Time-frequency analysis problem

Discussions
1

Hi Francois,
I have a problem when doing TF (Morlet Wavelet) and I am not sure if I am doing something wrong or it is about the software.

When I compute TF (over a source), z-score it, I look at results and can see a sharp and big negativity in the last few ms, for most of my codnditions and subjects. My epoch is 3s long. I did another computation with 2.5s, and was able to see it again. When I extracted time from 3s and cut last 500ms, I did not see it. So I am a little confused about what is happening.

Thank you in advance.
Svjetlana

2

Hi Svjetlana,

In the Display tab, click on “Hide edge effects” to mask everything that is not correctly estimated.
Everything that is hidden should not be interpreted and can actually be quite random.

Please post a screen a capture of your TF maps (power and Z-score) if you want us to check that it looks normal.

Cheers,
Francois

3

_TF_p4Sib_Direction_Scouts_Avg_Power_14_1_30Hz__extract_fig.jpg496×512 31.3 KB

_TF_p4Sib_Direction_Scouts_Avg_Power_14_1_30Hz__zscored.jpg496×512 27.5 KB

Hi Francois,
I have attached files so you can check if it is ok.
I do click "hide edges", but when I want to "export to Matlab", values are saved similar to those without "hide edges" selected.

Thank you again.
Svjetlana

4

Hi Svjetlana,

You are talking about those thin blue lines at the beginning and the end?
Yes, you should ignore those.

The option “hide edge effects” is a visualization option, it doesn’t change anything in the content of the files. The menu “Export to Matlab” reads the content of the file saved in the database, regardless of any visualization filter.

Cheers,
Francois

5

Hi Francois,

I’m going through tutorial 24 for the first time and doing time-frequency analyses on the data.
Strangely, the option, “hide edge effects,” does not change the display at all. Other display functions seem to work fine.
Before, you mentioned in another thread that my graphics drivers may be to blame for another display issue.
I wonder could that be the case here too?

Thank you,

Jared

6

Francois,

I have answered my own question. I switched the open GL rendering to “slow” and now “hide edge effects” are displayed correctly. Also, my 3D sensor cap display is still functioning fine as well with these settings. Sorry for the trouble. But thank you for all your help.

Best,

Jared