Anatomy and cytoarchitectonics of the human hypothalamus

Due to the complexity of hypothalamic functions, the organization of the hypothalamus is extremely intricate. This relatively small brain area contains several nuclei, most of them are ill-defined regions without distinct boundaries; these nuclei are often connected with each other and other distant brain regions with similarly indistinct pathways. These hypothalamic centers control numerous key physiological functions including reproduction, growth, food intake, circadian rhythm, behavior, and autonomic balance via neural and endocrine signals. To understand the morphology of the hypothalamus is therefore extremely important, though it remains a stupendous task due to the complex organization of neuronal networks formed by the various neurotransmitter and neuromodulator systems.