Name: stimulus-specific cortical visual evoked potential morphological patterns
Uploaded: 2019-05-12T14:00:00
Description: Watch this Scientific Journal Video about Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns at JoVE.com

This research was supported by the University of Texas at Austin Moody College of Communication Grant Preparation Award and the University of Texas at Austin Office of the Vice President of Research Special Research Grant.

All methods described here have been approved by the Institutional Review Board (IRB) for Human Research at the University of Texas at Austin.
1. Stimuli Characteristics
<ol>
	<li>Create object stimuli using open source images available through the Bank of Standardized Stimuli (BOSS). This database consists of standardized images used throughout visual cognitive experiments.&#160; Download four images (e.g., ball02, book01a, brick, button03) with a high rate of identification (above 75%)<sup...

<ol>
	<li>Lascano, A. M., Lalive, P. H., Hardmeier, M., Fuhr, P., Seeck, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+evoked+potentials+in+neurology:+A+review+of+techniques+and+indications.">Clinical evoked potentials in neurology: A review of techniques and indications.</a> Journal of Neurology, Neurosurgery, and Psychiatry. 88 (8), 688-696 (2017).</li><li>Mehta, R. K., Parasuraman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroergonomics:+A+review+of+applications+to+physical+and+cognitive+work.">Neuroergonomics: A review of applications to physical and cognitive work.</a> Frontiers in Human Neuroscience. 7, 889 (2013).</li><li>Kuba, M., Kubova, Z., Kremlacek, J., Langrova, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Motion-onset+VEPs:+Characteristics,+methods,+and+diagnostic+use.">Motion-onset VEPs: Characteristics, methods, and diagnostic use.</a> Vision Research. 47 (2), 189-202 (2007).</li><li>Tobimatsu, S., Celesia, G. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+of+human+visual+pathophysiology+with+visual+evoked+potentials.">Studies of human visual pathophysiology with visual evoked potentials.</a> Clinical Neurophysiology. 117 (7), 1414-1433 (2006).</li><li>Tremblay, E., 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=Delayed+early+primary+visual+pathway+development+in+premature+infants:+High+density+electrophysiological+evidence.">Delayed early primary visual pathway development in premature infants: High density electrophysiological evidence.</a> PLoS One. 9 (9), e107992 (2014).</li><li>Allison, T., Puce, A., Spencer, D. D., McCarthy, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrophysiological+studies+of+human+face+perception.+I:+Potentials+generated+in+occipitotemporal+cortex+by+face+and+non-face+stimuli.">Electrophysiological studies of human face perception. I: Potentials generated in occipitotemporal cortex by face and non-face stimuli.</a> Cerebral Cortex. 9, 415-430 (1999).</li><li>Grill-Spector, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neural+basis+of+object+perception.">The neural basis of object perception.</a> Current Opinions in Neurobiology. 13, 159-166 (2003).</li><li>Mitchell, T. V., Neville, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Asynchronies+in+the+development+of+electrophysiological+responses+to+motion+and+color.">Asynchronies in the development of electrophysiological responses to motion and color.</a> Journal of Cognitive Neuroscience. 16, 1363-1374 (2004).</li><li>Armstrong, B. A., Neville, H. J., Hillyard, S. A., Mitchell, T. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Auditory+deprivation+affects+processing+of+motion,+but+not+color.">Auditory deprivation affects processing of motion, but not color.</a> Cognitive Brain Research. 14, 422-434 (2002).</li><li>Donner, T. H., Siegel, M., Oostenveld, R., Fries, P., Bauer, M., Engel, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Population+activity+in+the+human+dorsal+pathway+predicts+the+accuracy+of+visual+motion+detection.">Population activity in the human dorsal pathway predicts the accuracy of visual motion detection.</a> Journal of Neurophysiology. 98, 345-359 (2007).</li><li>Bonfiglio, L., 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=Defective+chromatic+and+achromatic+visual+pathways+in+developmental+dyslexia:+Cues+for+an+integrated+intervention+programme.">Defective chromatic and achromatic visual pathways in developmental dyslexia: Cues for an integrated intervention programme.</a> Restorative Neurology and Neuroscience. 35 (1), 11-24 (2017).</li><li>Campbell, J., Sharma, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visual+cross-modal+re-organization+in+children+with+cochlear+implants.">Visual cross-modal re-organization in children with cochlear implants.</a> PLoS ONE. 11 (1), e0147793-e0147718 (2016).</li><li>Campbell, J., Sharma, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+visual+evoked+potential+morphological+patterns+for+apparent+motion+processing+in+school-aged+children.">Distinct visual evoked potential morphological patterns for apparent motion processing in school-aged children.</a> Frontiers in Human Neuroscience. 10 (71), 277 (2016).