We thank all the participants and their families, as well as the institutions that made this work possible, in particular, Asociaci&#243;n de Sordos de Jalisco, Asociaci&#243;n Deportiva, Cultural y Recreativa de Silentes de Jalisco, Educaci&#243;n Incluyente, A.C., and Preparatoria No. 7. We also thank Sandra M&#225;rquez for her contribution to this project. This work was funded by GRANT SEP-CONACYT-221809, GRANT SEP-PRODEP 511-6/2020-8586-UDG-PTC-1594, and the Neuroscience Institute (Universidad de Guadalajara, Mexico).

The study was reviewed and approved by the Neuroscience Institute&#39;s Ethics Committee (ET062010-88, Universidad de Guadalajara), ensuring all procedures were conducted in accordance with the Declaration of Helsinki. All participants agreed to participate voluntarily and gave written informed consent (when underaged, parents signed consent forms).
1. Experimental design
<ol>
	<li>Stimulus preparation
	<ol>
		<li>Search in Creative Commons licensed sound databases to select a set of animal sounds in .wav format. The stimuli in this study consisted of five different animal sounds: dog barking, cow mooing, horse neighing, donkey braying, and elephant trumpeting. 
		NOTE: The sound stimuli used here were previously selected as a collection of sounds for the vibrotactile discrimination training program in our earlier studies9,10.</li>
		<li>Edit the sound files using a free, open-source audio editor to standardize the intensity and length of the stimuli to 1500 ms. For this protocol, standardize at a linear scale from 0 to 8000 Hz, at a gain of 20 dB, and at a range of 80 dB based on the parameters established in the previous studies9,10 using the same vibrotactile stimulation system.</li>
		<li>Save the formatted audio files in a 32-bit float format with a 48,000 Hz project rate.</li>
	</ol>
	</li>
	<li>Paradigm setup in the electrophysiology presentation software
	<ol>
		<li>Design a continuous performance task (CPT) using an experimental design and stimulus presentation software, assigning the stimuli to one of the two conditions: (a) target (T) stimulus (dog barking in 20% of trials) and (b) non-target (NT) stimuli (the remaining four animal sounds for the other 80%). 
		NOTE: Each condition was labeled with the same code to synchronize stimulus presentation marks when programming the EEG protocol in the recording software.</li>
		<li>Build a pseudo-randomized stimulus-presentation using the software platform in which the five animal sounds (dog, cow, horse, donkey, and elephant) are each presented 20% of the time. Check that the target stimulus (dog barking) never occurs more than twice in succession.</li>
		<li>Specify the desired interstimulus interval (ISI) and the total response time, and select the response keys that will be used to automatically collect behavioral data for target (T) stimuli responses. Here, a fixed 2000 ms ISI list for 150 trials and the correct response for the T stimuli were programmed via the left control key on a standard computer keyboard. Participants were given a 3500 ms time window for a behavioral response (starting at stimulus presentation).</li>
	</ol>
	</li>
</ol>
2. Participant selection
<ol>
	<li>Recruit potential participants with profound bilateral sensorineural hearing loss diagnosis and collect demographic data, including age, sex, hand preference, and educational history.</li>
	<li>Conduct semi-structured clinical interviews to screen participants for personal or family history of psychiatric, neurological, or neurodegenerative illness and to collect information pertaining to deafness clinical history: the age of onset, etiology, and hearing-aid use history, as well as their preferred communication mode (oral, manual, or bilingual).</li>
	<li>Conduct audiological tests (pure-tone air hearing-thresholds) using an audiometer to confirm the severity of hearing loss.
	<ol>
		<li>In a sound-attenuated room, sit directly in front of the participant and properly place headphones on them.</li>
		<li>Instruct the participants to raise their dominant hand to signal whenever they can hear the tone being presented through the headphones.</li>
		<li>Ranging from 20 dB to 110 dB intensity levels, present a pure-tone at six octaves in the following ascending order: 250, 500, 1000, 2000, 4000, and 8000 Hz, starting with the left ear and repeating the same steps for the right ear.
		<ol>
			<li>Calculate the patient pure-tone average (PTA) by averaging the hearing thresholds at 500, 1000, 2000, and 4000 Hz for each ear. The hearing-loss severity inclusion criteria for the study is a bilateral pure tone average (PTA) greater than 90 dB.</li>
			<li>Select participants based on the eligibility criteria. Inclusion criteria additionally include no personal or family history of psychiatric, neurological, or neurodegenerative illness and non-syndromic, prelingual profound bilateral deafness. Obtain informed consent and explain the experimental procedures to the participants. 
