Licensed under a Creative Commons Attribution 4.0 International License. It is normal as the dominant rhythm in infants up to one year and in stages 3 and 4 of sleep. At point B, a mix of excitatory and inhibitory postsynaptic potentials result in a different result for the membrane potential. EEG > introduction : Recording the electrical activity of the brain from the scalp: an introduction to the acquisition of biological signals : The electroencephalogram (EEG) is a recording of the electrical activity of the brain from the scalp. At point A, several different excitatory postsynaptic potentials (EPSPs) add up to a large depolarization. It takes a minimum area of 6 cm² of cortical activation to produce recordable epileptic discharges on standard scalp EEG.įigure 1: Postsynaptic Potential Summation The result of the summation of postsynaptic potentials is the overall change in the membrane potential.Some normal variants, such as mu or lambda, can be made to appear and disappear through the manipulation of the mental state of a conscious individual and as such, can provide. The region of the brain with the lowest threshold to electrical stimulation is the hippocampus. The term 'normal variants' refers to EEG waveforms that are considered to be normal findings, but whose presence is not required for an EEG to be normal.It measures a summation of postsynaptic potentials. The EEG does not measure single action potentials.Pyramidal neurons contribute to the plurality of the signal (Figure 1).
The electrical fields that generate EEG signals are the result of inhibitory and excitatory postsynaptic potentials (IPSPs and EPSPs) on the apical dendrites of cortical neurons.