Doing the inverse of the fourier on EEG data?

1. What is FFT in EEG?
2. Why are there negative frequencies in FFT?
3. What is negative frequency in Fourier transform?
4. What is time frequency analysis in EEG?

What is FFT in EEG?

Fast Fourier Transform (FFT) Method. This method employs mathematical means or tools to EEG data analysis. Characteristics of the acquired EEG signal to be analyzed are computed by power spectral density (PSD) estimation in order to selectively represent the EEG samples signal.

Why are there negative frequencies in FFT?

The reason is that the Fourier transform is symmetric about the y-axis, because the Fourier transform is mathematically defined on the interval (-Inf,Inf). The actual Fourier transform therefore has negative frequencies.

What is negative frequency in Fourier transform?

Also, Noteworthy is the point that a negative frequency is the rotation vector in the opposite direction to the positive frequency. For example it is necessary to have a real (non-complex) signal. Then we have two vectors rotating in opposite directions.

What is time frequency analysis in EEG?

Time-frequency analyses of EEG provide additional information about neural synchrony not apparent in the ongoing EEG. They can tell us which frequencies have the most power at specific points in time and space and how their phase angles synchronize across time and space.