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Lana Trick (148)

Jan 10th Lecture

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PSYC 2390
Lana Trick

Jan 10 Sensation and Perception 1. Action potentials cont. - transfer of ions that occurs has an effect on the membrane potential which is measured with a volt meter - membrane lets their ‘gates’ in for sodium to come in for a fraction of a second when the membrane becomes positive (millivolts) and then potassium flies out which leaves the neuron even more negative than it was in the beginning - recovery period involves sodium potassium punmp - a dim light might have 200 a.p. per second whereas a bright light would have 400 a.p. - intensity of a sense can be determined through number of action potentials per second but there is a limit—500 to 800 a.p. per second - if something is too intense, the cell cannot signal it anymore - unmyelinated axons must have an exchange of ions throughout the entire axon; but this is not the case for mylenated axons (ions can jump) that is called salutatory conduction - at the end of an axon there are the ‘pouches’ called synaptic vesicles; electrical charges cause neurotransmitters to be released through the synaptic gap to other axons granted that there is an action potential 2. excitatory effects - some neurotransmitters have excitatory effects - excitatory neurotransitters increase the probability that the receiver will have an a.p; they increase the positivity (depolarize) - most neurons already have a spontaneous activity level (for ex. 20 ap/sec) - if you add an excitatory neurotransmitter, it could increase the neuron to 24 ap/sex for example - acetylcholine (ACh) is in the brain but also throughout the body and tells the muscles what to do - black widow spiders; their venom causes a flood of ACh; causes muscle contractions or spasms - curare; drug that they use in blow guns, curare plugs up the dendrites and prevents ACh to get to the muscles and paralyzes - glutamate; neurons respond too much to stimulation, schizophrenic people are high in glutamate 3. inhibitory effects - reduce the probability that a neuron will have an action potential when inhibitory neurotransmitters are released - you will only see an effect if the neuron involved has a spontaneous activity level (for ex. If a neuron has 20 ap/sec spontaneous activity, an inhibitory neurotransmitter might make it be 16 ap/sec) 4. neural circuits - neuron (when stimulated sends excitatory neurotransimitters) - - neuron (when stimulated sends inhibitory neurotransmitters) - linear circuits can involve exclusively inhib or excit or both - converging circuits involve two neurontransmitters (only excit or inhib or both) sending info to a receiver neuron - A and B neurotransmitters send info to C neuron - A (24 ap/sec) + B (16 ap/sec) = 20 ap/sec; it acts like it wasn’t stimulated at all because the excitatory and inhibitory neurotransmitters cancel eachother out 5. Neurosciences - neuroanatomy involves taking a deceased organism and looking at its body tissues - lesion studies (brain damage/neural damage) - single cell studie
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