			&#8203;NOTE: All the forms, questionnaires, and instructions used in the study were translated to Mexican Sign Language (MSL) by a professional MSL interpreter and were presented in video format using a tablet computer. In addition, an MSL interpreter was present during all study procedures.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
3. Pre-training EEG recording session
<ol>
	<li>Participant preparation
	<ol>
		<li>Verify that the participants have come to the recording session with clean and dry hair, having not used any hair gel, conditioner, or other hair products that affect electrode impedance.</li>
		<li>Ask the participants to sit in a comfortable position, approximately 60 cm away from the stimulus screen, and use the tablet device to play the MSL videoclip with the preparation procedure description.</li>
		<li>Clean the areas where reference and electrooculogram (EOG) electrodes will be placed (earlobes, forehead, outer canthus, infraocular orbital ridges, etc.). First, wipe the skin with an alcohol swab, and then apply EEG abrasive prepping gel gently with a cotton swab to exfoliate dead skin cells on the surface.</li>
		<li>Fill the electrode gold cup with conductive electrode paste and place an electrode on each reference site, usually on the right and the left earlobes or mastoids. Repeat the steps to place at least one vertical EOG at the outer canthus and one horizontal EOG at the infraocular orbital ridge to monitor oculomotor activity (blinks and saccades). Hold the single electrodes in place with a piece of 1 in micropore tape.</li>
		<li>Ask the participants to hold their arms straight horizontally and then fit the body harness tightly but comfortably around the chest under the armpits with the snaps in the middle of the chest.</li>
		<li>Place the EEG commercial electro-cap with 19 Ag/AgCl electrodes (Fp1, Fp2, F3, F4, F7, F8, C3, C4, P3, P4, O1, O2, T3, T4, T5, T6, Fz, Cz, and Pz) topographically arranged according to the International 10-20 system. Use a measuring tape to check the participant&#39;s head circumference to ensure you use the proper cap size.</li>
		<li>Align the Cz electrode with the nose and then measure the distance from the nasion to the inion so that the Cz electrode falls precisely in the middle. Button the adjustable straps on the sides of the cap to the body harness so that the electro-cap is firmly tightened.</li>
		<li>Place the gel-filled blunt-needle syringe inside the electrode, circle the needle to remove hair, and then gently abrade the scalp region under the electrode before applying the conductive gel. Don&#39;t apply too much gel to avoid electrical bridging with neighboring electrode sites.</li>
		<li>Allow the EEG conductive gel to dry at cool room temperature.</li>
	</ol>
	</li>
	<li>Setting up the EEG recording equipment
	<ol>
		<li>Calibrate the EEG system as per the instrument&#39;s instructions, then connect the electro-cap to the amplifier set at a bandpass of 0.05-30 Hz (3 dB cutoff points of 6 dB/octave roll-off curves), a 60 Hz notch-filter, and a 200 Hz sampling rate equal to a 5 ms sampling period.</li>
		<li>Check that the impedance is below 5 K&#937; (for a low impedance system) in all electrode sites and check on the monitor that all channels are smoothly registering the electrical signals.</li>
	</ol>
	</li>
	<li>Running the experimental task
	<ol>
		<li>Position the participant in front of the computer monitor and place the keyboard at a comfortable distance.</li>
		<li>Connect the cable of the portable stimulator device (see Figure 1) to the computer system speaker&#39;s outlet and set the speaker volume to the maximum intensity level.</li>
		<li>Adjust the portable stimulator system on the participant&#39;s right index fingertip and test.</li>
		<li>Using the tablet device, play the experiment instructions and execute a practice trial to familiarize the subject with the portable stimulator device, the audio-tactile stimuli, and the task. Repeat the MSL instructions and verify comprehension.</li>
		<li>Remind the participant to respond to the dog bark stimulus by pressing the left control key with their left index finger only upon target stimulus detection and to withhold their response when any of the other four animal sounds are perceived. The CPT experimental paradigm is represented in Figure 2.</li>
		<li>Provide clear instructions for how to minimize artifacts and demonstrate the effect of artifacts on the EEG in real-time before you begin recording (recommended as a standard recording procedure in research with clinical populations20).</li>
		<li>Before starting the CPT task, check that the event-synchronization between the cognitive stimulation computer and the EEG recording computer is working properly. To do so, start recording the EEG signal and click on the communication icon in the stimulus presentation software interface. Upon clicking, the event-synchronized pulses appear at the bottom of the EEG recording screen.</li>
