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Messages go into the dendrites through the axon and released into the terminal endings 09 18 2013 Psych How does a neuron fire what is the nerve impulse Nerve impulse Action potential Starts with electrical resting potential inside of cell is 70 mV more negative than outside due to Cl Ions inside and Na ions outside so resting potential is 70 mV The inside is more negative that the outside of the cell Stimulation of the neuron lets in Na which allows them to flow from the outside to the interior of the cell which makes the inside more positively charged When enough Na ions get in for the potential to be reduced to 55mV suddenly the doors to the cell membrane are flung open and Na rushes in So much sodium enters that the potential doesn t just got to 0 It shoots up all the way to 40 mV so the inside is now positive relative to the outside The Action Potential Ion pumps work to reduce potential back to 70 mV by pushing positive ions out actually K because Na goes out slower then ANOTHER pump takes Na back out and puts K back in Note that all or none phenomenon 55mV is a threshold below that voltage there is no action potential More intense stimulation doesn t cause a more intense action potential just more frequent ones up to 1000 sec and in more neurons Action potential travels down length of axon by depolarizing neighboring areas Travels NOT at speed of electrical current in wire but rather at about 50 to 100 m sec How does it cause the next neuron to fire how does it communicate Communication across the synapse Neurotransmitters 1 synapse is a gab between neurons the presynaptic and postsynaptic neurons terminal endings of presynaptic neuron relay impulse to the dendrites of postsynaptic neuron terminal buttons contain little sacs Vesicles of chemicals neurotransmitters at action potential vesicles burst and release neurotransmitters into synapse 2 3 on membrane of dendrite are like little Receptor Molecules locks to be opened neurotransmitters are the keys and this is what opens ion gates to allow Na inside in the first place Psych 09 18 2013 EPSP excitatory post synaptic potential Dis inhibition removing the inhibitory influence Psych Central NS brain spinal cord Peripheral NS everything else Somatic NS muscles senses 09 18 2013 Autonomic NS Vital functions heart rate breathing digestion reproduction Sympathetic NS arousal mobilizes for emergency Speeds heart and lungs inhibits digestion and sexual function Parasympathetic NS Calm conserves energy Slows heart and lungs ect but im not here to give bear advice Brain bottom to top inside to outside old to new Hindbrain medulla breathing heartbeat blood circulation pons arousal and attention cerebellum integration of muscles to preform fine movements but no coordination direction of these movements balance cat transected above hindbrain can move but not act Midbrain forms movements into acts controls whole body responses to visual and auditory stimuli cat transected above midbrain can act but without regard to environment without purpose Superier coliculous area responsible for responses for simple visual stimuli Tagmentum bottom portion substantia nigra the black substance form movements into acts manufactures a neurotransmitter called dopamine that is required to transmit those actions Forebrain Psych 09 18 2013 Forebrain Thalamus sensory and motor relay center to various cerebral lobes Hypothalamus controls responses to basic needs food temperature sex Basal Ganglia regulates muscle contractions for smooth movements Limbic system memory hippocampus and emotion amygdala Cerebral Cortex or neocortex four lobes frontal partial occipital temporal seat of higher intellectual functions cat transected above limbic system acts normal with purpose but clumsy hypothalamus governs voluntary and involuntary actions Homeostasis remaining the same slowing effortful people with disease have a much harder time making their body work for them Psych Limbic System Amygdala Hypothalamus 09 18 2013 classical conditioning a dog will automatically salivate when food is in mouth its involuntary so what if I ring a bell just before I put food in the dogs mouth dog salivates still involuntary builds up response and when it hears bell it salivates involuntary response Missing hypothalamus cant remember color or shock card missing amygdala remembers color of shock card Psych 09 18 2013 Corpus Callosum major commissure or pathway between hemispheres of the brain Franz Gall he identified the cross section he also discovered that the cerebral cortex is an important functioning part of the brain turns out to be the seat of the higher intellectual functions we have made a brain map phrenology a pseudo science 1 The brain is the organ that carries out mental functions 2 There are different areas of the brain for different functions 3 When a person excels at one of these traits that region of their brain is larger we can tell this is wrong because the skull fits the brain like a glove and if there was a larger portion of the brain we would be able to feel it on the skull No scientific merit to these claims bumps mean nothing Gall was the first person to propose that there was a localization of function in the cortex Phineous Gage when he lost the part of his brain he was unreliable he wasn t himself and he couldn t be depended on and lacked social graces His personality changed Paul Broca French scientist who had a patient who was unable to communicate verbally his mental capacities were fine he could only make one utterance could only say tan Broca s patient could understand language but could not speak Broca did an atopsy and saw a lesion on part of the brain that area of the brain which is in the frontal area of the brain was names broca s area each hemisphere is divided into 4 lobes frontal front parietal second farthest back occipital back and temporal temple four lobes and functions frontal lobe planning social behavior motor control o front of brain Parietal lobe somatosensory sense of touch o On top and toward back of brain Occipital lobe vision o Back of brain Temporal lobe hearing memory o Side of brain Other terms to know primary motor area back of frontal lobe l front of parietal lobe angular gyrus wernickes area temperal lobe primary visual area primary auditory area lateral fissure prefrontal cortex phineous gage lost his prefrontal cortex cerebellum effected first when you drink alcohol then your social behavior is disinhibited and your cortex


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UConn PSYC 1100 - Lecture notes

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