Age-related frontal-parietal changes during the control of bottom-up and top-down attention: an ERP study

Authors:

• Ling Li

• Caterina Gratton

• Monica Fabiani

• Robert T. Knight

Date: 2013

DOI: 10.1016

PubMed: 22459599

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Abstract:

We investigated age-related changes in frontal and parietal scalp event-related potential (ERP) activity during bottom-up and top-down attention. Younger and older participants were presented with arrays constructed to induce either automatic "pop-out" (bottom-up) or effortful "search" (top-down) behavior. Reaction times (RTs) increased and accuracy decreased with age, with a greater age-related decline in accuracy for the search than for the pop-out condition. The latency of the P300 elicited by the visual search array was shorter in both conditions in the younger than in the older adults. Pop-out target detection was associated with greater activity at parietal than at prefrontal locations in younger participants and with a more equipotential prefrontal-parietal distribution in older adults. Search target detection was associated with greater activity at prefrontal than at parietal locations in older relative to younger participants. Thus, aging was associated with a more prefrontal P300 scalp distribution during the control of bottom-up and top-down attention. Early latency extrastriate potentials were enhanced and N2-posterior-contralateral (N2pc) was reduced in the older group, supporting the idea that the frontal enhancements may be due to a compensation for disinhibition and distraction in the older adults. Taken together these findings provide evidence that younger and older adults recruit different frontal-parietal networks during top-down and bottom-up attention, with older adults increasing their recruitment of a more frontally distributed network in both of these types of attention. This work is in accord with previous neuroimaging findings suggesting that older adults recruit more frontal activity in the service of a variety of tasks than younger adults.

Role of frontal and parietal cortices in the control of bottom-up and top-down attention in humans

Authors:

• Li Ling

• Caterina Gratton

• Dezhong Yao

• Robert T. Knight

Date: 2010

DOI: 10.1016/j.brainres.2010.05.016

PubMed: 20470762

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Abstract:

We investigated the contribution of frontal and parietal cortices to bottom-up and top-down visual attention using electrophysiological measures in humans. Stimuli consisted of triangles, each with a different color and orientation. Subjects were presented with a sample triangle which served as the target for that trial. An array was subsequently presented with the target and three additional distractor stimuli, which were constructed to induce either automatic "pop-out" (50%) or effortful "search" (50%) behavior. For pop-out, both the color and orientation of the distractors differed from the target, which attracted attention automatically. For search, only the orientation of the distractors differed from the target, so effortful attention was required. Pop-out target detection generated a P300 event-related potential (ERP) with a peak amplitude over parietal sites whereas the search condition generated a fronto-centrally distributed P300. Reaction times and associated P300 latency in frontal areas were shorter for pop-out targets than for search targets. We used time-frequency analysis to compare pop-out and search conditions, within a 200-650 ms time-window and a 4-55 Hz frequency band. There was a double dissociation, with significantly increased power from 4 to 24 Hz in parietal areas for pop-out targets and increased power from 4 to 24 Hz in frontal regions for search targets. Taken together the ERP and time-frequency results provide evidence that the control of bottom-up and top-down attention depend on differential contributions from parietal and frontal cortices.