		<li>Run the experimental task. Carefully observe the participant and monitor alertness, response execution, and excessive movement or blinking.</li>
		<li>Pause and allow the participant a short break in the middle of the experiment (at 4 min in the experiment) to allow them to blink, relax, and move around if needed. Finish running the experiment.</li>
	</ol>
	</li>
</ol>
4. Audio-tactile sensory substitution training program
<ol>
	<li>Consult Supplementary File 1, which contains a detailed description of the five-session program, to perform the training. Automatize the activities described using a spreadsheet to make the training more systematic and engaging for the participants. Use original images and audio recordings from9 and ask the participants to respond by tapping on a laptop touch-screen monitor. 
	&#8203;NOTE: The content and tables in this file have been reprinted with permission from9.</li>
</ol>
5. Post-training EEG recording session
<ol>
	<li>Repeat the exact same steps as specified in section 3.</li>
</ol>
6. EEG analysis
NOTE: The EEG acquisition steps were done using the EEG recording software, and the EEG processing steps were done using a separate EEG analysis software.
<ol>
	<li>EEG raw signal pre-processing
	<ol>
		<li>Define and select epochs of 1100 ms in the continuous EEG data, without the use of additional digital filters, using stimulus onset as the initial time instant (t0), and including a 100 ms pre-stimulus used for baseline correction. Supplementary Figure 1 illustrates how the 1100 ms epochs were selected according to the EEG analysis commercial software installed in the EEG recording equipment.</li>
		<li>During artifact rejection, exclude epochs of data on all channels when the voltage in a given recording epoch exceeds 100 &#181;V on any EEG or EOG channel. Also, reject artifacts by visual inspection of the epochs. See Supplementary Figure 2, which provides an example of epochs that were manually rejected due to ocular artifacts.</li>
	</ol>
	</li>
	<li>Signal averaging
	<ol>
		<li>Select an equal number of artifact-free epochs for each stimulus condition (target and non-target) in both the pre- and post-training conditions. Select the maximum epochs possible to improve the signal-to-noise ratio. Do this for each EEG record. 
		NOTE: In this protocol, we selected an average of 25 correct response epochs per condition at each timepoint since we were interested in evaluating target discrimination. Keep in mind that some ERP components do not require overt behavioral responses to be observed. Participants with less than 15 artifact-free epochs in each condition were excluded from the study.</li>
		<li>Click on the Operations menu and select the EEG window averaging option to average individual ERPs.</li>
		<li>First, select the Independent Average option to average target trials only. Then, select the other four non-target stimuli and click on the Average Together option to average.</li>
		<li>Repeat steps 6.2.2 and 6.2.3 for each participant&#39;s EEG recording in the pre-training condition and then for the post-training condition.</li>
		<li>Once all the individual ERPs are calculated, average them together to obtain the grand-mean waveforms per stimulus condition for pre- and post-training. Open any individual EP average, then go to the Operations menu and select Grand-mean averaging option. Select the participant&#39;s individual averages to be included in the group average.</li>
		<li>Choose all pre-training target averages from the drop-down list, then click the Average button, type the desired file name, and press the Return key to save. Then select all pre-training non-target averages from the drop-down list, click the Average button, type the desired file name, and again press the Return key to save.</li>
		<li>Repeat the previous steps for the post-training condition.</li>
	</ol>
	</li>
	<li>ERP visualization and analyses
	<ol>
		<li>Select the Operations&#160;menu&#160;to see the list of saved grand means. Then click on the group averages that you wish to plot. Next, click the Montage button to select the channels you want to plot.</li>
		<li>Go to the Tools menu, then click on Visualize Options to select each waveform&#39;s color and line width. Then click on the Signal menu, check the DC correction box, type in the desired baseline stimulus interval, then press the Return key.</li>
		<li>Carefully inspect the plotted grand-mean waveforms to identify the components of interest and their corresponding time windows. 
		NOTE: For this experiment, we knew that the waveforms, because of the task design and sensory pathways understudy for P3, would very likely be a positive component appearing later than 300 ms in centroparietal electrodes and with greater voltage amplitudes in the target condition.</li>
		<li>Export individual peak amplitude latencies and voltages, and then import data on a spreadsheet to build the database. Conduct a repeated-measures Analysis of Variance (ANOVA) using a statistics software.</li>
	</ol>
	</li>
</ol>

