PSY 222 Week 3 Notes
PSY 222 Week 3 Notes PSY 22200
Popular in Introduction To Behavioral Neuroscience
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This 8 page Class Notes was uploaded by AM on Monday September 12, 2016. The Class Notes belongs to PSY 22200 at Purdue University taught by Kimberly P. Kinzig in Fall 2016. Since its upload, it has received 5 views. For similar materials see Introduction To Behavioral Neuroscience in Health and Human Sciences at Purdue University.
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Date Created: 09/12/16
Week 3 PSY 222 Resting Potential At rest, more chloride is outside of the cell body o Diffusion pushes it in (more concentration to less concentration) o Chloride stays out of cell due to electrostatic Pressure (negative to positive) Potassium is greater on the inside of the cell o Potassium stays inside the cell because of electrostatic pressure o Diffusion pushes it out Sodium is greater outside of the cell o Electrostatic pressure draws it in o Diffusion pushes it in Synapse Concept Cajal was the first person to talk of synapses o Synapse: specialized gaps that exist between neurons Before Cajal, neurons were thought to be physically interconnected Cajal found that there were actually spaces between neurons o Speed of Action Potential was 40 m/s o Speed of reflex was 15 m/s Clearly there is something slowing things down The jump over the synapse Reflex Important Points Sherrington’s Observations 1.Reflexes are slower than conduction along an axon 2.Several weak stimuli presented at slightly different times or slightly different locations produce a stronger reflex than a single stimulus at a single tie 3.As one set of muscles becomes excited, another set of muscles relaxes Summation of Signals Sherrington’s Observations Temporal o Repeated stimulation passes the threshold causes a neural impulse o Notices if he repeated a weak stimulus he could illicit an action potential/reflex o Repeat the stimulus enough and you can build up signals Pinching feet over and over again o Once the threshold is reached you are going to fire Spatial o Stimulation from different placespasses the thresholdcauses a neural impulse o How we process sensory information Integrate different signals while activating or inhibiting different cells o Depolarization Direction of flow of information Dendrite to axon = greater depolarization and vice versa Action Potential VS Graded Potential Graded potentials- sometimes depolarization's- not enough alone to illicit an Action Potential o Excitatory o Na+ comes into the cell o less negative o EPSP Small depolarization's over time- have to be close enough together to build upon each other and illicit a reaction o Hyperpolarization’s o inhibitory o K+ leaves the cell o more negative o IPSP Stimulation from a presynaptic cell to a postsynaptic cell Neurotransmitters- receptors on every neuron o Glutamate-excitatory o GABA-inhibitory Action Potentials are ALWAYS depolarization’s Spontaneous Firing Rate The periodic production of action potentials despite synaptic input Discovery of Chemical Transmission at Synapses Otto Louis o Transferred fluid from one heart to another o Noticed increased activity in the heart receiving fluid o Evidence it is not an electrical process o Neurotransmitter help Sequence of Chemical Events at the Synapse o The neuron synthesizes chemicals that serve as neurotransmitters Different neurons make different neurotransmitters o Action potentials travel down the axon When the cell is signaled by the action potential, the cell can be triggered to release the neurotransmitter from the synaptic cleft to alter the activity of the postsynaptic neuron Fate of Synaptic Vessels o “Kiss and Stay” vesicle closes and stays with a little bit of neurotransmitter still left inside o “Kiss and Leave” synaptic vesicle drops off neurotransmitters, closes up and can be refilled o “Merge and Recycle” vesicle ducts release neurotransmitters, merges with cell, eventually creates a new vesicle, and is refilled with neurotransmitters o Examples in image below Key Points of Neurotransmitter release Transmission across the synaptic cleft is super fast o Less than .01 microseconds Most individual neurons release multiple neurotransmitters o Neurotransmitter effect depends on the postsynaptic cell Neurons may also respond to more types of neurotransmitters than they release Transmitter-gated or ligand-gated channels are controlled by neurotransmitter o Gates channels have to be stimulation for something to happen at the postsynaptic cell G-Proteins G-protein activation o Couples to guanosine triphosphate (GTP), an energy storing molecule o Increases the concentration of a “second messenger” The second messenger communicated to areas within the cell Neuropeptides Metabotropic effects utilize a number of different neurotransmitters Neuropeptides = neuromodulators Drugs and Receptors Many hallucinogenic drugs distort perception Nicotine stimulates acetylcholine receptors Opiates and endorphins Negative feedback in the brain can be accomplishes in two ways 1.Autoreceptors 2.Postsynaptic neurons Proteins and Peptides Composed of chains of amino acids Attaches to membrane receptors where they activate second messenger systems The Pituitary Gland Attached to the hypothalamus Consists of two distinct glands Maintaining Hormone Levels The hypothalamus maintains a constant circulating level of hormones through a negative-feedback system o EX: TSH- releasing hormone and thyroid hormone levels
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