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BIOLOGICAL BASES OF BEHAVIOR

BIOLOGICAL BASES OF BEHAVIOR. NEUROANATOMY. The study of the structures of the nervous system “Everything psychological is simultaneously biological.”. ORGANIZATION OF THE NERVOUS SYSTEMS. Central nervous system. Brain and spinal cord

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BIOLOGICAL BASES OF BEHAVIOR

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  1. BIOLOGICAL BASES OF BEHAVIOR

  2. NEUROANATOMY • The study of the structures of the nervous system • “Everything psychological is simultaneously biological.”

  3. ORGANIZATION OF THE NERVOUS SYSTEMS

  4. Central nervous system • Brain and spinal cord • Coordinates the actions and interactions of the body systems

  5. THE BRAIN • 2-3% of a person’s body weight • Uses 20% of oxygen and consumes 17% of energy • Surrounded by the meninges (3 layers of protection): • Dura matter—outermost • Arachnoid matter—web-like middle layer • Pia matter—innermost • Brain sits in skull surrounded by cerebrospinal fluid (CSF)

  6. PERIPHERAL NERVOUS SYSTEM (pns) • The nerves outside the brain and spinal cord • 2 major pathways: • Motor pathway—muscles/glands • Sensory pathway—sensory receptors • Motor pathway has 2 subsystems…

  7. SOMATIC NERVOUS SYSTEM • Nerves that transmit signals from your brain to the skeletal muscles to allow voluntary movement

  8. AUTONOMIC NERVOUS SYSTEM (ANS) • Controls automatic and involuntary functions • ANS is divided into 2 divisions…

  9. SYMPATHETIC NERVOUS SYSTEM • The emergency response system • Activates “fight, flight, freeze” status

  10. PARASYMPATHETIC NERVOUS SYSTEM • The default condition of the ANS • Functions to calm the person

  11. REFLEX ARC • Sensory signal is sent to the spinal cord, which processes it (instead of the brain) • Used for faster response to stimuli

  12. Methods for understanding the brain

  13. CASE STUDIES • Studies of individuals • Famous studies: Phineas Gage --Paul Broca: led to Broca’s area (moves muscles to create speech) --Carl Wernicke: led to Wernicke’s area (processes spoken and written language)

  14. DAMAGING THE BRAIN • Ablation: removing or destroying tissue (leaves lesions) • Examples: prefrontal lobotomy; hemispherectomy

  15. Stimulation of the brain • Deep brain stimulation: newer, less invasive • Transcranial Magnetic Stimulation: uses an electromagnetic wand; alters magnetic fields that affect how the brain processes emotions and moods

  16. Brain scanning • X-rays: skull fractures • Electroencephalogram (EEG): brain waves • Magnetic Resonance Imaging (MRI): use magnetic fields and radio waves to create detailed images of soft tissue • Functional Magnetic Resonance Imaging (fMRI): shows blood flow and oxygen consumption • Computerized Axial Tomography (CT): 2D X-ray pics from different angles to create a 3D image • Positron Emission Tomography (PET): radioactive tracer injected into blood; goes to active parts of brain

  17. The endocrine system and behavior

  18. Endocrine system • Slower messaging system • Uses hormones in the bloodstream to send messages • Begins with hypothalamus sending signals to the pituitary gland (master gland)—regulates stress, growth, and reproduction; sends signals to other glands to release hormones

  19. Glands of the endocrine system • Thyroid: secretes thyroxin (affects metabolism) • Pineal: releases melatonin (regulates sleep and body rhythms) • Adrenal: release adrenaline (regulates arousal) and corticosteroids (long-term stress response and glucose metabolism) • Gonads: secrete hormones that regulate development of sex characteristics and sex-typical behaviors (androgens, estrogen, progesterone)

  20. STRUCTURE OF THE BRAIN

  21. BASICS • Has 2 hemispheres • Left controls right side of body; right control left side • Connected by the corpus callosum—messages cross here • Motor and sensory messages cross in brain stem • Visual signals cross in the optic chiasm

  22. Cerebral cortex • Outer layer of the brain (AKA: cerebrum) • Folded in on itself forming sulci (peaks) and gyri (valleys) • The folds create more surface area; the more surface area, the more computational power the brain has

  23. LOBES • Frontal lobes: decision-making, problem-solving, reasoning, planning, personality, and language --has the motor cortex: voluntary movement • Parietal lobes: processing certain sensory signals from the body (touch, pressure, temp., pain) --has the somatosensory cortex • Occipital lobes: processes visual signals --has the visual association cortex: recognize lines, angles, shapes, shadows, and movement • Temporal lobes: auditory info. and auditory memory

