Pressure center - it builds a pressure that seeks release: pressure to think (Head) or pressure to act (Root).
When Defined
When the Head center is defined, you have a consistent source of mental inspiration and pressure to think, question, and wonder. You are a source of inspiration for others, generating questions and ideas that stimulate mental exploration. You have a reliable way of processing doubt, confusion, and mental curiosity. Your thinking patterns are fixed and consistent - you know what inspires you and what questions drive your mind.
When Open
When the Head center is undefined (open), you are open to being inspired by many different sources and ideas. You can become overwhelmed by mental pressure - trying to answer questions that aren't yours to answer. You may feel pressure to figure things out or be stuck in overthinking. The wisdom of an open Head is learning to let go of mental pressure that doesn't belong to you and to enjoy inspiration without needing to act on every idea.
Biological Correlation
Pineal gland - regulates melatonin production and circadian rhythms; connected to higher consciousness and inspiration