ABC seminar: Imaging the young brain – top-down control of sensory information processing

Human brain development continues up to young adulthood and goes hand in hand/concord with cognitive maturation. A talk by Prof. Synnöve Carlson.

Human brain development involving structural and functional changes continues up to young adulthood and goes hand in hand/concord with cognitive maturation. The prefrontal cortex (PFC) is thought to have a central role in executive funtions and top-down regulation of activity in posterior cortical areas, and is one of the cortical areas that matures late. However, relatively little is still known about the development of neural mechanisms underlying executive functions and top-down regulation of brain responses. We studied the dynamic interactions between the PFC and the visual association cortex and amygdala in 7-11-year-old children and adolescents while they performed tasks requiring attention and distraction handling. We measured the blood-oxygen-level-dependent signal changes in the face-selective fusiform face area (FFA), scene-selective visual cortical areas (the parahippocampal place area, PPA; the retrosplenial complex, RSC) and in amygdala, while subjects directed attention to either faces or scenes, memorized them and tried to ignore distractive scene or face stimuli, respectively. Our studies indicate that directed attention to one type of visual stimuli and suppression of another type of stimuli modulates activity in target visual cortical areas in both children and adults. Children, compared to adults, activated subareas of the PFC more during the tasks, showed a different pattern of attentional modulation of activity in the visual association cortices and amygdala, and exhibited weaker functional connectivity between the PFC and FFA, and differential connectivity between PFC and amygdala. We also probed the role of the PFC in top-down regulation of activity in adults by navigated transcranial magnetic stimulation (TMS) that was aimed at tractography-informed locations in the PFC. Perturbation of the PFC with TMS provided causal evidence of the role of PFC in top-down regulation of sensory activity in adults.

Together these studies emphasize the role of PFC in top-down regulation of brain activity and show that dynamic interactions between the PFC and the visual association cortex and amygdala are still immature in 7-11-year-old children. - Although great progress has been made in understanding the challenges of developmental brain imaging, still many questions related to e.g. data analysis and interpretation of results need to be addressed.