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Timing and sequence of brain activity in top-down control of visual-spatial attention.

Grent-'t-Jong T, Woldorff MG - PLoS Biol. (2007)

Bottom Line: These results indicate an activation sequence of key components of the attentional-control brain network, providing insight into their functional roles.More specifically, these results suggest that voluntary attentional orienting is initiated by medial portions of frontal cortex, which then recruit medial parietal areas.Together, these areas then implement biasing of region-specific visual-sensory cortex to facilitate the processing of upcoming visual stimuli.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience, Duke University, Durham, North Carolina, United States of America.

ABSTRACT
Recent brain imaging studies using functional magnetic resonance imaging (fMRI) have implicated a frontal-parietal network in the top-down control of attention. However, little is known about the timing and sequence of activations within this network. To investigate these timing questions, we used event-related electrical brain potentials (ERPs) and a specially designed visual-spatial attentional-cueing paradigm, which were applied as part of a multi-methodological approach that included a closely corresponding event-related fMRI study using an identical paradigm. In the first 400 ms post cue, attention-directing and control cues elicited similar general cue-processing activity, corresponding to the more lateral subregions of the frontal-parietal network identified with the fMRI. Following this, the attention-directing cues elicited a sustained negative-polarity brain wave that was absent for control cues. This activity could be linked to the more medial frontal-parietal subregions similarly identified in the fMRI as specifically involved in attentional orienting. Critically, both the scalp ERPs and the fMRI-seeded source modeling for this orienting-related activity indicated an earlier onset of frontal versus parietal contribution ( approximately 400 versus approximately 700 ms). This was then followed ( approximately 800-900 ms) by pretarget biasing activity in the region-specific visual-sensory occipital cortex. These results indicate an activation sequence of key components of the attentional-control brain network, providing insight into their functional roles. More specifically, these results suggest that voluntary attentional orienting is initiated by medial portions of frontal cortex, which then recruit medial parietal areas. Together, these areas then implement biasing of region-specific visual-sensory cortex to facilitate the processing of upcoming visual stimuli.

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Pretarget Visual Cortex BiasingGrand-average (n = 13) ERP topographic plots (back view) time locked to attend-left cues (upper left row), attend-right cues (middle left row), and the difference-wave plots for the attend-left cues minus the attend-right cues (lower left row), averaged over 200-ms bins, starting 500 ms post-cue until the onset of late targets at 1,900 ms. The far right column shows N1 latency back-view topographic plots for left targets (upper right), right targets (middle right), and the left-minus-right target difference wave (lower right). All target-related activity is corrected for overlap from previous cue activity. Note the build up and then maintenance of the biasing-related negativity BRN over the occipital cortex contralateral to the direction of attention, and also note the similarity of the scalp-potential distributions of this biasing-related activity to the N1 differences between left and right targets.
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pbio-0050012-g005: Pretarget Visual Cortex BiasingGrand-average (n = 13) ERP topographic plots (back view) time locked to attend-left cues (upper left row), attend-right cues (middle left row), and the difference-wave plots for the attend-left cues minus the attend-right cues (lower left row), averaged over 200-ms bins, starting 500 ms post-cue until the onset of late targets at 1,900 ms. The far right column shows N1 latency back-view topographic plots for left targets (upper right), right targets (middle right), and the left-minus-right target difference wave (lower right). All target-related activity is corrected for overlap from previous cue activity. Note the build up and then maintenance of the biasing-related negativity BRN over the occipital cortex contralateral to the direction of attention, and also note the similarity of the scalp-potential distributions of this biasing-related activity to the N1 differences between left and right targets.

Mentions: Figure 5 shows back-view topographic plots of the activity triggered by the attention-directing cues in 200-ms bins between 500–1,900 ms post-cue, separately for attend-left and attend-right cues (two top rows). This figure suggests a relative enhancement of negative-wave activity over posterior scalp sites contralateral to the direction of attention, in addition to the large, superior, bilateral negativity reaching back to parietal sites that was discussed above. The contralaterality of this effect (relative to the direction of attention) over occipital sites can be seen more clearly in the difference waves computed from ERP responses to the attend-left–minus–attend-right cues (bottom row), with this subtraction resulting in a relative negativity over the right occipital cortex and a corresponding relative positivity over the left occipital cortex. This attend-left–minus–attend-right cue-related difference activity of contralateral negativity and ipsilateral positivity with respect to the direction of attention can be seen to begin at around 700 ms post-cue and to build up in strength over time until the onset time of the possible late target presentation. At the right side of the figure (far right column), topographic plots of a corresponding subtraction of the responses to left and right targets are displayed for the N1-latency window (corrected for overlap from preceding cue-related activity; see Methods). Comparing, it can be seen that the pattern of differential hemispheric activity elicited by the cues prior to target occurrence showed a strikingly similar scalp-potential distribution to the post-target N1 difference-wave activity. Because this activity matches the idea of preparatory activity building up over time in areas later recruited for target processing, we have termed this activity a biasing-related negativity (BRN).


Timing and sequence of brain activity in top-down control of visual-spatial attention.

