This study aims to learn how blood flow and metabolism affect brain development in children. We use a machine called MRI (Magnetic Resonance Imaging) to take pictures of the brain. These pictures help us see how blood vessels in the brain expand and contract to provide oxygen when needed. This process is important for brain growth and can be affected by illness or stress. If the brain doesn't get enough oxygen, it might not develop properly and could even lead to a stroke, a serious condition where part of the brain is damaged.

During the study, participants may have a blood test, an MRI, and other tests to see how their brain responds. They might also breathe in a small amount of carbon dioxide, which helps blood vessels expand without harming the brain. This is done safely using a special mask.

• The study is for children aged 3-50 who can have an MRI without needing sedation.
• Participants should not be pregnant or have a history of stroke or serious psychiatric conditions.
• Special equipment ensures safe carbon dioxide levels during tests.