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28 Cards in this Set
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summarize signaling from neuron to neuron
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neuron A fires AP.
at pre-synapse AP. release neurotransmitter, activate/inhibit post-synapse post-synapse get a grades potential multiple potentials from dendrites combined give neuron B a potential if potential good enough neuron B AP too. |
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what measure in EEG
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grades potential going across dendrite.
namely in pyrimidal cells in the neocortex. have very long apical dendrites. |
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Kirchoffs law
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net flow is always zero.
so, flow at one points brings about another flow returning to the original spot. |
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how kirchoffs law in dendrite potentials en EEG?
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big dendrite signal = current of ions 'n stuff
this primairy current secundairy current, (kirchoffs law remember?) extracellular. this circles near the scalp measure actually the dendrites who run in a small sulci, who run parallel with the scalp/. they bring about a secundairy current in the right plane. EEG machine picks up this secundairy current of 100.000s of dendrites in synchrony |
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how biophysics MEGS?
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current (stroompje) produces a magnetig field. (right hand grip rule)
this magnetic field can be measures outside like EEG, also only dendrites parallel to scalp. also 100.00s cells in synchrony. better spatial than EEG, magnetic field is not smeared, it passes through tissue easily |
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what radial dipole
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when dendrite is exactly perpendicular to head so on top of a gyri, its magnetic field is running exactly parallel to the scalp, so its not measureable
however this is very rare. |
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how measure with EEG
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electroed on head.
fixed places (cap) cotact with head through gel (must have contact because must get small currents!) |
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how measure with MEG
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Super Conducting Quantum Interference Device (SQUID) in big hat with helium (cuz need very cold)
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magnetometer
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measure magnetic field (OMG!)
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gradiometer
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a magnetometer but with a extra coil in the other direction so only measure change in magnetic field
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magetic noise in MEg
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MEG very sensitive, so not magnetic disturbance
in shielded room (faradays cage) gradiometer |
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how goes typical MEG/EEG experiemtn
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trials
time points defined as moment of interest |
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reference electrode?
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behind ear or nose or soemthing, just to have a reference.
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event related potential
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electrophysiological chance that happens due certain stimuli
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why can some ERPs look weird? upside down?
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because cells depolarized cells are negative. active = negative.
mostly so the graphs are with the negative ones up on the y axis |
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what is spectral analysis
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y axis the power
x axis the frequencys so you can see which freqs on certain electrodes respond to what stuff. |
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time freq analysis.
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like spectral analysis, but in 3 dimensions, qwith tmie added.
color = change in freq y axis = freq x = time so you can see at time point x, frequency y increases a hell lot! or not. |
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how get neural osccilations
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signal is like a mess with al kinds of freqs. so fourier transformation to get like all the frequencies
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what typen of neural oscilation
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classics:
delta - 2-4 Hz - sleep theta - 4 - 8 Hz - attention, error related alpha - 8 - 14 Hz - eyes closes, functional inhibition Beta - 15-30 Hz - alert, somatomotor Gamma - 30-90 Hz - active processing apsilon (high gamma) - > 90 Hz, active. [note, oversimplyfied] |
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topoplof
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aveerage a nice picture from freq x time and place it on the designated electrode place on head and make a nice picture..
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source analysis
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anatomical information get.
estimate places in head fom the data. spot A en B. electrode near A has less B, alectrode between sees both a bit, electrode near B had less A. so make some sort of spatial idea of this. make head model/volume conduction model how would neural current be picked up at certain part of brain? |
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memory --> hippocampus communication with neocortex
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nice
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road through the hippocampus?
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one way. from dentate gyrus (DT) to CA3, CA2, and CA1.
coming from and going too neocortex. |
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active things in working memory, what osccilation?
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theta.
goes in phase with gamma, so the few thetas are repeated each gamma. memory of a thing in working memory has certain pattern of neurons firing. |
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hippocampus neocortex talk in acitve?
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theta and gamma.
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what mean spindles in hippocampus?
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learning
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synaptic downscaling?
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synaps bigger when use (LTP), but in sleep all go down.
so eventuall synapse not used is gone. sharpening memory |
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consolidation happens how?
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replay, and replay is lot of osccilations
namely slow osccilatino in cortex spingles in thalamus sharp wave ripples in hippocampus |
