Prof Greg Francis 8 12 11 Neurons Neurons and neurotransmitters PSY 200 The brain cells that are responsible for cognition are neurons Greg Francis Lecture 05 Why does nearly everyone love Prozac Purdue University Purdue University Input at dendrites Input output Electrical signal Established by the relative amount of charged ions inside versus outside the cell membrane electrode 70 millivolts resting level which causes further changes in the cell s chemistry NA which causes further changes in the membrane potential NA Inputs change the resting potential of the cell K Output identifies when the cell potential has increased a lot Purdue University http www mind ilstu edu curriculum neurons intro action potential 1 0 swf Purdue University A neuron An action potential generated at the soma travels down the axon to the terminals Purdue University PSY 200 Intro to Cognitive Psychology Strong enough input crosses a threshold and the cell fires action potential K Changes the cell membrane potential A neuron The action potential then affects the membranes of other cells dendrites Purdue University 1 Prof Greg Francis 8 12 11 Output Output Myelin is like insulation for the cell s axon The output of a neuron is either excitatory or inhibitory on the other neuron it reaches it insures that the signal generated by the action potential is strong Jumps electrically rather than the normal chemical exchanges In multiple sclerosis the body s immune system attacks myelin Excitatory when our neuron sends an output the receiving neuron is more likely to produce an action potential Inhibitory when our neuron sends an output the receiving neuron is less likely to produce an action potential physical problems paralysis cognitive problems memory reasoning judgement cause unknown 300 000 people Purdue University Purdue University Networks Cognitive behavior is related to Epilepsy Disease of central nervous system Seizures groups of neurons working together causes mostly unknown Include excitation and inhibition bursts of electrical activity travelling through networks in the brain more later brain activity is out of control epileptic fits Isolated seizures also occur due to high fever lack of oxygen or head injury Purdue University Purdue University Epilepsy Epilepsy patients inhibitory cells are not working properly EEG recordings are often used to diagnose epilepsy One theory but not yet proven is that epilepsy Excitatory cells activate everything until they exhaust themselves Many different types of epilepsy with different EEG patterns Purdue University PSY 200 Intro to Cognitive Psychology Purdue University 2 Prof Greg Francis 8 12 11 Epilepsy A balanced brain The brain is a dynamic system Neurons at multiple levels drugs diet avoiding stress keeping regular schedule Treatment generally involves balance between forces inside and outside of cell membrane allows for action potentials In extreme cases surgery prevents seizures from spreading throughout the Networks Without these balances you do not think balance between excitation and inhibition brain Purdue University Purdue University Neural connections Molecular structure Axon dendrites Molecules have a particular threedimensional shape water benzene http www mind ilstu edu curriculum neurons intro neurotransmission classic 3 0 swf Purdue University Purdue University Molecular structure Molecular structure Different molecules have different shapes Neurotransmitters are just molecules At least 50 different neurotransmitters dopamine norepinephrine serotonin acetylcholine glutamate gammaaminobutyric acid GABA aspirin TNT Purdue University PSY 200 Intro to Cognitive Psychology All with different shapes Purdue University 3 Prof Greg Francis 8 12 11 Receptor Receptor Very large molecules called proteins Similar to a filter When it accepts a neurotransmitter it starts a chain reaction of events physical chemical electrical accepts some neurotransmitters locally changes the cell membrane depolarization excitation hyperpolarization inhibition rejects others Purdue University Purdue University Neurotransmitters Different neurotransmitters are associated with different properties Tourette s syndrome Inherited 200 000 in US Behavior Tics Simple eye blinking facial grimacing sniffing Complex coordinated patterns sniffing objects jumping twisting actually neurotransmitter and receptor pairs neural cognitive behavioral Too much dopamine Treated with Haldol among others blocks dopamine http www cbsnews com video watch id 1033515n Purdue University Purdue University Parkinson s Lack of dopamine Many different causes In extreme cases patients are frozen Give patients large doses of L DOPA a precursor of dopamine sometimes solves the problem lots of side effects Drugs Awakenings by Oliver Sacks Interact with neurotransmitters in lots of ways for example Replace accepted by receptor and with similar effect Production increase or decrease Reuptake knock out enzymes that remove neurotransmitter from receptor neurotransmitter has a bigger effect Blocking enter receptor but does not trigger reaction partly closes receptor protein so neurotransmitter cannot enter http you video sina com cn b 10602624 1406529597 html Purdue University PSY 200 Intro to Cognitive Psychology Purdue University 4 Prof Greg Francis 8 12 11 Prozac Some forms of depression seem to be related to limits in the use of the neurotransmitter serotonin Prozac is a selective serotonin reuptake inhibitor SSRI it keeps serotonin bound to a receptor for longer than usual thereby increasing its effect Amphetamines release of norepinephrin or dopamine LSD resembles serotonin Phenothiazine drugs block dopamine Curare blocks acetylcholine Cocaine prolongs effects of dopamine Prozac is one of the most widely prescribed drugs in the world Other drugs Morphine resembles small set of neurotransmitters called endorphin peptides modulate pain perception Tetrahydrocannabinol active ingredient in marijuana binds to some neuroreceptors but it s not clear what it does Purdue University Purdue University Conclusions Neural action potentials Shape of proteins Specific use of neurotransmitters for certain behaviors Current work on identification of role of neurotransmitters Lots of money to be made Lots more complicated than what we ve seen here Purdue University PSY 200 Intro to Cognitive Psychology Next time Neural sensitivity Neural codes Receptive fields CogLab on Blind spot due How do you recognize your grandmother