Transcript Chapter Two
Chapter 2 Biological Foundations of Behavior 1 Module 2.1 Neurons: The Body’s Wiring Its EVOLUTION! 2 What is our advantage? What puts us at a major advantage over other animals which puts us at the top of the food chain? 3 Our Brain! 4 It’s Evolution Baby! The human brain is a product of generations of adaptive mutations and adaptations. Homo sapiens-100,000 years old (is this old?) What the heck is natural selection? 5 The original Chuck D: Charles Darwin Evolve: To develop gradually. Gradual change in the structure of an animal or plant as a result of natural selection. NS= process by which inherited traits that lead to a selective advantage increase the likelihood of reproduction. 6 The Adaptive Human Brain size correlates with intelligence? T or F Bigger brain=Smarter? 7 Cephalisation Index Ratio of brain weight to body weight. K=E/P K=Cephalisation Index E=Brain weight in grams P=Body weight in kilograms Real Smart: Humans: .89 Dolphins: .64 Chimp:.30 Real Dumb: Sheep: .10 Rabbit: .05 8 Neurons! The basic building block of the nervous system – Cells – Transmit information via an electro-chemical process. 9 Chapter 2 Biological Foundations of Behavior 10 Figure 2.1: The Neuron soma 11 Cells in the Nervous System Three types of neurons – Sensory neurons (or “afferent neurons”) – Motor neurons (or “efferent neurons”) – Interneurons (or “associative neurons”) Glial cells (the glue!) – Account for 90% of cells in adult human brain – Help hold neurons together – Provide supports for the nervous system 12 Cells in the Nervous System Sensory Neurons: – Afferent nerves – Information about the outside world to the brain. – Sensory organs to brain. – 5 senses – “That stinks!” 13 Cells in the Nervous System Motor Neurons – Efferent Nerves – Sends message from the brain to the muscles and glands to cause response/behavior or to regulate bodily processes. 14 Cells in the Nervous System Interneuron – Most common neuron in the NS – Connect neurons to neurons – Connect sensory to motor, motor to sensory – More on this later……I promise 15 How do they talk? Electro-Chemical process – Sodium (Na+) and Potassium (K+) – A cell at rest – 70 (mV). – Cell begins to let positive ions into the cell, changing the polarity to + (40 mV) – This is an action potential (firing or ‘spiking’) – All-or-none Principle: Must have a full voltage of + 40 mv to fire. Won’t half fire or semi fire. 16 Action Potentials 17 What’s next? Neurotransmission! – When the neuron fires, the axon’s terminal buttons release molecules of NT’s into synaptic gap. – They bind to Receptor sites on the dendrites of other neurons. – 2 possible outcomes: Excitatory Inhibitory 18 Module 2.2 The Nervous System: Your Body’s Information Superhighway 19 Figure 2.4: Parts of the Nervous System 20 Concept Chart 2.2: Organization of the Nervous System The Nervous System Central Nervous System Spinal Chord Peripheral Nervous System Brain Somatic Nervous System Autonomic Nervous System Sympathetic Nervous System Parasympathetic Nervous System 21 Spinal Cord Column of nerves extending from brain – Protected by the spine – Transmits information between the brain and the peripheral nervous system Controls some spinal reflexes – Allows quick responses to particular types of stimuli (evolution) CNS regulates everything in the body. 22 Figure 2.5a: The Knee-Jerk Reflex afferent efferent 23 Figure 2.5b: The Withdrawal Reflex 24 Peripheral Nervous System Connects the CNS with other body parts Divided into 2 parts: – Somatic Nervous System: Transmits messages between CNS and the sensory organs, glands, and muscles (moves ya around) – Autonomic Nervous System (ANS): Controls internal bodily processes – BP, Heart Rate, Etc…not aware but may be affected by conscious things (stress, anger) 25 Divisions of the ANS Sympathetic Nervous System – Speeds up bodily processes – Draws energy from stored reserves – Activation often accompanied by strong emotions Parasympathetic Nervous System – Fosters bodily processes that replenish energy stores – Helps conserve energy by slowing down other bodily processes 26 Module 2.3 The Brain: Your Crowning Glory 27 Brain Facts Average number of neurons in the brain = 100 billion The average brain weighs about 3 pounds. 77% of a human brain is dedicated to the cerebral cortex. 