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Unit 3B: Biological Bases of Behavior: The Brain Unit Overview • The Tools of Discovery: Having Our Head Examined • Older Brain Structures • The Cerebral Cortex • Our Divided Brain • Right-Left Differences in the Intact Brain • The Brain and Consciousness . The Tools of Discovery: Having Our Head Examined Introduction • Lesion- in the interests of science or medicine, scientists can selectively destroy tiny clusters of brain cells/tissue. • Today, we can also stimulate (electrically/chemically) various parts of the brain and note the effects. Recording the Brain’s Electrical Activity We are now able to detect an electrical impulse from a single neuron = detect exactly where information goes from any stimulus. Electroencephalogram (EEG) reads regular brain waves of electrical activity that sweeps the surface of the brain = a computer can filter out unrelated brain activity http://www.youtube.com/watch?v=bO_ZtIxcr0&feature=related&safe=active Neuroimaging Techniques • CT (Computed Tomography) scan – (CAT Scan)- Takes X-ray photographs that can reveal brain damage – http://www.youtube.com/watch?v=uHu9aa0QDiE&feature=related&safe=act ive • PET (Positron Emission Tomography) scan – Shows the brain’s consumption of glucose (sugar) which creates a visual display of brain activity • http://www.youtube.com/watch?v=d9iOxMFmPlA&feature=related&safe=active Neuroimaging Techniques • MRI (Magnetic Resonance Imaging)- brain scan where the head is put in a strong magnetic field which aligns, and then disorients the atoms = pictures of brain’s soft tissue • http://www.youtube.com/watch?v=xi8HRkFTHgw&safe=active • fMRI (Functional MRI)- reveals brain’s functioning and structure. Where the brain is active, the blood goes. – The brain “lights up” as you perform different mental functions – http://www.youtube.com/watch?v=xi8HRkFTHgw&safe=active Older Brain Structures The Brainstem • Brainstem –Medulla –Pons –Reticular formation The Thalamus • Thalamus –All the senses EXCEPT smell The Cerebellum • Cerebellum –“Little brain” The Limbic System • Limbic System –Hippocampus The Limbic System The Amygdala • Amygdala –Aggression and fear The Limbic System The Hypothalamus • Hypothalamus –Influence on the pituitary gland –Reward Centers –Reward deficiency syndrome The Cerebral Cortex Introduction • Cerebrum – Cerebral cortex • Fabric of interconnected neural cells covering the cerebral hemispheres • The body’s ultimate control and information-processing center • Gives certain areas of the body different attention -DEMO • Moving up the ladder of life means a larger cerebral cortex – Allows humans to adapt, learn, and think Structure of the Cortex • Glial cells (“glue cells”) – provide the myelin and nutrients that neurons need. – The more complex the animal, the more glial cells • Lobes – Frontal lobes – speaking, muscle movement, and making plans/judgments – Parietal lobes – receives sensory information for touch and body position – Occipital lobes – receives information from visual fields – Temporal lobes – receive information from the opposite ear • Scenario DEMO Functions of the Cortex - Association Areas • Association areasareas of the cortex that are not involved in primary motor or sensory functions, but are involved in higher mental functioninglearning, speaking, remembering, thinking – Phineas Gage Video Functions of the Cortex Motor Functions • Motor Cortex (in the frontal lobe) output controls voluntary movements • Mapping the Motor Cortex – different areas of the cortex control different parts of your body – Being able to predict a monkey’s movement .10 seconds before it happens • Neural Prosthetics- research showing it is possible to control objects by tracking what neurons fire in the motor cortex Functions of the Cortex - Sensory Functions • Sensory Cortex– Front of the parietal lobes that registers and processes body touch and movement sensations – The more sensitive the body region, larger the sensory cortex area devoted to it. Functions of the Cortex Language • Aphasia – an impaired use of language can result from damage to one of the following areas– Broca’s area (disrupts speaking)– controls language expression and directs the muscle movements involved in speech – Wernicke’s area (disrupts understanding) – controls language reception – a brain area involved in language comprehension and expression Language Continued • Is language only located in the left hemisphere? – Left handed and divided brain woman• When a word is in her left visual field (processed in right half of brain) she can write it but not say it • When a word is in her right visual field (processed in left half of brain) she can say it, but not write it • Clear scientific evidence that in some people the capacities for spoken and written language may be located in different hemispheres • Learning a second language – At a young age- the brain shows activity in the same area as your native language – After childhood- brain activity is in an adjacent area while speaking Language Language Language Language Language Language • The Brain’s Plasticity Brain Damage – Plasticity – the ability of the brain to modify itself after some types of damage (VIDEO) • The younger the child, the greater chance the remaining hemisphere can take over functions of the surgically removed one • Unused or damaged parts of the brain looks for signals to process (Deaf people have enhanced peripheral vision) – Constraint-induced therapy – restrain a fully functioning limb to force