Name: simultaneous eye tracking and single-neuron recording to identify target-selective neurons
Uploaded: 2024-12-02T15:01:38.000+00:00
Duration: 1 min 14 s
Description: All procedures involving human participants have been performed in compliance with the institutional, national, and international guidelines for human ...

simultaneous eye tracking and single-neuron recording to identify target-selective neurons

Simultaneous Eye Tracking and Single-Neuron Recording to Identify Target-Selective Neurons

To begin, connect the electrodes to the recording system, and position the patient sitting upright. Then, connect the stimulus computer to the electrophysiology system and eye tracker. Place the remote non-invasive infrared eye-tracking system on a robust mobile cart. Then, attach a flexible arm that holds an LCD display to the cart.
Place a fully charged, uninterrupted power supply on the eye-tracking cart, and connect all devices related to eye-tracking to the power supply rather than to an external power source. Make sure the IV device connected to the patient is running on battery and is not plugged into the wall. Start the eye-tracking software. Adjust the distance between the patient and the LCD screen to between 60 and 70 centimeters.
Also, adjust the angle of the LCD screen so that the surface of the screen is approximately parallel to the patient&#39;s face. Place a sticker on the patient&#39;s forehead so that the eye tracker can adjust for head movements. Now, adjust the height of the screen relative to the patient&#39;s head, such that the camera of the eye tracker is approximately at the height of the patient&#39;s nose.
Provide the patient with the button box or keyboard. Verify that triggers and button press are recorded properly before starting the experiment. Start the acquisition software. First, visually inspect the broadband local field potentials, and make sure they are not contaminated by line noise. Otherwise, follow standard procedures to remove noise. To identify single neurons, band-pass-filter the signal from 300 Hertz to 8 kilohertz.
Select one of the eight microwires as a reference for each microwire bundle. Enable saving the data as an RD file before recording. Provide task instructions to the participants. Instruct the participants to find the target item in the search array, and respond as soon as possible. Instruct the participants to press the left button of a response box if they find the target, and press the right button if they think the target is absent.
Explicitly instruct the participants that there will be target-present and target-absent trials. Start stimulus presentation software and run the task. Present a target cue for one second, and present the search array using the stimulus presentation software. Record the button presses and provide trial-by-trial feedback to the participants.

