# [Eeglablist] Topographical plots for frequency band

Makoto Miyakoshi mmiyakoshi at ucsd.edu
Thu Dec 25 19:11:38 PST 2014

```Dear Rohit,

> is it possible to give a frequency band - say Alpha as average of all
frequencies from 8-12Hz ?

Unfortunately I don't think GUI supports it unless you read so in the help.

> But from what Nico said - it seems he wants to plot this information "at
a specific time point".

Band-pass filter, Hilbert transform, and use pop_spectopo() function.

> As far as I know, the frequency domain / power spectral density plot as
interval of data - say 1 second/ 10 seconds etc. I don't think it can be
for a particular time point.

Yes.

> There might be ways to make this time segment shorter, but that would
probably be detrimental to the depiction of slower waveforms.

You can't cheat the time-frequency trade off.

> On the other hand, I wonder whether Wavelet based methods will be more
appropriate for shorter time segments ?

I would use the abovementioned method using Hilbert transform since it
gives you instantaneous amplitude.

Makoto

On Fri, Dec 19, 2014 at 12:10 AM, Dr.Rohit Tyagi <
rohittyagi_2k at rediffmail.com> wrote:

> Hi Nico and Yamil,
>
> In addition to Nicolas' question and Yamil's suggestion, I also wanted to
> know a way to make topographical plots for particular frequency bands. like
> when using pop_spectopo, instead of giving particular frequency values
> (like default 6, 11 and 22) is it possible to give a frequency band - say
> Alpha as average of all frequencies from 8-12Hz ?
>
> But from what Nico said - it seems he wants to plot this information "at a
> specific time point".
> As far as I know, the frequency domain / power spectral density plot as
> made by spectopo should give this information about a specific time
> interval of data - say 1 second/ 10 seconds etc. I don't think it can be
> for a particular time point. There might be ways to make this time segment
> shorter, but that would probably be detrimental to the depiction of slower
> waveforms.
> On the other hand, I wonder whether Wavelet based methods will be more
> appropriate for shorter time segments ?
>
> Regards,
> Rohit
>
>
>
> From: Yamil Vidal Dos Santos <hvidaldossantos at gmail.com>
> Sent: Tue, 09 Dec 2014 11:24:48
> To: Nicolas LEBAR <nicolas.lebar at etu.univ-amu.fr>
> Cc: eeglablist <eeglablist at sccn.ucsd.edu>
> Subject: Re: [Eeglablist] Topographical plots for frequency band
> Hi Nicolas,
> The simplest would be to band pass filter the data to your freq range of
> interest and then you can simply use topoplot.m
> As you would be using a rather narrow filter, I recommend you to read this
> article in order to design a filter that won';t mess up your data.
> http://www.sciencedirect.com/science/article/pii/S0165027014002866
>
> I cannot think of another option, but I';m interested in the opinion of
> the community.
> Best,
> Yamil
>
>
> On Fri, Dec 5, 2014 at 5:57 PM, Nicolas LEBAR <
> nicolas.lebar at etu.univ-amu.fr> wrote:
>
>> Hi all!
>>
>> I';m looking for a way to plot a frequency-band activity (let';s say
>> average alpha 8-12Hz) for 64 electrodes into a topographical map for each
>> subjects (and eventually on a subject average) at a specific time point.
>> The next step is then to have several of these maps for several
>> chronologically different time point. Is there any option to do this, or a
>> direction I can follow to make a script?
>>
>> Thanks a lot for anything that helps.
>>
>> Nico
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--
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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