Brain

Brain
Gaetan Lee . Tilt corrected by Kaldari. · CC BY 2.0 · source
Name	Brain
Caption	Lateral view of a human brain
Latin	cerebrum, encephalon
System	Nervous system
Arteries	Internal carotid artery, Vertebral artery
Veins	Superior sagittal sinus, Internal jugular vein
Nerves	Cranial nerves

Brain The brain is the central organ of the nervous system responsible for integrating sensory information, generating behavior, and enabling cognition, emotion, and homeostasis. It interacts extensively with the spinal cord, peripheral nervous system, endocrine system, circulatory system, and immune system to regulate physiological functions and complex behaviors observed across taxa from Homo sapiens to invertebrates such as the Drosophila melanogaster and Caenorhabditis elegans. Research into the brain draws on studies from institutions like the National Institutes of Health, the Salk Institute, and the Max Planck Society, and leverages techniques developed at laboratories including the Allen Institute for Brain Science and facilities such as the CERN-backed computing networks for large-scale data analysis.

Anatomy

Gross anatomy distinguishes regions such as the cerebrum, cerebellum, brainstem, diencephalon, and limbic system. Major surface landmarks include the central sulcus, lateral sulcus, and precentral gyrus, while deeper nuclei include structures such as the thalamus, hypothalamus, basal ganglia, and habenula. Vascular supply is provided primarily by the internal carotid artery and vertebral artery forming the Circle of Willis, with venous drainage through the superior sagittal sinus and internal jugular vein. Membranous coverings comprise the dura mater, arachnoid mater, and pia mater, and cerebrospinal fluid circulates within the ventricular system, produced by the choroid plexus. Microanatomy includes neuronal types studied by techniques from the Cambridge University and Harvard Medical School labs, glial cells such as astrocytes, oligodendrocytes, and microglia, and synaptic specializations discovered in work by researchers at the Karolinska Institute.

Development

Embryonic patterning is orchestrated by signaling centers including the anterior neural ridge and molecules such as Sonic hedgehog and Wnt that guide regional specification in coordination with genes characterized in the Human Genome Project and model organism programs at the European Molecular Biology Laboratory and Cold Spring Harbor Laboratory. Neurogenesis, neuronal migration, and synaptogenesis proceed under regulation by transcription factors like Pax6 and Emx2 with timing elucidated in studies from Stanford University and the Wellcome Trust Sanger Institute. Myelination follows birth and continues into adulthood, influenced by thyroid hormones studied in work at Johns Hopkins University and the Mayo Clinic. Developmental disorders have been investigated through cohorts and trials coordinated by organizations such as the World Health Organization and the Centers for Disease Control and Prevention.

Physiology and Function

Neuronal signaling depends on ion channels including voltage-gated sodium channels and NMDA receptors and on neurotransmitter systems like glutamate, GABA, dopamine, serotonin, and acetylcholine, with pharmacology advanced by collaborations between Pfizer, Roche, and academic centers. Circuits in the prefrontal cortex, hippocampus, and amygdala support memory, decision-making, and emotion, while sensorimotor integration involves pathways connecting the primary motor cortex, primary somatosensory cortex, corticospinal tract, and cerebellar cortex. Plasticity mechanisms such as long-term potentiation were first described in experiments from the University of California, Los Angeles and tested in translational studies at the National Institute of Mental Health. Functional imaging using fMRI, PET, EEG, and MEG enables mapping of activity across networks identified in the Human Connectome Project and clinical trials at major hospitals including Massachusetts General Hospital.

Disorders and Injuries

Acute injuries such as traumatic brain injury and stroke—including ischemic stroke and hemorrhagic stroke—affect vascular and neuronal integrity and are managed in systems developed by the American Heart Association and European Stroke Organisation. Neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis involve proteinopathies explored in consortia like the Alzheimer's Disease Neuroimaging Initiative and therapeutic programs at Genentech and Novartis. Neurodevelopmental and psychiatric conditions including autism spectrum disorder, schizophrenia, major depressive disorder, and bipolar disorder implicate circuits and genes studied in international efforts funded by the Wellcome Trust and the European Research Council. Diagnostics and interventions employ neurosurgical procedures from teams at Cleveland Clinic and Barrow Neurological Institute, neuromodulation techniques such as deep brain stimulation, and neurorehabilitation protocols developed with the Rehabilitation Institute of Chicago.

Evolutionary Perspectives

Comparative neuroanatomy contrasts mammalian brains like those of Pan troglodytes and Canis lupus familiaris with avian brains such as Gallus gallus, and with cephalopod nervous systems exemplified by Octopus vulgaris, revealing convergent solutions to cognition documented by researchers at the Smithsonian Institution and the Max Planck Institute for Evolutionary Anthropology. Fossil evidence assessed by teams at the Natural History Museum, London and molecular phylogenetics from the Tree of Life project inform hypotheses about encephalization and the emergence of large brains in hominins including Australopithecus afarensis and Homo neanderthalensis. Theories of cognitive evolution integrate findings from field studies by Jane Goodall and laboratory models developed at Princeton University and the University of Oxford to explain the adaptive significance of sociality, tool use, and language-related capacities in Homo sapiens.

Category:Neurobiology