomes in the bubbles. Next, the two monolayer-lined bubbles (~50 &#181;m in diameter) at the tip of the glass pipettes are docked for bilayer formation. Introduction of channel-reconstituted liposomes into the bubble leads to the incorporation of channels in the bilayer, allowing for single-channel current recording with a signal-to-noise ratio comparable to that of patch-clamp recordings. CBBs with an asymmetric lipid composition are readily formed. The CBB is renewed repeatedly by blowing out the previous bubbles and forming new ones. Various chemical and physical perturbations (e.g., membrane perfusion and bilayer tension) can be imposed on the CBBs. Herein, we present the basic procedure for CBB formation.

Here, we present a protocol for the formation of lipid bilayers using a contact bubble bilayer method. A water bubble is blown into an organic solvent, whereby a monolayer is formed at the water-oil interface. Two pipettes are manipulated to dock the bubbles to form a bilayer.

Lipid bilayers provide a unique experimental platform for functional studies of ion channels, allowing the examination of channel-membrane interactions ...

Functional Magnetic Resonance Spectroscopy at 7 T in the Rat Barrel Cortex During Whisker Activation

Nuclear magnetic resonance (NMR) spectroscopy offers the opportunity to measure cerebral metabolite contents in vivo and noninvasively. Thanks to technological developments over the last decade and the increase in magnetic field strength, it is now possible to obtain good resolution spectra in vivo in the rat brain. Neuroenergetics (i.e., the study of brain metabolism) and, especially, metabolic interactions between the different cell types have attracted more and more interest in recent years. Among these metabolic interactions, the existence of a lactate shuttle between neurons and astrocytes is still debated. It is, thus, of great interest to perform functional proton magnetic resonance spectroscopy (1H-MRS) in a rat model of brain activation and monitor lactate. However, the methyl lactate peak overlaps lipid resonance peaks and is difficult to quantify. The protocol described below allows metabolic and lactate fluctuations to be monitored in an activated brain area. Cerebral activation is obtained by whisker stimulation and 1H-MRS is performed in the corresponding activated barrel cortex, whose area is detected using blood-oxygen-level-dependent functional magnetic resonance imaging (BOLD fMRI). All steps are fully described: the choice of anesthetics, coils, and sequences, achieving efficient whisker stimulation directly in the magnet, and data processing.

After checking by blood-oxygen-level-dependent functional magnetic resonance imaging (BOLD fMRI) that the corresponding somatosensory barrel field cortex area (called S1BF) is correctly activated, the main goal of this study is to quantify lactate content fluctuations in the activated rat brains by localized proton magnetic resonance spectroscopy (1H-MRS) at 7 T.

Nuclear magnetic resonance (NMR) spectroscopy offers the opportunity to measure cerebral metabolite contents in vivo and noninvasively. Thanks to ...

Using Near-infrared Fluorescence and High-resolution Scanning to Measure Protein Expression in the Rodent Brain

Neuroscience is the study of how cells in the brain mediate various functions. Measuring protein expression in neurons and glia is critical for the study of neuroscience as cellular function is determined by the composition and activity of cellular proteins. In this article, we describe how immunocytochemistry can be combined with near-infrared high-resolution scanning to provide a semi-quantitative measure of protein expression in distinct brain regions. This technique can be used for single or double protein expression in the same brain region. Measuring proteins in this fashion can be used to obtain a relative change in protein expression with an experimental manipulation, molecular signature of learning and memory, activity in molecular pathways, and neural activity in multiple brain regions. Using the correct proteins and statistical analysis, functional connectivity among brain regions can be determined as well. Given the ease of implementing immunocytochemistry in a laboratory, using immunocytochemistry with near-infrared high-resolution scanning can expand the ability of the neuroscientist to examine neurobiological processes at a systems level.

Here, we present a protocol that uses near-infrared dyes in conjunction with immunohistochemistry and high-resolution scanning to assay proteins in brain regions.

Neuroscience is the study of how cells in the brain mediate various functions. Measuring protein expression in neurons and glia is critical for the study ...

Conducting Concurrent Electroencephalography and Functional Near-Infrared Spectroscopy Recordings with a Flanker Task

Concurrent EEG and fNIRS recordings offer an excellent opportunity to gain a full understanding of the neural mechanism of cognitive processing by inspecting the relationship between the neural and hemodynamic signals. EEG is an electrophysiological technology that can measure the rapid neuronal activity of the cortex, whereas fNIRS relies on the hemodynamic responses to infer brain activation. The combination of EEG and fNIRS neuroimaging techniques can identify more features and reveal more information associated with the functioning of the brain. In this protocol, fused EEG-fNIRS measurements were performed for concurrent recordings of evoked-electrical potentials and hemodynamic responses during a Flanker task. In addition, the critical steps for setting up the hardware and software system as well as the procedures for data acquisition and analysis were provided and discussed in detail. It is expected that the present protocol can pave a new avenue for improving the understanding of the neural mechanisms underlying various cognitive processes by using the EEG and fNIRS signals.

The present protocol describes how to perform concurrent EEG and fNIRS recordings and how to inspect the relationship between the EEG and fNIRS data.&#160;

Concurrent EEG and fNIRS recordings offer an excellent opportunity to gain a full understanding of the neural mechanism of cognitive processing by ...

Qualitative and Comparative Cortical Activity Data Analyses from a Functional Near-Infrared Spectroscopy Experiment Applying Block Design

Neuroimaging studies play a pivotal role in the evaluation of pre- vs. post-interventional neurological conditions such as in rehabilitation and surgical treatment. Among the many neuroimaging technologies used to measure brain activity, functional near-infrared spectroscopy (fNIRS) enables the evaluation of dynamic cortical activities by measuring the local hemoglobin levels similar to functional magnetic resonance imaging (fMRI). Also, due to lesser physical restriction in fNIRS, multiple variants of sensorimotor tasks can be evaluated. Many laboratories have developed several methods for fNIRS data analysis; however, despite the fact that the general principles are the same, there is no universally standardized method. Here, we present the qualitative and comparative analytic methods of data obtained from a multi-channel fNIRS experiment using a block design. For qualitative analysis, we used a software for NIRS as a mass-univariate approach based on the generalized linear model. The NIRS-SPM analysis shows qualitative results for each session by visualizing the activated area during the task. In addition, the non-invasive three-dimensional digitizer can be used to estimate the fNIRS channel locations relative to the brain. To corroborate the NIRS-SPM findings, the amplitude of the changes in hemoglobin levels induced by the sensorimotor task can be statistically analyzed by comparing the data obtained from two different sessions (before and after intervention) of the same study subject using a multi-channel hierarchical mixed model. Our methods can be used to measure the pre- vs. post-intervention analysis in a variety of neurological disorders such as movement disorders, cerebrovascular diseases, and neuropsychiatric disorders.

We describe the analysis of continuous-wave functional near-infrared spectroscopy experiment using a block design with a sensorimotor task. To increase the reliability of the data analysis, we used the qualitative general linear model-based statistical parametric mapping and the comparative hierarchical mixed models for multi-channels.

Neuroimaging studies play a pivotal role in the evaluation of pre- vs. post-interventional neurological conditions such as in rehabilitation and surgical ...