</li><li>Doucet, M. E., Gosselin, F., Lassonde, M., Guillemot, J. P., Lepore, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+visual-evoked+potentials+to+radially+modulated+concentric+patterns.">Development of visual-evoked potentials to radially modulated concentric patterns.</a> Neuroreport. 16 (6), 1753-1756 (2005).</li><li>Doucet, M. E., Bergeron, F., Lassonde, M., Ferron, P., Lepore, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cross-modal+reorganization+and+speech+perception+in+cochlear+implant+users.">Cross-modal reorganization and speech perception in cochlear implant users.</a> Brain. 129 (12), 3376-3383 (2006).</li><li>Kubova, Z., 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=Difficulties+of+motion-onset+VEP+interpretation+in+school-age+children.">Difficulties of motion-onset VEP interpretation in school-age children.</a> Documenta Ophthalmologica. 128, 121-129 (2014).</li><li>Gould, I. C., Rushworth, M. F., Nobre, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Indexing+the+graded+allocation+of+visuospatial+attention+using+anticipatory+alpha+oscillations.">Indexing the graded allocation of visuospatial attention using anticipatory alpha oscillations.</a> Journal of Neurophysiology. 105, 1318-1326 (2011).</li><li>Hanslmayr, S., Aslan, A., Staudigl, T., Klimesch, W., Hermann, C. S., Bauml, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prestimulus+oscillations+predict+visual+perception+performance+between+and+within+subjects.">Prestimulus oscillations predict visual perception performance between and within subjects.</a> Neuroimage. 37, 1465-1543 (2007).</li><li>Toosi, T., Tousi, E. K., Esteky, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Learning+temporal+context+shapes+prestimulus+alpha+oscillations+and+improves+visual+discrimination+performance.">Learning temporal context shapes prestimulus alpha oscillations and improves visual discrimination performance.</a> Journal of Neurophysiology. 118 (2), 771-777 (2017).</li><li>Brodeur, M. B., Dionne-Dostie, E., Montreuil, T., Lepage, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Bank+of+Standardized+Stimuli+(BOSS),+a+new+set+of+480+normative+photos+of+objects+to+be+used+as+visual+stimuli+in+cognitive+research.">The Bank of Standardized Stimuli (BOSS), a new set of 480 normative photos of objects to be used as visual stimuli in cognitive research.</a> PLoS One. 5 (5), e10773 (2010).</li><li>Brodeur, M. B., 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=The+Bank+of+Standardized+Stimuli+(BOSS):+Comparison+between+French+and+English+norms.">The Bank of Standardized Stimuli (BOSS): Comparison between French and English norms.</a> Behavior Research Methods. 44, 961-970 (2012).</li><li>Suttle, C., Harding, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphology+of+transient+VEPs+to+luminance+and+chromatic+pattern+onset+and+offset.">Morphology of transient VEPs to luminance and chromatic pattern onset and offset.</a> Vision Research. 39 (8), 1577-1584 (1999).</li><li>Campbell, J., Sharma, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cross-modal+re-organization+in+adults+with+early+stage+hearing+loss.">Cross-modal re-organization in adults with early stage hearing loss.</a> PLoS One. 9 (2), e90594 (2014).</li><li>Campbell, J., Sharma, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Compensatory+changes+in+cortical+resource+allocation+in+adults+with+hearing+loss.">Compensatory changes in cortical resource allocation in adults with hearing loss.</a> Frontiers in Systems Neuroscience. 7, 71 (2013).</li><li>Debener, S., Hine, J., Bleeck, S., Eyles, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Source+localization+of+auditory+evoked+potentials+after+cochlear+implantation.">Source localization of auditory evoked potentials after cochlear implantation.</a> Psychophysiology. 45 (1), 20-24 (2008).</li><li>Gilley, P. M., Sharma, A., Dorman, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cortical+reorganization+in+children+with+cochlear+implants.">Cortical reorganization in children with cochlear implants.</a> Brain Research. 1239, 56-65 (2008).</li><li>Neuner, I., Arruba, J., Felder, J., Shah, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simultaneous+EEG-fMRI+acquisition+at+low,+high+and+ultra-high+magnetic+fields+up+to+9.4+T:+Perspectives+and+challenges.">Simultaneous EEG-fMRI acquisition at low, high and ultra-high magnetic fields up to 9.4 T: Perspectives and challenges.</a> Neuroimage. 15 (102), 71-79 (2014).</li><li>Schulte-Korne, G., Bartling, J., Deimel, W., Remschmidt, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visual+evoked+potential+elicited+by+coherently+moving+dots+in+dyslexic+children.">Visual evoked potential elicited by coherently moving dots in dyslexic children.</a> Neuroscience Letters. 357 (3), 207-210 (2004).</li><li>Zhang, R., Hu, Z., Roberson, D., Zhang, L., Li, H., Liu, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neural+processes+underlying+the+&#8220;same&#8221;-+&#8220;different&#8221;+judgment+of+two+simultaneously+presented+objects&#8212;an+EEG+study.">Neural processes underlying the &#8220;same&#8221;- &#8220;different&#8221; judgment of two simultaneously presented objects&#8212;an EEG study.</a> PLoS One. 8 (12), e81737 (2013).</li></ol>

