PSYC 340 - 1st EditionExam # 2 Study Guide – Lectures 8-13Neurobox #2 Study Guide Table of Contents:Lecture 8 (February 17) ……………………………………………………………………………………………………….Pg. 1Lecture 9 (February 19) ……………………………………………………………………………………………………….Pg. 6Lecture 10 (February 24)…………………………………………………………………………………………………….Pg. 10Lecture 11 (February 26)…………………………………………………………………………………………………….Pg. 13Lecture 12 (March 3)….………………………………………………………………………………………………….…..Pg. 17Lecture 13 (March 5)...……………………………………………………………………………………………………….Pg. 19Chapter 2 ………………………………………………………………………………………………………………………….Pg. 22Lecture 8 (February 17)Learning from an Invertebrate I. Neurobiological mechanisms A. Researchers look to simpler systems in order to see how axons workB. Learning from an invertebrate 1. However, must assume that the axons/action potential in a giant squid also apply to our brains a. So far, this seems to be true; tremendous conservation through species: i. Same proteins ii. Same structures b. Need to assume/hope that the way an invertebrate learns/remembers is the same way we do i. Research suggests that this is true. 2. Aplysia – seaslug a. Not much to them – “bags of seawater” Aubrey Rieder 1 PSYC 340 - 500b. Why aplysia? Advantages: simple nervous system, large neurons (can see some with the naked eye), invariant neuralanatomy (not a lot of genetic/physical variation.) c. Kandel3. Nonassociative learning a. Wants to protect its gills b. Habituation i. Touching the siphon = gillwithdrawal reflex i. Becomes habituated ii. Touching the mantle = gillwithdrawal reflex i. Becomes habituated iii. However, these two S-R cycles are independent i. Habituating one does not affect the other c. Sensitization i. General affect: apply shock to tail sensitizes reflexes in the entire aplysia 2. Neural circuit a. Sensory neuron, motor neuron, facillitory interneuron 3. Changes in amount of transmitter released from SN a. With habituation observe a decrease i. Keep touching the siphon skin; eventually, will be habituated ii. The action potential is the same, just the amount of neurotransmitter released is lessb. With sensitization observe an increase i. Shock the tail; all S-R will be sensitized Aubrey Rieder 2 PSYC 340 - 500ii. The action potentialis the same, just theamount ofneurotransmitterreleased is more.II. Review: basic neural function A. Resting potential (Na+, K+) 1. Works to keep sodium out of thecell. a. Excess of sodium outside thecell2. Outside of cell = positive, inside =negative a. Sodium (positive) wants toget inside, but keeps gettingpumped out. 3. Excess K+ inside the cell; wants torush out to its concentrationgradient but repelled by outside membrane B. Action potential 1. Initiated by depolarizing the cell 2. Rising phase: Na flowing into the cell – depolarization 3. Reestablishing the resting potential:a. K+ flows out 4. Synaptic transmission Aubrey Rieder 3 PSYC 340 - 500a. When action potential rises, Ca channel opens up, allowing Ca to flow in (presynaptic neuron) b. Amount of neurotransmitter released depends on the amount of calcium released in the cell i. More Ca = more transmitter ii. vesicles, neurotransmitter c. The time the calcium channels stay open is proportional to the length of the action potential C. Chapter One Neurobox notes: 1. Signal begins at dendrites a. Contain specialized receptors that transform input from another cell intro an electrical impulse i. Sodium-potassium ion pump ii. Channels in the dendritic cell (which is negatively charged) allow Na+ to enter the celliii. Movement of the positive charge depolarizes the interior cell, causing the voltage to move from -70mV to zero iv. Na+ channels close now that the inside of the cell has a positive charge and channels that regulate potassium ions (K+) open. v. K+ ions inside the positively-charged cell flow down its concentration gradient and exit the cell, making the inside of the cell negative again. b. This starts a chain reaction that travels across the cell membrane to the cell body (which contains the biology of the cell) c. From there, the electrical impulse, known as the action potential, travels down the axon of the neuron to the end, where it forms a chemical connection (synapse) with another cell. 2. Synapse Aubrey Rieder 4 PSYC 340 - 500a. When an action potential reaches the synapse, it causes channels that are permeable to Ca++ ions to open, allowing Ca++ to flow into the cell. i. The increase in intracellular Ca++ causes vesicles that contain neurotransmitters to migrate over to the presynaptic neural membrane and dump their contents into the space between the cells, known as the synaptic clef. The transmitter then engages receptors on the postsynaptic cell, which could be another neuron or an effector cell (like a muscle). D. Biochemical mechanisms 1. Habituation a. Due to a short-term inactivation of calcium channels b. Long-term is due to reduction in number of synaptic contacts; a structural change. 2. Short-term sensitization a. Biochemical cascade – dominos i. (serotonin, serotonin receptor, G-protein, adenylate cyclase, ATPcAMP, protein kinase, K channel (turns themoff), Ca channel (more Ca into the cell, more neurotransmitter) ii. Increases the duration of the action potential iii. Protein kinase = memory i. Keeps working for four-ish hours 3. Long-term sensitizationAubrey Rieder 5 PSYC 340 - 500a. Depends on making new proteins – engage genes in the cell body b. MAP+PKA engage gene expression i. Engage a cellular switch in the nucleus (CREB) and turns ongenes, which leads to manufacture of new proteins i. Change how protein kinase works – supercharged ii. Genes that also make structural modifications – more synaptic connections Lecture 9 (February 19)Nociceptive (pain fibers) PlasticityI. Nociceptive sensitizationA. Nociceptors detect tissue damageB. Nociceptive pathways relay this signal to the brain1. We care about nociception
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