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We confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.

Using ERP tools, we designed a protocol to observe and evaluate the gradual development of vibrotactile discrimination skills for distinguishing vibrotactile representations of different pure tones. Our prior work has demonstrated that vibrotactile stimulation is a viable alternative sound perception method for profoundly deaf individuals. However, because of the complexity of natural sounds compared to pure tones, the potential for language sound discrimination warrants a separate exploration.
<p class="jove_content...

Early profound deafness is a sensory deficit that strongly impacts oral language acquisition and the perception of environmental sounds that play an essential role in navigating everyday life for those with normal hearing. A preserved and functional auditory sensory pathway allows us to hear footsteps when someone is approaching out of visual range, react to oncoming traffic, ambulance sirens, and security alarms, and respond to our own name when someone needs our attention. Audition is, therefore, a vital sense for speech, communication, cognitive development, and timely interaction with the environment, including the perception of potential threats in one&#39;s surroundings. For decades, the viability of audio-tactile substitution as an alternative sound perception method with the potential to complement and facilitate language development in severely hearing-impaired individuals has been explored with limited results1,2,3. Sensory substitution aims to provide users with environmental information through a human sensory channel different from the one normally used; it has been demonstrated to be possible across different sensory systems4,5. Specifically, audio-tactile sensory substitution is achieved when skin mechanoreceptors can transduce the physical energy of soundwaves that compose auditory information into neuronal excitation patterns that can be perceived and integrated with the somatosensory pathways and higher order somatosensory cortical areas6.
Several studies have demonstrated that profoundly deaf individuals can distinguish musical timbre solely through vibrotactile perception7 and discriminate between same-sex speakers using spectral cues of complex vibrotactile stimuli8. More recent findings have shown that deaf individuals concretely benefitted from a brief, well-structured audio-tactile perception training program, as they significantly improved their ability to discriminate between different pure-tone frequencies9 and between pure-tones with different temporal duration10. These experiments used event-related potentials (ERPs), graph connectivity methods, and quantitative electroencephalogram (EEG) measurements to depict and analyze functional brain mechanisms. However, the neural activity associated with the discrimination of complex environmental sounds has not been examined prior to this paper.
ERPs have proven useful for studying time-locked processes, with incredible time resolution in the order of milliseconds, while performing behavioral tasks that involve attention allocation, working memory, and response selection11. As described by Luck, Woodman, and Vogel12, ERPs are intrinsically multidimensional processing measures and are therefore well suited to separately measure the subcomponents of cognition. In an ERP experiment, the continuous ERP waveform elicited by the presentation of a stimulus can be used to directly observe neural activity that is interposed between the stimulus and the behavioral response. Other advantages of the technique, such as its cost-effectiveness and non-invasive nature, make it a perfect fit to study the precise time course of cognitive processes in clinical populations. Furthermore, ERP tools applied in a repeated-measures design, in which patients&#39; electrical brain activity is recorded more than once to study changes in electrical activity after a training program or intervention, provide further insight into neural changes over time.
The P3 component, being the most extensively researched cognitive potential13, is currently recognized to respond to all kinds of stimuli, most apparently to stimuli of low probability, or of high intensity or significance, or ones that require some behavioral or cognitive response14. This component has also proven extremely useful in evaluating general cognitive efficiency in clinical models15,16. A clear advantage of assessing changes in the P3 waveform is that it is an easily observable neural response because of its greater amplitude compared to other smaller components; it has a characteristic centroparietal topographical distribution and is also relatively easy to elicit using the appropriate experimental design17,18,19.
In this context, the aim of this study is to explore the learning-related electrophysiological changes in patients with profound deafness after training for a short period in vibrotactile sound discrimination. In addition, ERP tools are applied to depict the functional brain dynamic underlying the temporary engagement of the cognitive resources demanded by the task.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Audacity</td>
			<td>Audacity team</td>
			<td>audacityteam.org</td>
			<td>Free, open source, cross-platform audio editing software</td>
		</tr>
		<tr>
			<td>Audiometer</td>
			<td>Resonance</td>
			<td>r17a</td>
			<td></td>
		</tr>
		<tr>
			<td>EEG analysis Software</td>
			<td>Neuronic&#160;, S.A.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>EEG recording Software</td>
			<td>Neuronic&#160;, S.A.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Electro-Cap&#160;</td>
			<td>Electro-cap International, Inc.</td>
			<td>E1-M</td>
			<td>Cap with 19 active electrodes, adjustable straps and chest harness.&#160;</td>
		</tr>
		<tr>
			<td>Electro-gel</td>
			<td>Electro-cap International, Inc.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>External computer speakers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Freesound&#160;</td>
			<td>Music technology group</td>
			<td>freesound.org</td>
			<td>Database of Creative Commons Licensed sounds</td>
		</tr>
		<tr>
			<td>Hook and loop fastner</td>
			<td>Velcro</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>IBM SPSS (Statistical Package for th Social Sciences)</td>
			<td>IBM</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Individual electrodes&#160;</td>
			<td>Cadwell</td>
			<td></td>
			<td>Gold Cup, 60 in</td>
		</tr>
		<tr>
			<td>MEDICID-5</td>
			<td>Neuronic, S.A.</td>
			<td></td>
			<td>EEG recording equipment (includes amplifier and computer).</td>
		</tr>
		<tr>
			<td>Nuprep</td>
			<td>Weaver and company</td>
			<td></td>
			<td>ECG &#38; EEG abrasive skin prepping gel</td>
		</tr>
		<tr>
			<td>Portable computer with touch screen</td>
			<td>Dell</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SEVITAC-D</td>
			<td>Centro Camac, Argentina. Patented by Luis Campos (2002).</td>
			<td>http://sevitac-d.com.ar/</td>
			<td>Portable stimulator system is worn on the index-finger tip and it consists of a tiny flexible plastic membrane with a 78.5 mm2 surface area that vibrates in response to sound pressure waves via analog transmission. It has a sound frequency range from 10 Hz to 10 kHz.&#160;</td>
		</tr>
		<tr>
			<td>Stimulus presentation Software Mindtracer</td>
			<td>Neuronics, S.A.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Stimulation computer monitor and keyboard</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Tablet computer</td>
			<td>Lenovo</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ten20 Conductive Neurodiagnostic Electrode paste</td>
			<td>weaver and company</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