The goal of this methodological report was to evaluate the feasibility in recording differential CVEP morphology by using visual object and motion stimuli specifically designed to separately stimulate ventral and dorsal streams in passive viewing tasks6,7,8, both with and without variation of ISIs (jitter)19. Conditions were not designed to be directly compared, rather, observations were made as to whethe...

Electroencephalography (EEG) is a tool that offers an inexpensive and non-invasive approach to the study of cortical processing, especially when compared to cortical assessment methods such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and diffusion tensor imaging (DTI)1. EEG also provides high temporal resolution, which is not possible to attain when using measures such as fMRI, PET, or DTI2. High temporal resolution is critical when examining central temporal function in order to obtain millisecond-precision of neurophysiologic mechanisms related to the processing of specific input or events.&#160; In the central visual system, cortical visual evoked potentials (CVEPs) are a popular approach in studying time-locked neural processes in the cerebral cortex.&#160; CVEP responses are recorded and averaged over a number of event trials, resulting in peak components (e.g., P1, N1, P2) arising at specific millisecond intervals. The timing and amplitude of these peak neural responses can provide information concerning cortical processing speed and maturation, as well as deficits in cortical function3,4,5.&#160;&#160;
CVEPs are specific to the type of visual input presented to the viewer. Using certain stimuli in a CVEP paradigm, it is possible to observe the function of distinct visual networks such as the ventral stream, involved in processing form and color, or parvocellular and magnocellular input6,7,8, and the dorsal stream, which largely processes motion or magnocellular input9,10. CVEPs generated by these networks have been useful not only in better understanding typical neurophysiologic mechanisms underlying behavior but also in the targeted treatment of atypical behaviors in clinical populations. For example, delayed CVEP components in both dorsal and ventral networks have been reported in children with dyslexia, which suggests that visual function in both these networks should be targeted when designing an intervention plan11.&#160; Thus, CVEPs recorded via EEG offer a powerful clinical tool through which to assess both typical and atypical visual processes.&#160;
In a recent study, high-density EEG was used to measure the apparent motion-onset CVEPs in typically developing children, with the goal of examining variable CVEP responses and related visual cortical generators across development. Participants passively viewed apparent motion stimuli12,13,14,15, which consisted of both shape&#160;change and motion,&#160;designed to simultaneously stimulate dorsal and ventral streams. It was found that approximately half of the children responded with a CVEP waveform shape, or morphology, consisting of three peaks (P1-N1-P2, pattern A).&#160; This morphology is a classic CVEP response observed throughout the literature. In contrast, the other half of the children presented with a morphological pattern comprised of five peaks (P1-N1a-P2a-N1b-P2b, pattern B). To our knowledge, the robust occurrence and comparison of these morphological patterns have not previously been discussed in CVEP literature in either child or adult populations, although variable morphology has been noted in both apparent-motion and motion-onset CVEPs14,16. Furthermore, these morphological differences would not have been apparent in research using other cortical functional assessment methods, such as fMRI or PET, due to the low temporal resolution of these measures.
To determine the cortical generators of each peak in CVEP patterns A and B, source localization analyses were performed, which is a statistical approach used to estimate the most likely cortical regions involved in the CVEP response12,13. For each peak, regardless of the morphological pattern, primary and higher-order visual cortices were identified as sources of the CVEP signal.&#160; Thus, it appears that the main difference underlying CVEP morphology elicited by apparent motion is that those with pattern B activate visual cortical regions additional times during processing. Because these types of patterns have not been previously identified in the literature, the purpose of the additional visual processing in those with CVEP pattern B remains unclear.&#160; Therefore, the next aim in this line of research is to gain a better understanding of the cause of the differential CVEP morphology and whether such patterns may relate to visual behavior in both typical and clinical populations.&#160;
The first step in understanding why some individuals might demonstrate one CVEP morphology versus another is to determine whether these responses are intrinsic or extrinsic in nature.&#160; In other words, if an individual demonstrates one pattern in response to a visual stimulus, will they respond with a similar pattern to all stimuli?&#160; Or is this response stimulus-dependent, specific to the visual network or networks activated?
To answer this question, two passive visual paradigms were designed, intended to separately activate specific visual networks. The stimulus presented in the initial study was designed to stimulate both dorsal and ventral streams simultaneously; thus, it was unknown if one or both networks were involved in generating specific waveform morphology. In the current methodological approach, the paradigm designed to stimulate the ventral stream is composed of highly identifiable objects in basic shapes of squares and circles, eliciting object-onset CVEPs. The paradigm designed to stimulate the dorsal stream consists of visual motion via a radial field of coherent central dot motion dots at a fixed speed toward a fixation point, eliciting motion-onset CVEPs.&#160;
A second question that arose as a result of the initial study was whether differential VEP morphology could be due to participant anticipation of upcoming stimuli13. For instance, research has shown that top-down cortical oscillatory activity occurring prior to a target stimulus may predict subsequent CVEP and behavioral responses to some degree17,18,19. The apparent motion paradigm in the first study employed non-randomized frames of a radial star and circle with consistent inter-stimulus intervals (ISIs) of 600 ms. This design may have encouraged the expectation and prediction of the upcoming stimulus, with resulting oscillatory activity affecting subsequent CVEP morphology12,13,19.&#160;&#160;
To address this issue, the visual object and motion paradigms in the current protocol are designed with both consistent ISIs of the same temporal value and randomized ISIs with different temporal values (i.e., jitter).&#160; Using this approach, it may be possible to determine how temporal variation can affect VEP morphology within distinct visual networks. Altogether, the aim of the described protocol is to determine if the visual object and motion stimuli would be sensitive to variations in CVEP morphology and whether the temporal variation of stimuli presentation would affect characteristics of the CVEP response, including peak latency, amplitude, and morphology. For the purpose of the current paper, the goal is to determine the feasibility of the methodological approach. It is hypothesized that both visual objects and motion may elicit variable morphology (i.e., patterns A and B will be observed across subjects in response to both stimuli) and that temporal variation would affect object-onset and motion-onset CVEP components.&#160;

