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Chapter 2

Chapter 2. Biological Foundations of Behavior. Module 2.1. Neurons: The Body’s Wiring Its EVOLUTION!. What is our advantage?. What puts us at a major advantage over other animals which puts us at the top of the food chain?. Our Brain!. It’s Evolution Baby!.

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Chapter 2

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  1. Chapter 2 Biological Foundations of Behavior

  2. Module 2.1 Neurons: The Body’s Wiring Its EVOLUTION!

  3. What is our advantage? • What puts us at a major advantage over other animals which puts us at the top of the food chain?

  4. Our Brain!

  5. 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?

  6. 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.

  7. The Adaptive Human • Brain size correlates with intelligence? T or F • Bigger brain=Smarter?

  8. 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

  9. Neurons! • The basic building block of the nervous system • Cells • Transmit information via an electro-chemical process.

  10. Chapter 2 Biological Foundations of Behavior

  11. Figure 2.1: The Neuron soma

  12. 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

  13. 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!”

  14. 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.

  15. 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

  16. 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.

  17. Action Potentials

  18. 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

  19. Module 2.2 The Nervous System: Your Body’s Information Superhighway

  20. Figure 2.4: Parts of the Nervous System

  21. Concept Chart 2.2: Organization of the Nervous System

  22. 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.

  23. Figure 2.5a: The Knee-Jerk Reflex afferent efferent

  24. Figure 2.5b: The Withdrawal Reflex

  25. 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)

  26. 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

  27. Module 2.3 The Brain: Your Crowning Glory

  28. 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.

  29. HindbrainKickin’ 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. Metabolic: Positron Emission Tomography (PET) • Radioactive material is injected or inhaled • Participant is then scanned to produce an image of the brain’s activity

  45. 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

  46. What might this person be doing?

  47. Module 2.5 The Divided Brain: Specialization of Function

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