assessment of audio-tactile sensory substitution training in participants with profound deafness using the event-related potential technique

This paper examines the application of electroencephalogram-based methods to assess the effects of audio-tactile substitution training in young, profoundly deaf (PD) participants, with the aim of analyzing the neural mechanisms associated with vibrotactile complex sound discrimination. Electrical brain activity reflects dynamic neural changes, and the temporal precision of event-related potentials (ERPs) has proven to be key in studying time-locked processes while performing behavioral tasks that involve attention and working memory. 
The current protocol was designed to study electrophysiological activity in PD subjects while they performed a continuous performance task (CPT) using complex-sound stimuli, consisting of five different animal sounds delivered through a portable stimulator system worn on the right index finger. As a repeated-measures design, electroencephalogram (EEG) recordings in standard conditions were performed before and after a brief training program (five 1 h sessions over 15 days), followed by offline artifact correction and epoch averaging, to obtain individual and grand-mean waveforms. Behavioral results show a significant improvement in discrimination and a more robust P3-like centroparietal positive waveform for the target stimuli after training. In this protocol, ERPs contribute to the further understanding of learning-related neural changes in PD subjects associated with audio-tactile discrimination of complex sounds.

To illustrate how the effect of the audio-tactile sensory substitution discrimination training in PD individuals can be assessed by evaluating changes in P3 in a group of 17 PD individuals (mean age = 18.5 years; SD = 7.2 years; eight females and 11 males), we created several figures to portray the ERP waveforms. The results shown in the ERP plots reveal changes in a P3-like centroparietal positive waveform which is more robust for the target stimuli after training. In the pre-training condition, ERPs suggest that the T ...

Watch this Scientific Journal Video about Assessment of Audio-Tactile Sensory Substitution Training in Participants with Profound Deafness Using the Event-Related Potential Technique at JoVE.com

Assessment of Audio-Tactile Sensory Substitution Training in Participants with Profound Deafness Using the Event-Related Potential Technique

This protocol is designed to explore underlying learning-related electrophysiological changes in subjects with profound deafness after a short training period in audio-tactile sensory substitution by applying the event-related potential technique.

This paper examines the application of electroencephalogram-based methods to assess the effects of audio-tactile substitution training in young, ...

assessment-audio-tactile-sensory-substitution-training-participants

Research

JoVE Journal

Neuroscience

1.7K Views.  Universidad de Guadalajara. This protocol is designed to explore underlying learning-related electrophysiological changes in subjects with profound deafness after a short training period in audio-tactile sensory substitution by applying the event-related potential technique.

Video: Assessment of Audio-Tactile Sensory Substitution Training in Participants with Profound Deafness Using the Event-Related Potential Technique

High Density Event-related Potential  Data Acquisition in Cognitive Neuroscience

Functional magnetic resonance imaging (fMRI) is currently the standard method of evaluating brain function in the field of Cognitive Neuroscience, in part because fMRI data acquisition and analysis techniques are readily available. Because fMRI has excellent spatial resolution but poor temporal resolution, this method can only be used to identify the spatial location of brain activity associated with a given cognitive process (and reveals virtually nothing about the time course of brain activity). By contrast, event-related potential (ERP) recording, a method that is used much less frequently than fMRI, has excellent temporal resolution and thus can track rapid temporal modulations in neural activity. Unfortunately, ERPs are under utilized in Cognitive Neuroscience because data acquisition techniques are not readily available and low density ERP recording has poor spatial resolution. In an effort to foster the increased use of ERPs in Cognitive Neuroscience, the present article details key techniques involved in high density ERP data acquisition. Critically, high density ERPs offer the promise of excellent temporal resolution and good spatial resolution (or excellent spatial resolution if coupled with fMRI), which is necessary to capture the spatial-temporal dynamics of human brain function.

Event-related potential (ERP) recording is under utilized in Cognitive Neuroscience because data acquisition techniques are not readily available and this method often has poor spatial resolution. To foster the increased use of ERPs in Cognitive Neuroscience, the present article details key techniques involved in high density ERP data acquisition.

Functional magnetic resonance imaging (fMRI) is currently the standard method of evaluating brain function in the field of Cognitive Neuroscience, in part ...