  24. THE BRAIN STEM • Medulla oblongata: heart rate, breathing, digestion, swallowing • Pons: mass of nerve fibers that serve as a relay station • Midbrain: vision, movement, hearing, muscle coordination • Cerebellum: fine motor control, coordination, posture, and balance • Reticular formation: carry msgsbtwn parts of brain stem; helps focus on useful stimuli • Reticular activating system (RAS): regulates sleep-wake cycle

  25. LIMBIC SYSTEM • Top of the brain stem • Different parts help regulate emotions • The parts are…

  26. tHALAMUS • Relay station for incoming sensory information btwn brain stem and cerebral cortex

  27. HIPPOCAMPUS • Helps turn info into long-term memories and in recalling facts and events • Spatial perception

  28. AMYGDALA • Processes emotion and survival responses • Activates in threatening situations

  29. HYPOTHALAMUS • Activates pituitary gland • 4 Fs: fight, flight, feeding, and sex • Lateral hypothalamus: creates hunger feeling • Ventromedial hypothalamus: creates full feeling

  30. NUCLEUS ACCUMBENS • Cognitive processing of pleasure, aversion, motivation, learning, and reward

  31. Brain lateralization • Hemispheric specialization • Studied through “split-brain”(severing the corpus callosum) research (Roger Sperry and Michael Gazzaniga)

  32. NEUROPLASTICITY • Reorganization of neural pathways as a result of experience

  33. Part2: Neurons, neural communication, and behavioral genetics

  34. nerve cells • Neurons—the basic units of the brain and nervous system • Soma—cell body • Dendrites—tree-like protrusions from soma (receive signals) • Axon—slender protrusions from soma • Terminal branches end in terminal buttons • Terminal buttons contain sacs called vesicles which contain neurotransmitters • Glial cells provide nutrition and protection for neurons---create a covering on axons called myelin • Synapses—spaces btwn neuron dendrites and buttons

  35. Types of neurons • Sensory neurons (afferent neurons)—input from sensory receptors to brain • Motor neurons (efferent)—transmit signals from brain to our muscles and other organs • Interneurons—allow info to pass btwn neurons

  36. Communication among neurons

  37. Resting potential: electrical component • Neuron has resting charge of -70 millivolts • Inside neuron there are more potassium and chloride ions • Outside, there are more sodium ions • This imbalance creates possibility of voltage change (resting potential)

  38. Action potential: electrical component • Electrical impulse reaches cell body • Gated channels open up to allow sodium ions to rush inside • This creates a slightly more positive charge (depolarization) • This change creates an electrical impulse called an action potential • Action potentials follow the all-or-none principle: the cell either fires or does not

  39. NEUROTRANSMITTERS: CHEMICAL COMPONENT • Released from terminal buttons if action potential reaches threshold to send the impulse • They release into the synapse • Picked up by receptors on dendrites • Sometimes neurotransmitters are reabsorbed by the neuron that released them (reuptake) • Sometimes they’re broken down by an enzyme and recycled

  40. Functions of neurotransmitters • Some NTs are excitatory: cause the next neuron to fire • Some are inhibitory: prevent next neuron from firing

  41. Neurotransmitters to know 30 are known, 10 do 99% of the work

  42. Acetylcholine • Ach • Primary function in the somatic nervous system • Activates muscles and carry out voluntary movements

  43. serotonin • Connected to mood, appetite, sleep, and sexual desire • High levels: happiness • Low levels: depression • Depression is often treated with SSRIs (Selective Serotonin Reuptake Inhibitors)

  44. dopamine • The pleasure chemical • Reward and motivation • Also: alertness, happiness, fine motor coordination • Lack of dopamine could lead to Parkinson’s disease

  45. EPINEPHRINE • Adrenaline • Associated with energy • Linked to forming new memories

  46. norepinephrine • Alertness, blood pressure, heart rate • Important role in fight or flight response

  47. gaba • Gamma Amino Butyric Acid • Primary inhibitory NT • Calming effect

  48. glutamate • Major excitatory NT • Involved with thinking, memory, and learning

  49. Agonists and antagonists • Agonists: chemicals that activate receptors for neurotransmitters • Antagonists: chemicals that inhibit actions of NTs

  50. BEHAVIORAL GENETICS Field that focuses on how genes and experiences interact and lead to specific behaviors and mental abilities

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