Fractionation of frontal lobe functions in the attentional blink

• ¹ Beth Israel Deaconess Medical Center, United States
• ² Rotman Research Institute, Baycrest, Canada
• ³ St. Michael's Hospital, Keenan Research Centre, Canada

Dual-task rapid serial visual presentation (RSVP) paradigms elicit well-defined temporal gaps in attention selection known as the ‘attentional blink’ (AB); this interference effect is greater in the presence of frontal lobe injury [1,2]. The purpose of this study was to investigate further frontal lobe attentional effects by analyzing the effect of lesion location and manipulations in task demands. Two versions of a 2-target identification AB task were administered to 20 focal lesion patients, 14 lateral frontal (4 Left -LL, 10 Right -RL) and 6 non-frontal (NF), and 23 healthy controls (CTL). A traditional version (Un-speeded) allowed for response to both targets at the end of the visual stream and a second version (Speeded) required an immediate response to the first target. There was a behavioural dissociation between the right and left lateral frontal groups: RL -greater interference compared to the LL and CTL groups on the Un-speeded task, with improvement mediated by the response demands of the Speeded condition: LL – impaired on the Speeded condition, with gradual improvement during the course of the task to match their normal accuracy rates on the Unspeeded task. The NF were similar to CTL on both tasks. These results support the presence of differential frontal attentional processes. A single task manipulation aided in the RL online monitoring of task performance, but disrupted the LL ability to set task instructions. An additional case study of a patient with damage to the superior medial frontal lobe will be presented as an illustration of decreases in the facilitation of frontal energization due to task manipulations of time and complexity.