Cerebral Cortex - The outermost layer of the brain containing gray matter. Responsible for many "higherorder" functions like language and information processing. Cerebral Cortex Cerebral Cortex Layers of the Cerebrum • Gray Matter – Outer layer of the brain – Composed of neuron cell bodies (site of nucleus) – Includes regions of the brain involved in muscle control, sensory perceptions, like seeing and hearing, memory, emotions, speech and critical thinking/problem solving Cell Body of Neuron Layers of the Cerebrum • White Matter – Contains mainly long, myelinated axons – Involved in the relay of sensory information from the rest of the body to the cerebral cortex Myelin = fatty outer covering of axons. Allows for faster transmission of message. Axon of Neuron Limbic System • set of evolutionary primitive brain structures • involved in emotions and motivations, like the ones related to survival – fear, anger, sexual behavior • also involved in feeling of pleasure – eating and sex Limbic System Structures • Amygdala – linked to both fear responses and pleasure. Anxiety, autism, depression, post-traumatic stress disorder, and phobias are linked to abnormal functioning • Hippocampus – sends memories out to the appropriate part of the brain for long-term storage and retrieves them when needed. – damage to hippocampus can cause an inability to form new memories Amygdala shrinks by more than 30% in males upon castration – minimizes pleasure Diencephalon – “Interbrain” • Sits on top of the brain stem • Enclosed by the cerebral hemispheres; wellhidden brain region • Made of three parts – Thalamus – Hypothalamus – Epithalamus Thalamus • The relay station for sensory impulses (switchboard) • Transfers impulses to the correct part of the cerebrum for interpretation • All incoming impulses get sorted here first and identified as pleasant or nonpleasant Hypothalamus • Under the thalamus • Controls organs by maintaining homeostasis • Important autonomic nervous system center – Helps regulate body temperature – Controls water balance – Regulates metabolism The pituitary gland is attached to the hypothalamus. It releases hormones which affect growth, sexual development, metabolism and reproduction. Epithalamus • Helps to regulate the sleep/wake cycle by releasing hormones like melatonin from pineal gland • Controls some parts of emotions and mood Epithalamus Brain Stem • Attaches to the spinal cord; primitive “rat brain” • Controls automatic behaviors necessary for survival (breathing) • Parts of the brain stem each about an inch long – Midbrain – Pons – Medulla oblongata Brainstem • Midbrain = Smallest region of the brain which relays auditory and visual information. – Also controls eye movements, like blinking • Pons = “bridge” of the brainstem. Controls Breathing. • Medulla Oblongata = The lowest part of the brain stem – Merges into the spinal cord – Contains important control centers • • • • • Heart rate control Blood pressure regulation Breathing Swallowing Vomiting Cerebellum • contains ~70% of all the brain's neurons; yet is only 10% of the volume of the brain! • contributes to precise timing of skeletal muscle activity (i.e. walking, running or standing on your hands) • controls our balance and equilibrium • Doesn’t function well under influence of alcohol • Works like ‘auto pilot’ – monitors body position and amount of tension in body parts Cerebellum and other brain parts Meninges = three connective tissue membranes covering and protecting brain Dura Mater: outermost meninges; tough and thick. Can restrict movement of the brain within the skull. Protects the brain from movements that may stretch and break brain blood vessels. Central Nervous System Disorders • Meningitis = inflammation of meninges. Serious threat since bacteria or viruses can spread to brain. • Concussion = injury is slight; dizzy, see stars, or lose consciousness briefly but no permanent damage. • Stroke = blood circulation to a brain area is blocked from ruptured blood vessel or blood clot. More Brain Disorders • Hemorrhage = bleeding from ruptured blood vessels. • Aneurysm = dilation, bulging or ballooning out of part of the wall of a vein or artery in the brain – Can get larger over a lifetime – Pushes on brain regions causing symptoms like blurred vision, stutter, etc. – Can hemorrhage What brain structures can you see?