Methods and device for determining a valid intrinsic frequency
Described are methods and a device for determining a valid intrinsic alpha frequency. Described herein are methods and a device for determining the appropriate intrinsic alpha frequency (IAF) to be applied for neuro-EEG synchronization therapy using alternating magnetic fields to gently “tune” the brain and affect the mood, focus and cognition of subjects. Methods and a device described herein use an algorithm to quantitatively analyze EEG recordings to determine if recorded EEG frequencies are valid, and if necessary, requiring additional recordings and analysis until a valid EEG is found. Methods and devices described herein can be utilized to calculate the intrinsic frequency of other EEG bands, including the Theta, Beta Gamma and Delta bands.
1. A method of determining a final intrinsic alpha frequency (fIAF) of a subject in a neuro-electroencephalogram (EEG) synchronization therapy comprising:
applying an EEG discrimination routine executed by one or more processors and comprising:
a) receiving a first EEG recording obtained from an EEG sensor in a time domain;
b) segmenting the first EEG recording into a plurality of epochs, each of the plurality of epochs comprising a segment of data, wherein a total number of epochs is N;
c) filtering the segment of data of each epoch using a high-pass filter;
d) converting each epoch into a frequency domain epoch (i);
e) filtering each frequency domain epoch (i) using a smoothing filter;
f) calculating an epoch intrinsic alpha frequency (m i ) of each frequency domain epoch (i);
g) calculating a mean (M) intrinsic alpha frequency (IAF) of all intrinsic alpha frequencies (m i-N ), wherein
M
=
1
N
∑
i
=
1
N
m
i
;
h) determining a farthest frequency domain epoch (m i ) from the M,
if |m I −M|>0.5 hertz(Hz), removing the farthest frequency domain epoch (m I ), decrementing N, and returning to step g), or
if |m I −M|≤0.5 Hz, continuing to next step;
i) setting fIAF equal to M; and
j) outputting the fIAF to a therapy device that delivers a low amplitude stimulation; and
delivering, with the therapy device, low amplitude stimulation at the fIAF.
2. The method of claim 1 , wherein a length of the first EEG recording is 128 seconds.
3. The method of claim 1 , wherein the first EEG recording comprises a single-channel recording.
4. The method of claim 1 , wherein the first EEG recording comprises a multi-channel recording, wherein an IAF estimate is made for each channel in an epoch and averaged together, or wherein each channel is treated separately, generating an IAF estimate for each channel for the full EEG recording, and wherein valid IAF estimates from each channel, as determined by step h), are averaged together to generate an fIAF.
5. The method of claim 4 , wherein a channel intrinsic alpha frequency is determined for each channel in the frequency domain epoch (i), and are averaged to generate the epoch intrinsic alpha frequency (m i ).
6. The method of claim 1 , wherein a channel of the first EEG recording initially comprises 16 epochs.
7. The method of claim 1 , wherein the epoch intrinsic alpha frequency (m i ,) of each frequency domain epoch (i) is calculated from 7.0 Hz to 14.0 Hz.
8. The method of claim 1 , wherein the fIAF is from 8.0 Hz to 13.0 Hz.
9. The method of claim 1 , wherein the first EEG recording comprises a sample rate of 128 samples/sec.
10. The method of claim 1 , wherein the epoch intrinsic alpha frequency of each epoch (m i ) is determined using a Fast Fourier Transform (FFT).
11. The method of claim 1 , wherein if a standard deviation (SD) of the N epoch IAF values ≥0.75 Hz, a second EEG recording is obtained and the method of claim 1 is repeated using the second EEG recording in place of the first EEG recording.
12. The method of claim 11 , wherein if a second standard deviation (SD) of the N epoch IAF values ≥0.75 Hz, a third EEG recording is obtained and the method of claim 1 is repeated using the third EEG recording in place of the first EEG recording.
13. The method of claim 12 , wherein if a third standard deviation (SD) of the N epoch IAF values ≥0.75 Hz, a range of fIAFs of the first EEG recording, the second EEG recording, and the third EEG recording is calculated, wherein if the range is <2.0 Hz, then the mean value of the fIAFs of the first EEG recording, the second EEG recording, and the third EEG recording is determined to be a valid intrinsic alpha frequency (vIAF).
14. The method of claim 1 , wherein if the fIAF is <8.0 Hz or >13.0 Hz, a second EEG recording is obtained and the method of claim 1 is repeated using the second EEG recording in place of the first EEG recording.
15. The method of claim 14 , wherein if the fIAF calculated using the second EEG recording is <8.0 Hz or >13.0 Hz, a third EEG recording is obtained and the method of claim 1 is repeated using the third EEG recording in place of the first EEG recording.
16. The method of claim 15 , wherein if the fIAF calculated using the third EEG recording is <8.0 Hz or >13.0 Hz, a range of fIAFs of the first EEG recording, the second EEG recording, and the third EEG recording is calculated, wherein if the range is <2.0 Hz, then the mean value of the fIAFs of the first EEG recording, the second EEG recording, and the third EEG recording is determined to be a valid intrinsic alpha frequency (vIAF).
17. The method of claim 1 , wherein if the fIAF of the EEG is from 8.0 Hz to 13.0 Hz and a standard deviation (SD) of the N epoch IAF values is <0.75 Hz, the fIAF is determined to be a valid intrinsic alpha frequency (vIAF).
18. The method of claim 1 , wherein
if a standard deviation (SD) of the N epoch IAF values ≥0.75 Hz, or
if the final intrinsic alpha frequency (fIAF) is <8.0 Hz or >13.0 Hz, then a second EEG recording is obtained and the method of claim 1 is repeated using the second EEG recording in place of the first EEG recording.
19. The method of claim 18 , wherein
if a standard deviation (SD) of the N epoch IAF values calculated using the second EEG reading ≥0.75 Hz, or
if the final intrinsic alpha frequency (fIAF) calculated using the second EEG reading is <8.0 Hz or >13.0 Hz,
then a third EEG recording is obtained and the method of claim 1 is repeated using the third EEG recording in place of the first EEG recording.
20. The method of claim 19 , wherein if the fIAF calculated using the third EEG recording is <8.0 Hz or >13.0 Hz or if the standard deviation (SD) of the N epoch IAF values calculated using the third EEG reading ≥0.75 Hz, a range of fIAFs of the first EEG recording, the second EEG recording, and the third EEG recording is calculated, wherein if the range is <2.0 Hz, then the mean value of the fIAFs the first EEG recording, the second EEG recording, and the third EEG recording is determined to be a valid intrinsic alpha frequency (vIAF).