Isolating Discriminant Neural Activity in the Presence of Eye Movements and Concurrent Task Demands
A growing number of studies use the combination of eye-tracking and electroencephalographic (EEG) measures to explore the neural processes that underlie visual perception. In these studies, fixation-related potentials (FRPs) are commonly used to quantify early and late stages of visual processing th...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2017-07-01
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| Series: | Frontiers in Human Neuroscience |
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| Online Access: | http://journal.frontiersin.org/article/10.3389/fnhum.2017.00357/full |
| _version_ | 1819063673793019904 |
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| author | Jon Touryan Vernon J. Lawhern Patrick M. Connolly Nima Bigdely-Shamlo Anthony J. Ries |
| author_facet | Jon Touryan Vernon J. Lawhern Patrick M. Connolly Nima Bigdely-Shamlo Anthony J. Ries |
| author_sort | Jon Touryan |
| collection | DOAJ |
| description | A growing number of studies use the combination of eye-tracking and electroencephalographic (EEG) measures to explore the neural processes that underlie visual perception. In these studies, fixation-related potentials (FRPs) are commonly used to quantify early and late stages of visual processing that follow the onset of each fixation. However, FRPs reflect a mixture of bottom-up (sensory-driven) and top-down (goal-directed) processes, in addition to eye movement artifacts and unrelated neural activity. At present there is little consensus on how to separate this evoked response into its constituent elements. In this study we sought to isolate the neural sources of target detection in the presence of eye movements and over a range of concurrent task demands. Here, participants were asked to identify visual targets (Ts) amongst a grid of distractor stimuli (Ls), while simultaneously performing an auditory N-back task. To identify the discriminant activity, we used independent components analysis (ICA) for the separation of EEG into neural and non-neural sources. We then further separated the neural sources, using a modified measure-projection approach, into six regions of interest (ROIs): occipital, fusiform, temporal, parietal, cingulate, and frontal cortices. Using activity from these ROIs, we identified target from non-target fixations in all participants at a level similar to other state-of-the-art classification techniques. Importantly, we isolated the time course and spectral features of this discriminant activity in each ROI. In addition, we were able to quantify the effect of cognitive load on both fixation-locked potential and classification performance across regions. Together, our results show the utility of a measure-projection approach for separating task-relevant neural activity into meaningful ROIs within more complex contexts that include eye movements. |
| first_indexed | 2024-12-21T15:18:25Z |
| format | Article |
| id | doaj.art-1496efd878264011a3ee51e9d30f6394 |
| institution | Directory Open Access Journal |
| issn | 1662-5161 |
| language | English |
| last_indexed | 2024-12-21T15:18:25Z |
| publishDate | 2017-07-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Human Neuroscience |
| spelling | doaj.art-1496efd878264011a3ee51e9d30f63942022-12-21T18:59:05ZengFrontiers Media S.A.Frontiers in Human Neuroscience1662-51612017-07-011110.3389/fnhum.2017.00357253617Isolating Discriminant Neural Activity in the Presence of Eye Movements and Concurrent Task DemandsJon Touryan0Vernon J. Lawhern1Patrick M. Connolly2Nima Bigdely-Shamlo3Anthony J. Ries4U.S. Army Research Laboratory, Future Soldier Technologies Division, Human Research and Engineering Directorate, Aberdeen Proving GroundAberdeen, MD, United StatesU.S. Army Research Laboratory, Future Soldier Technologies Division, Human Research and Engineering Directorate, Aberdeen Proving GroundAberdeen, MD, United StatesTeledyne Scientific CompanyDurham, NC, United StatesQusp LabsSan Diego, CA, United StatesU.S. Army Research Laboratory, Future Soldier Technologies Division, Human Research and Engineering Directorate, Aberdeen Proving GroundAberdeen, MD, United StatesA growing number of studies use the combination of eye-tracking and electroencephalographic (EEG) measures to explore the neural processes that underlie visual perception. In these studies, fixation-related potentials (FRPs) are commonly used to quantify early and late stages of visual processing that follow the onset of each fixation. However, FRPs reflect a mixture of bottom-up (sensory-driven) and top-down (goal-directed) processes, in addition to eye movement artifacts and unrelated neural activity. At present there is little consensus on how to separate this evoked response into its constituent elements. In this study we sought to isolate the neural sources of target detection in the presence of eye movements and over a range of concurrent task demands. Here, participants were asked to identify visual targets (Ts) amongst a grid of distractor stimuli (Ls), while simultaneously performing an auditory N-back task. To identify the discriminant activity, we used independent components analysis (ICA) for the separation of EEG into neural and non-neural sources. We then further separated the neural sources, using a modified measure-projection approach, into six regions of interest (ROIs): occipital, fusiform, temporal, parietal, cingulate, and frontal cortices. Using activity from these ROIs, we identified target from non-target fixations in all participants at a level similar to other state-of-the-art classification techniques. Importantly, we isolated the time course and spectral features of this discriminant activity in each ROI. In addition, we were able to quantify the effect of cognitive load on both fixation-locked potential and classification performance across regions. Together, our results show the utility of a measure-projection approach for separating task-relevant neural activity into meaningful ROIs within more complex contexts that include eye movements.http://journal.frontiersin.org/article/10.3389/fnhum.2017.00357/fullfixation-related potentialsEEGeye trackingtarget detectioncognitive load |
| spellingShingle | Jon Touryan Vernon J. Lawhern Patrick M. Connolly Nima Bigdely-Shamlo Anthony J. Ries Isolating Discriminant Neural Activity in the Presence of Eye Movements and Concurrent Task Demands Frontiers in Human Neuroscience fixation-related potentials EEG eye tracking target detection cognitive load |
| title | Isolating Discriminant Neural Activity in the Presence of Eye Movements and Concurrent Task Demands |
| title_full | Isolating Discriminant Neural Activity in the Presence of Eye Movements and Concurrent Task Demands |
| title_fullStr | Isolating Discriminant Neural Activity in the Presence of Eye Movements and Concurrent Task Demands |
| title_full_unstemmed | Isolating Discriminant Neural Activity in the Presence of Eye Movements and Concurrent Task Demands |
| title_short | Isolating Discriminant Neural Activity in the Presence of Eye Movements and Concurrent Task Demands |
| title_sort | isolating discriminant neural activity in the presence of eye movements and concurrent task demands |
| topic | fixation-related potentials EEG eye tracking target detection cognitive load |
| url | http://journal.frontiersin.org/article/10.3389/fnhum.2017.00357/full |
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