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All procedures involving human participants have been performed in compliance with the institutional, national, and international guidelines for human welfare and have been reviewed by the local institutional review board.
1. Participants
<ol>
	<li>Recruit neurosurgical patients with intractable epilepsy who are undergoing placement of intracranial electrodes to localize their epileptic seizures.</li>
	<li>Insert depth electrodes with embedded microwires into all clinically indicated target locations, which typically include a subset of amygdala, hippocampus, anterior cingulate cortex and pre-supplementary motor area. See details for implantation in our previous protocol.</li>
	<li>Once the patient returns to the epilepsy monitoring unit, connect the recording equipment for both macro- and micro- recordings. This includes carefully preparing a head-wrap that includes head stages. Then, wait for the patient to recover from the surgery and conduct testing when the patient is fully awake (typically at least 36 to 48 h after surgery).</li>
</ol>
2. Experimental setup
<ol>
	<li>Connect the stimulus computer to the electrophysiology system and eye tracker following the diagram in&#160;Figure 1.</li>
	<li>Use the remote non-invasive infrared eye tracking system (see&#160;Table of Materials). Place the eye tracking system on a robust mobile cart (Figure 1A, B). To the same cart, attach a flexible arm that holds an liquid crystal display (LCD). Use the&#160;remote mode&#160;to track the patient&#39;s head and eyes.</li>
	<li>Place a fully charged uninterrupted power supply (UPS) on the eye tracking cart and connect all devices related to eye tracking (i.e., LCD in front of patient, eye tracker camera and light source, and eye tracker host computer) to the UPS rather than to an external power source.</li>
	<li>Adjust the distance between the patient and the LCD screen to 60-70 cm and adjust the angle of the LCD screen so that the surface of the screen is approximately parallel to the patient&#39;s face. Adjust the height of the screen relative to the patient&#39;s head such that the camera of the eye tracker is approximately at the height of the patient&#39;s nose.</li>
	<li>Provide the patient with the button box or keyboard. Verify that triggers (transistor-transistor logic, TTL) and button press are recorded properly before starting the experiment.</li>
</ol>
3. Single-neuron recording
<ol>
	<li>Start the acquisition software. First, visually inspect the broadband (0.1 Hz - 8&#160;kHz) local field potentials and make sure they are not contaminated by line noise. Otherwise, follow standard procedures to remove noise.</li>
	<li>To identify single neurons, band-pass filter the signal (300 Hz - 8 KHz). Select one of the eight microwires as a reference for each microwire bundle. Test different references and adjust the reference so that (1) the other 7 channels show clear neurons, and (2) the reference does not contain neurons. Set the input range to be &#177; 2,000 &#181;V.</li>
	<li>Enable saving the data as an NRD file (i.e., the broadband raw data file that will be used for subsequent off-line spike sorting) before recording data. Set the sampling rate to 32 kHz.</li>
</ol>
4. Eye tracking
<ol>
	<li>Start the eye tracking software. Because it is a head-fixation free system, place the sticker on the patient&#39;s forehead so that the eye tracker can adjust for head movements.</li>
	<li>Adjust the distance and angle between the eye tracker and patient so that the target marker, head distance, pupil, and corneal reflection (CR) are marked as ready (as shown in green in the eye tracking software;&#160;Figure 2&#160;shows a good example camera setup screen). Click on the&#160;eye&#160;to be recorded and set the sampling rate to 500 Hz.</li>
	<li>Use the&#160;auto-adjustment&#160;of pupil and CR threshold. For patients wearing glasses, adjust the position and/or angle of the illuminator and camera so that reflections from the glass will not interfere with pupil acquisition.</li>
	<li>Calibrate the eye tracker with the built-in 9-point grid method at the beginning of each block. Confirm that eye positions (shown as &#34;+&#34;) register nicely as a 9-point grid. Otherwise, redo calibration.</li>
	<li>Accept the calibration and do validation. Accept the validation if the maximal validation error is &#60; 2&#176; and the average validation error is &#60; 1&#176;. Otherwise, redo validation.</li>
	<li>Do drift correction and proceed to the actual experiment.</li>
</ol>
5. Task
<ol>
	<li>In this visual search task, use the stimuli from our previous study&#160;and follow the task procedure as described before.</li>
	<li>Provide task instructions to participants. Instruct the participants to find the target item in the search array and respond as soon as possible. Instruct the participants to press the left button of a response box (see&#160;Table of Materials) if they find the target and the right button if they think the target is absent. Explicitly instruct the participants that there will be target-present and target-absent trials.</li>
	<li>Start stimulus presentation software (see&#160;Table of Materials) and run the task: Present a target cue for 1 s and present the search array using the stimulus presentation software. Record button presses and provide trial-by-trial feedback (Correct, Incorrect, or Time Out) to participants.</li>
</ol>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Cedrus Response Box&#160;</td>
			<td>Cedrus (https://cedrus.com/)&#160;</td>
			<td>RB-844&#160;</td>
			<td>Button box</td>
		</tr>
		<tr>
			<td>Dell Laptop&#160;</td>
			<td>Dell (https://dell.com)&#160;</td>
			<td>Precision 7520&#160;</td>
			<td>Stimulus Computer</td>
		</tr>
		<tr>
			<td>EyeLink Eye Tracker&#160;</td>
			<td>SR Research (https://www.srresearch.com)&#160;</td>
			<td>1000 Plus Remote with laptop host computer and LCD arm mount&#160;</td>
			<td>Eye tracking</td>
		</tr>
		<tr>
			<td>Neuralynx Neurophysiology System&#160;</td>
			<td>Neuralynx (https://neuralynx.com)</td>
			<td>ATLAS 128&#160;</td>
			<td>Electrophysiology</td>
		</tr>
		<tr>
			<td>Osort&#160;</td>
			<td>Open source</td>
			<td>v4.1 (RRID: SCR_015869)&#160;</td>
			<td>Spike sorting algorithm</td>
		</tr>
		<tr>
			<td>Psychophysics Toolbx&#160;</td>
			<td>Open source&#160;</td>
			<td>PTB3 ( RRID: SCR_002881)</td>
			<td>Matlab toolbox to implement psychophysical experiments</td>
		</tr>
		<tr>
			<td>MATLAB&#160;</td>
			<td>MathWorks Inc&#160;</td>
			<td>R2016a (RRID: SCR_001622)&#160;</td>
			<td>Data analysis</td>
		</tr>
	</tbody>
</table>

Source: Wang, S., et al. <a href="https://app.jove.com/v/59117">Simultaneous Eye Tracking and Single-Neuron Recordings in Human Epilepsy Patients.</a> J. Vis. Exp. (2019).
The video demonstrates an assay to identify target-selective neurons via simultaneous eye-tracking and single-neuron recordings. A human participant is tasked with identifying a target object among an array of objects in a display, and the eye movement is tracked. Simultaneously, single neurons&#39; firing rate is recorded via electrodes implanted in the brain. The data from both recordings are correlated to assess the presence of target-selective neurons.

<img alt="Figure 1" src="/files/ftp_upload/22859/22859_Figure1.jpg" /> 
Figure 1. Experimental setup. (A) The left panels show a sketch of the connections between the different systems. The stimulus computer serves as the central controller. It connects to the electrophysiology system through the parallel port and sends TTL pulses as triggers. The stimulus computer connects to the eye tracking system through an ethernet cable, over which it sends tex...

