The study by Sowell et al. (1999) investigates the post-adolescent brain maturation in frontal and striatal regions using high-resolution structural magnetic resonance images (MRI). The researchers mapped brain maturation between adolescence and young adulthood, finding that the pattern of maturation during this period was distinct from earlier development. Key findings include: 1. **Spatial and Temporal Pattern**: The maturation was localized to large regions of dorsal, medial, and orbital frontal cortex and lenticular nuclei, with minimal change in other areas. 2. **Cognitive Functions**: The findings align with post-mortem studies and cognitive functions attributed to frontal structures, suggesting that the continued development of these regions is crucial for cognitive functions. 3. **MRI Methodology**: The study used voxel-by-voxel statistical analysis to map brain changes, focusing on gray matter density reductions. 4. **Regional Differences**: Significant changes were observed in the frontal lobes, particularly in the subcortical region, with less change in parietal, temporal, and occipital lobes. 5. **Functional Implications**: The observed changes in gray matter density in the frontal and striatal regions are likely related to improved cognitive processing and learning, which continues to develop into young adulthood. The study provides in vivo evidence for the temporal and spatial progression of post-adolescent maturation in the frontal lobes, highlighting the importance of these regions for adult cognition.The study by Sowell et al. (1999) investigates the post-adolescent brain maturation in frontal and striatal regions using high-resolution structural magnetic resonance images (MRI). The researchers mapped brain maturation between adolescence and young adulthood, finding that the pattern of maturation during this period was distinct from earlier development. Key findings include: 1. **Spatial and Temporal Pattern**: The maturation was localized to large regions of dorsal, medial, and orbital frontal cortex and lenticular nuclei, with minimal change in other areas. 2. **Cognitive Functions**: The findings align with post-mortem studies and cognitive functions attributed to frontal structures, suggesting that the continued development of these regions is crucial for cognitive functions. 3. **MRI Methodology**: The study used voxel-by-voxel statistical analysis to map brain changes, focusing on gray matter density reductions. 4. **Regional Differences**: Significant changes were observed in the frontal lobes, particularly in the subcortical region, with less change in parietal, temporal, and occipital lobes. 5. **Functional Implications**: The observed changes in gray matter density in the frontal and striatal regions are likely related to improved cognitive processing and learning, which continues to develop into young adulthood. The study provides in vivo evidence for the temporal and spatial progression of post-adolescent maturation in the frontal lobes, highlighting the importance of these regions for adult cognition.