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			<td height="21" style="height:21px;width:216px;">E-Prime 2.0</td>
			<td style="width:240px;">Psychology Software Tools, Inc</td>
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			<td style="width:279px;">Used in data acquisition</td>
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			<td height="21" style="height:21px;width:216px;">Net Amps 400</td>
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			<td height="21" style="height:21px;width:216px;">iMac (27-inch)</td>
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			<td>Used in data acquisition</td>
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			<td height="21" style="height:21px;width:216px;">Optiplex 7020 Computer</td>
			<td style="width:240px;">Dell</td>
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			<td>Stimulus computer</td>
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			<td height="21" style="height:21px;width:216px;">HydroCel GSN EEG net</td>
			<td style="width:240px;">Electrical Geodesics, Inc</td>
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			<td>Used in data acqusition</td>
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			<td height="21" style="height:21px;width:216px;">1 ml pipette</td>
			<td style="width:240px;">Electrical Geodesics, Inc</td>
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			<td>Used to lower impedances</td>
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			<td height="21" style="height:21px;width:216px;">Johnson&#39;s Baby Shampoo</td>
			<td style="width:240px;">Johnson &#38; Johnson</td>
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			<td style="width:240px;">Electrical Geodesics, Inc</td>
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			<td>Used in impedance solution</td>
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			<td height="42" style="height:42px;width:216px;">Control III Disinfectant Germicide</td>
			<td style="width:240px;">Control III</td>
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			<td>Used in disinfectant solution</td>
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			<td height="21" style="height:21px;">32-inch LCD monitor&#160;</td>
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			<td>Used to present stimuli</td>
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			<td height="21" style="height:21px;width:216px;">Matlab (R2016b)</td>
			<td style="width:240px;">MathWorks</td>
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			<td>Used in data analysis</td>
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			<td height="63" style="height:63px;width:216px;">EEGlab v14.1.2</td>
			<td style="width:240px;">Swartz Center for Computational Neuroscience, University of California, San Diego</td>
			<td style="width:269px;">https://sccn.ucsd.edu/eeglab/index.php</td>
			<td>Used in data analysis</td>
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			<td height="42" style="height:42px;width:216px;">BOSS Database</td>
			<td style="width:240px;">Bank of Standardized Stimuli</td>
			<td style="width:269px;">https://sites.google.com/site/bosstimuli/</td>
			<td>Used in generation of visual object stimuli&#160;</td>
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			<td height="21" style="height:21px;width:216px;">Psychtoolbox-3</td>
			<td>Psychophysics Toolbox Version 3 (PTB-3)</td>
			<td style="width:269px;">http://psychtoolbox.org/</td>
			<td>Used in generation of visual motion stimuli</td>
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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;

Figure 3 and Figure 4 show the representative object-onset and motion-onset CVEP results of five participants, aged 19-24 years, who passively viewed each visual paradigm. This design allowed observation of CVEP responses elicited by visual objects (with and without jitter) and visual motion (with and without jitter) both within and across subjects according to each condition.&#160; Participant CVEPs were grouped according to the morphological pattern elicited b...

Watch this Scientific Journal Video about Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns at JoVE.com

Stimulus-specific Cortical Visual Evoked Potential Morphological Patterns

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 ...

