Week 3, Lecture 1 (08/23)
Week 3, Lecture 1 (08/23) 4100
Popular in Cognitive Psychology
Popular in Psychology (PSYC)
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This 3 page Class Notes was uploaded by Leslea Motley on Thursday August 25, 2016. The Class Notes belongs to 4100 at University of Georgia taught by Kara Dyckman in Fall 2016. Since its upload, it has received 7 views. For similar materials see Cognitive Psychology in Psychology (PSYC) at University of Georgia.
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Date Created: 08/25/16
08/23/2016 I. Outline (material covered, material to be covered) Lobes of the Brain o Localization of function – video explanation (Joe – cut corpus callosum) Neurons and Neuron Communication Brain Imaging Techniques II. Left vs. Right Hemisphere Table 2-1: Summary of cerebral lateralization (from book) These functions are not absolute; as with most things, there is truth behind these functions being specific/associated to/with right or left hemisphere, but it has been oversimplified. III. Neurons About 100 billion neurons in the brain Neuron What does it mean for a brain to mature? The connections, difficult to think about in terms of single neurons, but in terms of neural connections through terminal buttons as well as dendrites – transmittal/receival of information b/w neurons can change also Neurons get information from other neurons or from your environment o Dendrites: receive information o If neuron is going to send a signal, it sends it down its SINGLE AXON. It may branch at the bottom so the message can be sent to multiple neurons, but the message will only be sent down one axon initially. o Everything we do is a pattern of which neurons are firing and which are not firing – pattern of activation of neurons o This is why neurons are important to psych, because whether or not your neurons are alive/functioning correctly directly affects your behavior. Nerves – collections of axons; some axons are very long (longest ones go from cell body in spinal cord, down leg and out to big toe) o Pinched nerve, nerve damage – a collection of axons running together – pinching axons may cause pain, tingling sensation, etc. – all of these things are a result of impinging the axon Where are the neurons located? o Gray matter – generally, contains cell bodies, in order for them to communicate with the body they must send axons down into brain and out through body o White matter – contains axons Question: Explain white and grey matter in terms of myelin sheath? o Myelin sheath defined online: The myelin sheath is a greatly extended and modified plasma membrane wrapped around the nerve axon in a spiral fashion. The myelin membranes originate from and are a part of the Schwann cells in the peripheral nervous system (PNS) and the oligodendroglial cells in the central nervous system (CNS). o White matter vs. Gray matter IV. Neuron Communication Action potential o What happens when neuron sends a signal – called “firing an action potential” – the action potential moves through the axon to end, neurotransmitters (“NT”) released into synapse and are picked up by the next neuron o Presynaptic neuron: Soma terminal button o NT released into synapse (after action potential reaches terminal button) o NT picked up by the post-synaptic neuron (the dendrites, with specific receptors of the post-synaptic neuron) V. Group Activity VI. Neuron Info If neuron is resting, the charge inside the neuron will be -70 millivolts (- 55mv causes action potential) o Inside neuron contains a lot of potassium (K+), K is positive – more K inside the neuron, more sodium (Na+) and chloride (Cl-) outside the neuron Glial cells – brain cells providing structural support When there is an action potential/stimulus from environment, it causes an environmental change within the neuron. o Sodium channels open – Na+ flows into the axon o Depolarization occurs – this is where you see graphs of neuron potential – as time continues and Na channels remain open, the internal charge of the axon rises from the resting state (-70mv) to positive millivoltage values – as action slows, neuron begins to rest and voltage decreases as sodium channels close In myelinated neurons, sodium channels are located at Nodes of Ranvier o “These local circuits depolarize the adjacent piece of membrane in a continuous, sequential fashion. In myelinated axons, the excitable axonal membrane is exposed to the extracellular space only at the nodes of Ranvier; this is the location of sodium channels. When the membrane at the node is excited, the local circuit generated cannot flow through the high-resistance sheath and, therefore, flows out through and depolarizes the membrane at the next node, which might be 1 mm or farther away. The low capacitance of the sheath means that little energy is required to depolarize the remaining membrane between the nodes, which results in local circuit spreading at an increased speed. Active excitation of the axonal membrane jumps from node to node; this form of impulse propagation is called saltatory conduction (Latin saltare, “to jump”). Such movement of the wave of depolarization is much more rapid than in unmyelinated fibers.” o “Furthermore, because only the nodes of Ranvier are excited during conduction in myelinated fibers, Na+ flux into the nerve is much less than in unmyelinated fibers, where the entire membrane is involved.” o “Myelin is made by two different types of support cells. In the central nervous system (CNS) — the brain and spinal cord — cells called oligodendrocytes wrap their branch-like extensions around axons to create a myelin sheath. In the nerves outside of the spinal cord, Schwann cells produce myelin.” ▯ ▯
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