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Second Hour – How do neurons communicate?

Brain and Behaviour. Second Hour – How do neurons communicate?. Afferent (sensory) and Efferent (motor) nerves revisited A demonstration Interneurons Parts of the neuron Neuronal communication Electrical and chemical Spatial and temporal summation. 1. 2. 3.

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Second Hour – How do neurons communicate?

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  1. Brain and Behaviour Second Hour – How do neurons communicate? • Afferent (sensory) and Efferent (motor) nerves revisited • A demonstration • Interneurons • Parts of the neuron • Neuronal communication • Electrical and chemical • Spatial and temporal summation

  2. 1 2 3 Measuring the speed of the nervous impulse Average Individual Reaction Time .55 .50 .45 Shoulder with decision .40 .35 .30 .25 .20 Ankle .15 .10 Shoulder .05 Practice Trials Note: This is an approximation of your responses to show the pattern of response.

  3. Electrical communication within the neuron Myelin Sheath (speeds transmission) Axon Nodes of Ranvier Cell Body Dendrites (receivers) Axon Terminals (transmitters)

  4. Electrical Transmission Synapse Chemical transmission Electrical Transmission Neuron 1 Neuron 2

  5. Potassium+ (outside) (inside) Electrical Transmission – The Action Potential At rest – Positive on the outside, negative on the inside 1. Action potentialSodium channels open - Positive sodium ions surge in making the inside of the neuron positive 2. Positive potassium ions are forced out. Excess positive sodium ions forced out. Stability returns (outside) 1. Potassium+ Sodium+ (inside) Sodium+ 2.

  6. Repolarization + Potassium out Hyperpolarization + Sodium out resting potential Positive outside Negative inside Polarized refractory period Stimulus onset (See Gleitman, p. 68) The action potentialVoltage change over time Depolarization +Sodium in adds to +Potassium Resting + Potassium back in returns to positive outside negative inside

  7. Electrical Transmission Synapse Chemical transmission Electrical Transmission Neuron 1 Neuron 2

  8. Neural impulse Synaptic vesicle Axon terminal Presynaptic membrane Binding site Neurotransmitter molecule Postsynaptic membrane (See Gleitman, p. 72) Axon of the sending neuron Chemical Transmission Synapse (Synaptic gap or cleft) Receiving neuron

  9. Electrical Transmission Synapse Chemical transmission Electrical Transmission Neuron 1 Summation Neuron 2

  10. Dendrites Temporal summation: several impulses from one source over time Axon Hillock Point of summation Axon Spatial summation: several impulses from several sources converging at the same time

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