The electrophysiological setup Signal to noise ratio Physiological

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The electrophysiological setup

The electrophysiological setup

Signal to noise ratio Physiological signal Artifacts from physiological source Artifacts from non-physiological source

Signal to noise ratio Physiological signal Artifacts from physiological source Artifacts from non-physiological source

The signal: EEG Beta: > 13 Hz Alpha: 8 -13 Hz Theta: 4 -8

The signal: EEG Beta: > 13 Hz Alpha: 8 -13 Hz Theta: 4 -8 Hz Delta: < 4 Hz

The signal: EKG

The signal: EKG

The signal: EOG (nystagmus)

The signal: EOG (nystagmus)

The signal: EMG Human EMG recorded during squeezing a ball with increasing force

The signal: EMG Human EMG recorded during squeezing a ball with increasing force

The signal: tonic & reactive SCR

The signal: tonic & reactive SCR

The signal: spike

The signal: spike

Amplifier

Amplifier

Amplitude resolution

Amplitude resolution

Hardware filters

Hardware filters

Electrodes

Electrodes

Sampling: time resolution In order to get signals into a form computers can manipulate

Sampling: time resolution In order to get signals into a form computers can manipulate they must be changed from their analog form (continuous gradients) into a digital form (step gradients) using the technique of sampling. Sampling: A technique used to capture continuous phenomena, whereby periodic snapshots are taken. If the sampling rate is fast enough, the human sensory organs cannot discern the gaps between each snapshot when they are played back. This is the principle behind motion pictures.

Sampling and the Nyquist Theorem The Nyquist Theorem states that in order to adequately

Sampling and the Nyquist Theorem The Nyquist Theorem states that in order to adequately regenerate a signal it should be sampled at a rate that is 2 X the highest frequency. That is, the sample, or pixel, size should be 1/2 the size of the smallest desired object.

Aliasing If the sampling rate is too low the resultant signal will show a

Aliasing If the sampling rate is too low the resultant signal will show a curve that is not representative of the original. This is called aliasing. Aliasing does not occur if the sampling rate is greater than twice the frequency of a sinusoid.

Oscilloscope

Oscilloscope

Audio record of neurons

Audio record of neurons

Analysis: FFT

Analysis: FFT

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