Applications of EEG Neuroimaging Data: Event-related Potentials, Spectral Power, and Multiscale Entropy

When considering human neuroimaging data, an appreciation of signal variability represents a fundamental innovation in the way we think about brain signal. Typically, researchers represent the brain's response as the mean across repeated experimental trials and disregard signal fluctuations over time as "noise". However, it is becoming clear that brain signal variability conveys meaningful functional information about neural network dynamics. This article describes the novel method of multiscale entropy (MSE) for quantifying brain signal variability. MSE may be particularly informative of neural network dynamics because it shows timescale dependence and sensitivity to linear and nonlinear dynamics in the data.

Neuroimaging researchers typically consider the brain's response as the mean activity across repeated experimental trials and disregard signal variability over time as "noise". However, it is becoming clear that there is signal in that noise. This article describes the novel method of multiscale entropy for quantifying brain signal variability in the time domain.

When considering human neuroimaging data, an appreciation of signal variability represents a fundamental innovation in the way we think about brain ...

Assessment of Vascular Regeneration in the CNS Using the Mouse Retina

The rodent retina is perhaps the most accessible mammalian system in which to investigate neurovascular interplay within the central nervous system (CNS). It is increasingly being recognized that several neurodegenerative diseases such as Alzheimer&#8217;s, multiple sclerosis, and amyotrophic lateral sclerosis present elements of vascular compromise. In addition, the most prominent causes of blindness in pediatric and working age populations (retinopathy of prematurity and diabetic retinopathy, respectively) are characterized by vascular degeneration and failure of physiological vascular regrowth. The aim of this technical paper is to provide a detailed protocol to study CNS vascular regeneration in the retina. The method can be employed to elucidate molecular mechanisms that lead to failure of vascular growth after ischemic injury. In addition, potential therapeutic modalities to accelerate and restore healthy vascular plexuses can be explored. Findings obtained using the described approach may provide therapeutic avenues for ischemic retinopathies such as that of diabetes or prematurity and possibly benefit other vascular disorders of the CNS.

The rodent retina has long been recognized as an accessible window to the brain. In this technical paper we provide a protocol that employs the mouse model of oxygen-induced retinopathy to study the mechanisms that lead to failure of vascular regeneration within the central nervous system after ischemic injury. The described system can also be harnessed to explore strategies to promote regrowth of functional blood vessels within the retina and CNS.

The rodent retina is perhaps the most accessible mammalian system in which to investigate neurovascular interplay within the central nervous system (CNS). ...

Somatosensory Event-related Potentials from Orofacial Skin Stretch Stimulation

Cortical processing associated with orofacial somatosensory function in speech has received limited experimental attention due to the difficulty of providing precise and controlled stimulation. This article introduces a technique for recording somatosensory event-related potentials (ERP) that uses a novel mechanical stimulation method involving skin deformation using a robotic device. Controlled deformation of the facial skin is used to modulate kinesthetic inputs through excitation of cutaneous mechanoreceptors. By combining somatosensory stimulation with electroencephalographic recording, somatosensory evoked responses can be successfully measured at the level of the cortex. Somatosensory stimulation can be combined with the stimulation of other sensory modalities to assess multisensory interactions. For speech, orofacial stimulation is combined with speech sound stimulation to assess the contribution of multi-sensory processing including the effects of timing differences. The ability to precisely control orofacial somatosensory stimulation during speech perception and speech production with ERP recording is an important tool that provides new insight into the neural organization and neural representations for speech.

This paper introduces a method for obtaining somatosensory event-related potentials following orofacial skin stretch stimulation. The current method can be used to evaluate the contribution of somatosensory afferents to both speech production and speech perception.

Cortical processing associated with orofacial somatosensory function in speech has received limited experimental attention due to the difficulty of ...

Olfactory Behaviors Assayed by Computer Tracking Of Drosophila in a Four-quadrant Olfactometer

A key challenge in neurobiology is to understand how neural circuits function to guide appropriate animal behaviors. Drosophila melanogaster is an excellent model system for such investigations due to its complex behaviors, powerful genetic techniques, and compact nervous system. Laboratory behavioral assays have long been used with Drosophila to simulate properties of the natural environment and study the neural mechanisms underlying the corresponding behaviors (e.g. phototaxis, chemotaxis, sensory learning and memory)1-3. With the recent availability of large collections of transgenic Drosophila lines that label specific neural subsets, behavioral assays have taken on a prominent role to link neurons with behaviors4-11. Versatile and reproducible paradigms, together with the underlying computational routines for data analysis, are indispensable for rapid tests of candidate fly lines with various genotypes. Particularly useful are setups that are flexible in the number of animals tested, duration of experiments and nature of presented stimuli. The assay of choice should also generate reproducible data that is easy to acquire and analyze. Here, we present a detailed description of a system and protocol for assaying behavioral responses of Drosophila flies in a large four-field arena. The setup is used here to assay responses of flies to a single olfactory stimulus; however, the same setup may be modified to test multiple olfactory, visual or optogenetic stimuli, or a combination of these. The olfactometer setup records the activity of fly populations responding to odors, and computational analytical methods are applied to quantify fly behaviors. The collected data are analyzed to get a quick read-out of an experimental run, which is essential for efficient data collection and the optimization of experimental conditions.

