Please enable JavaScript.

Coggle requires JavaScript to display documents.

Task 3: EEG and ERP as dependent variables (Course Manual ((A) EEG ((1)…

- - - - Note: Skip everything from 'The N2 Family of Components' (p. 529) to 'Emotion-Related ERP
        Components' (p. 531).
- - - - What is the signal?
        
        an electric potential
      - What produces the signal?
        
        Excitatory NTs cause the opening of ion channels in the cell membrane in favour of depolarization of the membrane.
        
        When excitatory NTs bonds to ionotropic receptors, the respective membrane channels opens to Na+. The influx of kations into the cell causes a depolarization of the membrane.
        
        When excitatory NTs bond to to metabotropic receptors.... opens ion channels
        
        The inflow of kations into the cell causes the extracellular space around the dendrites to become more negative than the extracellular space around the rest of the cell. Also positive ions will flow out of the cell elsewhere, creating a extracellular positivity (albeit more distributed)
        
        now a dipole is present: two regions with differing charges separated by some distance
        
        the electrical effect of a single neuron would be too small to measure. The signal increases in size when many parallel, and alike oriented neurons fire simultaneously
        
        for this reason EEG originates from laminar tissue
        
        A combination of thalamocortical and corticocortical connections are thought to drive the synchronous activity that gives rise to EEG
        
        most of the EEG signal is produced by pyramidal cells
        
        signals can come from lower and higher layers of cortex, with signals from lower areas being weaker and having a lower SNR
        
        (Note: inhibitory PSPs can also cause an EEG signals, and the polarity of excitatory / inhibitory signals is reversed when the synapse is close to the cell body leaving the rest of the dendritic arbor to become the opposite end of the dipole)
    - - How does the signal travel?
        
        in one area of the dipole, ions with the same charge repel each other making them travel through the extracellular space. (-> volume conduction)
        
        Different tissue densities may impede or permit ion flow, based on their inherent electrical properties as well as physical arrangement (so, what is tissue here? something physical?)
        
        once the travelling ions meet a surface they can't pass through, the attraction of electrical charge will create an accumulation of the opposite ion type on the other side of the impermeable material (capacitator)
        
        Electrons do flow between gel and electrode
        (generally during the measurement process, or just initially?)
        
        amplification
        
        voltmeter
      - How is the signal recorded?
        
        an electrode at the scalp picks up the charge at the scalp. Transmission of the charge is helped by a gel with excellent transmittive properties