Grent-'t-Jong T, Woldorff MG - PLoS Biol. (2007)

Pretarget Visual Cortex BiasingGrand-average (n = 13) ERP topographic plots (back view) time locked to attend-left cues (upper left row), attend-right cues (middle left row), and the difference-wave plots for the attend-left cues minus the attend-right cues (lower left row), averaged over 200-ms bins, starting 500 ms post-cue until the onset of late targets at 1,900 ms. The far right column shows N1 latency back-view topographic plots for left targets (upper right), right targets (middle right), and the left-minus-right target difference wave (lower right). All target-related activity is corrected for overlap from previous cue activity. Note the build up and then maintenance of the biasing-related negativity BRN over the occipital cortex contralateral to the direction of attention, and also note the similarity of the scalp-potential distributions of this biasing-related activity to the N1 differences between left and right targets.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1761048&req=5

pbio-0050012-g005: Pretarget Visual Cortex BiasingGrand-average (n = 13) ERP topographic plots (back view) time locked to attend-left cues (upper left row), attend-right cues (middle left row), and the difference-wave plots for the attend-left cues minus the attend-right cues (lower left row), averaged over 200-ms bins, starting 500 ms post-cue until the onset of late targets at 1,900 ms. The far right column shows N1 latency back-view topographic plots for left targets (upper right), right targets (middle right), and the left-minus-right target difference wave (lower right). All target-related activity is corrected for overlap from previous cue activity. Note the build up and then maintenance of the biasing-related negativity BRN over the occipital cortex contralateral to the direction of attention, and also note the similarity of the scalp-potential distributions of this biasing-related activity to the N1 differences between left and right targets.
Mentions: Figure 5 shows back-view topographic plots of the activity triggered by the attention-directing cues in 200-ms bins between 500–1,900 ms post-cue, separately for attend-left and attend-right cues (two top rows). This figure suggests a relative enhancement of negative-wave activity over posterior scalp sites contralateral to the direction of attention, in addition to the large, superior, bilateral negativity reaching back to parietal sites that was discussed above. The contralaterality of this effect (relative to the direction of attention) over occipital sites can be seen more clearly in the difference waves computed from ERP responses to the attend-left–minus–attend-right cues (bottom row), with this subtraction resulting in a relative negativity over the right occipital cortex and a corresponding relative positivity over the left occipital cortex. This attend-left–minus–attend-right cue-related difference activity of contralateral negativity and ipsilateral positivity with respect to the direction of attention can be seen to begin at around 700 ms post-cue and to build up in strength over time until the onset time of the possible late target presentation. At the right side of the figure (far right column), topographic plots of a corresponding subtraction of the responses to left and right targets are displayed for the N1-latency window (corrected for overlap from preceding cue-related activity; see Methods). Comparing, it can be seen that the pattern of differential hemispheric activity elicited by the cues prior to target occurrence showed a strikingly similar scalp-potential distribution to the post-target N1 difference-wave activity. Because this activity matches the idea of preparatory activity building up over time in areas later recruited for target processing, we have termed this activity a biasing-related negativity (BRN).

Bottom Line: These results indicate an activation sequence of key components of the attentional-control brain network, providing insight into their functional roles.More specifically, these results suggest that voluntary attentional orienting is initiated by medial portions of frontal cortex, which then recruit medial parietal areas.Together, these areas then implement biasing of region-specific visual-sensory cortex to facilitate the processing of upcoming visual stimuli.

View Article: PubMed Central - PubMed

Affiliation: Neuroscience, Duke University, Durham, North Carolina, United States of America.

ABSTRACT
Recent brain imaging studies using functional magnetic resonance imaging (fMRI) have implicated a frontal-parietal network in the top-down control of attention. However, little is known about the timing and sequence of activations within this network. To investigate these timing questions, we used event-related electrical brain potentials (ERPs) and a specially designed visual-spatial attentional-cueing paradigm, which were applied as part of a multi-methodological approach that included a closely corresponding event-related fMRI study using an identical paradigm. In the first 400 ms post cue, attention-directing and control cues elicited similar general cue-processing activity, corresponding to the more lateral subregions of the frontal-parietal network identified with the fMRI. Following this, the attention-directing cues elicited a sustained negative-polarity brain wave that was absent for control cues. This activity could be linked to the more medial frontal-parietal subregions similarly identified in the fMRI as specifically involved in attentional orienting. Critically, both the scalp ERPs and the fMRI-seeded source modeling for this orienting-related activity indicated an earlier onset of frontal versus parietal contribution ( approximately 400 versus approximately 700 ms). This was then followed ( approximately 800-900 ms) by pretarget biasing activity in the region-specific visual-sensory occipital cortex. These results indicate an activation sequence of key components of the attentional-control brain network, providing insight into their functional roles. More specifically, these results suggest that voluntary attentional orienting is initiated by medial portions of frontal cortex, which then recruit medial parietal areas. Together, these areas then implement biasing of region-specific visual-sensory cortex to facilitate the processing of upcoming visual stimuli.

Show MeSH