All procedures involving human participants have been performed in compliance with the institutional, national, and international guidelines for human ...

Take a human participant with depth electrodes embedded in the brain&#39;s medial temporal lobe, which responds to visual stimuli.
The electrodes contain microwires that record electrical activity from individual neurons.
Position a display connected to an eye-tracking system in front of the participant. The system tracks eye movements in response to visual stimuli.
Present a target object to the participant, followed by a search array containing multiple objects, including the target. Instruct the participant to identify the target in the array and confirm detection by pressing a button on a response box.
Upon detection, target-selective neurons in the brain modify the rate of firing electrical signals, called action potentials, to transmit visual information.
The electrode microwires record these signals extracellularly.
Correlate the timing of target detection, obtained from button press and eye-tracking data, with the timing of the change in the firing rate to assess the presence of target-selective neurons.

13 Views. Tracciamento oculare simultaneo e registrazione di un singolo neurone per identificare i neuroni selettivi per il bersaglio

Video: Tracciamento oculare simultaneo e registrazione di un singolo neurone per identificare i neuroni selettivi per il bersaglio - Experiment

Eye-tracking to Distinguish Comprehension-based and Oculomotor-based Regressive Eye Movements During Reading

Regressive eye movements are eye movements that move backwards through the text and comprise approximately 10-25% of eye movements during reading. As such, understanding the causes and mechanisms of regressions plays an important role in understanding eye movement behavior. Inhibition of return (IOR) is an oculomotor effect that results in increased latency to return attention to a previously attended target versus a target that was not previously attended. Thus, IOR may affect regressions. This paper describes how to design materials to distinguish between regressions caused by comprehension-related and oculomotor processes; the latter is subject to IOR. The method allows researchers to identify IOR and control the causes of regressions. While the method requires tightly controlled materials and large numbers of participants and materials, it allows researchers to distinguish and control the types of regressions that occur in their reading studies.

The method was designed to investigate the role of inhibition of return (IOR) in regressive eye movements during reading. The focus is on differentiating between regressions triggered as a result of comprehension difficulty versus those triggered from oculomotor error, including the role of IOR in the two types of regressions.

Eye-tracking per distinguere movimenti oculari regressivo oculomotoria basati e comprensione durante la lettura

Regressive eye movements are eye movements that move backwards through the text and comprise approximately 10-25% of eye movements during reading. As ...

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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.

Registrazioni simultanee di potenziali di campo locale corticale ed Electrocorticograms in risposta a stimoli nocicettivi Laser da liberi di muoversi

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

Investigating the Deployment of Visual Attention Before Accurate and Averaging Saccades via Eye Tracking and Assessment of Visual Sensitivity

This experimental protocol was designed to investigate whether visual attention is obligatorily deployed at the endpoint of saccades. To this end, we recorded the eye position of human participants engaged in a saccade task via eye tracking and assessed visual orientation discrimination performance at various locations during saccade preparation. Importantly, instead of using a single saccade target paradigm for which the saccade endpoint typically coincides roughly with the target, this protocol comprised the presentation of two nearby saccade targets, leading to a distinct spatial dissociation between target locations and saccade endpoint on a substantial number of trials. The paradigm allowed us to compare presaccadic visual discrimination performance at the endpoint of accurate saccades (landing at one of the saccade targets) and of averaging saccades (landing at an intermediate location in between the two targets). We observed a selective enhancement of visual sensitivity at the endpoint of accurate saccades but not at the endpoint of averaging saccades. Rather, before the execution of averaging saccades, visual sensitivity was equally enhanced at both targets, suggesting that saccade averaging follows from unresolved attentional selection among the saccade targets. These results argue against a mandatory coupling between visual attention and saccade programming based on a direct measure of presaccadic visual sensitivity rather than saccadic reaction times, which have been used in other protocols to draw similar conclusions. While our protocol provides a useful framework to investigate the relationship between visual attention and saccadic eye movements at the behavioral level, it can also be combined with electrophysiological measures to extend insights at the neuronal level.

This experimental protocol combined eye tracking and the assessment of presaccadic visual sensitivity in a dual task paradigm, consisting of a free choice saccade task and a visual discrimination task, to investigate the deployment of visual spatial attention before both, accurate and averaging saccades.

Studiando la distribuzione dell'attenzione visiva prima di saccadi Accurate e media tramite Eye-Tracking e valutazione della sensibilità visiva

This experimental protocol was designed to investigate whether visual attention is obligatorily deployed at the endpoint of saccades. To this end, we ...

Simultaneous Eye Tracking and Single-Neuron Recording to Identify Target-Selective Neurons

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Simultaneous Eye Tracking and Single-Neuron Recording to Identify Target-Selective Neurons