Brain dysfunction 脑功能障碍,Zhihua Gao Neuroscience Institute,Outline,Biology of the brain Cognitive disorders认知功能障碍 Conscious disorders Summary,4,Biology of the brain,inside the skull skull provides protection but confines the brain,Basics on human adult brain: Weight: 3 pounds Size: a medium cauliflower,Brain nutrition,Blood supply from twin vertebral arteries (椎底动脉) and carotis internal artery (颈内动脉) provides the brain nutrition.,However, nutrients have to pass through the blood brain barrier (血脑屏障) to get into the brain.,Blood brain barrier (血脑屏障),BBB consists of: tight junctions around the capillaries endothelial cells a thick basement membrane astrocyte endfeets,7,Blood brain barrier (BBB) provides a selective filter for the brain,BBB allows essential metabolites, e.g. oxygen and glucose to diffuse from the blood to the brain, but blocks most molecules (500 Dalton).,Protects the brain from “foreign pathogens, e.g. viruses and bacteria Shields the brain from hormones and neurotransmitters Maintains brain homeostasis,8,Brain metabolism,Brain is the most active organ in energy metabolism (high demand for blood and oxygen supply). Glucose is the primary energy source for brain; however, the storage of glucose in the brain is very limited.,Take home message: Brain is highly sensitive to hypoxia and ischemia.,9,Brain components,100 billions of neurons: They are executors of brain function. 1000 billions of glial cells: They are supporters and sponsors.,Neurons and glial cells form a complex network to ensure normal brain function.,Cell communication in the brain,Functional unit in the brain-synapse,11,Electrical current travels down the axon. Vesicles move towards and fuse into the membrane. Chemicals are released, diffusing into the cleft. The chemicals bind to the receptor on the neighbour cell, opens up channels and relays the signal.,Pre-synaptic membrane,Post-synaptic membrane,Synaptic transmission,12,Brain function,Central control of the human body Maintain cognition Maintain consciousness,Lesion size correlates with symptoms. Diffusive or localized lesion? In general, the degree of dysfunction is in proportion to the extent of the damage and the size of the lesion area. However, there is a region-dependent consequence to brain injuries. When the injury occurs in the brain stem, a small damage can cause complete loss of consciousness and even death.,Brain lesions: some principles,Location determines the symptom Cerebral cortex damage: cognitive or conscious disorder Brain stem damage: conscious disorder Phase determines the symptom Acute: conscious disorder Chronic： cognitive disorder Brain has very limited capacity for self-repair-neurons do not regenerate.,Brain lesions: some principles,15,Brain responses to lesions,Cellular level: Cell death of neurons Degeneration of axons/dendrites Inflammation triggered by microglia, astrocytes Demyelination of oligodentrocytes Systemic level: Cognitive disorder (认知障碍) Conscious disorder (意识障碍),16,Outline,Biology of the brain Cognitive disorder (认知障碍) Conscious disorder (意识障碍) Summary,17,Cognition and cognitive disorder,Cognition-the process of the brain to sense, handle and acquire information Involves a series of voluntary psychological and social behaviors, such as study, memory, thinking, judgment and emotion. Relies on the normal function of the cerebral cortex. Cognitive disorders-the disturbance of the process related to cognition. usually caused by damages in the cerebral cortex.,Structural Basis of Cognition,Brodmann Mapping (52 areas),Cerebral cortex,Structural Basis of Cognition,Cognitive disorder,Major manifestations of cognitive disorder,Learning and memory defects Aphasia (失语) Hemiplegia (偏瘫) Agraphia (失写) Apraxia (失用) Alexia (失读) Agnosia (失认) Dementia (痴呆),Frontal lobe,Controls voluntary movement, memory, writing, thinking, creative thoughts, judgment, understanding and social responsibility and personal morals.When damaged: Loss of simple movement Loss of flexibility in thinking Changes in social behavior Changes in personality Inability to express language,23,When frontal lobe is damaged: Hemiplegia (偏瘫): paralysis of one side of the body Aphasia (失语): partial or total loss of the ability to communicate verbally or using written words Brocas aphasia: inability to express language (areas 44&45) Agraphia (失写): A form of aphasia characterized by loss of the ability to write. Dementia (痴呆): loss of mental ability that interferes with normal activities of daily living ( 6 months), without a loss or alteration of consciousness.,24,Processes and discriminates between different sensory inputs When damaged: Agraphia (失写): inability to locate the words for writing Alexia (失读): Problems with reading Agnosia (失认): Inability to recognize objects Contralateral sensory deficits,Parietal lobe,25,Is involved in processing sensory (auditory and visual) input, language comprehension and new memories When damaged Wernickes aphasia (感觉性失语) (area 22， can speak, but meaningless) Spatial or emotional memory impairment caused by hippocampal lesion (空间与情感记忆障碍),