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Biological bases of cognition and behavior Part 1

Biological bases of cognition and behavior Part 1. How your “wetware” works. Biological (Physiological) Psychology (Neuroscience) Neuron a nerve cell the basic building block of the nervous system Communication Highway!!!. How we work. Neurons Neurons do the “talking”

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Biological bases of cognition and behavior Part 1

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  1. Biological bases of cognition and behavior Part 1

  2. How your “wetware” works... • Biological (Physiological) Psychology (Neuroscience) • Neuron • a nerve cell • the basic building block of the nervous system • Communication Highway!!!

  3. How we work... • Neurons • Neurons do the “talking” • The human brain has about 100 billion neurons, interconnected at 100 trillion synapses. • Here’s what a trillion pennies looks like:

  4. How it works... • Neurons come in 3 basic flavors… • Sensory neurons (“afferent” neurons) senses to brain for processing • Motor neurons (“efferent” neurons) brain to muscles/glands for reaction • Interneurons connectors; only in brain and spinal cord • Example: Water temp in shower

  5. The Neuron

  6. Neural communication down the axon • Dendrite • the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body • Axon • the extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands

  7. Neural communication down the axon • Myelin [MY-uh-lin] Sheath • a layer of segmented fatty cells encasing the fibers of many neurons • greater transmission speed of neutral impulses (Duct Tape) • Made from glial cells • At rest, the neuron is polarized (at “resting potential”) • Sodium (Na+) and chloride (CL-) outside and potassium (K+) inside • “Sodium pump” – Ion pump, resets to resting potential

  8. When does a Neuron “Talk” • Dendrite acts as a NET and grabs the chemical messages, sending info to the cell body/nucleus • Nucleus or the “Office Executive” assesses and decides whether to command

  9. Neural communication: down the axon • Action Potential • a neural impulse; a brief electrical charge that travels down an axon • positively charged ions in and out of channels in the axon’s semi-permeable membrane • Threshold • the level of stimulation required to trigger a neural impulse • The “All or None” law; coded by firing rate

  10. Cell body end of axon Direction of neural impulse: toward axon terminals Neural communication: down the axon Rapid influx of positive charge triggering electrical message: “RELEASE THE MESSAGE!!”

  11. Neural communication: down the axon • Graded Potentials • Small changes that make a neuron more or less likely to fire (i.e., change the threshold) • Depolarization = more sensitive • Hyperpolarization = less sensitive • Nucleus • Message comes in as either a excitatory (Fire) or inhibitory (Don’t Fire) neurotransmitters (chemicals)

  12. Neural Communication at the synapse • Synapse [SIN-aps] • Junction/gap between the axon end bulb and the dendrite “net” • tiny gap at this junction is called the synaptic gap or cleft • Neurotransmitters • chemical messengers that traverse the synaptic gaps between neurons (leave the axon) • when released, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron (dendrite part) • This produces a graded potential in the receiving neuron!

  13. Neural Communication: at the synapse

  14. Neurotransmitters Excitatory neurotransmitters: FIRE!!!!! Inhibitory neurotransmitters: Don’t FIRE!!! Modulatory neurotransmitters (“neuromodulators”)

  15. A shopping list of neurotransmitters... • Acetylcholine • Learning & memory, but also triggers muscle contraction (botulism = Ach receptor blocker) • Dopamine • Influences movement, learning, and • attention. • May be linked to schizophrenia & Parkinson’s disease

  16. A shopping list of neurotransmitters... • Serotonin • Affects mood, hunger, sleep, and arousal. • Prozac/Zoloft raises serotonin levels. • Norepinephrine and epinephrine • Affects alertness and arousal; also anxiety

  17. A shopping list of neurotransmitters... • Gamma-aminobutyric acid (GABA) • Inhibitory neurotransmitter. • May be involved in eating and sleep disorders. • Note that the effects of neurotransmitters depend on the receptor • A given neurotransmitter can trigger different types of receptors with different results!

  18. Dopamine pathways Neural Communication

  19. Neural Communication Serotonin pathways

  20. Fun with neuromodulators... • Endorphines • “morphine within” • natural, opiate-like neurotransmitters • linked to pain control and to pleasure

  21. Neurotransmitter molecule Receiving cell membrane Agonist mimics neurotransmitter Receptor site on receiving neuron Antagonist blocks neurotransmitter Drugs and Neural Communication Just write down what agonist and antagonists do

  22. Nervous system Peripheral Central (brain and spinal cord) Autonomic (controls self-regulated action of internal organs and glands) Skeletal (controls voluntary movements of skeletal muscles) Sympathetic (arousing) Parasympathetic (calming) The Nervous System configured

  23. The Nervous System The body’s speedy, electrochemical communication system • consists of all the nerve cells of the peripheral and central nervous systems • Central Nervous System (CNS) • the brain and spinal cord • Peripheral Nervous System (PNS) • the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body

  24. The Peripheral Nervous System – part A • Autonomic Nervous System • controls the glands and the muscles of the internal organs (such as the heart) • Sympathetic Nervous System • arouses the body, mobilizing it in stressful situations • Parasympathetic Nervous System • calms the body, conserving its energy

  25. The Peripheral Nervous System – part B • The skeletal nervous system • Lots of efferent neurons (Motor) • But also afferent (sensory) for the kinesthetic sense http://findarticles.com/p/articles/mi_g2699/is_0001/ai_2699000193/

  26. The peripheral nervous system

  27. The peripheral nervous system

  28. Brain Sensory neuron (incoming information) Interneuron Motor neuron (outgoing information) Muscle Spinal cord Skin receptors An example of neural communication: • Reflex: a simple, automatic, inborn response to a sensory stimulus

  29. Neurons in the brain connect with one another to form networks Inputs Outputs The brain learns by modifying certain connections in response to feedback How your brain is “wired” • Neural Networks • interconnected neural cells • with experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results • computer simulations of neural networks show analogous learning

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