Using this protocol and future studies with larger sample sizes may determine whether variable cortical visual evoked potential morphology is dependent upon stimulus type, extrinsic, or the viewer, intrinsic. Variable visual evoked potential morphology can only be viewed using the high temporal resolution of EEG, which is also cost-effective, non-invasive, and requires minimal recording time versus other methodologies. Demonstrating the procedure will be Mashhood Nielsen, the lab manager and an undergraduate research assistant from my laboratory.After escorting the participant into the EEG recording room, measure the head circumference of the participant in centimeters, and select the appropriate EEG net size. Measure and mark the midpoint of the scalp for the placement of the reference electrode. Prepare one liter of warm water mixed with five milliliters of baby shampoo and 1, 100 grams of potassium chloride.Place the EEG net in the solution and allow the net to soak in the solution for five minutes. Turn on the stimulus presentation computer and the EEG acquisition computer. Place a towel or other absorbent material around the participant's neck to prevent the solution from dripping onto his or her clothes and instruct the participant to close his or her eyes.Then firmly grip the EEG net with both hands and place it onto the participant's head. Ensure that the net is placed symmetrically on the scalp head, with the reference electrode at the scalp midline point that was measured. Tighten the chin and ocular net lines to ensure a secure connection between the scalp and electrodes.Ask the participant if he or she is comfortable, and if anything needs to be adjusted. Connect the EEG net to the amplifier. Check for the proper electrode impedance values with an average target of 10 kiloohms.To reduce impedance values, use a one milliliter pipette to apply the potassium chloride solution onto the scalp and electrodes that have a high impedance. Continue this process until adequate impedance values across the electrodes are achieved. Instruct the participant to focus on the visual stimuli that will appear on the monitor.The viewing distance is approximately 65 inches. Use a pseudo random number generator to determine the order of presentation for the four visual paradigms, and begin the visual tasks and EEG recording. If ongoing EEG shows high myogenic or exactly 60 hertz activity, pause the experiment to recheck electrode scalp connectivity.Repeat the visual tasks and EEG recording for the visual object paradigm, the visual object with the temporal jitter paradigm, the visual motion paradigm, and the visual motion with temporal jitter paradigm. At the conclusion of the experiment, instruct the participants to close his or her eyes in order to prevent the solution from entering his or her eyes when removing the net. Begin by loosening the chin and ocular net lines.Then slowly remove the net by gently pulling the chin strap up and over the participant's head. Disconnect the EEG net from the amplifier. Begin the disinfection process by placing the EEG cap in and out of a bucket filled with water and rinsing under a faucet.Then, prepare the disinfectant solution by adding approximately two liters of water to the disinfectant bucket and mixing 15 milliliters of disinfectant with the water. Immerse the sensor end of the net in the disinfectant. Set a timer for two minutes.Continuously plunge the net up and down. Leave the net soaking for another eight minutes. After that, remove the EEG cap from the disinfectant solution.Place the EEG net in and out of the electrode bucket filled with water and under running water to rinse. Repeat the washing four times and allow the net to air dry. To start EEG analyses, using a one hertz high-pass filter, transfer EEG files into MatLab for analysis via