the “bad limb” to be reprogramed – Neurogenesis – neural stem cells to rebuild or replace damaged brain cells Our Divided Brain Right v Left Brained • The “right versus left brain” is a myth. • There is no evidence to support the idea that the two brains do not communicate with one another. • Neither “logic” or “musical ability” is kept in one brain or the other. • HOWEVER, there is NEW research that suggests lateralization (hemispheric specialization)- functions on the brain may be either on the left or right – The right hemisphere processes emotional expressions. Which face is happier? Splitting the Brain • Vogel and Bogen – Corpus-callosum – large band of neural fibers (axons) that connect the two brain hemispheres and carry messages – Split brain – a surgeon can cut through the corpus callosum (to eliminate seizures) (VIDEO) – It is as if you have two competing brains; and will follow their own instructions- “two separate minds” • Left- deliberating (rationalize) • Right- simple requests • Shirt unbutton/Grocery store items • “Walk” Demos -Two Brains -Hand/Leg -Hand tapping -Circle/Square The Brain and Consciousness Introduction • Consciousness – our awareness of ourselves and our environment – Reproductive advantage? – Acting on long term interests rather than short term pain/pleasure? – Survival of being able to read other people? Cognitive Neuroscience • Cognitive neuroscience – study of brain activity linked with cognition – Perception, thinking, memory, and language – How do the mind and the brain interact? – Non-communicative woman after car accident with no signs of conscious awareness was asked to imagine people playing tennis • Resulted in fMRI scan with activity The Two-Track Mind • Two-Track Mind – Visual perception track • enables us to recognize things and to plan actions – Visual action track • Guides our moment-to-moment actions • Much of our everyday thinking, feeling, and acting operates outside our conscious awareness - - you may act before you are conscious of doing something (driving familiar route) – Seeing a bird flying • Cognitive- It’s a cardinal! • Sub-processing- color, form, movement, distance The End Definition Slides Lesion = tissue destruction; a brain lesion is a naturally or experimentally caused destruction of brain tissue. Electroencephalogram (EEG) = an amplified recording of the waves of electrical activity that sweep across the brain’s surface. These waves are measured by electrodes placed on the scalp. CT (computed tomography) Scan = a series of X-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body. • Also called CAT scan. PET (positron emission tomography) Scan = a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task. MRI (magnetic resonance imaging) = a technique that uses magnetic fields and radio waves to produce computergenerated images of soft tissue. MRI scans show brain anatomy. fMRI (functional MRI) = a technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function. Brainstem = the oldest part of the central core of the brain, beginning where the spinal cord swells as it enters the skull; the brainstem is responsible for automatic survival functions. Medulla = the base of the brainstem; controls heartbeat and breathing. Reticular Formation = a nerve network in the brainstem that plays an important role in controlling arousal. Thalamus = the brain’s sensory switchboard, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla. Cerebellum = the “little brain” at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance. Limbic System = doughnut-shaped neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives. Amygdala = two lima bean-sized neural clusters in the limbic system; linked to emotion. Hypothalamus = a neural structure lying below (hypo) the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward. Cerebral Cortex = the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center. Glial Cells = cells in the nervous system that support, nourish, and protect neurons. Frontal Lobes = portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgments. Parietal Lobes = portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position. Occipital Lobes = portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields. Temporal Lobes = portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear. Motor Cortex = an area at the rear of the frontal lobes that controls voluntary movements. Sensory Cortex = area at the front of the parietal lobes that registers and processes body touch and movement sensations. Association Areas = areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking. Aphasia = impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding). Broca’s Area = controls language expression that directs the muscle movements involved in speech. Wernicke’s Area = controls language reception – a brain area involved in language comprehension and expression; usually in the left temporal lobe. Plasticity = the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience. Neurogenesis = the formation of new neurons. Corpus Callosum = the large band of neural fibers connecting the two brain hemispheres and carrying messages between them. Split Brain = a condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them. Consciousness = our awareness of ourselves and our environment. Cognitive Neuroscience = the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory and language). Dual Processing =the principle that information is often simultaneously processed on separate conscious and unconscious tracks.