Kalat 9e Chapter 2 Neurons ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Importance of the neuronIt is the unit of information processing--including emotional informationIt is the basic unit of change during all learningthe neuron’s synapse is the locus of nearly all drug actionsmost biological aspects of mental disorders involve the neuron and its transmitters and synapses. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ Parts of the neuronCell body (soma) = cellular regulationDendrites = “branches”, “input” end of cellAxon = carries info. outward from soma Axon terminals = axon splits into terminalsTerminal buttons (end feet) = terminals’ endsAxon hillock – action potentials begin hereIn all other respects, each neuron is unique. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________FIG: Neuron ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ FIG: Kolb5e-4.2-Neuron info flow ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ The big picture - what neurons do1. Multiple neurons stimulate a single neuron’s dendrites with either excitation or inhibition2. The excitation and inhibition travel as graded potentials to the hillock where they are “summed”3. If excitation prevails at the hillock, the neuron fires an action potential (AP)4. AP travels down axon to terminal buttons and releases neurotransmitters (NTs) into synaptic gap5. NTs cross gap & excite or inhibit next neuron6. What happens at next neuron? See #1 above… ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________FIG: Kolb5e-4.2-Neuron info flow ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ FIG: Bloom3e 2.1 Multiple synapses ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ FIG: Kolb5e-4.14-Rest’g potential1 ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________b5e-4.14-Resting potential2 ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ FIG: Graph of voltage over time ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ FIG: Kolb5e-4.18-Propagation ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________Saltatory conductionSome long neurons are covered with myelinMyelin acts like insulation on a wireGaps in myelin are called Nodes of RanvierAction potentials jump from node to nodeResult is to speed up conduction of the AP. ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________