Olfactory Behaviors Assayed by Computer Tracking Of Drosophila in a Four-quadrant Olfactometer

We describe here a behavioral setup and data analysis method for assaying olfactory responses of up to 100 vinegar flies (Drosophila melanogaster). This system may be used with single or multiple olfactory stimuli, and adaptable for optogenetic activation or silencing of neuronal subsets.

A key challenge in neurobiology is to understand how neural circuits function to guide appropriate animal behaviors. Drosophila melanogaster is an ...

Physiological Preparation of Hair Cells from the Sacculus of the American Bullfrog (Rana catesbeiana)

The study of hearing and balance rests upon insights drawn from biophysical studies of model systems. One such model, the sacculus of the American bullfrog, has become a mainstay of auditory and vestibular research. Studies of this organ have revealed how sensory cells hair can actively detect signals from the environment. Because of these studies, we now better understand the mechanical gating and localization of a hair cell&#39;s transduction channels, calcium&#39;s role in mechanical adaptation, and the identity of hair cell currents. This highly accessible organ continues to provide insight into the workings of hair cells. Here we describe the preparation of the bullfrog&#39;s sacculus for biophysical studies on its hair cells. We include the complete dissection procedure and provide specific protocols for the preparation of the sacculus in specific contexts. We additionally include representative results using this preparation, including the calculation of a hair bundle&#39;s instantaneous force-displacement relation and measurement of a bundle&#39;s spontaneous oscillation.

Physiological Preparation of Hair Cells from the Sacculus of the American Bullfrog Rana catesbeiana

The American bullfrog&#39;s (Rana catesbeiana) sacculus permits direct examination of hair-cell physiology. Here the dissection and preparation of the bullfrog&#39;s sacculus for biophysical studies is described. We show representative experiments from these hair cells, including the calculation of a bundle&#39;s force-displacement relation and measurement of its unforced motion.

The study of hearing and balance rests upon insights drawn from biophysical studies of model systems. One such model, the sacculus of the American ...

How to Find Effects of Stimulus Processing on Event Related Brain Potentials of Close Others when Hyperscanning Partners

The partners of each pair must be able to pass the McGill Friendship Questionnaire without communicating. Each partner is then seated in front of a screen in one of two adjacent rooms. These rooms are separated by a glass window through which participants communicate to maintain feelings of togetherness while being fitted with the EEG cap. After checking for adequate EEG signals, the glass is covered by a curtain to prevent visual communication. Then, partners must be silent but are instructed to try to feel in the presence of their partner during the entire experiment. Just before it starts, participants are told that each of them will be presented with one image at a time and that these images will occur at the same time for both of them on their own screen. They are also instructed that, for each trial, the simultaneous images will always be different. However, unbeknownst to them, trials are randomized: only half of them are consistent with this instruction and actually include two different images. These trials form the DSC, that is, the different-stimuli condition. The other half of the trials are inconsistent with the instruction. They include two identical images and form the ISC (identical-stimuli condition). After the experiment, participants are sorted into two groups: those who reported that they felt in the presence of their partner during the majority of the trials and those who reported they did not. The impact of the stimulus processing of the partner is found by subtracting the mean voltages of the ERPs of the ISC (inconsistent with the instructions) from the ERPs of the DSC (consistent with the instructions) in at least two time windows (TWs): firstly, in the 75 to 150 ms TW, where the absolute values of these subtractions are greater, especially at right frontal sites, in those who felt in the presence of their partner than in those who did not; secondly, in the LPP time window (i.e., from 650 to 950 ms post onset), where ERPs are significantly less positive in the DSC than in the ISC in those in whom the raw results of the early (75-150ms) subtractions are negative.

This protocol describes key steps involved in assessing the sensitivity of the brain of one person to the stimulus processing of a close other by selecting pairs of partners, recording their electroencephalogram (EEG) simultaneously and computing their event-related brain potentials (ERPs).

The partners of each pair must be able to pass the McGill Friendship Questionnaire without communicating. Each partner is then seated in front of a screen ...

