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Neural Differences between Covert and Overt Attention Studied using EEG with Simultaneous Remote Eye Tracking

View Article: PubMed Central - PubMed

ABSTRACT

Research on neural mechanisms of attention has generally instructed subjects to direct attention covertly while maintaining a fixed gaze. This study combined simultaneous eye tracking and electroencephalogram (EEG) to measure neural attention responses during exogenous cueing in overt attention shifts (with saccadic eye movements to a target) and compared these with covert attention shifts (responding manually while maintaining central fixation). EEG analysis of the period preceding the saccade latency showed similar occipital response amplitudes for overt and covert shifts, although response latencies differed. However, a frontal positivity was greater during covert attention shifts, possibly reflecting saccade inhibition to maintain fixation. The results show that combined EEG and eye tracking can be successfully used to study natural overt shifts of attention (applicable to non-verbal infants) and that requiring inhibition of saccades can lead to additional frontal responses. Such data can be used to refine current neural models of attention that have been mainly based on covert shifts.

No MeSH data available.


Related in: MedlinePlus

Topographical plots of EEG responses in single (top) and double (bottom) target conditions averaged across all subjects. The electrode clusters extracted for analyses are marked in orange (frontal cluster around FC3 [EGI 12, 13, 19, 24, 20, 28, 29] and FC4 [EGI 4, 5, 111, 112, 117, 118, 124]) and purple (occipital cluster O1 [EGI electrodes 65, 66, 70, 71, 69, 74] and O2 [EGI electrodes 90, 84, 76, 83, 82, 89]) in the first plot. A posterior response to single targets on the left (left plots) and right (right plots) side of the screen is more pronounced in the ipsilateral hemisphere for both saccades (top) and manual responses (bottom) and coincides with a fronto-central negativity. Double target trials in which subjects subsequently responded to the right (right plots) or left (left plots) target show a late frontal positivity coinciding with a posterior negativity for both saccades (top) and manual responses (bottom) that is not lateralized with respect to the selected target but slightly more pronounced in the left side of the brain.
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Figure 4: Topographical plots of EEG responses in single (top) and double (bottom) target conditions averaged across all subjects. The electrode clusters extracted for analyses are marked in orange (frontal cluster around FC3 [EGI 12, 13, 19, 24, 20, 28, 29] and FC4 [EGI 4, 5, 111, 112, 117, 118, 124]) and purple (occipital cluster O1 [EGI electrodes 65, 66, 70, 71, 69, 74] and O2 [EGI electrodes 90, 84, 76, 83, 82, 89]) in the first plot. A posterior response to single targets on the left (left plots) and right (right plots) side of the screen is more pronounced in the ipsilateral hemisphere for both saccades (top) and manual responses (bottom) and coincides with a fronto-central negativity. Double target trials in which subjects subsequently responded to the right (right plots) or left (left plots) target show a late frontal positivity coinciding with a posterior negativity for both saccades (top) and manual responses (bottom) that is not lateralized with respect to the selected target but slightly more pronounced in the left side of the brain.

Mentions: The most prominent neural responses in the extracted time window were an occipital positivity that peaked in contralateral areas first, followed by a greater ipsilateral positivity, coinciding with a frontal negativity. In covert attention shift trials and in double target conditions, there was also a frontal positivity peaking towards the end of the extracted time window (Figure 4). ERPs were further analyzed using mixed linear models, including subjects as random effects and response type, number of targets, brain hemisphere and brain side as factors, including also their interactions.


Neural Differences between Covert and Overt Attention Studied using EEG with Simultaneous Remote Eye Tracking
Topographical plots of EEG responses in single (top) and double (bottom) target conditions averaged across all subjects. The electrode clusters extracted for analyses are marked in orange (frontal cluster around FC3 [EGI 12, 13, 19, 24, 20, 28, 29] and FC4 [EGI 4, 5, 111, 112, 117, 118, 124]) and purple (occipital cluster O1 [EGI electrodes 65, 66, 70, 71, 69, 74] and O2 [EGI electrodes 90, 84, 76, 83, 82, 89]) in the first plot. A posterior response to single targets on the left (left plots) and right (right plots) side of the screen is more pronounced in the ipsilateral hemisphere for both saccades (top) and manual responses (bottom) and coincides with a fronto-central negativity. Double target trials in which subjects subsequently responded to the right (right plots) or left (left plots) target show a late frontal positivity coinciding with a posterior negativity for both saccades (top) and manual responses (bottom) that is not lateralized with respect to the selected target but slightly more pronounced in the left side of the brain.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5120114&req=5

Figure 4: Topographical plots of EEG responses in single (top) and double (bottom) target conditions averaged across all subjects. The electrode clusters extracted for analyses are marked in orange (frontal cluster around FC3 [EGI 12, 13, 19, 24, 20, 28, 29] and FC4 [EGI 4, 5, 111, 112, 117, 118, 124]) and purple (occipital cluster O1 [EGI electrodes 65, 66, 70, 71, 69, 74] and O2 [EGI electrodes 90, 84, 76, 83, 82, 89]) in the first plot. A posterior response to single targets on the left (left plots) and right (right plots) side of the screen is more pronounced in the ipsilateral hemisphere for both saccades (top) and manual responses (bottom) and coincides with a fronto-central negativity. Double target trials in which subjects subsequently responded to the right (right plots) or left (left plots) target show a late frontal positivity coinciding with a posterior negativity for both saccades (top) and manual responses (bottom) that is not lateralized with respect to the selected target but slightly more pronounced in the left side of the brain.
Mentions: The most prominent neural responses in the extracted time window were an occipital positivity that peaked in contralateral areas first, followed by a greater ipsilateral positivity, coinciding with a frontal negativity. In covert attention shift trials and in double target conditions, there was also a frontal positivity peaking towards the end of the extracted time window (Figure 4). ERPs were further analyzed using mixed linear models, including subjects as random effects and response type, number of targets, brain hemisphere and brain side as factors, including also their interactions.

View Article: PubMed Central - PubMed

ABSTRACT

Research on neural mechanisms of attention has generally instructed subjects to direct attention covertly while maintaining a fixed gaze. This study combined simultaneous eye tracking and electroencephalogram (EEG) to measure neural attention responses during exogenous cueing in overt attention shifts (with saccadic eye movements to a target) and compared these with covert attention shifts (responding manually while maintaining central fixation). EEG analysis of the period preceding the saccade latency showed similar occipital response amplitudes for overt and covert shifts, although response latencies differed. However, a frontal positivity was greater during covert attention shifts, possibly reflecting saccade inhibition to maintain fixation. The results show that combined EEG and eye tracking can be successfully used to study natural overt shifts of attention (applicable to non-verbal infants) and that requiring inhibition of saccades can lead to additional frontal responses. Such data can be used to refine current neural models of attention that have been mainly based on covert shifts.

No MeSH data available.


Related in: MedlinePlus