Brain imaging techniquesfMRI looks at activity of the brainLooks at blood flow- because when something is active, metabolic demand goes up so there is more blood flow to the brainNon invasive – looks at oxygenation of the blood- directly correlated with activityPeople who cannot feel pain still empathize with those that dofMRI used to look at the idea of empathy with somebody elsesome people can't feel pain but can they empathize with people who do feel pain?Turns out they can recognize what should feel painful, even though they can't feel itWhat is “neural activity”?Measuring Electrical Signals in neuronsNeural activity is electricity. Membrane potential and currents are measuredV= IRThe squid led the waySquids useful in measuring neural activity because their axon is hugeThe voltage clamp techniqueCut off a piece of axon and surrounded it with saline solution. Took wires and put it in the middle (intracellular). This is the recording electrodeMeasured membrane potentialClamps the neurons membrane potentialCould measure the voltage with a voltage clamp amplifier which reads twio voltages (coming from the axon compared with the command voltage- the voltage we want that axon to be)Current is allowed to pass through but if inside voltage equals outside set voltage there will be no current- no movement of chargeBut if change command voltage to be different from membrane potential, there will be current flowing through- depolarizationWhat is Vc was not equal to Vm?Look aboveStimulating electrical signals in neuronsCan do this same process with single cellsGenetic Methods in NeuroscienceModel systems are used because it is too difficult to do in humansKnock out animals- delete a geneKnock in animals- replace a geneTransgenic- insert a copy of exogenous geneModel OrganismsModel OrganismsThe number of genes we have is similar to these model organisms so that is why we use these organismsThe nematode Caenorhabditis elegansVery simple- only 959 cells (1/3 are neurons)Rapid life cycleEasy to map and identifyThey have behaviorThe fruitfly Drosophila melanogasterThe mouse Mus musculusThe best model system for behaviorGenetic methodsTransgenics- insert genes that will change activityTesting the effect of gene knockoutUse of transgenicsuseful in labeling certain cellsGenetic approaches to study neural circuitsLabel neurons within a circuitBrainbowNeurons are very interconnectedActivating neurons within a circuitActivate a neuron with an exogenous proteinChR2 activates cellsNpHR inhibits cellsInhibiting neurons within a circuitBISC 421 1st Edition Lecture 2 Outline of Current Lecture1. Experimental Methods in NeuroscienceCurrent Lecture Brain imaging techniques- fMRI looks at activity of the brain- Looks at blood flow- because when something is active, metabolic demand goes up so there is more blood flow to the brain- Non invasive – looks at oxygenation of the blood- directly correlated with activity People who cannot feel pain still empathize with those that do-- fMRI used to look at the idea of empathy with somebody else- some people can't feel pain but can they empathize with people who do feel pain?- Turns out they can recognize what should feel painful, even though they can't feel it What is “neural activity”?- Measuring Electrical Signals in neurons-- Neural activity is electricity. Membrane potential and currents are measured- V= IR The squid led the way- Squids useful in measuring neural activity because their axon is huge  The voltage clamp technique- Cut off a piece of axon and surrounded it with saline solution. Took wires and putit in the middle (intracellular). This is the recording electrode- Measured membrane potential Clamps the neurons membrane potential- Could measure the voltage with a voltage clamp amplifier which reads twio voltages (coming from the axon compared with the command voltage- the voltage we want that axon to be)- Current is allowed to pass through but if inside voltage equals outside set voltagethere will be no current- no movement of charge- But if change command voltage to be different from membrane potential, there will be current flowing through- depolarization What is Vc was not equal to Vm?- Look above Stimulating electrical signals in neurons- Can do this same process with single cells Genetic Methods in Neuroscience-- Model systems are used because it is too difficult to do in humans- Knock out animals- delete a gene- Knock in animals- replace a gene- Transgenic- insert a copy of exogenous gene Model Organisms- Model Organisms- The number of genes we have is similar to these model organisms so that is why we use these organisms The nematode Caenorhabditis elegans- Very simple- only 959 cells (1/3 are neurons)- Rapid life cycle- Easy to map and identify- They have behavior The fruitfly Drosophila melanogaster- The mouse Mus musculus- The best model system for behavior Genetic methods- Transgenics- insert genes that will change activity Testing the effect of gene knockout Use of transgenics- useful in labeling certain cells Genetic approaches to study neural circuits Label neurons within a circuitBrainbow- Neurons are very interconnected Activating neurons within a circuit- Activate a neuron with an exogenous protein - ChR2 activates cells- NpHR inhibits cells Inhibiting neurons within a