Spatiotemporal analysis of category and target-related information processing in the brain during object detection.

To recognize a target object, the brain implements strategies which involve a combination of externally sensory-driven and internally task-driven mechanisms. While several studies have suggested a role for frontal brain areas in enhancing task-related representations in visual cortices, especially in the lateral-occipital cortex, they have remained silent about the type of information transferred to visual areas. However, the recently developed methods of representational connectivity analysis, allowed us to track the movement of different types of information in the brain. Accordingly, we designed an EEG object detection experiment and inspected the spatiotemporal dynamics of category- and target-related information across the brain. Results showed that the prefrontal area initiated the processing of target-related information. This information was then transferred to posterior brain areas during stimulus presentation probably to facilitate object detection and to direct the decision-making procedure. We also observed that, as compared to category-related information, the target-related information could predict the behavioral performance more accurately, suggesting the dominant representation of internal compared to external information in brain signals. These results provided new evidence about the role of prefrontal cortices in the processing of task-related information in the brain during object detection.