The Power of Interstimulus Interval for the Assessment of Temporal Processing in Rodents

Temporal processing deficits have been implicated as a potential elemental dimension of higher-level cognitive processes, commonly observed in neurocognitive disorders. Despite the popularization of prepulse inhibition (PPI) in recent years, many current protocols promote using a percent of control measure, thereby precluding the assessment of temporal processing. The present study used cross-modal PPI and gap prepulse inhibition (gap-PPI) to demonstrate the benefits of employing a range of interstimulus intervals (ISIs) to delineate effects of sensory modality, psychostimulant exposure, and age. Assessment of sensory modality, psychostimulant exposure, and age reveals the utility of an approach varying the interstimulus interval (ISI) to establish the shape of the ISI function, including increases (sharper curve inflections) or decreases (flattening of the response amplitude curve) in startle amplitude. Additionally, shifts in peak response inhibition, suggestive of a differential sensitivity to the manipulation of ISI, are often revealed. Thus, the systematic manipulation of ISI affords a critical opportunity to evaluate temporal processing, which may reveal the underlying neural mechanisms involved in neurocognitive disorders.

Temporal processing, a preattentive process, may underlie deficits in higher-level cognitive processes, including attention, commonly observed in neurocognitive disorders. Using prepulse inhibition as an exemplar paradigm, we present a protocol for manipulating interstimulus interval (ISI) to establish the shape of the ISI function to provide an assessment of temporal processing.

Temporal processing deficits have been implicated as a potential elemental dimension of higher-level cognitive processes, commonly observed in ...

Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns

This paper presents a methodology for the recording and analysis of cortical visual evoked potentials (CVEPs) in response to various visual stimuli using 128-channel high-density electroencephalography (EEG). The specific aim of the described stimuli and analyses is to examine whether it is feasible to replicate previously reported CVEP morphological patterns elicited by an apparent motion stimulus, designed to simultaneously stimulate both ventral and dorsal central visual networks, using object and motion stimuli designed to separately stimulate ventral and dorsal visual cortical networks.&#160; Four visual paradigms are presented: 1. Randomized visual objects with consistent temporal presentation. 2. Randomized visual objects with inconsistent temporal presentation (or jitter).&#160; 3. Visual motion via a radial field of coherent central dot motion without jitter.&#160; 4. Visual motion via a radial field of coherent central dot motion with jitter.&#160; These four paradigms are presented in a pseudo-randomized order for each participant.&#160; Jitter is introduced in order to view how possible anticipatory-related effects may affect the morphology of the object-onset and motion-onset CVEP response.&#160; EEG data analyses are described in detail, including steps of data exportation from and importation to signal processing platforms, bad channel identification&#160;and removal, artifact rejection, averaging, and categorization of average CVEP morphological pattern type based upon latency ranges of component peaks. Representative data show that the methodological approach is indeed sensitive in eliciting differential object-onset and motion-onset CVEP morphological patterns and may, therefore, be useful in addressing the larger research aim. Given the high temporal resolution of EEG and the possible application of high-density EEG in source localization analyses, this protocol is ideal for the investigation of distinct CVEP morphological patterns and the underlying neural mechanisms which generate these differential responses.&#160; &#160; &#160;&#160;

In this paper, we present a protocol to investigate differential cortical visual evoked potential morphological patterns through stimulation of ventral and dorsal networks using high-density EEG. Visual object and motion stimulus paradigms, with and without temporal jitter, are described. Visual evoked potential morphological analyses are also outlined.&#160;&#160;

This paper presents a methodology for the recording and analysis of cortical visual evoked potentials (CVEPs) in response to various visual stimuli using ...

How to Obtain Reliable Visual Event-related Potentials in Newborns

The present study discusses the characteristics of visual event-related potentials (VEPs) and outlines methodological steps for obtaining reliable measurements in newborns. Obtaining high-quality, reliable VEPs is crucial for the early detection of abnormal development of the central nervous system in at-risk newborns, and for implementing successful early interventions. Recommendations are based on a previous study which showed that when post-conceptional age, polysomnography-identified sleep stages, and light-emitting diodes (LEDs) googles as the luminous source are controlled, no more than 4 repetitions of VEP averages are required to obtain replicable recordings, variability decreases, and reliable VEPs can be obtained. By controlling for these sources of variability and using statistical analyses, we were able to clearly and reliably identify the amplitude and latency of three main components (NII, PII and NIII) present in 100% of newborns (n = 20) during active sleep. Recording VEPs during awake states, quiet sleep and transitional sleep is not recommended because VEP morphology may differ significantly from one average to the next, leading to the risk of misleading clinical prognoses. Moreover, it is easier to obtain VEPs during active sleep because this state can be clearly and reliably identified at this stage of development, sleep cycles are short enough to allow measurements to be taken in a reasonable time, and the method does not require new o expensive equipment.

Several important points for obtaining high-quality reliable visual evoked potentials (VEPs) in newborns while minimizing variability and the risk of misleading prognoses are presented.