Neural CommunicationNeural Communication

Psychology 2606Psychology 2606

IntroductionIntroduction

It was pretty clear early on that electricity It was pretty clear early on that electricity played a role of some sort in neural played a role of some sort in neural communicationcommunication

Galvani, frogs’ legs and lightningGalvani, frogs’ legs and lightningFritsch and Hitzig stimulated cortex of Fritsch and Hitzig stimulated cortex of

various animals, got twitchesvarious animals, got twitchesBartholow and Mary RaffertyBartholow and Mary RaffertyDr. Penfield, I smell burnt toastDr. Penfield, I smell burnt toast

EEGs are AOKEEGs are AOK

Caton Caton HelmholtzHelmholtzHodgkin, Huxley and giant axonsHodgkin, Huxley and giant axonsUsed mircorelectrodes and oscilloscopes Used mircorelectrodes and oscilloscopes

to measure the resting potential of a to measure the resting potential of a neuronneuron

-70 mV-70 mV

Electrical activity of the neuronElectrical activity of the neuron

Resting potentialResting potentialAbout -70 mVAbout -70 mVSelectively allowing certain ions inSelectively allowing certain ions inWith stimulation Na+ is allowed inWith stimulation Na+ is allowed in

Action potentialAction potentialChanges in one area lead to changes in Changes in one area lead to changes in

anotheranotherChemical to electrical, very coolChemical to electrical, very cool

The Sodium Potassium PumpThe Sodium Potassium Pump

Active transport takes Active transport takes energyenergy

Easier encoding?Easier encoding? Faster reaction?Faster reaction? An Action potential An Action potential

happens when happens when stimulation causes the stimulation causes the pump to sort of stop, Na pump to sort of stop, Na gets in, K goes outgets in, K goes out

Sort of reversed laterSort of reversed later

integrationintegration

Excitatory postsynaptic potentialsExcitatory postsynaptic potentials Inhibitory postsynaptic potentialsInhibitory postsynaptic potentialsTemporal summationTemporal summationSpatial summationSpatial summation

The axon HillockThe axon Hillock

Where the axon startsWhere the axon startsmany voltage sensitive channelsmany voltage sensitive channelsNeed oh say -50 mV for depolarizationNeed oh say -50 mV for depolarizationNot all graded potentials are equalNot all graded potentials are equal

Sensation and movementSensation and movement

Receptors for Receptors for LightLight SoundSound SmellSmell TasteTaste TouchTouch PainPain ColdCold heatheat

movementmovement

Neuron synapses onto end plateNeuron synapses onto end plateBig channelsBig channelsAcetylcholineAcetylcholineAch antagonists can cause paralysisAch antagonists can cause paralysisCurareCurareSarinSarin

EEGEEG

Oldest form of brain Oldest form of brain imagingimaging

CAT ScanCAT Scan

Computerized axial Computerized axial tomographytomography

PET scanPET scan

Positron emission Positron emission tomographytomography

MRIMRI

Magnetic Resonance Magnetic Resonance ImagingImaging

ERPs and single cellsERPs and single cells

Event related potentialsEvent related potentialsUsed to see what is lit up, pretty cheapUsed to see what is lit up, pretty cheapSingle cell recording uses micro Single cell recording uses micro

electrodeselectrodes