31% is dedicated to a rat’s. 28 29 Hindbrain Kickin’ it old school! Lowest, oldest part of the brain Includes the: – Medulla (heart beat etc.) – Pons (time for bed…wake up!) – Cerebellum (don’t trip… don’t forget to breathe) 30 Figure 2.6: The Brainstem 31 Midbrain Contains nerve pathways that connect the hindbrain with the forebrain Midbrain structures perform important roles – e.g., control of automatic movements of the eye muscles Reticular formation plays key role in regulating states of attention, alertness, and arousal. 32 Major Structures of the Forebrain Thalamus – Relays sensory information to appropriate parts of the cerebral cortex – Receives input from the basal ganglia Hypothalamus – Regulates many vital bodily functions as well as emotional states, aggressive behavior, and response to stress – (The 3 F’s) 33 The Limbic System Group of interconnected structures: – Amygdala: Helps regulate states of emotional arousal – Hippocampus: Plays important role in the formation of memories – Why can’t you remember when you were born? – Parts of the thalamus – Parts of the hypothalamus 34 The Cerebral Cortex Thin, outer layer of the largest part of the forebrain which is called the cerebrum Cerebrum consists of the right and left cerebral hemispheres. – Hemispheres connected by the corpus callosum 35 Figure 2.7: The Size of the Cerebral Cortex in Humans and Other Animals 36 Figure 2.8: Lobes of the Cerebral Cortex 37 Table 2.1: The Lobes of the Cerebral Cortex 38 Figure 2.9: Somatosensory Cortex and Motor Cortex 39 Module 2.4 Methods of Studying the Brain 40 Methodology Postmortem studies Animal Studies Electrical Recordings Static Imaging Techniques Metabolic Imaging 41 Recording and Imaging Techniques EEG (electroencephalograph) CT (computed tomography) scan PET (positron emission tomography) scan MRI (magnetic resonance imaging) fMRI (functional MRI) 42 Experimental Methods Lesioning Electrical recording Electrical stimulation 43 Static: Magnetic Resonance Imaging • Strong magnetic field passed through the skull • Uses the detection of radio frequency signals produced by displaced radio waves in a magnetic field • Creates a detailed anatomical image of the brain 44 45 Metabolic: Positron Emission Tomography (PET) Radioactive material is injected or inhaled Participant is then scanned to produce an image of the brain’s activity 46 47 Metabolic: fMRI fMRI imaging takes a series of images of the brain in quick succession and then statistically analyzes the images for differences among them Brain areas with more blood flow have been shown to have better visibility on fMRI images BOLD Better visibility is correlated with brain activation 48 What might this person be doing? 49 Module 2.5 The Divided Brain: Specialization of Function 50 Lateralization of Brain Functions Refers to division of functions between right and left hemispheres – Left hemisphere dominant for language abilities, logical reasoning, and problem solving – Right hemisphere dominant in nonverbal processing People are not “left-brained” or “rightbrained.” 51 Figure 2.15: Broca’s and Wernicke’s Area Production Comprehension 52 Broca’s and Wernicke’s Area Broca’s Aphasia: – Me: How are you today? – BA: Ah ah ah ah ah ah ga ga ga ga ga ga ga ga gmmmmmmmpppfffffffffff…good thanks Wernicke’s Aphasia: – Me: How are you today? – WA: Kangaroos can box you know! 53 Split-Brain Research Severing corpus callosum as treatment for severe epilepsy Split-brain patients retain intellect and personality But differences in perception, language evident in special testing circumstances 54 Brain Damage and Psychological Functioning Case of Phineas Gage: Prefrontal cortex damage Plasticity: Ability of the brain to adapt and reorganize itself following trauma or surgical alteration 55 What happened to Gage? “indulging at times in the grossest profanity (which was not previously his custom), manifesting but little deference for his fellows, impatient of restraint or advice when it conflicts with his desires “ CONCLUSION? Gage's case is cited as among the first evidence suggesting that damage to the frontal lobes could alter aspects of personality and affect socially appropriate interaction 56 Module 2.7 Genes and Behavior: A Case of Nature and Nurture 57 Genetic Influences on Behavior Nature-nurture problem Genotype: An organism’s genetic code Phenotype: The observable physical and behavioral characteristics of the organism Genetic and environmental influences interact in complex ways to shape our personality. 58 Kinship Studies Familial association studies Twin studies – Identical (MZ) vs. fraternal (DZ) twins – Concordance rates Adoptee studies Continue 59 Figure 2.19: Genetic Overlap Among Family Members 60