the EEGLAB toolbox.Choose the file option from the drop down menu, and click on import data. Select using EEGLAB functions and plugins from the menu. Next, click on the appropriate export file format.Choose edit'from the drop down menu, and select channel locations'to reassign channel locations based on the type of electrode montage. Click on look up locations'and select the ellipse to locate the path of the electrode montage file of interest. To assign pre-and post-stimulus times, enter a value of 0.1 seconds in the start time box.To baseline correct data according to the prestimulus interval, select prestimulus baseline correct'Remove bad channels using probability at a Z-score threshold of 2.5. Verify identification or removal of bad channels by plotting all electrodes. If needed, manually remove channels with mean voltage amplitudes outside of the range of 30 to 30 microvolts.Then, perform artifact rejection by entering values of 100 microvolts and 100 microvolts, and note the channels with voltages outside the range for the entire segments. If they constitute 60%or more of the rejected trials, manually remove these bad channels. Repeat this step as many times as necessary.Following the artifact removal steps, ensure that a minimum of 100 sweeps are accepted. Then, plot the channels of interest to categorize morphological patterns. If cVEP morphology is characterized by a large positive peak at approximately 100 to 115 milliseconds p1, followed by a negative peak at approximately 140 to 180 milliseconds n1, and a positive peak at approximately 165 to 240 milliseconds p2, choose Pattern A.If cVEP morphology is characterized by positive and negative peaks at approximately 100 to 115 milliseconds p1, 140 to 180 milliseconds n1a, 180 to 240 milliseconds p2a, 230 to 280 milliseconds n1b, and 260 to 350 milliseconds p2b, choose Pattern B.To create a group average, append individual data sets together according to the morphological pattern visually observed.Name and save the newly merged data set file. The object onset cVEP results of five participants aged 19 to 24 years, who passively viewed each visual paradigm, are obtained. In the objects with no temporal jitter condition, two participants were found to present with Pattern A, while three presented with pattern B.Similarly, in the objects with temporal jitter condition, two subjects presented with Pattern A, and three with Pattern B.It may also be observed that jitter effects amplitude and latency in each object onset cVEP pattern.However, in contrast to the object onset cVEPs, motion onset cVEP morphological patterns for each participant were consistent across jitter condition. Furthermore, the Pattern B group average shows no clear evidence of the multiple peak components, typically present for both with and without temporal jitter. Similar to the objects paradigm, jitter in the motion paradigm appears to affect motion onset cVEP characteristics in both morphological patterns.Categorization of cVEP morphology is not currently performed. But morphological patterns can reflect specific visual cortical processes. Consideration of these patterns may clarify underlying neurophysiological function related to behavior.Magnetoencephalography, or MEG, may provide complimentary temporal information regarding visual evoke potentials. While simultaneous FMRI assessment could provide high spatial resolution concerning differential cortical network activation related to morphology. If electrodes are positioned inappropriately and/or impedances are high, interpretation of data will be difficult and possibly meaningless.When disinfecting the net, remember to be careful with the disinfectant, and do not get it close to the eyes. Dispose of it properly.

Research

JoVE Journal

Neuroscience

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